Merge pull request 'fix(page-tree/dnd): drop-раскрытие + guard от потери детей (#523)' (#532) from fix/523-tree-dnd into fix/525-insert-unloaded

Reviewed-on: #532

.env.example

@@ -124,6 +124,40 @@ MCP_DOCMOST_PASSWORD=
 # MCP_TOKEN=
 # MCP_SESSION_IDLE_MS=1800000
 #
+# --- MCP collaboration write path: concurrency + rights-staleness (#449) ------
+# MCP content writes (update_page, insert/replace nodes, comments-in-body, etc.)
+# go over the collaboration websocket and are serialized PER PAGE by an
+# in-process mutex (a module-level Map, one promise-chain per page UUID). This
+# guarantees no two MCP writes on the SAME page overlap and clobber each other.
+#
+# DEPLOY REQUIREMENT — SINGLE INSTANCE or STICKY SESSIONS. The mutex is
+# process-local. Behind a multi-replica load balancer WITHOUT sticky sessions,
+# two replicas can each "hold" the lock for the same page at the same time and
+# serialization is silently lost (concurrent full-document writes race on the
+# live Yjs fragment). Run the MCP/app as a SINGLE instance, OR pin a page's
+# traffic to one replica (sticky sessions / consistent hashing on page id). The
+# same constraint applies to the RAM-only stash_page blob store above. There is
+# deliberately no cross-process (e.g. Postgres advisory) lock yet — this is a
+# CONSCIOUS documented constraint, not an oversight (#449).
+#
+# To reduce connect-storms the write path caches ONE live collab session per
+# (wsUrl, page, token). Tunables (all optional; defaults are safe):
+# MCP_COLLAB_SESSION_IDLE_MS=60000     # idle TTL, reset per op; 0 disables cache
+# MCP_COLLAB_SESSION_MAX_ENTRIES=32    # LRU cap on cached sessions
+# MCP_COLLAB_TOKEN_TTL_MS=300000       # per-client collab-token cache (5 min)
+#
+# RIGHTS-STALENESS TRADE-OFF. A cached collab session writes under the token
+# captured at CONNECT time, and the collab-token cache reuses a token for its TTL.
+# So if a user's access to a page is REVOKED, MCP writes on an already-open
+# session may keep succeeding until the session ages out. MCP_COLLAB_SESSION_MAX_AGE_MS
+# is the HARD lifetime (checked at each acquire) that BOUNDS this window: after it,
+# the session is torn down and the next write re-auths with a fresh token, picking
+# up the revocation. Default 10 min. LOWER it to shorten the revocation lag at the
+# cost of more reconnects; RAISE it to reduce reconnects at the cost of a longer
+# stale-rights window. There is intentionally no push-based cache invalidation on
+# a rights change — this bounded window is the accepted trade-off (#449).
+# MCP_COLLAB_SESSION_MAX_AGE_MS=600000
+#
 # BLOB SANDBOX (stash_page). An in-RAM, process-local store that hands large page
 # content + images to an external consumer WITHOUT bloating the model context or
 # requiring Docmost auth. The stash_page tool serializes a page, mirrors its
@@ -191,11 +225,26 @@ MCP_DOCMOST_PASSWORD=
 
 # Silence timeout (ms) for EXTERNAL-MCP transport ONLY (not the chat provider).
 # Tighter than AI_STREAM_TIMEOUT_MS so a byte-silent/hung MCP server is broken in
-# ~1 min instead of 15. Note it also cuts a legitimately long but byte-silent
+# ~1 min instead of 15. It cuts a legitimately long but byte-silent single tool
-# single tool call (a slow crawl that emits nothing until done) and an SSE
+# call (a slow crawl that emits nothing until done) on the HTTP (streamable)
-# transport idling >1 min BETWEEN tool calls. Default 60000 (1 min).
+# transport, which opens a fresh request per call. The SSE transport — one
+# long-lived body across many calls — is NO LONGER governed by this timeout
+# (as of #489): its idle-BETWEEN-calls window has its own, raised bodyTimeout,
+# AI_MCP_SSE_BODY_TIMEOUT_MS below. Default 60000 (1 min).
 # AI_MCP_STREAM_TIMEOUT_MS=60000
 
+# bodyTimeout (ms) for the EXTERNAL-MCP SSE transport ONLY (#489). The SSE
+# transport holds ONE response body open across many tool calls, so undici's
+# bodyTimeout (time between body bytes) counts the LEGITIMATE silence BETWEEN the
+# model's tool calls, not just a hung single call. At the tight 1-min silence
+# timeout above, a normal >1-min gap between calls would break the SSE socket and
+# the cache would serve a dead client until TTL — so the SSE transport gets its
+# OWN, RAISED bodyTimeout. A single stuck call is still bounded by the per-call
+# cap (AI_MCP_CALL_TIMEOUT_MS), and a socket that does break is healed by the
+# in-run transport-error retry. The HTTP (streamable) transport keeps the tight
+# timeout. Default 600000 (10 min).
+# AI_MCP_SSE_BODY_TIMEOUT_MS=600000
+
 # Total wall-clock cap (ms) for ONE external MCP tool call (app-level, not
 # transport). Aborts a tool that keeps the socket warm (SSE heartbeats / trickle)
 # but never returns a result — which the silence timeout above never breaks.
@@ -254,6 +303,29 @@ MCP_DOCMOST_PASSWORD=
 # registry is process-local).
 # AI_CHAT_RESUMABLE_STREAM=false
 
+# --- Run lifecycle tunables (#487) ---
+# These govern the universal run machinery (every turn is now a first-class run,
+# both modes) and rarely need changing.
+#
+# How long a server-side SUPERSEDE ("interrupt and send now") waits for the target
+# run to settle after issuing Stop before it degrades to a 409 SUPERSEDE_TIMEOUT
+# (nothing sent, the composer keeps the user's text). 10s is generous under a
+# healthy DB; do NOT raise it to paper over a slow DB — a SUPERSEDE_TIMEOUT is the
+# honest signal. Default 10000 (10s).
+# AI_CHAT_SUPERSEDE_TIMEOUT_MS=10000
+#
+# How often the periodic bidirectional reconcile job runs (heals runs/messages
+# left dangling by a crash or a lost terminal write). Default 120000 (2 min).
+# AI_CHAT_RECONCILE_INTERVAL_MS=120000
+#
+# Wall-clock cap for a SINGLE in-app tool call (a long paginated read, or a content
+# write whose collab commit hangs) — the per-call half of the composite abort
+# signal every in-app tool is wrapped with (the other half is the turn's Stop).
+# The reconcile staleness floor is derived as max(2 x this cap, 15min), so a very
+# high value delays stale-run recovery (the server boot-warns above 30min). Default
+# 120000 (2 min).
+# AI_CHAT_INAPP_TOOL_CALL_CAP_MS=120000
+
 # --- Anonymous public-share AI assistant ---
 # Opt-in per workspace (AI settings -> "public share assistant"; off by default).
 # When enabled, anonymous visitors of a published share can ask an AI about that
@@ -301,6 +373,20 @@ MCP_DOCMOST_PASSWORD=
 #    VictoriaMetrics/Prometheus reaching it as <host>:<port>/metrics.
 # METRICS_PORT=9464
 #
+#    METRICS_BIND — interface the /metrics listener binds to. DEFAULT 127.0.0.1
+#    (loopback only), so the unauthenticated endpoint is NOT exposed on all
+#    interfaces. If the scraper runs in a SEPARATE container and reaches this as
+#    docmost:9464, set METRICS_BIND=0.0.0.0 — but then also set METRICS_TOKEN
+#    and/or keep the port on a private network, since /metrics is otherwise open.
+# METRICS_BIND=127.0.0.1
+#
+#    METRICS_TOKEN — optional Bearer token guarding /metrics. When set, every
+#    scrape MUST send `Authorization: Bearer <token>` (others get 401). Configure
+#    the scraper with the same bearer token (e.g. VictoriaMetrics/vmagent
+#    `bearer_token`, Prometheus `authorization.credentials`). Leave unset only
+#    when the endpoint is bound to loopback or an otherwise-trusted network.
+# METRICS_TOKEN=
+#
 # 2) CLIENT_TELEMETRY_ENABLED — the public client perf-telemetry sink.
 #    OFF by default. When true, the unauthenticated POST /api/telemetry/vitals
 #    endpoint is registered and browsers collect + send web-vitals / editor

.github/workflows/develop.yml

@@ -62,6 +62,38 @@ jobs:
     needs: [test, e2e-server, e2e-mcp, build]
     runs-on: ubuntu-latest
     timeout-minutes: 30
+    # Image boot-smoke (issue #476): every other job tests code from the working
+    # tree, but the :develop IMAGE that watchtower pulls was never actually
+    # started anywhere (incident classes #353/#452/#361-boot: startup-migrator
+    # crash-loop, runtime module missing from the image, wrong static-asset
+    # headers). The services below back a smoke boot of the exact image right
+    # before it is pushed; a smoke failure blocks the push.
+    services:
+      postgres:
+        # via mirror.gcr.io (Docker Hub pull-through cache; avoids Hub anonymous
+        # pull rate-limit that randomly fails on shared GitHub runner IPs).
+        image: mirror.gcr.io/pgvector/pgvector:pg18
+        env:
+          POSTGRES_DB: docmost
+          POSTGRES_USER: docmost
+          POSTGRES_PASSWORD: docmost
+        ports:
+          - 5432:5432
+        options: >-
+          --health-cmd "pg_isready -U docmost"
+          --health-interval 5s
+          --health-timeout 5s
+          --health-retries 20
+      redis:
+        # via mirror.gcr.io (see postgres note above).
+        image: mirror.gcr.io/library/redis:7
+        ports:
+          - 6379:6379
+        options: >-
+          --health-cmd "redis-cli ping"
+          --health-interval 5s
+          --health-timeout 5s
+          --health-retries 20
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -82,6 +114,37 @@ jobs:
         id: version
         run: echo "value=$(git describe --tags --always)" >> "$GITHUB_OUTPUT"
 
+      # Load the image into the local docker daemon so it can be booted (the
+      # push step below exports straight to the registry and leaves nothing
+      # runnable locally). CONVENTION: build-args here must stay TEXTUALLY
+      # IDENTICAL to the push step's build-args — same cache scope + same args
+      # means the layers are reused and the image we smoke IS the image we push.
+      - name: Build image for smoke (load, no push)
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          platforms: linux/amd64
+          build-args: |
+            APP_VERSION=${{ steps.version.outputs.value }}
+            AI_AGENT_ROLES_CATALOG_URL=https://raw.githubusercontent.com/vvzvlad/gitmost/develop/agent-roles-catalog
+          load: true
+          push: false
+          tags: gitmost:smoke
+          cache-from: type=gha,scope=develop-amd64
+
+      # Boot-smoke the exact image against the job services (see the comment on
+      # `services:` above): health (startup migrator), auth/setup, client dist
+      # served, immutable + brotli asset headers. Fails the job (and therefore
+      # the push) on any miss.
+      - name: Smoke the built image
+        run: bash scripts/ci/image-smoke.sh gitmost:smoke
+
+      # The smoke script leaves the container running on failure precisely so
+      # the boot error (migration mismatch, stack trace) is diagnosable here.
+      - name: Dump smoke container log on failure
+        if: failure()
+        run: docker logs gitmost-smoke 2>&1 | tail -200 || true
+
       - name: Build and push develop image
         uses: docker/build-push-action@v6
         with:
@@ -157,6 +220,12 @@ jobs:
       - name: Build prosemirror-markdown
         run: pnpm --filter @docmost/prosemirror-markdown build
 
+      # docmost-client.loader.ts type-imports from @docmost/mcp (issue #446); its
+      # build/ is gitignored and `test:e2e` type-checks, so build it here or tsc
+      # fails with TS2307 (mirrors the e2e-mcp / mcp-server-parity jobs).
+      - name: Build mcp
+        run: pnpm --filter @docmost/mcp build
+
       - name: Run migrations
         run: pnpm --filter ./apps/server migration:latest
 

.github/workflows/nightly-property.yml

@@ -124,9 +124,17 @@ jobs:
           exit "$FAILED"
 
       # A GENUINE counterexample: fast-check printed a shrunk minimal case and its
-      # reproducing seed into property-output.txt. File a dedup-guarded issue whose
+      # reproducing seed into property-output.txt. File a dedup-guarded issue.
-      # title prefix is UNIQUE to counterexamples, so an infra failure (handled by
+      #
-      # the next step under a different title) can never poison this dedup.
+      # Dedup is keyed on a HASH of the SHRUNK COUNTEREXAMPLE (the minimal failing
+      # input), NOT on the issue title prefix. Keying on the prefix would let a
+      # single open issue swallow every OTHER counterexample (a different bug B whose
+      # title shares the prefix would be treated as a duplicate and stay silent until
+      # the first issue is closed). Hashing the shrunk example instead means two
+      # DIFFERENT counterexamples get two DIFFERENT issues, while a re-find of the
+      # SAME counterexample still dedupes onto the existing one. The infra-failure
+      # step (below) still keys on its own distinct title, so it can never poison
+      # this dedup either.
       - name: File counterexample issue
         # always() is REQUIRED: the fuzz step exits nonzero on a failing shard,
         # so a bare `if:` (implicitly success() && ...) would skip this step
@@ -146,25 +154,48 @@ jobs:
             echo "No fast-check counterexample signature — infra failure, handled by the next step."
             exit 0
           fi
-          TITLE="${TITLE_PREFIX} (seed=${FAIL_SEED})"
+          # Extract the SHRUNK counterexample block: the "Counterexample:" line(s)
+          # up to (but excluding) the "Shrunk N time(s)" / "Got error" line. This is
+          # the minimal failing INPUT and is STABLE across the different seeds/paths
+          # that reach the same bug — unlike the seed, path, or shrink count (which
+          # precede/follow this block and vary run-to-run) and unlike the whole
+          # output (which embeds those varying parts). Hashing THIS is what makes the
+          # dedup identity the bug itself rather than an incidental run detail.
+          CE_TEXT=$(awk '/Counterexample:/{c=1} /Shrunk [0-9]+ time|Got error/{c=0} c{print}' property-output.txt)
+          if [ -z "$CE_TEXT" ]; then
+            # No parseable shrunk block (unexpected — the signature check above
+            # already confirmed fast-check output). Fall back to the reproducing
+            # seed so we still emit a stable identity instead of silently deduping.
+            CE_TEXT="seed:${FAIL_SEED}"
+          fi
+          # Stable short id: first 12 hex chars of sha256 over the counterexample.
+          CE_HASH=$(printf '%s' "$CE_TEXT" | sha256sum | cut -c1-12)
+          # Machine-readable marker embedded in the issue body; the open-issue search
+          # below matches on it (and on the hash in the title) so identity travels
+          # with the issue regardless of any human title edits.
+          CE_MARKER="<!-- counterexample-hash: ${CE_HASH} -->"
+          export CE_HASH CE_MARKER
+          TITLE="${TITLE_PREFIX} [${CE_HASH}] (seed=${FAIL_SEED})"
 
-          # Best-effort dedup: skip if an open issue with the counterexample title
+          # Dedup on the counterexample hash: skip only if an OPEN issue already
-          # prefix already exists. A failure of this check must NOT block creation.
+          # carries this exact hash (in its title or its body marker). A different
+          # counterexample has a different hash and is NOT deduped. A failure of this
+          # check must NOT block creation.
           EXISTING=""
           if EXISTING=$(curl -sS \
               -H "Authorization: token ${GITHUB_TOKEN}" \
               "${GITHUB_API_URL}/repos/${GITHUB_REPOSITORY}/issues?state=open&limit=100"); then
             if printf '%s' "$EXISTING" \
-                | node -e 'let s="";process.stdin.on("data",d=>s+=d).on("end",()=>{let a;try{a=JSON.parse(s)}catch{process.exit(1)}if(!Array.isArray(a))process.exit(1);const p=process.env.TITLE_PREFIX;process.exit(a.some(i=>typeof i.title==="string"&&i.title.startsWith(p))?0:1)})'; then
+                | node -e 'let s="";process.stdin.on("data",d=>s+=d).on("end",()=>{let a;try{a=JSON.parse(s)}catch{process.exit(1)}if(!Array.isArray(a))process.exit(1);const h=process.env.CE_HASH,m=process.env.CE_MARKER;process.exit(a.some(i=>(typeof i.title==="string"&&i.title.includes(h))||(typeof i.body==="string"&&i.body.includes(m)))?0:1)})'; then
-              echo "An open '${TITLE_PREFIX}' issue already exists — skipping creation."
+              echo "An open issue for counterexample ${CE_HASH} already exists — skipping creation."
               exit 0
             fi
           fi
 
           # Build the JSON body with the test output SAFELY escaped (never hand-
           # interpolate the counterexample into JSON).
-          BODY_TEXT=$(printf 'A nightly property fuzz SHARD failed with a fast-check counterexample.\n\n- failing shard seed: `%s`\n- NUM_RUNS (per shard): `%s`\n- run: %s\n\nReproduce locally:\n\n```\nPROPERTY_SEED=%s PROPERTY_NUM_RUNS=%s pnpm --filter @docmost/prosemirror-markdown exec vitest run test/generative/\n```\n\nfast-check shrinks the failure to a minimal counterexample. Commit it as a permanent fixture under `packages/prosemirror-markdown/test/fixtures/counterexamples/` + a case in `counterexamples.test.ts`, then FIX the converter (do not weaken a property). See `packages/prosemirror-markdown/README.md`.\n\nTail of the test output (contains the shrunk counterexample):\n\n```\n%s\n```\n' \
+          BODY_TEXT=$(printf 'A nightly property fuzz SHARD failed with a fast-check counterexample.\n\n- counterexample hash: `%s`\n- failing shard seed: `%s`\n- NUM_RUNS (per shard): `%s`\n- run: %s\n\nReproduce locally:\n\n```\nPROPERTY_SEED=%s PROPERTY_NUM_RUNS=%s pnpm --filter @docmost/prosemirror-markdown exec vitest run test/generative/\n```\n\nfast-check shrinks the failure to a minimal counterexample. Commit it as a permanent fixture under `packages/prosemirror-markdown/test/fixtures/counterexamples/` + a case in `counterexamples.test.ts`, then FIX the converter (do not weaken a property). See `packages/prosemirror-markdown/README.md`.\n\nTail of the test output (contains the shrunk counterexample):\n\n```\n%s\n```\n\n%s\n' \
-            "$FAIL_SEED" "$NUM_RUNS" "$RUN_URL" "$FAIL_SEED" "$NUM_RUNS" "$(tail -n 120 property-output.txt)")
+            "$CE_HASH" "$FAIL_SEED" "$NUM_RUNS" "$RUN_URL" "$FAIL_SEED" "$NUM_RUNS" "$(tail -n 120 property-output.txt)" "$CE_MARKER")
 
           jq -n --arg title "$TITLE" --arg body "$BODY_TEXT" \
             '{title: $title, body: $body}' > payload.json

.github/workflows/test.yml

@@ -1,5 +1,13 @@
 name: Test
 
+# NO `paths:` filter on purpose (issue #447). The tool-spec REGISTRY is split
+# across two packages that MUST stay in sync: the specs live in `packages/mcp`
+# but the parity/tier guard tests that read them live in the `apps/server` jest
+# suite. A PR touching only `packages/mcp/**` must therefore still run the SERVER
+# suite (and vice-versa), or an in-app wiring break slips through green and only
+# surfaces on develop after merge. The `test` job below runs BOTH suites via
+# `pnpm -r test` on every PR; the dedicated `mcp-server-parity` job makes that
+# cross-package gate explicit and fast. Do not add a `paths:` filter here.
 on:
   pull_request:
   workflow_call:
@@ -17,37 +25,65 @@ jobs:
   # filename sorts BEFORE migrations already applied on the target branch (and
   # thus in prod). The Kysely startup migrator rejects that as "corrupted
   # migrations" and crash-loops the app on boot (incident #361). This gate fails
-  # the PR so the migration is renamed to a current timestamp before merge. Only
+  # the PR so the migration is renamed to a current timestamp before merge.
-  # runs for pull_request events (needs a base branch to diff against).
+  # Runs for pull_request (diff against the base branch) AND for push (#476
+  # retrospective: a DIRECT push to develop used to bypass this PR-only gate
+  # entirely — now the push is diffed against its `before` SHA; workflow_call
+  # from develop.yml inherits the caller's push event). workflow_dispatch has
+  # nothing to diff against and still skips the job.
   migration-order:
-    if: github.event_name == 'pull_request'
+    if: github.event_name == 'pull_request' || github.event_name == 'push'
     runs-on: ubuntu-latest
     timeout-minutes: 5
     steps:
-      - name: Checkout (full history for the base-branch diff)
+      - name: Checkout (full history for the base diff)
         uses: actions/checkout@v4
         with:
           fetch-depth: 0
-      - name: Added migrations must sort after the newest on the base branch
+      - name: Added migrations must sort after the newest on the base
         env:
           TARGET_BRANCH: ${{ github.base_ref }}
+          BEFORE_SHA: ${{ github.event.before }}
         run: |
           set -euo pipefail
           MIG_DIR="apps/server/src/database/migrations"
-          # checkout above already did fetch-depth:0 (full history). Fetch the base
+          if [ "${GITHUB_EVENT_NAME}" = "pull_request" ]; then
-          # WITHOUT --depth (a shallow graft would truncate the base history and
+            # checkout above already did fetch-depth:0 (full history). Fetch the base
-          # break the merge-base when the base has moved ahead of the PR merge —
+            # WITHOUT --depth (a shallow graft would truncate the base history and
-          # exactly the long-branch-vs-moving-base case this gate guards, #361).
+            # break the merge-base when the base has moved ahead of the PR merge —
-          git fetch --no-tags origin "$TARGET_BRANCH"
+            # exactly the long-branch-vs-moving-base case this gate guards, #361).
-          newest_on_target=$(git ls-tree -r --name-only "origin/${TARGET_BRANCH}" "$MIG_DIR" | sort | tail -1)
+            git fetch --no-tags origin "$TARGET_BRANCH"
+            BASE="origin/${TARGET_BRANCH}"
+          else
+            # push event: compare against the pre-push tip of the branch.
+            if [ "$BEFORE_SHA" = "0000000000000000000000000000000000000000" ]; then
+              echo "::notice::branch creation push — nothing to compare"
+              exit 0
+            fi
+            if ! git cat-file -e "${BEFORE_SHA}^{commit}" 2>/dev/null; then
+              # The before-SHA is not in the clone (a force-push rewrote history).
+              # One recovery attempt — refresh every remote head (cheap: the
+              # checkout is already fetch-depth:0); a fetch failure aborts via
+              # `set -e`, which is fail-closed too.
+              git fetch --no-tags origin '+refs/heads/*:refs/remotes/origin/*'
+            fi
+            if ! git cat-file -e "${BEFORE_SHA}^{commit}" 2>/dev/null; then
+              # FAIL-CLOSED: without the before-SHA there is no base to prove the
+              # ordering against, and a gate whose job is to BLOCK must not guess.
+              echo "::error::force-push detected — verify migration order manually, then re-run via workflow_dispatch"
+              exit 1
+            fi
+            BASE="$BEFORE_SHA"
+          fi
+          newest_on_target=$(git ls-tree -r --name-only "$BASE" "$MIG_DIR" | sort | tail -1)
           # NO `|| true`: a diff failure (e.g. an unresolved merge-base) must fail
           # the job CLOSED — a gate whose job is to BLOCK must never pass on error.
           # `set -e` above already aborts on a non-zero diff exit.
-          added=$(git diff --diff-filter=A --name-only "origin/${TARGET_BRANCH}...HEAD" -- "$MIG_DIR")
+          added=$(git diff --diff-filter=A --name-only "${BASE}...HEAD" -- "$MIG_DIR")
           bad=0
           for f in $added; do
             if [[ "$f" < "$newest_on_target" || "$f" == "$newest_on_target" ]]; then
-              echo "::error::Migration $f sorts at or before the newest on ${TARGET_BRANCH} ($newest_on_target) — rename it with a CURRENT timestamp before merge (do not change its contents). See incident #361."
+              echo "::error::Migration $f sorts at or before the newest on the base ($newest_on_target) — rename it with a CURRENT timestamp before merge (do not change its contents). See incident #361."
               bad=1
             fi
           done
@@ -132,3 +168,53 @@ jobs:
       # isolated `docmost_test` DB and migrates it to latest.
       - name: Run server integration tests
         run: pnpm --filter server test:int
+
+  # Cross-package tool-spec parity gate (issue #447). The tool-spec registry lives
+  # in `packages/mcp` but its parity/tier guard tests live in the `apps/server`
+  # jest suite, so a PR touching ONLY one of the two packages must still run BOTH
+  # sides — otherwise an in-app wiring break (e.g. PR #434 drawio) passes the mcp
+  # suite green and only surfaces on develop after merge. The `test` job already
+  # runs everything via `pnpm -r test`; this job is a fast, explicitly-named guard
+  # that runs the mcp `node --test` suite AND the server tool-guard jest specs
+  # together, so the coupling is visible and can never be accidentally split by a
+  # path filter. No Postgres/Redis needed: these specs mock the DB/loader.
+  mcp-server-parity:
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up pnpm
+        uses: pnpm/action-setup@v4
+
+      - name: Set up Node
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: pnpm
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+
+      # Shared deps first (build/ dirs are gitignored; see test.yml build order).
+      - name: Build editor-ext
+        run: pnpm --filter @docmost/editor-ext build
+
+      - name: Build prosemirror-markdown
+        run: pnpm --filter @docmost/prosemirror-markdown build
+
+      # Build the mcp package so build/ carries a FRESH REGISTRY_STAMP (#447): the
+      # build runs gen-registry-stamp.mjs before tsc, so a build/ vs src/ skew
+      # cannot slip into the tests that exercise the loader's stale-check.
+      - name: Build mcp (regenerates REGISTRY_STAMP)
+        run: pnpm --filter @docmost/mcp build
+
+      # mcp side: the standalone MCP server's own tool-spec / instructions guards.
+      - name: Run mcp tool-spec suite
+        run: pnpm --filter @docmost/mcp test
+
+      # server side: the parity + tier guards that read packages/mcp/src/tool-specs
+      # and assert the in-app AI-chat wiring matches it.
+      - name: Run server tool-spec guard specs
+        run: pnpm --filter server exec jest shared-tool-specs.contract tool-tiers ai-chat-tools.service --runInBand

.gitignore

@@ -2,6 +2,11 @@
 .env.dev
 .env.prod
 data
+# Exception: the committed draw.io shape catalog (issue #424) lives in a `data/`
+# dir, but the bare `data` ignore above is meant for runtime state, not this
+# bundled build asset. Re-include the directory and its contents.
+!packages/mcp/data/
+!packages/mcp/data/**
 # compiled output
 /dist
 node_modules
@@ -19,6 +24,15 @@ packages/prosemirror-markdown/build/
 # markdown convention; the package is private and rebuilt at deploy.
 packages/mcp/build/
 
+# mcp REGISTRY_STAMP codegen output (issue #447). Regenerated into src/ by
+# scripts/gen-registry-stamp.mjs on every `build`/`pretest` (before tsc), so it
+# is a build artifact like build/ — never committed, always fresh.
+packages/mcp/src/registry-stamp.generated.ts
+
+# token-estimate compiled output (#490; built in CI/Docker via `pnpm build` /
+# the server `pretest`, never committed, so src/ and prod can never diverge).
+packages/token-estimate/dist/
+
 # Logs
 logs
 *.log

AGENTS.md

@@ -5,6 +5,139 @@ repository. It has two layers: **how to run a task end-to-end** (the
 sections below), and **how the codebase is built** (the technical sections
 further down, formerly in `CLAUDE.md`).
 
+## ARCHITECTURAL INVARIANTS — NON-NEGOTIABLE
+
+THE TEN RULES BELOW ARE HARD CONSTRAINTS. Each one was paid for with a real
+production incident or a multi-PR bug chain in THIS repository (cited inline).
+They override convenience, deadlines and "it's just a small feature". A PR that
+violates any of them MUST be rejected in review regardless of how good the rest
+of it is. If a task genuinely seems to require breaking one — STOP and raise it
+with the owner; do not code around it.
+
+### 1. EVERY BUFFER, CACHE, HISTORY AND PAYLOAD HAS AN EXPLICIT SIZE BUDGET
+
+Nothing accumulates unboundedly. A row/item cap is NOT a byte cap. Anything
+replayed to a model, buffered in memory, persisted per step, or refetched by a
+poll must state its budget in bytes/tokens and enforce it. Rewriting a growing
+structure in full on every increment is FORBIDDEN — append or diff instead;
+O(n²) write/serialize patterns do not pass review.
+(Paid for by: full-row rewrite on every agent step — hundreds of MB of Postgres
+writes per 50-step run, with every tool output serialized twice; unbounded
+history replay killing long chats on the provider context window; 32 MB replay
+buffers per active run.)
+
+### 2. EVERYTHING LONG-RUNNING TERMINATES BY CONSTRUCTION
+
+Every run / row / session / lease / subscriber / queue entry must define AT
+DESIGN TIME: its owner; every terminal state; who writes the terminal state on
+EVERY path (success, error, abort, disconnect in each phase, process restart);
+retries for the terminal write; and a periodic sweeper that does not depend on
+a reboot. A best-effort terminal write with no retry and no sweep is FORBIDDEN.
+(Paid for by: assistant rows stuck 'streaming' forever; runs stuck 'running'
+409-locking their chat until a restart — the #183/#184 follow-up chain.)
+
+### 3. EVERY AWAIT IS CANCELLABLE AND DEADLINED; NEVER BLOCK THE EVENT LOOP
+
+Every async step inside a request or agent turn honors the turn's AbortSignal
+AND a wall-clock deadline — including in-app tools, lock queues and pagination
+loops, not just external calls. Synchronous CPU work beyond ~50 ms goes to a
+worker_thread. Promise.race DOES NOT cancel synchronous work — using it as a
+"timeout" for sync computation is forbidden (the timer only fires after the
+event loop is free again, i.e. after the damage is done).
+(Paid for by: in-app tools ignoring abortSignal and writing pages AFTER Stop;
+the synchronous ELK layout freezing every SSE stream in the process; the
+step-0 MCP handshake hang — #397.)
+
+### 4. ONE SOURCE OF TRUTH; EVERYTHING ELSE IS A REBUILDABLE CACHE
+
+Postgres is the authoritative state. Every in-memory structure (registries,
+caches, client stores) must be reconstructible from the DB and treated as
+lossy. The client renders SERVER-DECLARED state — "a run is active" is a server
+fact delivered as data, never inferred from side signals (204 vs 2xx, the
+flavor of a disconnect). A new feature must name the owner of each piece of
+state before implementation starts.
+(Paid for by: the strip/restore resume machinery, silently frozen UIs and
+ghost sends after unmount — the #381→#432→#456 chain.)
+
+### 5. STATE MACHINES ARE EXPLICIT — ONE-SHOT FLAGS ARE FORBIDDEN
+
+A complex lifecycle (chat thread, resume/reconnect, run) lives in a named-state
+automaton (reducer / enum) where every state has an owner and a rendered
+representation — including the failure states. Adding a boolean ref that one
+callback arms and another reads-and-clears is FORBIDDEN in the AI-chat client.
+New behavior = a new named state + explicit transitions, and the interruption
+matrix (disconnect in each phase × restart × stop × supersede) is enumerated at
+design time, not discovered one incident at a time.
+(Paid for by: 26 one-shot useRef flags in chat-thread.tsx and the drip of
+"one more missing transition" across #381→#386/#389→#432→#456.)
+
+### 6. NO NEW MODE FORKS; A FLAG IS FOR ROLLOUT, THEN IT DIES
+
+A behavior flag that forks a code path must ship with a written sunset
+condition; stacking a new flag onto the existing matrix without deleting or
+scheduling an old one is forbidden. While a temporary fork exists, BOTH sides
+must share identical lifecycle handling (abort semantics, error listeners,
+concurrency gates) — asymmetric forks are outlawed.
+(Paid for by: legacy vs autonomous divergence — the one-active-run gate and
+the socket 'error' listener each existing on only ONE side; 2^4 flag
+combinations each with different abort semantics.)
+
+### 7. NO HAND-SYNCED MIRRORS — CODEGEN OR A CI PARITY TEST, NOTHING LESS
+
+Two copies of the same knowledge (schema, tool registry, glyph map, probe
+body, hash/normalize algorithm, label list) require either generation from a
+single source or a CI test that FAILS on drift. A "mirror this change over
+there" comment is NOT a guard and does not pass review.
+(Paid for by: #293 — three drifting converter copies losing data; #447 —
+REGISTRY_STAMP covering only one of the mirrored files; ~10 still-unguarded
+mirrors across the MCP layer.)
+
+### 8. CACHES, HEADERS, BUFFERS AND FSM TRANSITIONS GET AN INTEGRATION TEST OF THE OBSERVABLE PROPERTY
+
+A unit test of a pure helper DOES NOT COUNT for these. Test the real header on
+the real HTTP response, the real cache hit under real token sources, the real
+transition under a really-killed socket. If the observable property cannot be
+tested, the design is wrong — fix the design, not the test.
+(Paid for by: #431→#439 — a cache keyed on a fresh-per-call JWT, so it NEVER
+hit and became prod incident #435 while its unit tests stayed green; and by
+the #352→#455 immutable-cache header silently overwritten by a framework
+default AFTER the unit-tested code ran.)
+
+### 9. CLIENT INPUT IS HOSTILE UNTIL VALIDATED — ALSO BEFORE PERSISTENCE
+
+Anything from the browser (message parts, ids, titles, selections, flags) is
+validated/sanitized BEFORE it is persisted into a row that will later be
+replayed into a prompt, a converter or another subsystem. A poisoned row must
+never be able to permanently brick a chat or a page on every subsequent read.
+(Paid for by: unvalidated UIMessage parts persisted verbatim — one bad row
+500s the chat on every later turn; #159 client-spoofed page titles; #388
+selection re-sanitized server-side for the same reason.)
+
+### 10. FAILURES ARE LOUD AND SPECIFIC; SILENT DEGRADATION IS FORBIDDEN
+
+Extends the error convention below: a fire-and-forget write is allowed ONLY
+with a metric or a greppable ERROR log; a degraded mode (dead cached MCP
+client, stopped poll, exhausted retries, evicted buffer) must be VISIBLE to
+the user or the operator. A feature that can quietly stop working — a frozen
+"streaming…" UI, a poll that silently gives up, a cache serving corpses — does
+not pass review.
+(Paid for by: the degraded poll's silent 10-minute death leaving a forever-
+"streaming" answer; dead MCP clients served from cache while every external
+tool call failed; #435 being caught in minutes ONLY because metrics — #403 —
+existed.)
+
+## Default skill for feature design
+
+For any feature-design request — the user hands over a raw feature idea, asks
+to design or think through a feature, or to draft an issue («спроектируй»,
+«продумай фичу», «составь ишью», "design X", "write an issue for X") — invoke
+the `orchestrator-feature-designer` skill (Skill tool) BEFORE any other work.
+It is the default operating mode for design work in this repository: research
+→ design checklist (R1–R10) → forks resolved with the human → adversarial
+self-attack → filed PR-sized issues. Do not design features or write issues
+ad-hoc while this skill is available. This does not apply to non-design work
+(bug fixes, reviews, retrospectives, refactors already specified by an issue).
+
 ## Task lifecycle
 
 ### 1. Start: sync with develop
@@ -201,7 +334,7 @@ pnpm workspace (`pnpm@10.4.0`) orchestrated by **Nx**. Four workspace packages:
 | `apps/client` | `client` | React 18 + Vite + Mantine 8 + TanStack Query + Jotai | SPA frontend |
 | `packages/editor-ext` | `@docmost/editor-ext` | Tiptap/ProseMirror | Shared Tiptap node/mark extensions, imported by both the client and the server |
 | `packages/mcp` | `@docmost/mcp` | MCP SDK, Tiptap, Yjs | Standalone MCP server, also bundled into the server at `/mcp`. Consumes the shared converter/schema from `@docmost/prosemirror-markdown` (#293) — it no longer carries its own vendored converter/schema copy |
-| `packages/prosemirror-markdown` | `@docmost/prosemirror-markdown` | Tiptap, marked, jsdom | The single, canonical ProseMirror↔Markdown converter + Docmost schema mirror (#293). Consumed by `mcp`, `git-sync`, AND `apps/server` (server-side markdown import/export, #345); there is exactly ONE copy of the converter now |
+| `packages/prosemirror-markdown` | `@docmost/prosemirror-markdown` | Tiptap, marked; jsdom (Node only) | The single, canonical ProseMirror↔Markdown converter + Docmost schema mirror (#293). Consumed by `mcp`, `git-sync`, `apps/server` (server-side markdown import/export, #345), AND `apps/client` (markdown paste/copy + AI-chat render, via the `browser` entry — native `DOMParser`, no jsdom in the client bundle, #347); there is exactly ONE copy of the converter now |
 
 `build` targets are Nx-cached and dependency-ordered (`dependsOn: ["^build"]`), so `editor-ext` builds before the apps. `nx.json` sets `affected.defaultBase: main`.
 
@@ -248,6 +381,22 @@ pnpm collab:dev              # run the collaboration server process standalone (
 > that order). Reach for it whenever you run a consumer package's checks on their
 > own rather than through the full `pnpm build`.
 
+> **Editing an MCP tool spec requires a rebuild (issue #447).** The running
+> server loads the **compiled** `packages/mcp/build/` of `@docmost/mcp` (via the
+> runtime loader in `apps/server/src/core/ai-chat/tools/docmost-client.loader.ts`),
+> but the parity/tier guard tests read `packages/mcp/src/tool-specs.ts`. So if you
+> edit `tool-specs.ts` (any tool name, description, tier, catalog line, or input
+> schema) **without rebuilding**, `build/` and `src/` silently diverge — the tests
+> stay green while the server serves the OLD tools. To close that gap, the build
+> emits a `REGISTRY_STAMP` (a deterministic hash of the tool-specs content, via
+> `scripts/gen-registry-stamp.mjs` before `tsc`); on dev/test startup the loader
+> recomputes it from `src/` and **refuses to start with a "@docmost/mcp build is
+> stale …" error** on a mismatch (a pure no-op in prod, where only `build/` ships).
+> After editing tool specs, rebuild:
+> ```bash
+> pnpm --filter @docmost/mcp build     # or: pnpm --filter @docmost/mcp watch
+> ```
+
 **Lint** (per package — there is no root lint script):
 ```bash
 pnpm --filter server lint    # eslint --fix on server .ts
@@ -306,12 +455,12 @@ The API server is a Fastify app with a global `/api` prefix (`main.ts` excludes
    - `core/ai-chat/tools/` — the agent's ~40 read+write tools. Every tool runs under the **calling user's** CASL permissions via a per-user loopback access token (`docmost-client.loader.ts`), so the agent can never exceed what the user could do. Only **reversible** operations are exposed (page history + trash; no permanent delete). Agent edits get an "AI agent" provenance badge in page history (`20260616T130000-agent-provenance` migration).
    - `core/ai-chat/embedding/` — RAG indexer + a BullMQ consumer on `AI_QUEUE` that embeds pages into `page_embeddings` (vector search), complementing Postgres full-text search. Pages are (re)indexed on edit; `AI_EMBEDDING_TIMEOUT_MS` bounds a hung embeddings endpoint.
    - `core/ai-chat/external-mcp/` — admins can attach external MCP servers (e.g. Tavily) to give the agent web access. **`ssrf-guard.ts` validates outbound MCP URLs against SSRF** — keep that guard in the path when touching external-MCP connection logic.
-   - `core/ai-chat/ai-chat-run.service.ts` + `ai_chat_runs` — **detached/autonomous agent runs** (`#184`), behind the per-workspace `settings.ai.autonomousRuns` flag (off by default). When on, a turn becomes a server-side RUN that survives a browser disconnect; only an explicit `POST /ai-chat/stop` ends it, and a client reconnects/live-follows via `POST /ai-chat/run`. **DEPLOY CONSTRAINT — single-instance only in phase 1:** Stop and the AbortController that backs it are process-local, so a Stop only aborts a run executing on the **same** replica that owns it (cross-instance pub/sub stop is phase 2). Do **not** enable `autonomousRuns` on a horizontally-scaled deployment (multiple replicas behind a load balancer, or Docmost cloud `CLOUD=true`) — run a single instance instead. The server logs a startup WARNING when it detects a multi-instance deployment (`CLOUD=true`) so the constraint is visible. The startup sweep settles any run left dangling by a restart.
+   - `core/ai-chat/ai-chat-run.service.ts` + `ai_chat_runs` — **every agent turn is now a first-class server-side RUN** (`#184`, universalized in `#487`): its lifecycle is tracked in `ai_chat_runs` in **both** modes, and the single-active-run-per-chat concurrency gate is enforced universally (a legacy second tab now gets a clean `409 A_RUN_ALREADY_ACTIVE` instead of a second parallel stream that interleaved history). The per-workspace `settings.ai.autonomousRuns` flag (off by default) **no longer gates whether a turn is a run** — it now controls **only the browser-disconnect semantics**: when ON the run is *detached* (a disconnect leaves it executing server-side; only an explicit `POST /ai-chat/stop` ends it, and a client reconnects/live-follows via `POST /ai-chat/run`); when OFF (legacy) a disconnect ends the turn by stopping its run via the run's stop lever. `#487` also adds a server-side **supersede** CAS ("interrupt and send now") to `POST /ai-chat/stream` (`supersede: { runId }`): it atomically stops the chat's currently-active run and waits for it to settle before the new turn claims the slot, returning `SUPERSEDE_INVALID` / `SUPERSEDE_TARGET_MISMATCH` / `SUPERSEDE_TIMEOUT` on the non-proceed branches. **DEPLOY CONSTRAINT — single-instance only in phase 1:** Stop and the AbortController that backs it are process-local, so a Stop only aborts a run executing on the **same** replica that owns it (cross-instance pub/sub stop is phase 2). Do **not** enable `autonomousRuns` on a horizontally-scaled deployment (multiple replicas behind a load balancer, or Docmost cloud `CLOUD=true`) — run a single instance instead. The server logs a startup WARNING when it detects a multi-instance deployment (`CLOUD=true`) so the constraint is visible. The startup sweep settles any run left dangling by a restart.
 
 ### Client structure
 Vite SPA. Code is organized by feature under `apps/client/src/features/*` (mirrors the server domains: `page`, `space`, `comment`, `ai-chat`, `editor`, …). Conventions:
 - **TanStack Query** for server state (one `queries/` file per feature), **Jotai** atoms for local/shared UI state, **Mantine 8** + CSS modules (`*.module.css`) + `postcss-preset-mantine` for UI.
-- The editor is Tiptap; shared node/mark extensions live in `packages/editor-ext` and are imported by **both the client and the server** (collaboration, schema, `canonicalizeFootnotes`) — editor schema changes often need to be made in `editor-ext`, not just the client. Server-side markdown import/export no longer lives in `editor-ext`: it goes through the canonical converter (#345, see below). The ProseMirror↔Markdown converter and its Docmost schema mirror now live in a SINGLE package, `@docmost/prosemirror-markdown` (#293), consumed by `mcp`, `git-sync`, and `apps/server` (#345) — do NOT reintroduce a per-package copy. `editor-ext` is the upstream source of the Tiptap schema; the package's `docmost-schema.ts` mirrors it and a serializer-contract test (`packages/prosemirror-markdown/test/serializer-contract.test.ts`) guards the boundary (every schema node must have a converter case), so a drift surfaces as a failing test rather than silent divergence. For the converter's property-testing and counterexample→fixture process (P1–P4 invariants, the `PROPERTY_SEED`/`PROPERTY_NUM_RUNS` knobs, and the nightly fuzz workflow), see `packages/prosemirror-markdown/README.md`.
+- The editor is Tiptap; shared node/mark extensions live in `packages/editor-ext` and are imported by **both the client and the server** (collaboration, schema, `canonicalizeFootnotes`) — editor schema changes often need to be made in `editor-ext`, not just the client. Server-side markdown import/export no longer lives in `editor-ext`: it goes through the canonical converter (#345, see below). The ProseMirror↔Markdown converter and its Docmost schema mirror now live in a SINGLE package, `@docmost/prosemirror-markdown` (#293), consumed by `mcp`, `git-sync`, `apps/server` (#345), and `apps/client` (#347) — do NOT reintroduce a per-package copy. The client uses the package's `browser` entry (`@docmost/prosemirror-markdown/browser`): markdown paste (`markdown-clipboard.ts`), copy-as-markdown, and AI-chat rendering now all go through the canonical converter, so the hand-written `marked`/`turndown` markdown layer that used to live in `editor-ext` was deleted (#347). The browser entry runs the HTML→DOM stage on the native `DOMParser`, so jsdom stays out of the client bundle. `editor-ext` is the upstream source of the Tiptap schema; the package's `docmost-schema.ts` mirrors it and a serializer-contract test (`packages/prosemirror-markdown/test/serializer-contract.test.ts`) guards the boundary (every schema node must have a converter case), so a drift surfaces as a failing test rather than silent divergence. For the converter's property-testing and counterexample→fixture process (P1–P4 invariants, the `PROPERTY_SEED`/`PROPERTY_NUM_RUNS` knobs, and the nightly fuzz workflow), see `packages/prosemirror-markdown/README.md`.
 - API access goes through `apps/client/src/lib/api-client.ts` (axios). The `@` alias maps to `apps/client/src`.
 - Runtime config is injected at build time by `vite.config.ts` via `define` (`APP_URL`, `COLLAB_URL`, `APP_VERSION`, …) — these come from the root `.env`, not from `import.meta.env`.
 
@@ -321,8 +470,10 @@ Vite SPA. Code is organized by feature under `apps/client/src/features/*` (mirro
 - **Errors must never be swallowed or shown as generic messages.** Every caught error MUST (1) be logged in full to the console/logger — error name, message, stack, `cause`, and (for HTTP/provider failures) the status code and response body — and (2) be surfaced to the user with a *specific, human-readable explanation of what actually went wrong*, never a bare generic string like "Something went wrong" / "Could not start recording" / "Transcription failed". Include the real reason (the underlying error/provider message) in the user-facing text. On the server, wrap third-party/provider failures with `describeProviderError` (or equivalent) and rethrow as a meaningful HTTP status + message — never let them collapse into an opaque 500. On the client, `console.error(<context>, err)` the raw error AND show the extracted reason (e.g. `err.response?.data?.message`, or the error `name: message`) in the notification.
 - The version string shown in the UI comes from `APP_VERSION` (CI/Docker) or `git describe --tags --always` (local), resolved in `vite.config.ts` — not from `package.json`.
 - Server TS config is permissive (`noImplicitAny: false`, `strictNullChecks: false`, `no-explicit-any` lint disabled). Follow the existing relaxed style rather than tightening types broadly.
-- Dependency versions are heavily pinned via `pnpm.overrides` and `pnpm.patchedDependencies` (`scimmy`, `yjs`, `ai`) in the root `package.json`. Don't bump pinned/patched deps casually; the patches and overrides exist for compatibility/security reasons. The `ai@6.0.134` patch disables the SDK's O(n²) cumulative `partialOutput` accumulation when no output strategy is requested (server heap OOM on long agent runs, #184; tripwire test: `apps/server/src/integrations/ai/ai-sdk-partial-output.patch.spec.ts`) — it MUST be re-created via `pnpm patch` when bumping `ai`.
+- Dependency versions are heavily pinned via `pnpm.overrides` and `pnpm.patchedDependencies` (`scimmy`, `yjs`, `ai`) in the root `package.json`. Don't bump pinned/patched deps casually; the patches and overrides exist for compatibility/security reasons. The `ai@6.0.134` patch carries TWO independent server fixes, each with its own tripwire test: (1) it disables the SDK's O(n²) cumulative `partialOutput` accumulation when no output strategy is requested (server heap OOM on long agent runs, #184; tripwire: `apps/server/src/integrations/ai/ai-sdk-partial-output.patch.spec.ts`); (2) it fixes `writeToServerResponse`'s drain-hang — the loop awaited only `"drain"` under backpressure, so a mid-write client disconnect parked the pipe forever and leaked the reader/buffers until restart; it now races `"drain"` against `"close"`/`"error"`, cancels the reader on disconnect, and swallows the fire-and-forget read rejection (#486; tripwire: `apps/server/src/integrations/ai/ai-sdk-drain-hang.patch.spec.ts`). Both tripwires assert BOTH installed dist builds carry their patch marker. The patch MUST be re-created via `pnpm patch` when bumping `ai`.
-- **Adding/renaming/removing an MCP tool requires updating `SERVER_INSTRUCTIONS`** in `packages/mcp/src/index.ts` — the intent-routing guide MCP clients receive on initialize. This applies both to inline `server.registerTool(...)` calls in `index.ts` and to specs in `packages/mcp/src/tool-specs.ts`. Enforced by `packages/mcp/test/unit/server-instructions.test.mjs`, which fails when a registered tool is not mentioned in the guide (deliberate opt-outs go into its `EXCEPTIONS` list). `packages/mcp/build/` is gitignored and rebuilt in CI/Docker via `pnpm build` (same convention as `git-sync`/`prosemirror-markdown`) — never commit it; rebuild locally after editing to run the tests.
+  - **Upstream tracking (report the analysis upstream, don't just carry it):** both `ai` fixes and the hocuspocus one are candidates for upstreaming so we can eventually drop the local patch — the analysis is already written up in each patch's `PATCH(...)` header comments. File (a) an upstream **issue** on `vercel/ai` for the O(n²) cumulative `partialOutput` accumulation (heap OOM), (b) an upstream **issue** on `vercel/ai` for the `writeToServerResponse` drain-hang, and (c) an upstream **PR** on `@hocuspocus/server` for the connect-vs-unload race (local marker `PATCH(gitmost #401)` in `patches/@hocuspocus__server@3.4.4.patch`). Do NOT edit the patch files to add links — the patch bytes feed `patch_hash` in `pnpm-lock.yaml` (`ai@6.0.134` → `e8c599b3…`), so any content change there desyncs the lockfile pin and breaks `pnpm install`; keep upstream references here instead.
+  - **`ai` version is split across the monorepo and MUST be aligned deliberately, NOT casually:** the server pins `ai@6.0.134` (patched, exact — the `patchedDependencies` key forces that version), while the client declares `ai@6.0.207` (unpatched — the server-side `writeToServerResponse`/`partialOutput` fixes are dead code in the browser, so the mismatch is currently benign but is real drift). Alignment is a **planned, install-gated step**, never a bare `package.json` edit: (1) choose the target version; (2) re-create ALL THREE patch hunks (partialOutput publish-each, the `DefaultStreamTextResult` lazy-`output` wiring, and the drain-hang race) against the target dist via `pnpm patch` — the line offsets shift between versions, so the current patch WILL fail to apply as-is; (3) run a full `pnpm install` so the lockfile + new `patch_hash` regenerate together; (4) confirm both tripwire specs still find their markers. `pnpm install` FAILS HARD on an unapplied patch — that failure is the guardrail, so treat the port as a deliberate plan rather than discovering it as a deploy-time surprise.
+- **The MCP tool inventory in `SERVER_INSTRUCTIONS` is GENERATED from the registry** (`packages/mcp/src/server-instructions.ts`: `buildToolInventory()` over `SHARED_TOOL_SPECS`) and spliced into the hand-written routing prose (`ROUTING_PROSE`). So adding/renaming/removing a **shared** spec in `packages/mcp/src/tool-specs.ts` auto-updates the `<tool_inventory>` — no manual `SERVER_INSTRUCTIONS` edit needed. Only an **inline** MCP-only tool (those registered via `server.registerTool(...)` in `index.ts`, not through the registry) needs a one-line entry in `INLINE_MCP_INVENTORY`. Enforced by `packages/mcp/test/unit/tool-inventory.test.mjs`, which fails when a registered tool is missing from the generated inventory (there is no `EXCEPTIONS` opt-out anymore — every tool must appear). Update `ROUTING_PROSE` when a tool's *intent guidance* (when-to-use) changes. `packages/mcp/build/` is gitignored and rebuilt in CI/Docker via `pnpm build` (same convention as `git-sync`/`prosemirror-markdown`) — never commit it; rebuild locally after editing to run the tests.
 
 ## CI / release
 

CHANGELOG.md

@@ -10,8 +10,132 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Breaking Changes
+
+- **External MCP tool names are now camelCase (all renamed).** Every tool on the
+  external `/mcp` surface was renamed from `snake_case` to `camelCase`, so the
+  external MCP name now matches the in-app tool name exactly (one logical tool,
+  one name everywhere). For example `get_node` → `getNode`, `edit_page_text` →
+  `editPageText`, `patch_node` → `patchNode`. The tools' behaviour, inputs and
+  outputs are unchanged — only the names change. The single-word `search`
+  keeps its name.
+
+  *Migration (external MCP clients only — the in-app AI agent already used these
+  names and is unaffected):* update anything that refers to a tool by its
+  string name — permission allowlists (`mcp__gitmost-*__get_node` →
+  `mcp__gitmost-*__getNode`), saved prompts/skills, `.mcp.json` tool filters,
+  and metrics dashboards that group by the `tool` label — and roll it out in
+  lockstep with this deploy, because the old snake_case names stop resolving.
+  Released together with the `import_page_markdown`/`update_page_markdown`
+  change below so external configs break exactly once.
+
+  Full mapping (old → new):
+
+  | Old (snake_case) | New (camelCase) |
+  | --- | --- |
+  | `check_new_comments` | `checkNewComments` |
+  | `copy_page_content` | `copyPageContent` |
+  | `create_comment` | `createComment` |
+  | `create_page` | `createPage` |
+  | `delete_comment` | `deleteComment` |
+  | `delete_node` | `deleteNode` |
+  | `delete_page` | `deletePage` |
+  | `diff_page_versions` | `diffPageVersions` |
+  | `docmost_transform` | `docmostTransform` |
+  | `drawio_create` | `drawioCreate` |
+  | `drawio_get` | `drawioGet` |
+  | `drawio_guide` | `drawioGuide` |
+  | `drawio_shapes` | `drawioShapes` |
+  | `drawio_update` | `drawioUpdate` |
+  | `edit_page_text` | `editPageText` |
+  | `export_page_markdown` | `exportPageMarkdown` |
+  | `get_node` | `getNode` |
+  | `get_outline` | `getOutline` |
+  | `get_page` | `getPage` |
+  | `get_page_json` | `getPageJson` |
+  | `get_workspace` | `getWorkspace` |
+  | `insert_footnote` | `insertFootnote` |
+  | `insert_image` | `insertImage` |
+  | `insert_node` | `insertNode` |
+  | `list_comments` | `listComments` |
+  | `list_page_history` | `listPageHistory` |
+  | `list_pages` | `listPages` |
+  | `list_shares` | `listShares` |
+  | `list_spaces` | `listSpaces` |
+  | `move_page` | `movePage` |
+  | `patch_node` | `patchNode` |
+  | `rename_page` | `renamePage` |
+  | `replace_image` | `replaceImage` |
+  | `resolve_comment` | `resolveComment` |
+  | `restore_page_version` | `restorePageVersion` |
+  | `search` | `search` (unchanged) |
+  | `search_in_page` | `searchInPage` |
+  | `share_page` | `sharePage` |
+  | `stash_page` | `stashPage` |
+  | `table_delete_row` | `tableDeleteRow` |
+  | `table_get` | `tableGet` |
+  | `table_insert_row` | `tableInsertRow` |
+  | `table_update_cell` | `tableUpdateCell` |
+  | `unshare_page` | `unsharePage` |
+  | `update_comment` | `updateComment` |
+  | `update_page_json` | `updatePageJson` |
+  | `update_page_markdown` | `updatePageMarkdown` |
+
+  (#412)
+
+- **External MCP: `import_page_markdown` removed, `update_page_markdown` added.**
+  The external `/mcp` surface no longer exposes `importPageMarkdown` (the
+  round-trip parser for a self-contained *exported* Docmost-Markdown file). In
+  its place it now exposes **`updatePageMarkdown`** — a plain-Markdown
+  full-body replace (`{pageId, content, title?}`) that pairs with
+  `updatePageJson`, re-imports the whole body (block ids regenerate) and
+  parses Docmost-flavoured markdown including `^[...]` inline footnotes.
+  *Migration:* MCP clients that called `importPageMarkdown` to overwrite a
+  page's body from Markdown should call `updatePageMarkdown` instead (pass the
+  markdown as `content`). Round-tripping an exported Docmost-Markdown file with
+  comment anchors/diagrams is no longer available on the external MCP surface;
+  export remains via `exportPageMarkdown`. The in-app AI agent is unaffected —
+  it keeps both `importPageMarkdown` and the renamed `updatePageMarkdown` (was
+  `updatePageContent`). The total MCP tool count is unchanged (−1 / +1). The
+  external names shown here are the post-#412 camelCase names. (#411)
+
+- **`getNode` now returns Markdown by default (was ProseMirror JSON).** The
+  block-level read/write tools default to Markdown so a block round trip is
+  `getNode` (markdown) → edit → `patchNode` (markdown). `getNode` now returns
+  `{ …, format: "markdown", markdown }` unless you pass `format: "json"` (which
+  restores the previous `{ …, node }` ProseMirror subtree); comment anchors —
+  including resolved ones — are preserved in the markdown so a write-back never
+  orphans a thread, and a node that cannot be a document top-level block
+  (`tableRow`/`tableCell`/`tableHeader` addressed via `#<index>`) auto-falls back
+  to JSON with `format: "json"` in the response. `patchNode`/`insertNode` gain a
+  `markdown` input alongside `node` (provide exactly one): the markdown fragment
+  may rewrite/insert several blocks at once and supports `^[...]` footnotes.
+  *Migration (external MCP clients only):* a client that consumed `getNode`'s
+  `node` field must now either read `markdown`, or pass `format: "json"` to keep
+  the old ProseMirror-JSON output. Released together with the `#411`/`#412`
+  breaking window so external configs break exactly once. (#413)
+
+- **The Prometheus `/metrics` listener now binds to `127.0.0.1` (loopback) by
+  default instead of `0.0.0.0` (all interfaces).** This closes an unauthenticated
+  endpoint that was previously reachable on every interface. **DEPLOY MIGRATION —
+  cross-container scraping breaks silently otherwise:** if your scraper runs in a
+  SEPARATE container and reaches the app as `docmost:9464` (the exact topology the
+  old `0.0.0.0` hardcode served), you MUST now set `METRICS_BIND=0.0.0.0` — and,
+  because that re-exposes the endpoint, also set `METRICS_TOKEN=<secret>` and
+  configure the scraper with a matching Bearer token. Without `METRICS_BIND`, the
+  scraper can no longer connect and metrics go dark with no error. See the
+  `METRICS_BIND` / `METRICS_TOKEN` block in `.env.example` for the migration.
+  Same-host (loopback) scrapers need no change. (#486)
+
 ### Added
 
+- **A drifted comment suggestion can be re-synced instead of failing forever
+  with a 409.** A suggestion whose stored anchor no longer matched the live
+  document used to reject every apply attempt with an unrecoverable conflict; a
+  new resync path re-reads the live anchor so the suggestion applies against the
+  current text, and orphaned anchors (whose marked run was deleted) are
+  reconciled rather than left blocking. (#496)
+
 - **Place several images side by side in a row.** A new "Inline (side by
   side)" alignment mode in the image bubble menu renders consecutive inline
   images as a row that wraps onto the next line on narrow screens. The row is
@@ -85,6 +209,17 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   dangling by a restart. Phase 1 is single-instance-only (cross-instance Stop is
   not yet reliable); the server warns at startup on a horizontally-scaled
   deployment. (#184)
+- **Server-side "interrupt and send now" (supersede) for AI chat.** `POST
+  /ai-chat/stream` now accepts a `supersede: { runId }` field: when the user sends
+  a new message while a run is active, the server atomically stops that run and
+  waits for it to settle before the new turn claims the chat's single run slot,
+  instead of the send being rejected as concurrent. The compare-and-set surfaces
+  three codes on its non-proceed branches — `SUPERSEDE_INVALID` (the targeted run
+  is malformed / belongs to another chat), `SUPERSEDE_TARGET_MISMATCH` (a
+  different run is now active; carries the current `activeRunId`), and
+  `SUPERSEDE_TIMEOUT` (the previous run did not stop within the settle window, so
+  nothing was sent and the composer keeps the text). Tunable via
+  `AI_CHAT_SUPERSEDE_TIMEOUT_MS` (default 10s). (#487)
 - **Out-of-band page transfer via an in-RAM blob sandbox (`stash_page`).** A
   new MCP tool serializes a whole page (its full ProseMirror JSON, with every
   internal image/file mirrored) into an ephemeral in-RAM blob and returns only
@@ -146,9 +281,56 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   by physical key position and matched against the commands; genuine Cyrillic
   search terms keep priority over remapped candidates, and short wrong-layout
   prefixes match by command title. (#283, #285, #287)
+- **Opt-in substring "lookup" search mode for agents.** `/api/search` gains an
+  additive, opt-in mode (guarded by a new `substring` flag) that matches literal
+  substrings of page titles and body text — so technical tokens the full-text
+  tokenizer mangles (`backup-srv.local`, `10.0.12.5`, `WB-MGE-30D86B`) are found
+  even when the FTS query is empty. It returns a location `path`, a windowed
+  `snippet` and a per-response relevance `score`, supports `titleOnly` and a
+  `parentPageId` subtree scope, and applies the page-level permission filter
+  before the limit. The web UI never sets `substring`, so its full-text search
+  behaviour is byte-for-byte unchanged. The leading-wildcard `LIKE` predicates
+  are backed by GIN trigram indexes on `LOWER(f_unaccent(title))` and
+  `LOWER(f_unaccent(text_content))` so lookups use a bitmap index scan instead of
+  a sequential scan. (#443)
+- **MCP `search` tool returns richer, agent-oriented results.** The external MCP
+  `search` response shape changes for the agent surface: each hit now carries
+  `pageId` (renamed from `id`), plus `path`, `snippet` and `score`; the
+  UI-oriented `spaceId`, `rank` and `highlight` fields are dropped. (#443)
 
 ### Changed
 
+- **Every AI-chat turn is now a first-class server-side run, and one run per chat
+  is enforced in both modes.** The run machinery from `#184` was universalized: a
+  turn is tracked in `ai_chat_runs` and gated by the single-active-run-per-chat
+  index regardless of the `settings.ai.autonomousRuns` flag. **Behavior change:**
+  a second tab (or a double-submit) that starts a turn while one is already active
+  on the chat is now rejected up front with `409 A_RUN_ALREADY_ACTIVE` (carrying
+  the `activeRunId`); previously, on the legacy path, it opened a second parallel
+  stream on the same chat that interleaved history. The `autonomousRuns` flag no
+  longer controls whether a turn is a run — it now governs **only** the
+  browser-disconnect semantics (ON = detached/survives a disconnect; OFF = a
+  disconnect stops the run). (#487)
+- **Vendor `ai` patch: upstream-tracking + version-alignment plan documented.**
+  The two local `ai@6.0.134` fixes (O(n²) `partialOutput` heap-OOM; the
+  `writeToServerResponse` drain-hang) and the hocuspocus connect-vs-unload race
+  now have explicit upstream-reporting and `ai`-version-alignment steps recorded
+  in `AGENTS.md` (client `ai@6.0.207` vs server `ai@6.0.134`-patched drift). The
+  patch bytes are unchanged — they feed the lockfile `patch_hash`, so the
+  alignment is called out as an install-gated plan rather than a bare version
+  bump. No runtime change.
+- **Client markdown paste/copy and AI-chat rendering now go through the canonical
+  converter.** Pasting markdown into the editor, "Copy as markdown", the AI title
+  generator, and the AI-chat markdown renderer all now use
+  `@docmost/prosemirror-markdown` (via its new `browser` entry — native
+  `DOMParser`, no jsdom in the client bundle) instead of the hand-written
+  `marked`/`turndown` markdown layer in `editor-ext`, which was **deleted**. As a
+  result, pasting canonical markdown (`^[…]` footnotes, `<!--img …-->`,
+  `> [!type]` callouts, `$…$` math, `==…==` highlight, standalone `<!--subpages-->`
+  comments) now produces the SAME nodes the server import produces for the same
+  text. Chat/reasoning markdown now renders through the editor schema (list items
+  are wrapped in `<p>`; CSS keeps them tight). (#347)
+
 - **Enabling a public share no longer auto-shares the whole sub-tree.** Turning
   a page "Shared to web" now defaults to the page alone; descendant pages become
   public only when you explicitly turn on the dedicated "Include sub-pages"
@@ -169,6 +351,79 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- **MCP write tools no longer report a false failure that provokes a duplicate
+  write.** `drawioCreate` used to throw when the diagram landed as a NESTED block
+  (anchored inside a callout or table cell) because there is no `#<index>` handle
+  for it — but the diagram was already written, so a retry-prone agent re-created
+  it and produced a duplicate. It now returns success with `nodeId: null` plus a
+  warning that explains the write landed and how to re-read it (via
+  `getOutline` / `getPageJson` by `attachmentId`). Separately, when the live
+  collaboration-session cache hits its LRU entry cap, evicting a session whose
+  write is still in flight no longer rejects that write as a hard failure — it is
+  reported as INDETERMINATE ("the update may already have persisted; verify
+  before retry") so the agent re-reads instead of blind-retrying, and a
+  still-connecting session is no longer picked as an idle eviction victim by a
+  parallel acquire. (#494)
+- **A long AI chat no longer bricks on the model's context window, and each turn
+  stops re-persisting the whole tool-output history.** Tool outputs are now
+  stored ONCE, in `metadata.parts`; the `tool_calls` trace keeps only per-step
+  outcome flags (a v2 trace shape), ending the O(N²) write amplification that
+  re-wrote every prior output on every step (measured on a live Postgres via the
+  `pg_current_wal_lsn()` delta: the trace column shrank ~3200×, the full
+  assistant row ~51%). The persisted record is unchanged in content — the full
+  history still lives in `metadata.parts`. At REPLAY time only, the history sent
+  to the provider is now bounded by a deterministic, prompt-cache-friendly token
+  budget: `floor(0.7 × chatContextWindow)` when a window is configured (no cap —
+  anti-brick protection, not a cost limiter), a flat 100k fallback for installs
+  with no window set (exactly the ones that hit terminal overflow), or off when
+  the window is explicitly `0`. Trimming truncates old tool outputs first, then
+  mechanically collapses the oldest turns, always keeping the recent turns full
+  and the tool-call/result pairing balanced. A provider context-overflow 400 is
+  now classified and used as a reactive signal: the row is stamped so the NEXT
+  turn re-trims aggressively (0.5×), which un-bricks a chat that just 400'd. The
+  client token badge and the server budgeter now share one estimator (new
+  `@docmost/token-estimate` package) so they can never diverge. Deferred-tool
+  activation is also cached in the chat metadata to avoid re-resolving it each
+  turn. (#490)
+- **A chat with one malformed message part no longer 500s on every turn, and a
+  failed send no longer duplicates the user's message.** Incoming client parts
+  are now whitelisted to `text` (a forged tool-result part can no longer reach
+  the persisted history or the model context), and the turn is converted BEFORE
+  the user row is inserted, so a mid-flight failure cannot leave a duplicate
+  user row that a retry then compounds. A single part that still fails to convert
+  degrades to a `[tool context omitted]` marker on that one row instead of
+  bricking the whole chat. (#489)
+- **A transport drop to an external MCP server now heals within the same turn.**
+  On an undici transport error, a read-only MCP tool reconnects its server and
+  retries once within the run; a write is never auto-retried (it may already have
+  applied). One flapping server no longer nulls the shared client cache, so other
+  servers' cached clients are untouched. The SSE transport also gets a raised
+  body-timeout so a legitimate >1-min idle between the model's tool calls no
+  longer breaks a long-lived SSE socket (new `AI_MCP_SSE_BODY_TIMEOUT_MS`, default
+  10 min; see `.env.example`). (#489)
+- **Decisions on comment suggestions now leave a durable audit record.**
+  Applying or dismissing a comment suggestion hard-deletes the (childless)
+  subject comment, so the only surviving trace of who decided what is the audit
+  event — but the audit trail was wired to a Noop service that silently
+  swallowed every event. The trail is now DB-backed, so
+  `comment.suggestion_applied` / `comment.suggestion_dismissed` (and the other
+  comment-decision events) persist to the `audit` table and can be reviewed
+  after the comment is gone. A persistence failure is still swallowed with a
+  warning so it never breaks the originating request. (#496)
+- **Applying a comment suggestion no longer strips the replaced run's inline
+  formatting.** The suggested text was re-inserted carrying only the comment
+  anchor mark, silently dropping bold/italic/code/link on the affected run; the
+  prevailing formatting of the replaced run is now carried onto the applied
+  text. (#496)
+- **Markdown round-trips no longer silently drop a line that opens with a block
+  trigger.** When a document is exported to Markdown and re-imported (git-sync
+  stabilize, agent writes), a paragraph or continuation line (after a hard break)
+  that begins with a block marker — an ATX heading `#`, a blockquote/callout `>`,
+  a list marker (`-`/`*`/`+`/`N.`/`N)`), a code fence, a table `|`, a thematic
+  break (`---`), or a setext underline (`--`, `----`, or a lone `=`) — is now
+  backslash-escaped so it round-trips as text instead of being re-parsed into a
+  heading/list/quote/rule and losing its content. Front-matter stripping is
+  scoped to the import path only. (#493)
 - **The server no longer runs out of heap during long autonomous agent runs.** A
   new pnpm patch on `ai@6.0.134` stops the SDK from building a cumulative
   snapshot of the ENTIRE turn text on every streamed text-delta when no output
@@ -177,6 +432,39 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   `tee()` branch of the stream result — a ~20-step, ~28k-chunk agent run
   retained ~1.7 GB and OOM'd the 2 GB JS heap. Streaming granularity is
   unchanged; the patch must be re-created if `ai` is ever bumped. (#184)
+
+- **The server no longer leaks a hung stream pipe on every mid-run client
+  disconnect.** The same `ai@6.0.134` pnpm patch now also fixes the SDK's
+  `writeToServerResponse`, which awaited only a `"drain"` event under
+  backpressure: when a client disconnected mid-write the socket never drained, so
+  the write loop parked forever, `response.end()` was unreachable, and the stream
+  reader plus buffered chunks were pinned until process restart (every mid-run
+  disconnect in autonomous mode leaked one). The patch races `"drain"` against
+  `"close"`/`"error"`, cancels the reader and ends the response on disconnect, and
+  swallows the fire-and-forget read rejection instead of crashing on an
+  unhandledRejection. (#486)
+
+- **A failed autonomous agent-run start no longer becomes an unstoppable ghost
+  run.** When `beginRun` failed for a transient reason (e.g. a DB-pool blip),
+  the turn previously continued with NO run row — invisible to `/stop`, not
+  aborted on disconnect, and able to slip a second run past the one-run-per-chat
+  gate, leaving an unstoppable run until restart. The turn now fails fast with an
+  honest `503 A_RUN_BEGIN_FAILED` before the first byte (no orphan state), and the
+  client shows a "temporary — please try again" message instead of a misleading
+  "provider not configured". (#486)
+
+- **A pathological draw.io graph can no longer wedge the whole server.** The ELK
+  auto-layout (`layout:"elk"`) ran elkjs synchronously on the main event loop, so
+  a graph at the node/edge cap blocked ALL HTTP/SSE/loopback traffic while it
+  churned — and the old `setTimeout` "timeout" could never fire because the same
+  thread was blocked. Layout now runs in a worker thread with the timeout enforced
+  by `worker.terminate()`; the main loop stays responsive. (#486)
+
+- **The `/health` Redis probe no longer leaks a client on every tick while Redis
+  is down.** It built a new `ioredis` client per probe and disconnected it only on
+  success, so during an outage each health tick added another forever-reconnecting
+  client (an unbounded handle leak). A single long-lived probe client is now
+  reused and closed on shutdown. (#486)
 - **Internal links in exported Markdown no longer lose their visible text.** A
   link whose target page name had no file extension (e.g. a bare title) was
   collapsed to empty text during export, producing an unclickable, label-less
@@ -252,6 +540,37 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   through that exact share (its own share or an ancestor `includeSubPages`
   share); any other value now returns the generic "not found" instead of
   serving the page. (#218)
+- **MCP tool-allowlist semantics flipped: an empty `[]` now means deny-all
+  (previously it was coerced to "no restrictions").** For an external MCP server,
+  a stored `tool_allowlist` of `[]` now denies **every** tool of that server
+  (zero tools reach the agent) instead of being treated as an empty/unset filter
+  that allowed all of them. A corrupt or non-array stored value now **fails
+  closed** to deny-all rather than silently allowing everything. The admin form
+  no longer silently widens an existing deny-all server: leaving its tag field
+  empty preserves `[]` (deny-all) on save instead of NULL-ing the column to
+  allow-all, so a routine rename/toggle can no longer grant the agent every tool.
+  "No restrictions" is still expressible — a genuinely unrestricted server stores
+  NULL, and clearing the field on such a server keeps it NULL. Operationally
+  significant: audit any server that was created or left with a literal `[]`, as
+  it now exposes no tools until an explicit allowlist (or NULL) is set. (#476)
+
+- **Tool and provider error text no longer leaks to anonymous readers in the
+  public-share AI chat.** A failing tool's raw error (which could carry an
+  internal page title or a stack fragment) and a provider error (which bundles the
+  provider `statusCode` and response body — potentially the internal baseUrl or
+  model name) were streamed verbatim to the anonymous reader over SSE. Errors are
+  now sanitized at the source: the share toolset collapses any unclassified tool
+  error to a safe generic string (safe, classified tool messages still pass
+  through for the model's self-correction), and the anonymous stream `onError`
+  maps provider failures to a fixed set of neutral strings — the full detail goes
+  only to the server log. A UI render gate is layered on top. (closes #394)
+
+- **The Prometheus `/metrics` endpoint can now require Bearer authentication and
+  is loopback-bound by default.** Previously it listened on all interfaces with no
+  auth. Setting `METRICS_TOKEN` requires every scrape to present
+  `Authorization: Bearer <token>` (compared in constant time), and the listener
+  defaults to `127.0.0.1` (see the Breaking Changes entry for the cross-container
+  migration). (#486)
 
 ## [0.94.0] - 2026-06-26
 

Dockerfile

@@ -45,6 +45,11 @@ COPY --from=builder /app/packages/editor-ext/dist /app/packages/editor-ext/dist
 COPY --from=builder /app/packages/editor-ext/package.json /app/packages/editor-ext/package.json
 COPY --from=builder /app/packages/mcp/build /app/packages/mcp/build
 COPY --from=builder /app/packages/mcp/package.json /app/packages/mcp/package.json
+# The mcp package reads its data files (drawio-presets.json, drawio-shape-index.json.gz)
+# at runtime via `new URL("../../data/…", import.meta.url)` relative to build/lib/*.js,
+# i.e. from packages/mcp/data/. tsc emits only build/, so ship data/ explicitly or
+# drawioFromGraph and the shape catalog die with ENOENT on packages/mcp/data/*.
+COPY --from=builder /app/packages/mcp/data /app/packages/mcp/data
 # mcp now depends on @docmost/prosemirror-markdown (workspace:*) and eager-imports
 # it at runtime (the in-app ai-chat DocmostClient loads build/index.js -> lib/
 # markdown-converter.js). Ship the built package + its manifest, or the prod
@@ -81,4 +86,14 @@ VOLUME ["/app/data/storage"]
 
 EXPOSE 3000
 
+# DEPLOY REQUIREMENT — SINGLE INSTANCE or STICKY SESSIONS (#449).
+# MCP content writes are serialized per page by an IN-PROCESS mutex, and the
+# stash_page blob store + cached collab sessions are RAM-only and process-local.
+# Running MULTIPLE replicas of this image behind a load balancer WITHOUT sticky
+# sessions silently breaks per-page write serialization (two replicas can lock
+# the same page at once) and makes stash_page blobs unreachable across replicas.
+# Run a SINGLE instance, or pin each page's traffic to one replica (sticky
+# sessions / consistent hashing on page id). There is deliberately no
+# cross-process lock yet — a conscious constraint. See .env.example (the "MCP
+# collaboration write path" block) and packages/mcp/README.md for details.
 CMD ["pnpm", "start"]

apps/client/package.json

@@ -21,6 +21,8 @@
     "@atlaskit/pragmatic-drag-and-drop-live-region": "1.3.4",
     "@casl/react": "5.0.1",
     "@docmost/editor-ext": "workspace:*",
+    "@docmost/prosemirror-markdown": "workspace:*",
+    "@docmost/token-estimate": "workspace:*",
     "@excalidraw/excalidraw": "0.18.0-3a5ef40",
     "@mantine/core": "8.3.18",
     "@mantine/dates": "8.3.18",

apps/client/public/locales/ru-RU/translation.json

@@ -256,6 +256,9 @@
   "Invite link": "Ссылка для приглашения",
   "Copy": "Копировать",
   "Copy to space": "Копировать в пространство",
+  "Copy chat": "Копировать чат",
+  "Dock to sidebar": "Закрепить в боковой панели",
+  "Undock": "Открепить",
   "Copied": "Скопировано",
   "Failed to export chat": "Не удалось экспортировать чат",
   "Duplicate": "Дублировать",
@@ -285,6 +288,9 @@
   "Alt text": "Альтернативный текст",
   "Describe this for accessibility.": "Опишите это для специальных возможностей.",
   "Add a description": "Добавить описание",
+  "Caption": "Подпись",
+  "Add a caption": "Добавить подпись",
+  "Shown below the image.": "Отображается под изображением.",
   "Justify": "По ширине",
   "Merge cells": "Объединить ячейки",
   "Split cell": "Разделить ячейку",
@@ -388,22 +394,6 @@
   "Quote": "Цитата",
   "Image": "Изображение",
   "Audio": "Аудио",
-  "Transcribe": "Транскрибировать",
-  "Transcribing…": "Транскрибация…",
-  "No speech detected": "Речь не распознана",
-  "Transcription failed": "Не удалось распознать речь",
-  "Voice dictation is not configured": "Голосовой ввод не настроен",
-  "Start dictation": "Начать диктовку",
-  "Stop recording": "Остановить запись",
-  "Microphone access denied": "Доступ к микрофону запрещён",
-  "No microphone found": "Микрофон не найден",
-  "Microphone is unavailable or already in use": "Микрофон недоступен или уже используется",
-  "Could not start recording": "Не удалось начать запись",
-  "Audio recording is not available in this browser/context": "Запись аудио недоступна в этом браузере/контексте",
-  "Dictation": "Диктовка",
-  "Dictation becomes available once the page finishes connecting": "Диктовка станет доступна после подключения к документу",
-  "No connection to the collaboration server — dictation unavailable": "Нет связи с сервером совместного редактирования — диктовка недоступна",
-  "This page is read-only": "Страница открыта только для чтения",
   "Embed PDF": "Встроить PDF",
   "Upload and embed a PDF file.": "Загрузите и встроите PDF-файл.",
   "Embed as PDF": "Встроить как PDF",
@@ -419,9 +409,6 @@
   "Footnote {{number}}": "Сноска {{number}}",
   "Go to footnote": "Перейти к сноске",
   "Back to reference": "Вернуться к ссылке",
-  "Back to references": "Вернуться к ссылкам",
-  "Back to reference {{label}}": "Вернуться к ссылке {{label}}",
-  "Empty footnote": "Пустая сноска",
   "Math inline": "Строчная формула",
   "Insert inline math equation.": "Вставить математическое выражение в строку.",
   "Math block": "Блок формулы",
@@ -447,6 +434,9 @@
   "{{count}} command available_other": "Доступно {{count}} команд",
   "{{count}} result available_one": "Доступен 1 результат",
   "{{count}} result available_other": "Доступно {{count}} результатов",
+  "{{count}} result found_one": "Найден {{count}} результат",
+  "{{count}} result found_few": "Найдено {{count}} результата",
+  "{{count}} result found_other": "Найдено {{count}} результатов",
   "Equal columns": "Равные столбцы",
   "Left sidebar": "Левая боковая панель",
   "Right sidebar": "Правая боковая панель",
@@ -456,6 +446,7 @@
   "Names do not match": "Названия не совпадают",
   "Today, {{time}}": "Сегодня, {{time}}",
   "Yesterday, {{time}}": "Вчера, {{time}}",
+  "now": "сейчас",
   "Space created successfully": "Пространство успешно создано",
   "Space updated successfully": "Пространство успешно обновлено",
   "Space deleted successfully": "Пространство успешно удалено",
@@ -559,6 +550,7 @@
   "Add 2FA method": "Добавить метод 2FA",
   "Backup codes": "Резервные коды",
   "Disable": "Отключить",
+  "disabled": "отключено",
   "Invalid verification code": "Недействительный код подтверждения",
   "New backup codes have been generated": "Новые резервные коды сгенерированы",
   "Failed to regenerate backup codes": "Не удалось заново сгенерировать резервные коды",
@@ -702,62 +694,6 @@
   "AI search": "Поиск ИИ",
   "AI Answer": "Ответ ИИ",
   "Ask AI": "Спросить ИИ",
-  "AI agent": "AI-агент",
-  "Take a look at the current document": "Посмотри текущий документ",
-  "Start automatically": "Запускать автоматически",
-  "When on, picking this role sends a launch message and starts the chat. When off, the role is selected and you type the first message yourself.": "Когда включено, выбор этой роли отправляет стартовое сообщение и начинает чат. Когда выключено, роль выбирается, а первое сообщение вы вводите сами.",
-  "Launch message": "Стартовое сообщение",
-  "Sent automatically when this role is picked. Leave empty to use the default text. Ignored when “Start automatically” is off.": "Отправляется автоматически при выборе этой роли. Оставьте пустым, чтобы использовать текст по умолчанию. Игнорируется, когда «Запускать автоматически» выключено.",
-  "AI agent is typing…": "AI-агент печатает…",
-  "{{name}} is typing…": "{{name}} печатает…",
-  "Thinking…": "Думаю…",
-  "Thinking… · {{count}} tokens": "Думаю… · {{count}} токенов",
-  "Thinking… · {{count}} tokens_one": "Думаю… · {{count}} токен",
-  "Thinking… · {{count}} tokens_few": "Думаю… · {{count}} токена",
-  "Thinking… · {{count}} tokens_many": "Думаю… · {{count}} токенов",
-  "Thinking · {{count}} tokens": "Размышления · {{count}} токенов",
-  "Thinking · {{count}} tokens_one": "Размышления · {{count}} токен",
-  "Thinking · {{count}} tokens_few": "Размышления · {{count}} токена",
-  "Thinking · {{count}} tokens_many": "Размышления · {{count}} токенов",
-  "Agent role": "Роль агента",
-  "AI chat": "AI-чат",
-  "AI chat is disabled for this workspace.": "AI-чат отключён для этого рабочего пространства.",
-  "Ask a question about this documentation.": "Задайте вопрос об этой документации.",
-  "Ask a question…": "Задайте вопрос…",
-  "Ask the AI agent anything about your workspace.": "Спросите AI-агента о чём угодно по вашему рабочему пространству.",
-  "Ask the AI agent…": "Спросите AI-агента…",
-  "Copy chat": "Копировать чат",
-  "Dock to sidebar": "Закрепить в боковой панели",
-  "Undock": "Открепить",
-  "Created successfully": "Успешно создано",
-  "Context size / model limit": "Размер контекста / лимит модели",
-  "Context window (tokens)": "Окно контекста (токены)",
-  "Shown as used / total in the chat header. Leave empty to hide the limit.": "Показывается в шапке чата как использовано / всего. Пусто — лимит скрыт.",
-  "Delete this chat?": "Удалить этот чат?",
-  "Deleted successfully": "Успешно удалено",
-  "AI agent «{{role}}» on behalf of {{person}}": "AI-агент «{{role}}» от имени {{person}}",
-  "AI agent {{name}}": "AI-агент {{name}}",
-  "Failed to delete chat": "Не удалось удалить чат",
-  "Failed to rename chat": "Не удалось переименовать чат",
-  "Failed": "Ошибка",
-  "OK · {{n}}": "OK · {{n}}",
-  "Test": "Тест",
-  "No tools available": "Инструменты недоступны",
-  "Available tools": "Доступные инструменты",
-  "Minimize": "Свернуть",
-  "No chats yet.": "Чатов пока нет.",
-  "Send": "Отправить",
-  "Send when the agent finishes": "Отправить, когда агент закончит",
-  "Queue message": "Поставить в очередь",
-  "Remove queued message": "Убрать из очереди",
-  "Send now": "Отправить сейчас",
-  "Interrupt and send now": "Прервать и отправить сейчас",
-  "Something went wrong": "Что-то пошло не так",
-  "Stop": "Стоп",
-  "The AI agent could not respond. Please try again.": "AI-агент не смог ответить. Попробуйте ещё раз.",
-  "The AI provider is not configured. Ask an administrator to set it up.": "AI-провайдер не настроен. Попросите администратора настроить его.",
-  "Universal assistant": "Универсальный ассистент",
-  "You": "Вы",
   "AI is thinking...": "ИИ обрабатывает запрос...",
   "Thinking": "Думаю",
   "Ask a question...": "Задайте вопрос...",
@@ -784,8 +720,40 @@
   "Manage API keys for all users in the workspace. View the <anchor>API documentation</anchor> for usage details.": "Управляйте API-ключами для всех пользователей в рабочем пространстве. Смотрите <anchor>документацию по API</anchor> для получения информации об использовании.",
   "View the <anchor>API documentation</anchor> for usage details.": "Смотрите <anchor>документацию по API</anchor> для получения информации об использовании.",
   "View the <anchor>MCP documentation</anchor>.": "Смотрите <anchor>документацию по MCP</anchor>.",
-  "Instructions": "Инструкции",
+  "AI / Models": "ИИ / Модели",
+  "AI / External tools (MCP)": "ИИ / Внешние инструменты (MCP)",
+  "Add server": "Добавить сервер",
+  "Edit server": "Изменить сервер",
+  "Delete server": "Удалить сервер",
+  "Are you sure you want to delete this MCP server?": "Вы уверены, что хотите удалить этот MCP-сервер?",
+  "No external servers configured": "Внешние серверы не настроены",
+  "Server name": "Имя сервера",
+  "Transport": "Транспорт",
+  "URL": "URL",
+  "Authorization header": "Заголовок авторизации",
+  "Tool allowlist": "Список разрешённых инструментов",
+  "Optional. Leave empty to allow all tools the server exposes.": "Необязательно. Оставьте пустым, чтобы разрешить все инструменты, которые предоставляет сервер.",
   "Optional guidance for the agent on how and when to use this server's tools. Injected into the system prompt. The server's tools are namespaced as \"<server name>_*\".": "Необязательное указание агенту, как и когда использовать инструменты этого сервера. Добавляется в системный промпт. Инструменты сервера именуются с префиксом «<имя сервера>_*».",
+  "Test": "Тест",
+  "Available tools": "Доступные инструменты",
+  "No tools available": "Инструменты недоступны",
+  "Failed": "Ошибка",
+  "OK · {{n}}": "OK · {{n}}",
+  "Created successfully": "Успешно создано",
+  "Deleted successfully": "Успешно удалено",
+  "Clear": "Очистить",
+  "Provider": "Провайдер",
+  "•••• set": "•••• задан",
+  "Clear key": "Очистить ключ",
+  "Base URL": "Базовый URL",
+  "Chat model": "Модель чата",
+  "Embedding model": "Модель эмбеддингов",
+  "System message": "Системное сообщение",
+  "A built-in safety framework is always appended.": "Встроенный набор правил безопасности всегда добавляется автоматически.",
+  "Test connection": "Проверить соединение",
+  "Connection successful": "Соединение установлено",
+  "Connection failed": "Не удалось установить соединение",
+  "Only workspace admins can manage AI provider settings.": "Управлять настройками провайдера ИИ могут только администраторы рабочего пространства.",
   "Sources": "Источники",
   "AI Answers not available for attachments": "Ответы ИИ недоступны для вложений",
   "No answer available": "Ответ недоступен",
@@ -1013,6 +981,7 @@
   "Try again": "Попробовать снова",
   "Untitled chat": "Чат без названия",
   "No document": "Без документа",
+  "You": "Вы",
   "What can I help you with?": "Чем я могу вам помочь?",
   "Are you sure you want to revoke this {{credential}}": "Вы уверены, что хотите отозвать этот {{credential}}",
   "Automatically provision users and groups from your identity provider via SCIM.": "Автоматически предоставляйте доступ пользователям и группам из вашего провайдера удостоверений через SCIM.",
@@ -1041,6 +1010,9 @@
   "Page menu": "Меню страницы",
   "Expand": "Развернуть",
   "Collapse": "Свернуть",
+  "Expand all": "Развернуть все",
+  "Collapse all": "Свернуть все",
+  "Couldn't expand the tree: {{reason}}": "Не удалось развернуть дерево: {{reason}}",
   "Comment menu": "Меню комментария",
   "Group menu": "Меню группы",
   "Show hidden breadcrumbs": "Показать скрытые хлебные крошки",
@@ -1077,7 +1049,7 @@
   "Search pages and spaces...": "Поиск страниц и пространств...",
   "No results found": "Результаты не найдены",
   "You don't have permission to create pages here": "У вас нет прав на создание страниц здесь",
-  "Chat menu": "Меню чата",
+  "Chat menu for {{title}}": "Меню чата для {{title}}",
   "API key menu": "Меню API-ключа",
   "Jump to comment selection": "Перейти к выбору комментария",
   "Slash commands": "Команды со слешем",
@@ -1131,6 +1103,9 @@
   "Undo": "Отменить",
   "Redo": "Повторить",
   "Backlinks": "Обратные ссылки",
+  "Back to references": "Вернуться к ссылкам",
+  "Back to reference {{label}}": "Вернуться к ссылке {{label}}",
+  "Empty footnote": "Пустая сноска",
   "Last updated by": "Последний изменивший",
   "Last updated": "Последнее обновление",
   "Stats": "Статистика",
@@ -1164,6 +1139,7 @@
   "Page title": "Заголовок страницы",
   "Page content": "Содержимое страницы",
   "Member actions": "Действия с участником",
+  "Member actions for {{name}}": "Действия с участником {{name}}",
   "Toggle password visibility": "Переключить видимость пароля",
   "Send comment": "Отправить комментарий",
   "Token actions": "Действия с токеном",
@@ -1183,11 +1159,187 @@
   "Removed from favorites": "Удалено из избранного",
   "Added {{name}} to favorites": "{{name}} добавлено в избранное",
   "Removed {{name}} from favorites": "{{name}} удалено из избранного",
+  "Label added": "Метка добавлена",
+  "Label removed": "Метка удалена",
+  "Image updated": "Изображение обновлено",
+  "Unsupported image type": "Неподдерживаемый тип изображения",
+  "Member deactivated": "Участник деактивирован",
+  "Member activated": "Участник активирован",
+  "Name is required": "Укажите имя",
+  "Name must be 40 characters or fewer": "Имя должно содержать не более 40 символов",
+  "Group name must be at least 2 characters": "Название группы должно содержать не менее 2 символов",
+  "Group name must be 100 characters or fewer": "Название группы должно содержать не более 100 символов",
+  "Description must be 500 characters or fewer": "Описание должно содержать не более 500 символов",
+  "Invalid invitation link": "Недействительная ссылка-приглашение",
   "Page menu for {{name}}": "Меню страницы для {{name}}",
   "Create subpage of {{name}}": "Создать подстраницу для {{name}}",
+  "AI chat": "AI-чат",
+  "Ask a question about this documentation.": "Задайте вопрос об этой документации.",
+  "Ask a question…": "Задайте вопрос…",
+  "Thinking…": "Думаю…",
+  "Thinking… · {{count}} tokens": "Думаю… · {{count}} токенов",
+  "Thinking… · {{count}} tokens_one": "Думаю… · {{count}} токен",
+  "Thinking… · {{count}} tokens_few": "Думаю… · {{count}} токена",
+  "Thinking… · {{count}} tokens_many": "Думаю… · {{count}} токенов",
+  "Thinking… · {{count}} tokens_other": "Думаю… · {{count}} токенов",
+  "Thinking · {{count}} tokens": "Размышления · {{count}} токенов",
+  "Thinking · {{count}} tokens_one": "Размышления · {{count}} токен",
+  "Thinking · {{count}} tokens_few": "Размышления · {{count}} токена",
+  "Thinking · {{count}} tokens_many": "Размышления · {{count}} токенов",
+  "Thinking · {{count}} tokens_other": "Размышления · {{count}} токенов",
+  "The assistant is unavailable right now. Please try again.": "Ассистент сейчас недоступен. Попробуйте ещё раз.",
+  "Public share assistant": "Ассистент публичного доступа",
+  "Let anonymous visitors of public shares ask an AI assistant scoped to that share's pages. You pay for the tokens.": "Позвольте анонимным посетителям публичных ссылок обращаться к ИИ-ассистенту в рамках страниц этой публикации. Токены оплачиваете вы.",
+  "Public assistant model": "Модель публичного ассистента",
+  "Defaults to the chat model": "По умолчанию используется модель чата",
+  "Optional cheaper model id for the public assistant. Empty uses the chat model above.": "Необязательный более дешёвый идентификатор модели для публичного ассистента. Если пусто, используется модель чата выше.",
+  "Assistant identity": "Личность ассистента",
+  "Pick an agent role whose persona the public assistant adopts. The safety rules always still apply.": "Выберите роль агента, чью личность примет публичный ассистент. Правила безопасности всегда остаются в силе.",
+  "Built-in assistant persona": "Встроенная личность ассистента",
+  "Minimize": "Свернуть",
+  "Context size / model limit": "Размер контекста / лимит модели",
+  "Context window (tokens)": "Окно контекста (токены)",
+  "Shown as used / total in the chat header. Leave empty to hide the limit.": "Показывается в шапке чата как использовано / всего. Пусто — лимит скрыт.",
+  "AI agent": "AI-агент",
+  "Take a look at the current document": "Посмотри текущий документ",
+  "AI agent is typing…": "AI-агент печатает…",
+  "{{name}} is typing…": "{{name}} печатает…",
+  "Send": "Отправить",
+  "Send when the agent finishes": "Отправить, когда агент закончит",
+  "Queue message": "Поставить в очередь",
+  "Remove queued message": "Убрать из очереди",
+  "Send now": "Отправить сейчас",
+  "Interrupt and send now": "Прервать и отправить сейчас",
+  "Stop": "Стоп",
+  "Response stopped.": "Ответ остановлен.",
+  "Connection lost — the answer was interrupted.": "Соединение потеряно — ответ был прерван.",
+  "Response stopped (manually or the connection dropped).": "Ответ остановлен (вручную или из-за разрыва соединения).",
+  "Chat menu": "Меню чата",
+  "No chats yet.": "Чатов пока нет.",
+  "Delete this chat?": "Удалить этот чат?",
+  "Ask the AI agent…": "Спросите AI-агента…",
+  "Ask the AI agent anything about your workspace.": "Спросите AI-агента о чём угодно по вашему рабочему пространству.",
+  "Failed to rename chat": "Не удалось переименовать чат",
+  "Failed to delete chat": "Не удалось удалить чат",
+  "Something went wrong": "Что-то пошло не так",
+  "AI chat is disabled for this workspace.": "AI-чат отключён для этого рабочего пространства.",
+  "The AI provider is not configured. Ask an administrator to set it up.": "AI-провайдер не настроен. Попросите администратора настроить его.",
+  "The AI agent could not respond. Please try again.": "AI-агент не смог ответить. Попробуйте ещё раз.",
+  "Searched pages": "Поиск по страницам",
+  "Read page": "Прочитана страница",
+  "Created page": "Создана страница",
+  "Updated page": "Обновлена страница",
+  "Renamed page": "Переименована страница",
+  "Moved page": "Перемещена страница",
+  "Deleted page (to trash)": "Удалена страница (в корзину)",
+  "Commented": "Добавлен комментарий",
+  "Resolved comment": "Комментарий решён",
+  "Ran tool {{name}}": "Выполнен инструмент {{name}}",
+  "AI agent «{{role}}» on behalf of {{person}}": "AI-агент «{{role}}» от имени {{person}}",
+  "AI agent {{name}}": "AI-агент {{name}}",
+  "Endpoints": "Эндпоинты",
+  "where we fetch models": "откуда мы получаем модели",
+  "All endpoints are OpenAI-compatible. Point the Base URL at OpenAI, OpenRouter, a local Ollama, or any self-hosted server.": "Все эндпоинты совместимы с OpenAI. Укажите в базовом URL адрес OpenAI, OpenRouter, локального Ollama или любого self-hosted сервера.",
+  "Chat / LLM": "Чат / LLM",
+  "root": "корневой",
+  "Semantic search": "Семантический поиск",
+  "Voice / STT": "Голос / STT",
+  "Voice dictation": "Голосовой ввод",
+  "Streaming dictation": "Потоковый голосовой ввод",
+  "Transcribe as you speak, cutting on pauses": "Транскрибирование по мере речи, с разбивкой на паузах",
+  "Voice dictation is not available yet.": "Голосовой ввод пока недоступен.",
+  "Test endpoint": "Проверить эндпоинт",
+  "Save and test": "Сохранить и проверить",
+  "Save endpoints": "Сохранить эндпоинты",
+  "Configured and enabled": "Настроено и включено",
+  "Configured but disabled": "Настроено, но отключено",
+  "Enabled but not configured": "Включено, но не настроено",
+  "Not configured": "Не настроено",
+  "External tools": "Внешние инструменты",
+  "Gitmost as MCP client": "Gitmost как MCP-клиент",
+  "Servers the agent calls out to.": "Серверы, к которым обращается агент.",
+  "MCP server": "MCP-сервер",
+  "expose the workspace": "открыть доступ к рабочему пространству",
+  "Enable MCP server": "Включить MCP-сервер",
+  "Exposes the workspace as an MCP server at /mcp — this provides a capability, it doesn't consume a model.": "Открывает рабочее пространство как MCP-сервер по адресу /mcp — это предоставляет возможность, а не потребляет модель.",
+  "Resolves to {{url}}": "Разрешается в {{url}}",
+  "Model": "Модель",
+  "Done": "Готово",
+  "shared prompt · safety framework appended automatically": "общий промпт · правила безопасности добавляются автоматически",
+  "/v1/chat/completions · root endpoint — Embeddings and Voice inherit its URL and key": "/v1/chat/completions · корневой эндпоинт — Эмбеддинги и Голос наследуют его URL и ключ",
+  "/v1/embeddings · embeds pages so semantic search can find them": "/v1/embeddings · создаёт эмбеддинги страниц, чтобы их находил семантический поиск",
+  "/v1/audio/transcriptions · works with local whisper (speaches / faster-whisper-server)": "/v1/audio/transcriptions · работает с локальным whisper (speaches / faster-whisper-server)",
+  "Vector search · requires pgvector": "Векторный поиск · требуется pgvector",
+  "Embedding API key": "API-ключ для эмбеддингов",
+  "Embeddings": "Эмбеддинги",
+  "Leave empty to use the chat API key": "Оставьте пустым, чтобы использовать API-ключ чата",
+  "Leave empty to use the chat base URL": "Оставьте пустым, чтобы использовать базовый URL чата",
+  "Reindex now": "Переиндексировать сейчас",
+  "Start dictation": "Начать диктовку",
+  "Stop recording": "Остановить запись",
+  "Transcribing…": "Транскрибация…",
+  "Microphone access denied": "Доступ к микрофону запрещён",
+  "No microphone found": "Микрофон не найден",
+  "Could not start recording": "Не удалось начать запись",
+  "Transcription failed": "Не удалось распознать речь",
+  "Transcribe": "Транскрибировать",
+  "No speech detected": "Речь не распознана",
+  "Voice dictation is not configured": "Голосовой ввод не настроен",
+  "Microphone is unavailable or already in use": "Микрофон недоступен или уже используется",
+  "Audio recording is not available in this browser/context": "Запись аудио недоступна в этом браузере/контексте",
+  "Dictation": "Диктовка",
+  "Dictation becomes available once the page finishes connecting": "Диктовка станет доступна после подключения к документу",
+  "No connection to the collaboration server — dictation unavailable": "Нет связи с сервером совместного редактирования — диктовка недоступна",
+  "This page is read-only": "Страница открыта только для чтения",
+  "Request format": "Формат запроса",
+  "How transcription requests are sent to the endpoint": "Как запросы на транскрибирование отправляются на эндпоинт",
+  "OpenAI-compatible (multipart/form-data)": "Совместимо с OpenAI (multipart/form-data)",
+  "OpenRouter (JSON, base64 audio)": "OpenRouter (JSON, аудио в base64)",
   "Dictation language": "Язык диктовки",
   "Auto-detect": "Автоопределение",
   "Spoken language hint sent to the transcription model. Auto-detect lets the model decide.": "Подсказка языка речи для модели транскрипции. «Автоопределение» оставляет выбор за моделью.",
+  "Agent role": "Роль агента",
+  "Universal assistant": "Универсальный ассистент",
+  "Add role": "Добавить роль",
+  "Edit role": "Изменить роль",
+  "Role name": "Название роли",
+  "e.g. Proofreader": "напр. Корректор",
+  "Optional. Shown as the chat badge.": "Необязательно. Отображается как значок чата.",
+  "Optional. A short note about what this role does.": "Необязательно. Краткое описание того, что делает эта роль.",
+  "Instructions": "Инструкции",
+  "The built-in safety framework is always added automatically.": "Встроенный набор правил безопасности всегда добавляется автоматически.",
+  "Model provider override": "Переопределение провайдера модели",
+  "Optional. Defaults to the workspace provider.": "Необязательно. По умолчанию используется провайдер рабочего пространства.",
+  "Model override": "Переопределение модели",
+  "Optional. Defaults to the workspace model.": "Необязательно. По умолчанию используется модель рабочего пространства.",
+  "e.g. gpt-4o-mini": "напр. gpt-4o-mini",
+  "If you choose a different provider, it must already be configured in AI settings.": "Если вы выбираете другого провайдера, он уже должен быть настроен в настройках ИИ.",
+  "Start automatically": "Запускать автоматически",
+  "When on, picking this role sends a launch message and starts the chat. When off, the role is selected and you type the first message yourself.": "Когда включено, выбор этой роли отправляет стартовое сообщение и начинает чат. Когда выключено, роль выбирается, а первое сообщение вы вводите сами.",
+  "Launch message": "Стартовое сообщение",
+  "Sent automatically when this role is picked. Leave empty to use the default text. Ignored when “Start automatically” is off.": "Отправляется автоматически при выборе этой роли. Оставьте пустым, чтобы использовать текст по умолчанию. Игнорируется, когда «Запускать автоматически» выключено.",
+  "Agent roles": "Роли агента",
+  "Reusable presets that shape the agent's behavior (and optionally its model). Picked when starting a new chat.": "Многоразовые пресеты, определяющие поведение агента (и, при желании, его модель). Выбираются при запуске нового чата.",
+  "No roles configured": "Роли не настроены",
+  "Delete role": "Удалить роль",
+  "Are you sure you want to delete this role?": "Вы уверены, что хотите удалить эту роль?",
+  "HTML embed": "HTML-вставка",
+  "Edit HTML embed": "Изменить HTML-вставку",
+  "HTML embed is disabled in this workspace": "HTML-вставки отключены в этом рабочем пространстве",
+  "Click to add HTML / CSS / JS": "Нажмите, чтобы добавить HTML / CSS / JS",
+  "This HTML/CSS/JS runs in a sandboxed frame and cannot access the viewer's session, cookies, or API.": "Этот HTML/CSS/JS выполняется в изолированном фрейме и не имеет доступа к сессии, cookie или API просматривающего.",
+  "<script>...</script>": "<script>...</script>",
+  "Height (px, blank = auto)": "Высота (px, пусто = авто)",
+  "advanced": "дополнительно",
+  "Enable HTML embed": "Включить HTML-вставки",
+  "Allow members to insert raw HTML/CSS/JavaScript blocks. The block renders in a sandboxed frame and cannot access the viewer's session, cookies, or API. Off by default.": "Разрешить участникам вставлять блоки с необработанным HTML/CSS/JavaScript. Блок отображается в изолированном фрейме и не имеет доступа к сессии, cookie или API просматривающего. По умолчанию выключено.",
+  "When enabled, any member can insert an HTML embed block. The toggle just enables or disables the block type workspace-wide.": "Когда включено, любой участник может вставить блок HTML-вставки. Переключатель просто включает или отключает этот тип блока во всём рабочем пространстве.",
+  "Embeds run inside a sandboxed iframe with a separate origin, so they cannot read or modify the page they are embedded in.": "Вставки выполняются в изолированном iframe с отдельным источником, поэтому они не могут читать или изменять страницу, в которую встроены.",
+  "Turning this off hides existing embeds (they render as a disabled placeholder) and stops serving them on public share pages.": "Отключение этой опции скрывает существующие вставки (они отображаются как отключённая заглушка) и прекращает их показ на публичных страницах.",
+  "Analytics / tracker": "Аналитика / трекер",
+  "Injected verbatim into the <head> of PUBLIC SHARE pages only (same-origin). For analytics snippets (Google Analytics, Yandex.Metrika, etc.). Admin only.": "Вставляется дословно в <head> только ПУБЛИЧНЫХ страниц (тот же источник). Для сниппетов аналитики (Google Analytics, Яндекс.Метрика и т. п.). Только для администраторов.",
+  "Go to login page": "Перейти на страницу входа",
+  "Move to space": "Переместить в пространство",
   "Float left (wrap text)": "Обтекание слева",
   "Float right (wrap text)": "Обтекание справа",
   "Inline (side by side)": "В ряд",
@@ -1199,6 +1351,7 @@
   "Showing {{count}} subpages_one": "Показано {{count}} подстраница",
   "Showing {{count}} subpages_few": "Показано {{count}} подстраницы",
   "Showing {{count}} subpages_many": "Показано {{count}} подстраниц",
+  "Showing {{count}} subpages_other": "Показано {{count}} подстраниц",
   "Protocol": "Протокол",
   "How chat requests are sent and how reasoning is surfaced": "Как отправляются запросы чата и как показывается reasoning",
   "OpenAI-compatible (surfaces reasoning)": "OpenAI-совместимый (показывает reasoning)",
@@ -1268,7 +1421,6 @@
   "Retry": "Повторить",
   "The catalog is empty": "Каталог пуст",
   "No role bundles are published for this language yet. Try switching the content language.": "Для этого языка ещё не опубликовано ни одного набора ролей. Попробуйте сменить язык контента.",
-  "No roles configured": "Роли не настроены",
   "Already up to date": "Уже актуальна",
   "Updated to the latest version": "Обновлено до последней версии",
   "This role is no longer in the catalog": "Эта роль больше не представлена в каталоге",

apps/client/src/components/chunk-load-error-boundary.test.ts

@@ -1,5 +1,5 @@
 import { describe, it, expect } from "vitest";
-import { isChunkLoadError } from "./chunk-load-error-boundary";
+import { isChunkLoadError, shouldAutoReload } from "./chunk-load-error-boundary";
 
 // The detector decides whether a caught render error is a stale-deploy chunk-404
 // (→ auto-reload to fetch the new manifest) vs a genuine app error (→ generic
@@ -35,3 +35,31 @@ describe("isChunkLoadError", () => {
     expect(isChunkLoadError(err)).toBe(false);
   });
 });
+
+// The window gate replaces the old one-shot flag: it must permit recovery across
+// several deploys in one tab (each > window apart) while still stopping an infinite
+// reload loop when a lazy chunk is permanently broken (a second failure < window).
+describe("shouldAutoReload", () => {
+  const WINDOW = 5 * 60 * 1000;
+  const NOW = 1_000_000_000_000;
+
+  it("allows a reload when we have never auto-reloaded", () => {
+    expect(shouldAutoReload(NOW, null, WINDOW)).toBe(true);
+  });
+
+  it("allows a reload when the last one was 6 minutes ago (outside the window)", () => {
+    expect(shouldAutoReload(NOW, NOW - 6 * 60 * 1000, WINDOW)).toBe(true);
+  });
+
+  it("blocks a reload when the last one was 1 minute ago (inside the window)", () => {
+    expect(shouldAutoReload(NOW, NOW - 1 * 60 * 1000, WINDOW)).toBe(false);
+  });
+
+  it("blocks a reload exactly at the window boundary (not strictly older)", () => {
+    expect(shouldAutoReload(NOW, NOW - WINDOW, WINDOW)).toBe(false);
+  });
+
+  it("allows a reload when the stored timestamp is unparseable (NaN)", () => {
+    expect(shouldAutoReload(NOW, NaN, WINDOW)).toBe(true);
+  });
+});

apps/client/src/components/chunk-load-error-boundary.tsx

@@ -2,7 +2,25 @@ import { ReactNode } from "react";
 import { ErrorBoundary } from "react-error-boundary";
 import { Button, Center, Stack, Text } from "@mantine/core";
 
-const RELOAD_FLAG = "chunk-reload-attempted";
+// sessionStorage key holding the epoch-ms timestamp of the last automatic reload.
+const RELOAD_AT_KEY = "chunk-reload-at";
+// Allow at most one automatic reload per this window. A stale-deploy 404 is cured
+// by a single reload, so anything inside the window is treated as a reload loop
+// (permanently-broken chunk) and falls through to the manual UI. A window (rather
+// than a one-shot flag) lets a SECOND deploy in the same tab's lifetime recover too.
+const RELOAD_WINDOW_MS = 5 * 60 * 1000;
+
+// Pure window decision, unit-tested in isolation: auto-reload only if we have never
+// auto-reloaded (lastReloadAt null/NaN) or the last one was strictly older than the
+// window. Anything inside the window is suppressed to break an infinite reload loop.
+export function shouldAutoReload(
+  now: number,
+  lastReloadAt: number | null,
+  windowMs: number,
+): boolean {
+  if (lastReloadAt === null || Number.isNaN(lastReloadAt)) return true;
+  return now - lastReloadAt > windowMs;
+}
 
 // Heuristic detection of a failed dynamic import. Since the code-splitting work,
 // every route (plus Aside / AiChatWindow) is React.lazy: when a new deploy
@@ -24,12 +42,16 @@ export function isChunkLoadError(error: unknown): boolean {
 function handleError(error: unknown) {
   if (!isChunkLoadError(error)) return;
   // A stale-chunk 404 is cured by a full reload that re-fetches index.html and
-  // the new chunk manifest. Auto-reload once, guarding against a reload loop
+  // the new chunk manifest. Auto-reload at most once per RELOAD_WINDOW_MS: this
-  // (e.g. a genuinely missing chunk) with a one-shot sessionStorage flag. If the
+  // recovers across multiple deploys in a single tab's lifetime, yet a
-  // flag is already set we fall through to the manual recovery UI below.
+  // permanently-broken lazy chunk (which would loop) is stopped after the first
+  // reload and falls through to the manual recovery UI below.
   try {
-    if (sessionStorage.getItem(RELOAD_FLAG)) return;
+    const raw = sessionStorage.getItem(RELOAD_AT_KEY);
-    sessionStorage.setItem(RELOAD_FLAG, "1");
+    const lastReloadAt = raw === null ? null : Number.parseInt(raw, 10);
+    const now = Date.now();
+    if (!shouldAutoReload(now, lastReloadAt, RELOAD_WINDOW_MS)) return;
+    sessionStorage.setItem(RELOAD_AT_KEY, String(now));
   } catch {
     // sessionStorage unavailable (private mode / disabled): skip the automatic
     // reload rather than risk an unguarded loop; the fallback UI still recovers.

apps/client/src/features/ai-chat/components/ai-chat-window.tsx

@@ -86,19 +86,11 @@ const MIN_HEIGHT = 400;
 // Margin kept between the window and the viewport edges while dragging.
 const EDGE_MARGIN = 8;
 
-// #184 phase 1.5 / #430: backstop for the degraded-poll fallback. The poll is
+// #184 phase 1.5 / #430 / #488: the degraded-poll fallback. The window owns only
-// armed when a resume attempt could not attach to the live run and disarmed by the
+// a DUMB 2.5s timer, gated by an armed flag; the THREAD's run-lifecycle FSM owns
-// thread on settle / local stream; this cap is the ONLY backstop against an endless
+// arm/disarm AND the inactivity cap that turns a stuck run into a `stalled` banner
-// tick (a stuck 'streaming' row before the boot-sweep, or a user-tail 204 with no
+// (#488 commit 4a — the cap moved into the thread so polling->stalled is a single
-// run).
+// FSM transition; the window no longer silently stops polling at the cap).
-//
-// #430: measured from RUN ACTIVITY, not from arm-time. A real autonomous run takes
-// 11-25 min — longer than a fixed 10-min-from-start cap, which used to cut the poll
-// off mid-run. Instead we cap on INACTIVITY: keep polling as long as the run is
-// still making progress (its persisted rows keep changing), and only give up after
-// this long with NO new activity. A genuinely stuck run produces no row changes, so
-// the idle cap still bounds it; a long-but-progressing run polls to completion.
-const DEGRADED_POLL_IDLE_MAX_MS = 10 * 60_000;
 
 /** Compact token formatter: 1.2M / 3.4k / 950. */
 function formatTokens(n: number): string {
@@ -259,17 +251,13 @@ export default function AiChatWindow() {
     [roles],
   );
 
-  // #184 phase 1.5: degraded-poll fallback (replaces the F4/F5/F7 latches). When
+  // #184 phase 1.5 / #488: degraded-poll fallback. ChatThread's FSM arms this via
-  // ChatThread could not attach to a still-running run it arms this via
+  // onResumeFallback(true) when it enters a poll-bearing recovery (attach 204 /
-  // onResumeFallback(true); the thread disarms it on settle / local stream. The
+  // starved finish / stop) and disarms it on settle / local stream / stalled. The
-  // window only OWNS the timer (armedAtRef stamps when it was armed for the cap).
+  // window owns ONLY the dumb 2.5s timer; the THREAD owns arm/disarm AND the
+  // inactivity cap (a stuck run -> the thread's `stalled` banner disarms this).
   const [degradedPoll, setDegradedPoll] = useState(false);
-  // #430: timestamp of the LAST run activity while the poll is armed — stamped on
-  // arm and re-stamped whenever the polled rows change (see the effect below). The
-  // idle cap is measured from this, so a long-but-progressing run keeps polling.
-  const lastActivityAtRef = useRef(0);
   const onResumeFallback = useCallback((active: boolean): void => {
-    if (active) lastActivityAtRef.current = Date.now();
     setDegradedPoll(active);
   }, []);
   // Reset the degraded poll whenever the open chat changes: it is scoped to the
@@ -281,33 +269,17 @@ export default function AiChatWindow() {
   const { data: messageRows, isLoading: messagesLoading } =
     useAiChatMessagesQuery(
       activeChatId ?? undefined,
-      // DELIBERATELY DUMB (invariant 8 / task 2.4): poll every 2.5s while armed
+      // DELIBERATELY DUMB: poll every 2.5s WHILE ARMED, otherwise off. NO error
-      // and while the run is still active (#430: under the INACTIVITY cap, not a
+      // checks (TanStack resets fetchFailureCount each fetch; the poll must survive
-      // fixed-from-start cap); otherwise off. NO error checks (TanStack v5 resets
+      // a server restart), NO tail checks, NO cap here — the settled/stalled/idle-cap
-      // fetchFailureCount each fetch, so consecutive errors are not expressible —
+      // semantics all live in ChatThread's FSM, which disarms via onResumeFallback.
-      // and the poll must survive a server restart) and NO tail checks (the
+      () => (degradedPoll === true ? 2500 : false),
-      // settled/local-stream semantics live in ChatThread, which disarms via
-      // onResumeFallback(false)). The idle cap is the only backstop.
-      () =>
-        degradedPoll === true &&
-        Date.now() - lastActivityAtRef.current < DEGRADED_POLL_IDLE_MAX_MS
-          ? 2500
-          : false,
       // #344: gate on windowOpen too — no message history is fetched (and no
       // degraded poll runs) while the window is closed; it loads when the window
       // opens with an active chat.
       windowOpen,
     );
 
-  // #430: re-stamp the activity clock whenever the polled rows change while the
-  // poll is armed. TanStack keeps the same `messageRows` reference across refetches
-  // that return deep-equal data (structural sharing), so a new reference means the
-  // run genuinely progressed — which extends the inactivity cap above. A stuck run
-  // yields no reference change, so the cap eventually fires and stops the poll.
-  useEffect(() => {
-    if (degradedPoll) lastActivityAtRef.current = Date.now();
-  }, [degradedPoll, messageRows]);
-
   // #184 reconnect-and-live-follow. Whether detached agent runs are enabled for
   // this workspace. When the feature is off no runs are ever created, so the
   // resume attempt would only ever 204; gating ChatThread's resume on it avoids a

apps/client/src/features/ai-chat/components/ai-chat.module.css

@@ -55,6 +55,15 @@
     padding-inline-start: 1.4em;
 }
 
+/* The canonical converter renders list items through the editor schema, which
+   wraps each item's content in a <p> (listItem content is `paragraph+`). Drop
+   that paragraph's block margin so list items render TIGHT (no extra vertical
+   gap), matching the previous marked output — same rule already applied to
+   table cells above (issue #347). */
+.markdown li p {
+    margin: 0;
+}
+
 /* GFM tables in assistant markdown. The chat lives in a NARROW side panel, so a
    wide LLM table must scroll horizontally instead of collapsing its columns:
    `.markdown` sets `word-break: break-word`, which (with the default table
@@ -172,6 +181,14 @@
     margin: 0 0 4px;
 }
 
+/* Same as `.markdown li p` above: the canonical converter wraps every list
+   item's content in a <p>, so without this each reasoning-panel list item would
+   pick up `.reasoningText p`'s 4px bottom margin and render too loose. Drop it
+   so Reasoning-panel lists stay tight, mirroring the pre-#347 marked output. */
+.reasoningText li p {
+    margin: 0;
+}
+
 .inputWrapper {
     flex: 0 0 auto;
     padding-top: var(--mantine-spacing-xs);

apps/client/src/features/ai-chat/components/message-item.tsx

@@ -47,6 +47,13 @@ interface MessageItemProps {
    * agent's raw query/argument text.
    */
   showInput?: boolean;
+  /**
+   * Forwarded to ToolCallCard: whether a failed tool card renders its raw
+   * errorText. Defaults to true (internal chat). The public share passes false so
+   * internal detail in a tool error is never painted (belt to the server-side
+   * byte sanitization).
+   */
+  showErrors?: boolean;
   /**
    * Neutralize internal/relative markdown links in the rendered answer (drop
    * their href so they become inert text). Defaults to false (internal chat,
@@ -125,6 +132,7 @@ function MessageItem({
   message,
   showCitations = true,
   showInput = true,
+  showErrors = true,
   neutralizeInternalLinks = false,
   assistantName,
   turnStreaming = false,
@@ -219,6 +227,7 @@ function MessageItem({
               part={part as unknown as ToolUiPart}
               showCitations={showCitations}
               showInput={showInput}
+              showErrors={showErrors}
             />
           );
         }
@@ -284,6 +293,7 @@ export function arePropsEqual(
     prev.signature === next.signature &&
     prev.showCitations === next.showCitations &&
     prev.showInput === next.showInput &&
+    prev.showErrors === next.showErrors &&
     prev.neutralizeInternalLinks === next.neutralizeInternalLinks &&
     prev.assistantName === next.assistantName &&
     // The turn-end flip re-renders every row once (cheap, terminal event) —

apps/client/src/features/ai-chat/components/message-list.tsx

@@ -32,6 +32,12 @@ interface MessageListProps {
    * doesn't see the agent's raw query/argument text.
    */
   showInput?: boolean;
+  /**
+   * Forwarded to MessageItem -> ToolCallCard: whether a failed tool card renders
+   * its raw errorText. Defaults to true (internal chat). The public share passes
+   * false so internal detail in a tool error is never painted.
+   */
+  showErrors?: boolean;
   /**
    * Forwarded to MessageItem: neutralize internal/relative markdown links in
    * the rendered answers (drop their href so they render as inert text).
@@ -127,6 +133,7 @@ export default function MessageList({
   emptyState,
   showCitations = true,
   showInput = true,
+  showErrors = true,
   neutralizeInternalLinks = false,
   assistantName,
 }: MessageListProps) {
@@ -217,6 +224,7 @@ export default function MessageList({
             signature={messageSignature(message)}
             showCitations={showCitations}
             showInput={showInput}
+            showErrors={showErrors}
             neutralizeInternalLinks={neutralizeInternalLinks}
             assistantName={assistantName}
             // Turn-level liveness, gated to the TAIL row: only the tail message

apps/client/src/features/ai-chat/components/tool-call-card.tsx

@@ -30,6 +30,16 @@ interface ToolCallCardProps {
    * the extra summary line, leaving the card (the action log) intact.
    */
   showInput?: boolean;
+  /**
+   * Whether to render the tool's raw errorText on a failed call. Defaults to true
+   * (the internal chat, where the operator may debug). The public share passes
+   * false: a tool error string can carry internal detail (an internal page title,
+   * a stack fragment, a provider message). This is the RENDER gate only — the
+   * authoritative fix also sanitizes the bytes server-side (see
+   * PublicShareChatToolsService.forShare), so a share reader never receives raw
+   * error text over the wire, not just never sees it painted (#394).
+   */
+  showErrors?: boolean;
 }
 
 /**
@@ -41,6 +51,7 @@ export default function ToolCallCard({
   part,
   showCitations = true,
   showInput = true,
+  showErrors = true,
 }: ToolCallCardProps) {
   const { t } = useTranslation();
   const toolName = getToolName(part);
@@ -74,7 +85,7 @@ export default function ToolCallCard({
         </Text>
       )}
 
-      {state === "error" && part.errorText && (
+      {state === "error" && showErrors && part.errorText && (
         <Text size="xs" c="red" mt={2}>
           {part.errorText}
         </Text>

apps/client/src/features/ai-chat/services/ai-chat-service.ts

@@ -57,6 +57,25 @@ export async function stopRun(
   return req.data;
 }
 
+/**
+ * #488: the run-fact — "is a run active on this chat?" — first-class from the
+ * server (POST /ai-chat/run). Called on mount to seed the client FSM's run-fact
+ * and to VERIFY after a supersede mismatch (an observer following a superseded
+ * run asks for the latest run and follows it). Returns the latest run row (with
+ * its `id` and `status`) and its projected assistant message, or `run: null` when
+ * the chat has never had a run. Owner-gated server-side.
+ */
+export async function getRun(chatId: string): Promise<{
+  run: { id: string; status: string } | null;
+  message: IAiChatMessageRow | null;
+}> {
+  const req = await api.post<{
+    run: { id: string; status: string } | null;
+    message: IAiChatMessageRow | null;
+  }>("/ai-chat/run", { chatId });
+  return req.data;
+}
+
 /**
  * Resolve the chat bound to a document (the current user's most-recent chat
  * created on that page), or null when there is none. Drives auto-open-on-page.

apps/client/src/features/ai-chat/state/run-fsm.spec.md

@@ -0,0 +1,183 @@
+# AI-chat run-lifecycle FSM — design spec (#488)
+
+This is the written design that `run-fsm.ts` implements. It ships in the PR (issue
+#488 commit 1: "the spec is written FIRST and enters the PR"). It has four parts:
+(1) the event × state transition table, (2) the map of every `chat-thread.tsx` ref
+to {FSM state | FSM context | stays data}, (3) the run-fact protocol, (4) the
+invariants.
+
+The reducer is a **pure function** `reduce(machine, event) → machine`. The returned
+machine carries the **command effects** for that transition; a thin runtime in
+`chat-thread.tsx` dispatches events and executes effects. Because it is pure, the
+whole machine is enumerable and unit-tested directly (event × state → next state is
+the observable property) — see `run-fsm.test.ts`.
+
+---
+
+## 1. Event × state transition table
+
+Phases: `idle | sending | streaming | attaching | reconnecting(attempt,failed) |
+polling(reason) | stalled | stopping | superseding | error(kind)`.
+Context (orthogonal): `epoch`, `ownership: local|observer`, `runFact: {runId}|null`,
+`liveFollow` (are we following a live run we locally streamed — the reconnect
+ladder — vs a one-shot mount-attach resume? both are `observer`, but a live-follow
+drop RE-ENTERS the ladder (#488 commit 3) while a mount-resume drop polls).
+
+Legend: **†** = command-transition (bumps `epoch`, I1). Effects in `[…]`.
+
+| Event (source) | From phase(s) | → To phase | Effects / ctx |
+|---|---|---|---|
+| `SEND_LOCAL` (user send) | idle, error, polling, stalled, reconnecting | sending **†** | `[cancelReconnect, disarmPoll]`, ownership=local |
+| `STREAM_START{runId}` (SDK `start` metadata) | sending, attaching, reconnecting, superseding | streaming | `[cancelReconnect, disarmPoll]`, runFact←runId |
+| `FINISH_CLEAN` (onFinish clean) | streaming, … | idle | `[disarmPoll, cancelReconnect]`, runFact←null |
+| `FINISH_ABORT` (onFinish isAbort) | streaming, stopping | idle | `[disarmPoll, cancelReconnect]`, runFact←null (I4 exits stopping by this DATA) |
+| `FINISH_DISCONNECT` (observer, NOT liveFollow) | streaming(observer) | polling(disconnect-visible) | `[armPoll]` (a mount-resume drop polls) |
+| `FINISH_DISCONNECT{hasVisibleContent}` (local drop OR liveFollow) | streaming | reconnecting(1) **†** *iff runFact\|liveFollow* | `[scheduleReconnect(1)]` (+`armPoll` if visible), ownership=observer, liveFollow=true (commit 3: repeatable) |
+| `FINISH_DISCONNECT` (no runFact, not liveFollow) | streaming | idle | runFact←null (plain terminal "connection lost") |
+| `STREAM_INCOMPLETE{reason}` (observer starved/torn clean finish) | streaming(observer) | polling(reason) | `[armPoll(reason)]` |
+| `FINISH_ERROR{kind}` (onFinish isError) | any | error(kind) | `[disarmPoll, cancelReconnect]`, runFact←null |
+| `STREAM_START{runId}` (first assistant frame of a local turn) | sending | streaming | runFact←runId, `[cancelReconnect, disarmPoll]` |
+| `ATTACH_START{runId}` (mount resume) | **idle only** (F2) | attaching **†** | `[resumeStream]`, ownership=observer, runFact←runId; ignored from any non-idle phase |
+| `ATTACH_LIVE` (attach GET 2xx) | attaching | streaming | — |
+| `ATTACH_NONE` (attach GET 204/err/throw) | attaching | polling(attach-none) | `[armPoll(attach-none)]` |
+| `RECONNECT_ATTEMPT{n}` (backoff timer) | reconnecting | reconnecting(n) **†** | `[resumeStream]` |
+| `RECONNECT_ATTACHED` (reconnect GET 2xx) | reconnecting | streaming | `[cancelReconnect, disarmPoll]` — **counter reset** (commit 3) |
+| `RECONNECT_NONE` (reconnect GET 204/err), attempt<MAX | reconnecting | reconnecting(n+1) **†** | `[armPoll(attach-none), scheduleReconnect(n+1)]` |
+| `RECONNECT_NONE`, attempt=MAX | reconnecting | reconnecting(MAX, failed) | `[armPoll(reconnect-exhausted)]` |
+| `RETRY` (manual, failed banner) | reconnecting(failed) | reconnecting(1) **†** | `[resumeStream]` |
+| `RETRY` (manual, stalled banner) | stalled | polling(attach-none) **†** | `[armPoll]` |
+| `POLL_TERMINAL` (settled tail merged) | polling, reconnecting, stopping | idle | `[disarmPoll, cancelReconnect]`, runFact←null (I4) |
+| `POLL_IDLE_CAP` (inactivity cap) | polling, reconnecting | stalled | `[disarmPoll, cancelReconnect]` (commit 4a — no more silent) |
+| `RUN_FACT{null}` (POST /run → null/terminal, 204) | reconnecting/attaching/polling/stopping | idle | `[cancelReconnect, disarmPoll]`, runFact←null (I3 fresh-negative gate) |
+| `RUN_FACT{runId}` | any | (same) | runFact←runId (pessimism toward an attempt) |
+| `STOP_REQUESTED` (user Stop) | streaming, reconnecting, polling | stopping **†** | `[stopRun, abortAttach, cancelReconnect, armPoll]` (poll drives the terminal — I4 exit by data) |
+| `SUPERSEDE_REQUESTED{targetRunId}` (interrupt+send) | streaming, reconnecting, polling, error | superseding **†** | `[supersede(target), cancelReconnect, disarmPoll]` |
+| `SUPERSEDE_READY{runId}` (CAS ok) | superseding | streaming | ownership=local, runFact←runId |
+| `SUPERSEDE_MISMATCH{currentRunId}` (409 SUPERSEDE_TARGET_MISMATCH) | superseding | error(supersede-mismatch) | `[postRun(verify)]`, runFact←currentRunId |
+| `SUPERSEDE_TIMEOUT` (409 SUPERSEDE_TIMEOUT) | superseding | error(supersede-timeout) | — (composer keeps text; no auto-retry) |
+| `SUPERSEDE_INVALID` (409 SUPERSEDE_INVALID) | superseding | error(supersede-invalid) | — |
+| `RUN_ALREADY_ACTIVE{activeRunId}` (409 A_RUN_ALREADY_ACTIVE, plain POST) | sending | error(run-already-active) | runFact←activeRunId (composer offers supersede; NO auto-retry) |
+| `DISPOSE` (unmount) | any | idle **†** | `[abortAttach, cancelReconnect, disarmPoll]` (I1/I5 — epoch++ kills late callbacks) |
+
+**`stopping` honors any finish (re-review MEDIUM):** BEFORE the epoch filter, a
+stream finish (`FINISH_*`/`STREAM_INCOMPLETE`) arriving in phase `stopping` exits
+`stopping -> idle` regardless of generation. A plain Stop has no successor stream,
+so the aborted stream's finish IS the expected end (I4 exit by data) — and it
+carries the PRE-stop generation (STOP_REQUESTED bumped the epoch), so the filter
+would otherwise strand the machine in `stopping` (no idle-cap covers it). The filter
+stays in force for `superseding` (that is the F1 supersede drop).
+
+**Epoch filter (I1):** the reducer then drops any event carrying an `epoch` that
+does not equal the current `ctx.epoch`. Outcome events (`STREAM_START`, `ATTACH_*`,
+`RECONNECT_*`, `SUPERSEDE_*`, **`FINISH_*`/`STREAM_INCOMPLETE`**, `RUN_FACT`) are
+stamped with the generation the corresponding STREAM started under (the runtime
+holds a per-owned-stream `turnEpoch`); trigger events (user actions, fresh
+disconnects) carry no epoch. **F1:** this is what makes a SUPERSEDED stream's late
+`onFinish` (a dead stream A closing after the CAS started stream B) get dropped, so
+A cannot drive the live new run into a false reconnect or reset its run-fact. The
+supersede path additionally ABORTS A and starts B only from A's onFinish (a
+microtask), because ai@6 `AbstractChat.makeRequest` corrupts overlapping streams
+(A's `finally` reads then nulls the shared `activeResponse`).
+
+**Removed events (scope-cut, internal review):** `RUN_SUPERSEDED` (a ghost feature —
+never dispatched; the observer-superseded case is handled by the degraded poll,
+which follows the latest rows regardless of runId), `RECONNECT_BEGIN` (reconnect is
+entered by `FINISH_DISCONNECT`), and `POLL_ACTIVITY` (the window's activity clock was
+removed when the idle-cap moved into the thread). The reducer and this table now
+share exactly the dispatched event set.
+
+### 409-code → event map (the real #487 contract consumed here)
+
+| Server response | Event dispatched | error kind → banner |
+|---|---|---|
+| 409 `A_RUN_ALREADY_ACTIVE` (+ body.activeRunId) | `RUN_ALREADY_ACTIVE{activeRunId}` | run-already-active → "already answering / interrupt & send" |
+| 409 `SUPERSEDE_TARGET_MISMATCH` (+ body.activeRunId) | `SUPERSEDE_MISMATCH{currentRunId}` | supersede-mismatch → verify via /run |
+| 409 `SUPERSEDE_TIMEOUT` | `SUPERSEDE_TIMEOUT` | supersede-timeout → "couldn't interrupt in time, resend" |
+| 409 `SUPERSEDE_INVALID` | `SUPERSEDE_INVALID` | supersede-invalid → "couldn't interrupt this run" |
+| 503 `A_RUN_BEGIN_FAILED` | `FINISH_ERROR{begin-failed}` | begin-failed → "could not start, temporary" |
+
+---
+
+## 2. Ref-map — every `chat-thread.tsx` ref → its new home  (MIGRATION RESOLVED)
+
+The migration is COMPLETE: the 13 run-lifecycle FLAGS below are GONE from
+`chat-thread.tsx` (collapsed into FSM phase/ctx/effects, or deleted). What remains
+are identity/data mirrors, effect-owned controllers/timers, and ONE React-liveness
+bit — none of which is a run-lifecycle flag, so the post-merge "no new flags" rule
+holds. **Pending column: empty.**
+
+| # | Old ref | Resolved to | Where now |
+|---|---|---|---|
+| 1 | `reconcileTailRef` | **FSM phase** | reconcile-merge gated on `phase ∈ {polling, reconnecting, stopping}` |
+| 2 | `noStreamHandledRef` | **FSM epoch (I1)** | the attach outcome's epoch guard drops the stale/second outcome |
+| 3 | `onNoActiveStreamRef` | **FSM event** | transport → `handleAttachOutcome` dispatches `ATTACH_NONE`/`RECONNECT_NONE` |
+| 4 | `onReconnectAttachedRef` | **FSM event** | transport dispatches `ATTACH_LIVE` / `RECONNECT_ATTACHED` |
+| 5 | `resumedTurnRef` + `resumedTurn` state | **FSM ctx `ownership`** | `ownership==='observer'` ⇒ never flush; hides "Send now" |
+| 6 | `reconnectStateRef` + `reconnectState` state | **FSM phase** | `reconnecting(attempt,failed)` renders the banner |
+| 7 | `reconnectTimerRef` | **effect-owned timer** | owned by `scheduleReconnect`/`cancelReconnect` effects (not a flag) |
+| 8 | `flushOnAbortRef` | **DELETED** | the stop→flush dance is replaced by the CAS supersede (commit 5) |
+| 9 | `interruptNextSendRef` | **DELETED** | the server injects the interrupt note from the supersede itself |
+| 10 | `supersedeRetryRef` | **DELETED** (commit 5) | the client 409 retry ladder is gone; CAS supersede replaces it |
+| 11 | `stopPendingRef` | **FSM phase `stopping`** | the deferred stop fires from the chat-id adoption effect while `stopping` |
+| 12 | `mountedRef` | **retained (React liveness)** | orthogonal to run-lifecycle; gates imperative onFinish side-effects post-unmount. Epoch (I1) handles stale COMMAND-outcomes; DISPOSE bumps it |
+| 13 | `attemptResumeRef` | **FSM `ATTACH_START` + run-fact** | mount arms attach ONLY on a confirmed active run (commit 4b: streaming-tail status, or POST /run for a user tail) |
+| 14 | `stripRef` | **data** (attachStrategy) | strip+replay detail; the `resumeStream` effect reads it |
+| 15 | `strippedRowRef` | **data** (attachStrategy) | the anchor row |
+| 16 | `attachAbortRef` | **effect-owned controller** | aborted by the `abortAttach` effect in cleanup (I5) |
+| 17–25 | `chatIdRef`, `openPageRef`, `getEditorSelectionRef`, `roleIdRef`, `stableIdRef`, `queuedRef`, `sendMessageRef`, `statusRef`, `lastForwardedChatIdRef` | **data** (identity/send mirrors) | unchanged — not lifecycle flags |
+| NEW | `pendingSupersedeRef` | **data** (send-plumbing) | the runId injected into the next `POST /stream {supersede}`; the single replacement for the 3 DELETED one-shots (#8/#9/#10) — net −2 refs |
+| NEW | `idleCapTimerRef` | **effect-owned timer** | the stalled inactivity cap → `POLL_IDLE_CAP` (commit 4a); not a flag |
+
+Net: the 13 lifecycle flags (#1–#13) are eliminated: **8** → FSM phase/ctx/epoch/event
+(#1–#6, #11, #13), **3** deleted (#8/#9/#10), **`reconnectTimerRef` (#7)** becomes an
+effect-owned controller, and **`mountedRef` (#12)** is retained as React liveness
+(8 + 3 + 1 + 1 = 13). (`attachAbortRef` (#16) is outside the #1–#13 set — it was
+already an effect-owned controller.) Two effect-owned timers + one send-plumbing data
+ref are added — none is a boolean lifecycle latch.
+
+---
+
+## 3. Run-fact protocol (`runFact: {runId} | null`) — I3
+
+"A run is active" is first-class from the SERVER, not inferred from an assistant
+message. Sources, in the order they update `ctx.runFact`:
+
+1. **Init (mount):** `POST /ai-chat/run { chatId }` → `{ run, message }`. A `run`
+   with a non-terminal `status` seeds `runFact = { runId: run.id }`; a null/terminal
+   run seeds `null`. This is what arms the resume attempt (`ATTACH_START`) — the
+   attempt is armed ONLY on a positive fact (commit 4b: a user-tail with no active
+   run no longer arms a pointless poll on every open).
+2. **Live update:** the `start` stream metadata carries `runId` → `STREAM_START{runId}`.
+3. **Attach outcomes:** `ATTACH_LIVE` (2xx) confirms active; a 204 on a non-stripped
+   path is an authoritative NEGATIVE fact → the runtime dispatches `RUN_FACT{null}`,
+   which cancels recovery (I3 fresh-negative gate).
+4. **Poll (future resume-stack iteration #491):** the delta will carry the run field;
+   until then the poll drives to a terminal ROW, dispatched as `POLL_TERMINAL`.
+
+Pessimism rule: a stale-but-positive fact PERMITS entering recovery (attach); the
+204 then cuts it. A fresh negative fact gates recovery OUT immediately.
+
+---
+
+## 4. Invariants
+
+- **I1 — Epoch (generation counter).** Every command-emitting transition bumps
+  `ctx.epoch`; every async outcome event carries its issuing epoch; the reducer
+  drops stale-epoch outcomes. Replaces the one-shot-ref zoo (`noStreamHandledRef`,
+  the flush/interrupt/supersede one-shots, the `mountedRef` late-callback gate).
+- **I2 — Ownership is context, not state.** `local | observer` is orthogonal to the
+  transport phase. The queue flushes ONLY under local ownership; an observer
+  following a detached run never flushes (was `resumedTurnRef`).
+- **I3 — Run-fact is first-class from the server.** Reconnect is entered by the
+  run-fact, not by an assistant message (commit 2). A fresh negative fact cancels
+  recovery.
+- **I4 — Exit `stopping` by DATA.** A terminal row / negative run-fact / terminal
+  finish exits `stopping`, never the stopRun HTTP response (which returns after the
+  abort but before finalization — keying off it would unlock the composer on a 409).
+- **I5 — Dispose protocol.** Command controllers (attach GET, POST /stream, POST
+  /run) are effect-owned and aborted in cleanup (`abortAttach` on `DISPOSE`), not
+  render-phase refs. A client abort of an already-sent POST does not cancel the
+  server action, so disarming on unmount is safe.
+- **attachStrategy** (strip+replay today) is behind the `resumeStream` effect; the
+  resume-stack iteration (#491) swaps it to tail-only WITHOUT touching the FSM.
+- **Queue** stays a data structure; flush/interrupt decisions are transitions.

apps/client/src/features/ai-chat/state/run-fsm.test.ts

@@ -0,0 +1,482 @@
+import { describe, it, expect } from "vitest";
+import {
+  reduce,
+  initialMachine,
+  reconnectDelayMs,
+  RECONNECT_MAX_ATTEMPTS,
+  type Machine,
+  type Effect,
+  type Event,
+} from "./run-fsm";
+
+// Drive a sequence of events through the reducer, returning the final machine.
+function run(m: Machine, ...events: Event[]): Machine {
+  return events.reduce(reduce, m);
+}
+function withRunFact(runId = "run-1"): Machine {
+  return {
+    ...initialMachine(),
+    ctx: { epoch: 0, ownership: "local", runFact: { runId }, liveFollow: false },
+  };
+}
+function effectTypes(m: Machine): string[] {
+  return m.effects.map((e) => e.type);
+}
+function hasEffect(m: Machine, type: Effect["type"]): boolean {
+  return m.effects.some((e) => e.type === type);
+}
+
+describe("run-fsm — epoch invariant (I1)", () => {
+  it("drops an outcome carrying a stale epoch", () => {
+    // A command bumps the epoch; an outcome stamped with the OLD epoch is dropped.
+    const m0 = reduce(initialMachine(), { type: "ATTACH_START", runId: "r" }); // epoch 0->1, attaching
+    expect(m0.ctx.epoch).toBe(1);
+    expect(m0.phase.name).toBe("attaching");
+    // A late ATTACH_LIVE from a SUPERSEDED attempt (epoch 0) must NOT drive us.
+    const stale = reduce(m0, { type: "ATTACH_LIVE", epoch: 0 });
+    expect(stale.phase.name).toBe("attaching");
+    expect(stale.effects).toEqual([]);
+  });
+
+  it("applies an outcome carrying the current epoch", () => {
+    const m0 = reduce(initialMachine(), { type: "ATTACH_START", runId: "r" });
+    const live = reduce(m0, { type: "ATTACH_LIVE", epoch: m0.ctx.epoch });
+    expect(live.phase.name).toBe("streaming");
+  });
+
+  it("an outcome with no epoch is never dropped (trigger events)", () => {
+    const m0 = reduce(initialMachine(), { type: "ATTACH_START", runId: "r" });
+    const disposed = reduce(m0, { type: "DISPOSE" });
+    expect(disposed.phase.name).toBe("idle");
+    expect(hasEffect(disposed, "abortAttach")).toBe(true);
+  });
+
+  it("every command-transition increments the epoch exactly once", () => {
+    let m = initialMachine();
+    const before = m.ctx.epoch;
+    m = reduce(m, { type: "SEND_LOCAL" });
+    expect(m.ctx.epoch).toBe(before + 1);
+    m = reduce(m, { type: "STOP_REQUESTED" });
+    expect(m.ctx.epoch).toBe(before + 2);
+  });
+});
+
+describe("run-fsm — local turn", () => {
+  it("SEND_LOCAL → sending, local ownership, cancels recovery", () => {
+    const m = reduce(withRunFact(), { type: "SEND_LOCAL" });
+    expect(m.phase.name).toBe("sending");
+    expect(m.ctx.ownership).toBe("local");
+    expect(effectTypes(m)).toEqual(
+      expect.arrayContaining(["cancelReconnect", "disarmPoll"]),
+    );
+  });
+
+  it("STREAM_START adopts the runId into the run-fact and goes streaming", () => {
+    const m = run(initialMachine(), { type: "SEND_LOCAL" });
+    const s = reduce(m, { type: "STREAM_START", runId: "run-9", epoch: m.ctx.epoch });
+    expect(s.phase.name).toBe("streaming");
+    expect(s.ctx.runFact).toEqual({ runId: "run-9" });
+  });
+
+  it("FINISH_CLEAN → idle, run-fact cleared, poll/reconnect disarmed", () => {
+    const streaming = run(initialMachine(), { type: "SEND_LOCAL" }, { type: "STREAM_START", runId: "r" });
+    const done = reduce(streaming, { type: "FINISH_CLEAN" });
+    expect(done.phase.name).toBe("idle");
+    expect(done.ctx.runFact).toBeNull();
+  });
+});
+
+// #488 commit 2 — SSE break BEFORE the first assistant frame must still recover.
+describe("run-fsm — commit 2: reconnect by run-fact, not by assistant message", () => {
+  it("FINISH_DISCONNECT with an active run-fact → reconnecting (even with no visible content)", () => {
+    // Setup-phase break: no assistant frame yet, but a run-fact exists.
+    const streaming = withRunFact("run-2");
+    const m = reduce(streaming, {
+      type: "FINISH_DISCONNECT",
+      hasVisibleContent: false,
+      epoch: streaming.ctx.epoch,
+    });
+    expect(m.phase.name).toBe("reconnecting");
+    if (m.phase.name === "reconnecting") expect(m.phase.attempt).toBe(1);
+    expect(m.ctx.ownership).toBe("observer");
+    expect(hasEffect(m, "scheduleReconnect")).toBe(true);
+    // No visible content -> no poll arm yet (the reconnect ladder rebuilds it).
+    expect(hasEffect(m, "armPoll")).toBe(false);
+  });
+
+  it("FINISH_DISCONNECT WITH visible content also arms the poll", () => {
+    const m = reduce(withRunFact("run-2"), {
+      type: "FINISH_DISCONNECT",
+      hasVisibleContent: true,
+      epoch: 0,
+    });
+    expect(m.phase.name).toBe("reconnecting");
+    expect(hasEffect(m, "armPoll")).toBe(true);
+  });
+
+  it("FINISH_DISCONNECT with NO run-fact → idle (plain connection-lost)", () => {
+    const m = reduce(initialMachine(), {
+      type: "FINISH_DISCONNECT",
+      hasVisibleContent: true,
+      epoch: 0,
+    });
+    expect(m.phase.name).toBe("idle");
+  });
+});
+
+// #488 commit 3 — a SECOND break after a successful re-attach starts a NEW ladder.
+describe("run-fsm — commit 3: repeated reconnect cycles", () => {
+  it("two breaks in a row produce two reconnect cycles (counter resets on attach)", () => {
+    let m = withRunFact("run-3");
+    // First break -> reconnecting(1).
+    m = reduce(m, { type: "FINISH_DISCONNECT", hasVisibleContent: false, epoch: m.ctx.epoch });
+    expect(m.phase.name).toBe("reconnecting");
+    // Attempt fires, re-attaches live.
+    m = reduce(m, { type: "RECONNECT_ATTEMPT", attempt: 1, epoch: m.ctx.epoch });
+    m = reduce(m, { type: "RECONNECT_ATTACHED", epoch: m.ctx.epoch });
+    expect(m.phase.name).toBe("streaming");
+    // SECOND break: the counter was reset, so a fresh ladder starts at attempt 1
+    // (the old one-shot !wasResumed gate would have sent this to silent poll).
+    m = reduce(m, { type: "FINISH_DISCONNECT", hasVisibleContent: false, epoch: m.ctx.epoch });
+    expect(m.phase.name).toBe("reconnecting");
+    if (m.phase.name === "reconnecting") expect(m.phase.attempt).toBe(1);
+    expect(hasEffect(m, "scheduleReconnect")).toBe(true);
+  });
+
+  it("a MOUNT-attach observer drop falls to POLL, not the reconnect ladder", () => {
+    // Distinguishes commit 3 from a one-shot resume: an observer that never
+    // live-followed (liveFollow false) polls on a drop.
+    let m = reduce(initialMachine(), { type: "ATTACH_START", runId: "r" });
+    m = reduce(m, { type: "ATTACH_LIVE", epoch: m.ctx.epoch });
+    expect(m.ctx.ownership).toBe("observer");
+    expect(m.ctx.liveFollow).toBe(false);
+    m = reduce(m, { type: "FINISH_DISCONNECT", hasVisibleContent: true, epoch: m.ctx.epoch });
+    expect(m.phase.name).toBe("polling");
+    expect(hasEffect(m, "armPoll")).toBe(true);
+  });
+
+  it("STREAM_INCOMPLETE (observer starved/torn finish) → polling", () => {
+    let m = reduce(initialMachine(), { type: "ATTACH_START", runId: "r" });
+    m = reduce(m, { type: "ATTACH_LIVE", epoch: m.ctx.epoch });
+    m = reduce(m, { type: "STREAM_INCOMPLETE", reason: "starved", epoch: m.ctx.epoch });
+    expect(m.phase).toEqual({ name: "polling", reason: "starved" });
+    expect(hasEffect(m, "armPoll")).toBe(true);
+  });
+
+  it("liveFollow is set on the first local drop and kept across a re-attach", () => {
+    let m = withRunFact("run-3");
+    m = reduce(m, { type: "FINISH_DISCONNECT", hasVisibleContent: false, epoch: m.ctx.epoch });
+    expect(m.ctx.liveFollow).toBe(true);
+    m = reduce(m, { type: "RECONNECT_ATTEMPT", attempt: 1, epoch: m.ctx.epoch });
+    m = reduce(m, { type: "RECONNECT_ATTACHED", epoch: m.ctx.epoch });
+    expect(m.ctx.liveFollow).toBe(true); // kept — so a second drop reconnects
+    // A clean finish clears it.
+    m = reduce(m, { type: "FINISH_CLEAN", epoch: m.ctx.epoch });
+    expect(m.ctx.liveFollow).toBe(false);
+  });
+
+  it("RECONNECT_NONE backs off through the ladder, then fails at the cap", () => {
+    let m = withRunFact("run-3");
+    m = reduce(m, { type: "FINISH_DISCONNECT", hasVisibleContent: false, epoch: m.ctx.epoch });
+    for (let n = 1; n < RECONNECT_MAX_ATTEMPTS; n++) {
+      m = reduce(m, { type: "RECONNECT_ATTEMPT", attempt: n, epoch: m.ctx.epoch });
+      m = reduce(m, { type: "RECONNECT_NONE", epoch: m.ctx.epoch });
+      expect(m.phase.name).toBe("reconnecting");
+      if (m.phase.name === "reconnecting") {
+        expect(m.phase.attempt).toBe(n + 1);
+        expect(m.phase.failed).toBe(false);
+      }
+      // The belt-and-suspenders poll is armed each failed attempt.
+      expect(hasEffect(m, "armPoll")).toBe(true);
+    }
+    // Final attempt fails -> failed banner (Retry), poll armed.
+    m = reduce(m, { type: "RECONNECT_ATTEMPT", attempt: RECONNECT_MAX_ATTEMPTS, epoch: m.ctx.epoch });
+    m = reduce(m, { type: "RECONNECT_NONE", epoch: m.ctx.epoch });
+    expect(m.phase.name).toBe("reconnecting");
+    if (m.phase.name === "reconnecting") expect(m.phase.failed).toBe(true);
+    // RETRY restarts at attempt 1.
+    m = reduce(m, { type: "RETRY" });
+    expect(m.phase.name).toBe("reconnecting");
+    if (m.phase.name === "reconnecting") {
+      expect(m.phase.attempt).toBe(1);
+      expect(m.phase.failed).toBe(false);
+    }
+    expect(hasEffect(m, "resumeStream")).toBe(true);
+  });
+
+  it("reconnectDelayMs is the exponential backoff 1s,2s,4s,8s,16s", () => {
+    expect([1, 2, 3, 4, 5].map(reconnectDelayMs)).toEqual([1000, 2000, 4000, 8000, 16000]);
+  });
+});
+
+// #488 commit 4 — polling stalled-state + user-tail gating.
+describe("run-fsm — commit 4: stalled + run-fact gating", () => {
+  it("POLL_IDLE_CAP: polling → stalled with a banner (poll disarmed), not silent", () => {
+    let m = reduce(withRunFact(), { type: "ATTACH_START", runId: "r" });
+    m = reduce(m, { type: "ATTACH_NONE", epoch: m.ctx.epoch });
+    expect(m.phase.name).toBe("polling");
+    m = reduce(m, { type: "POLL_IDLE_CAP" });
+    expect(m.phase.name).toBe("stalled");
+    expect(hasEffect(m, "disarmPoll")).toBe(true);
+  });
+
+  it("RETRY from stalled re-arms the poll", () => {
+    let m = reduce(withRunFact(), { type: "ATTACH_START", runId: "r" });
+    m = reduce(m, { type: "ATTACH_NONE", epoch: m.ctx.epoch });
+    m = reduce(m, { type: "POLL_IDLE_CAP" });
+    m = reduce(m, { type: "RETRY" });
+    expect(m.phase.name).toBe("polling");
+    expect(hasEffect(m, "armPoll")).toBe(true);
+  });
+
+  it("a fresh NEGATIVE run-fact while attaching cancels recovery (user-tail, no active run)", () => {
+    // The mount POST /run returns no active run: attaching → idle, no poll armed.
+    let m = reduce(withRunFact(), { type: "ATTACH_START", runId: "r" });
+    m = reduce(m, { type: "RUN_FACT", runFact: null, epoch: m.ctx.epoch });
+    expect(m.phase.name).toBe("idle");
+    expect(m.ctx.runFact).toBeNull();
+    expect(hasEffect(m, "disarmPoll")).toBe(true);
+  });
+
+  it("a negative run-fact while polling stops the poll", () => {
+    let m = reduce(withRunFact(), { type: "ATTACH_START", runId: "r" });
+    m = reduce(m, { type: "ATTACH_NONE", epoch: m.ctx.epoch });
+    m = reduce(m, { type: "RUN_FACT", runFact: null, epoch: m.ctx.epoch });
+    expect(m.phase.name).toBe("idle");
+  });
+
+  it("POLL_TERMINAL settles polling → idle (I4 data-driven exit)", () => {
+    let m = reduce(withRunFact(), { type: "ATTACH_START", runId: "r" });
+    m = reduce(m, { type: "ATTACH_NONE", epoch: m.ctx.epoch });
+    m = reduce(m, { type: "POLL_TERMINAL" });
+    expect(m.phase.name).toBe("idle");
+    expect(m.ctx.runFact).toBeNull();
+  });
+});
+
+// #488 commit 5 — error classification + supersede CAS transitions.
+describe("run-fsm — commit 5: supersede CAS + error classification", () => {
+  it("SUPERSEDE_REQUESTED → superseding, fires the CAS effect, bumps epoch", () => {
+    const streaming = withRunFact("run-old");
+    const m = reduce(streaming, { type: "SUPERSEDE_REQUESTED", targetRunId: "run-old" });
+    expect(m.phase.name).toBe("superseding");
+    expect(m.ctx.epoch).toBe(streaming.ctx.epoch + 1);
+    const sup = m.effects.find((e) => e.type === "supersede");
+    expect(sup).toEqual({ type: "supersede", targetRunId: "run-old" });
+  });
+
+  it("SUPERSEDE_READY → streaming as the new local owner", () => {
+    let m = reduce(withRunFact("run-old"), { type: "SUPERSEDE_REQUESTED", targetRunId: "run-old" });
+    m = reduce(m, { type: "SUPERSEDE_READY", runId: "run-new", epoch: m.ctx.epoch });
+    expect(m.phase.name).toBe("streaming");
+    expect(m.ctx.ownership).toBe("local");
+    expect(m.ctx.runFact).toEqual({ runId: "run-new" });
+  });
+
+  it("SUPERSEDE_MISMATCH → error(supersede-mismatch) + verify via /run (no blind banner)", () => {
+    let m = reduce(withRunFact("run-old"), { type: "SUPERSEDE_REQUESTED", targetRunId: "run-old" });
+    m = reduce(m, { type: "SUPERSEDE_MISMATCH", currentRunId: "run-x", epoch: m.ctx.epoch });
+    expect(m.phase).toEqual({ name: "error", kind: "supersede-mismatch" });
+    expect(hasEffect(m, "postRun")).toBe(true);
+    expect(m.ctx.runFact).toEqual({ runId: "run-x" });
+  });
+
+  it("SUPERSEDE_TIMEOUT → error(supersede-timeout), no auto-retry effect", () => {
+    let m = reduce(withRunFact("run-old"), { type: "SUPERSEDE_REQUESTED", targetRunId: "run-old" });
+    m = reduce(m, { type: "SUPERSEDE_TIMEOUT", epoch: m.ctx.epoch });
+    expect(m.phase).toEqual({ name: "error", kind: "supersede-timeout" });
+    expect(m.effects).toEqual([]);
+  });
+
+  it("SUPERSEDE_INVALID → error(supersede-invalid)", () => {
+    let m = reduce(withRunFact("run-old"), { type: "SUPERSEDE_REQUESTED", targetRunId: "run-old" });
+    m = reduce(m, { type: "SUPERSEDE_INVALID", epoch: m.ctx.epoch });
+    expect(m.phase).toEqual({ name: "error", kind: "supersede-invalid" });
+  });
+
+  it("a stale SUPERSEDE outcome from a superseded epoch is dropped", () => {
+    let m = reduce(withRunFact("run-old"), { type: "SUPERSEDE_REQUESTED", targetRunId: "run-old" });
+    const supersedingEpoch = m.ctx.epoch;
+    // The user retriggers, bumping the epoch again.
+    m = reduce(m, { type: "SUPERSEDE_REQUESTED", targetRunId: "run-old" });
+    // The first CAS's late TIMEOUT (old epoch) must NOT knock us out of superseding.
+    const late = reduce(m, { type: "SUPERSEDE_TIMEOUT", epoch: supersedingEpoch });
+    expect(late.phase.name).toBe("superseding");
+  });
+
+  it("RUN_ALREADY_ACTIVE (plain POST gate) → error(run-already-active), no retry effect", () => {
+    const m = reduce(run(initialMachine(), { type: "SEND_LOCAL" }), { type: "RUN_ALREADY_ACTIVE" });
+    expect(m.phase).toEqual({ name: "error", kind: "run-already-active" });
+    expect(m.effects).toEqual([]);
+  });
+
+  it("#497/S4: RUN_ALREADY_ACTIVE{activeRunId} ADOPTS the server's active run as the run-fact", () => {
+    // The server sends `activeRunId` so a later supersede can TARGET that run
+    // instead of a blind promote+abort. Absorb it into runFact.
+    const m = reduce(run(initialMachine(), { type: "SEND_LOCAL" }), {
+      type: "RUN_ALREADY_ACTIVE",
+      activeRunId: "run-foreign",
+    });
+    expect(m.phase).toEqual({ name: "error", kind: "run-already-active" });
+    expect(m.ctx.runFact).toEqual({ runId: "run-foreign" });
+    expect(m.effects).toEqual([]);
+  });
+
+  it("#497/S4: RUN_ALREADY_ACTIVE without an activeRunId keeps the prior run-fact", () => {
+    const seeded = reduce(run(initialMachine(), { type: "SEND_LOCAL" }), {
+      type: "RUN_FACT",
+      runFact: { runId: "run-prior" },
+    });
+    const m = reduce(seeded, { type: "RUN_ALREADY_ACTIVE" });
+    expect(m.ctx.runFact).toEqual({ runId: "run-prior" });
+  });
+});
+
+// #488 F2 — a late mount `getRun → ATTACH_START` must not hijack a local turn.
+describe("run-fsm — F2: ATTACH_START only from idle", () => {
+  it("ATTACH_START from a local `sending` turn is ignored (no observer hijack)", () => {
+    const sending = reduce(initialMachine(), { type: "SEND_LOCAL" }); // idle -> sending, local
+    const m = reduce(sending, { type: "ATTACH_START", runId: "r" });
+    expect(m.phase.name).toBe("sending");
+    expect(m.ctx.ownership).toBe("local"); // NOT flipped to observer
+    expect(m.effects).toEqual([]); // no resumeStream
+  });
+
+  it("ATTACH_START from idle attaches as normal", () => {
+    const m = reduce(initialMachine(), { type: "ATTACH_START", runId: "r" });
+    expect(m.phase.name).toBe("attaching");
+    expect(m.ctx.ownership).toBe("observer");
+    expect(hasEffect(m, "resumeStream")).toBe(true);
+  });
+});
+
+describe("run-fsm — stop (I4: exit by data)", () => {
+  it("STOP_REQUESTED → stopping, fires stopRun + abortAttach, no data-independent exit", () => {
+    const m = reduce(withRunFact(), { type: "STOP_REQUESTED" });
+    expect(m.phase.name).toBe("stopping");
+    expect(effectTypes(m)).toEqual(expect.arrayContaining(["stopRun", "abortAttach"]));
+  });
+
+  it("stopping exits on the aborted stream's finish carrying the PRE-STOP epoch", () => {
+    // MEDIUM (#488 re-review): STOP_REQUESTED is a command that BUMPS the epoch, but
+    // the runtime stamps the aborted stream's onFinish with the stream's START (pre-
+    // stop) generation — exactly what the component sends. `stopping` must HONOR
+    // that finish regardless of generation (no idle-cap covers `stopping`).
+    // MUTATION-VERIFY: remove the honor-in-`stopping` branch and this hangs in
+    // `stopping` (the epoch filter drops the pre-stop finish) -> red.
+    const preStopEpoch = withRunFact().ctx.epoch; // E1 (the stream's start epoch)
+    let m = reduce(withRunFact(), { type: "STOP_REQUESTED" }); // E1 -> E2, stopping
+    expect(m.ctx.epoch).toBe(preStopEpoch + 1);
+    m = reduce(m, { type: "FINISH_ABORT", epoch: preStopEpoch }); // NOT the current epoch
+    expect(m.phase.name).toBe("idle");
+    expect(m.ctx.runFact).toBeNull();
+  });
+
+  it("stopping exits on a clean finish carrying the pre-stop epoch too", () => {
+    const preStopEpoch = withRunFact().ctx.epoch;
+    let m = reduce(withRunFact(), { type: "STOP_REQUESTED" });
+    m = reduce(m, { type: "FINISH_CLEAN", epoch: preStopEpoch });
+    expect(m.phase.name).toBe("idle");
+  });
+
+  it("stopping exits on a negative run-fact (data)", () => {
+    let m = reduce(withRunFact(), { type: "STOP_REQUESTED" });
+    m = reduce(m, { type: "RUN_FACT", runFact: null, epoch: m.ctx.epoch });
+    expect(m.phase.name).toBe("idle");
+  });
+
+  // Review #4: `stopping` arms the poll but had no inactivity backstop.
+  it("review-4: POLL_IDLE_CAP in `stopping` exits to idle (bounded), NOT stalled", () => {
+    let m = reduce(withRunFact(), { type: "STOP_REQUESTED" });
+    expect(m.phase.name).toBe("stopping");
+    expect(hasEffect(m, "armPoll")).toBe(true);
+    // MUTATION-VERIFY: drop the `stopping` branch in POLL_IDLE_CAP and this hangs
+    // in `stopping` (poll forever) -> red.
+    m = reduce(m, { type: "POLL_IDLE_CAP" });
+    expect(m.phase.name).toBe("idle");
+    expect(hasEffect(m, "disarmPoll")).toBe(true);
+    expect(m.ctx.ownership).toBe("local");
+  });
+});
+
+// Review #1: positive attach outcomes must be guarded by the SOURCE phase — the
+// epoch filter alone is insufficient because POLL_TERMINAL uses to() (no epoch
+// bump) and does not abort the in-flight GET.
+describe("run-fsm — review-1: attach outcomes guarded by source phase", () => {
+  it("a late RECONNECT_ATTACHED after POLL_TERMINAL stays idle (no phantom streaming)", () => {
+    let m = withRunFact("run-1");
+    m = reduce(m, { type: "FINISH_DISCONNECT", hasVisibleContent: true, epoch: m.ctx.epoch });
+    m = reduce(m, { type: "RECONNECT_ATTEMPT", attempt: 1, epoch: m.ctx.epoch }); // attach GET
+    const epoch = m.ctx.epoch;
+    // The armed degraded poll reaches the terminal row FIRST (epoch unchanged).
+    m = reduce(m, { type: "POLL_TERMINAL" });
+    expect(m.phase.name).toBe("idle");
+    expect(m.ctx.epoch).toBe(epoch); // POLL_TERMINAL did NOT bump the epoch
+    // The slow GET returns live 2xx under the SAME epoch — must NOT resurrect.
+    m = reduce(m, { type: "RECONNECT_ATTACHED", epoch });
+    expect(m.phase.name).toBe("idle");
+  });
+
+  it("a late ATTACH_LIVE / ATTACH_NONE after leaving `attaching` is ignored", () => {
+    let m = reduce(initialMachine(), { type: "ATTACH_START", runId: "r" });
+    const epoch = m.ctx.epoch;
+    m = reduce(m, { type: "ATTACH_NONE", epoch }); // attaching -> polling
+    m = reduce(m, { type: "POLL_TERMINAL" }); // -> idle (epoch unchanged)
+    expect(m.phase.name).toBe("idle");
+    m = reduce(m, { type: "ATTACH_LIVE", epoch }); // late 2xx, same epoch
+    expect(m.phase.name).toBe("idle");
+    // And a late ATTACH_NONE (not `attaching`) is a no-op too.
+    m = reduce(m, { type: "ATTACH_NONE", epoch });
+    expect(m.phase.name).toBe("idle");
+  });
+});
+
+// Review #2: every terminal transition resets ownership to local.
+describe("run-fsm — review-2: terminal transitions reset ownership to local", () => {
+  const observer = (): Machine => {
+    let m = reduce(initialMachine(), { type: "ATTACH_START", runId: "r" });
+    m = reduce(m, { type: "ATTACH_LIVE", epoch: m.ctx.epoch });
+    expect(m.ctx.ownership).toBe("observer");
+    return m;
+  };
+  it("FINISH_CLEAN resets ownership", () => {
+    const m = reduce(observer(), { type: "FINISH_CLEAN", epoch: observer().ctx.epoch });
+    expect(m.ctx.ownership).toBe("local");
+  });
+  it("FINISH_ERROR / POLL_TERMINAL / RUN_FACT(null) reset ownership", () => {
+    let o = observer();
+    expect(reduce(o, { type: "FINISH_ERROR", kind: "stream", epoch: o.ctx.epoch }).ctx.ownership).toBe("local");
+    // POLL_TERMINAL from an observer polling phase
+    let p = reduce(observer(), { type: "STREAM_INCOMPLETE", reason: "starved", epoch: observer().ctx.epoch });
+    expect(reduce(p, { type: "POLL_TERMINAL" }).ctx.ownership).toBe("local");
+    // RUN_FACT(null) from an observer attaching phase
+    let a = reduce(initialMachine(), { type: "ATTACH_START", runId: "r" });
+    expect(reduce(a, { type: "RUN_FACT", runFact: null, epoch: a.ctx.epoch }).ctx.ownership).toBe("local");
+  });
+});
+
+describe("run-fsm — ownership (I2) is context, orthogonal to phase", () => {
+  it("attach/reconnect set observer; send/supersede-ready set local", () => {
+    let m = reduce(initialMachine(), { type: "ATTACH_START", runId: "r" });
+    expect(m.ctx.ownership).toBe("observer");
+    m = reduce(m, { type: "ATTACH_LIVE", epoch: m.ctx.epoch });
+    expect(m.phase.name).toBe("streaming");
+    expect(m.ctx.ownership).toBe("observer"); // still observing a detached run
+    // A local send flips ownership back to local.
+    m = reduce(m, { type: "SEND_LOCAL" });
+    expect(m.ctx.ownership).toBe("local");
+  });
+});
+
+describe("run-fsm — dispose (I5)", () => {
+  it("DISPOSE from any phase aborts controllers and bumps epoch", () => {
+    let m = reduce(withRunFact(), { type: "ATTACH_START", runId: "r" });
+    const before = m.ctx.epoch;
+    m = reduce(m, { type: "DISPOSE" });
+    expect(m.phase.name).toBe("idle");
+    expect(m.ctx.epoch).toBe(before + 1);
+    expect(effectTypes(m)).toEqual(
+      expect.arrayContaining(["abortAttach", "cancelReconnect", "disarmPoll"]),
+    );
+  });
+});

apps/client/src/features/ai-chat/state/run-fsm.ts

@@ -0,0 +1,600 @@
+/**
+ * Run-lifecycle finite state machine for a single AI-chat thread (#488).
+ *
+ * ============================================================================
+ * WHY THIS EXISTS
+ * ----------------------------------------------------------------------------
+ * The resume/reconnect/poll/stop/supersede lifecycle used to be spread across
+ * ~26 `useRef` one-shot flags in `chat-thread.tsx`, each disarmed "on every
+ * path". Ownerless flag combinations produced silent UI freezes, and every fix
+ * added another ref (the #381 -> #432 -> #456 spiral). This module replaces that
+ * ref-zoo with ONE pure reducer whose transitions are enumerable and unit-
+ * testable in isolation (event x state -> next state is the observable property).
+ *
+ * The reducer is PURE: it owns no timers, no fetches, no React state. It maps
+ * `(machine, event) -> machine`, where the returned machine carries the list of
+ * COMMAND EFFECTS to run for that transition. A thin runtime in `chat-thread.tsx`
+ * dispatches events (from SDK callbacks / HTTP outcomes) and executes the
+ * effects (attach GET, POST /stream, POST /run, POST /stop, backoff timers,
+ * poll arm/disarm). The runtime lives in a THREAD, not the window, so a late SDK
+ * callback dies with the owner (kills the "event from a dead view" class, #161).
+ *
+ * ============================================================================
+ * INVARIANTS (see run-fsm.spec.md for the full spec + tables)
+ * ----------------------------------------------------------------------------
+ *  I1  EPOCH (generation counter). Commands (`resumeStream`, `postRun`, `stop`,
+ *      `supersede`, `scheduleReconnect`) are async; their outcomes arrive on the
+ *      SAME SDK/HTTP callbacks. Every command-emitting transition increments
+ *      `ctx.epoch`; every OUTCOME event carries the epoch it was issued under;
+ *      the reducer DROPS an outcome whose epoch != the current epoch. This is
+ *      what the one-shot-ref zoo used to approximate by hand.
+ *  I2  OWNERSHIP is a CONTEXT FIELD (`'local' | 'observer'`), not a state —
+ *      orthogonal to the transport phase. The queue is flushed ONLY by a local
+ *      owner (an observer following a detached run never flushes).
+ *  I3  RUN-FACT ("a run is active") is first-class from the server: `runFact`
+ *      holds the server-confirmed active run id (POST /run on mount, the `start`
+ *      metadata runId, attach outcomes). Reconnect is entered by the RUN-FACT,
+ *      not by the presence of an assistant message (#488 commit 2). A fresh
+ *      negative fact (null) cancels reconnect immediately.
+ *  I4  Exit `stopping` by DATA (a terminal row / negative run-fact), NEVER by the
+ *      stopRun HTTP response (which returns after abort, before finalization).
+ *  I5  Command controllers are effect-owned (abort in cleanup), NOT render-phase
+ *      refs — expressed here as the `abortAttach` effect on disposing transitions.
+ * ============================================================================
+ */
+
+// ---------------------------------------------------------------------------
+// Phases (the transport lifecycle). Ownership / runFact are CONTEXT, not here.
+// ---------------------------------------------------------------------------
+
+/** Why the degraded poll is the active recovery. */
+export type PollReason =
+  | "attach-none" // mount attach returned 204 / error — nothing live to attach
+  | "starved" // a resumed finish carried no visible content
+  | "disconnect-visible" // a live disconnect WITH on-screen content — poll to terminal
+  | "reconnect-exhausted"; // the live re-attach ladder gave up
+
+/** The classified error kind (drives the banner text + composer behavior). */
+export type ErrorKind =
+  | "stream" // a generic provider/network stream error (useChat error)
+  | "run-already-active" // 409 A_RUN_ALREADY_ACTIVE (a plain POST hit the gate)
+  | "supersede-mismatch" // 409 SUPERSEDE_TARGET_MISMATCH (CAS target moved)
+  | "supersede-timeout" // 409 SUPERSEDE_TIMEOUT (old run did not settle in W)
+  | "supersede-invalid" // 409 SUPERSEDE_INVALID (bad supersede target)
+  | "begin-failed"; // 503 A_RUN_BEGIN_FAILED (could not start the run)
+
+export type Phase =
+  | { name: "idle" }
+  | { name: "sending" } // local POST in flight, before the first frame
+  | { name: "streaming" } // receiving frames
+  | { name: "attaching" } // mount-time attach GET in flight
+  | { name: "reconnecting"; attempt: number; failed: boolean }
+  | { name: "polling"; reason: PollReason }
+  | { name: "stalled" } // poll hit the inactivity cap — banner + Retry
+  | { name: "stopping" }
+  | { name: "superseding" }
+  | { name: "error"; kind: ErrorKind };
+
+export type Ownership = "local" | "observer";
+
+/** The server-confirmed active run, or null when no run is active. */
+export type RunFact = { runId: string } | null;
+
+export interface Ctx {
+  /** I1: generation counter — every command-transition increments it. */
+  epoch: number;
+  /** I2: does THIS client own the turn's writes (local streamer) or observe? */
+  ownership: Ownership;
+  /** I3: the server-confirmed active run. */
+  runFact: RunFact;
+  /**
+   * Are we FOLLOWING a live run we were locally streaming (the reconnect ladder),
+   * as opposed to a one-shot mount-attach resume? Both are `ownership: 'observer'`,
+   * but they recover DIFFERENTLY on a drop: a live-follow drop RE-ENTERS the
+   * reconnect ladder (#488 commit 3 — the second break after a successful re-attach
+   * must reconnect again, not fall to silent poll), while a mount-resume drop falls
+   * to the degraded poll. This is the ctx bit that separates the two WITHOUT a new
+   * component ref (it is why commit 3 needs the FSM, not a surgical patch).
+   */
+  liveFollow: boolean;
+}
+
+export interface Machine {
+  phase: Phase;
+  ctx: Ctx;
+  /** Command effects to run for the transition that produced THIS machine.
+   *  The runtime executes them and does not read them again. */
+  effects: Effect[];
+}
+
+// ---------------------------------------------------------------------------
+// Command effects (the reducer's only side-channel — executed by the runtime).
+// ---------------------------------------------------------------------------
+
+export type Effect =
+  /** POST /run to (re)establish or verify the run-fact. `reason` is diagnostic. */
+  | { type: "postRun"; reason: "mount" | "verify" }
+  /** Trigger the SDK `resumeStream()` (attach GET via prepareReconnectToStream). */
+  | { type: "resumeStream" }
+  /** Schedule a reconnect attempt after a backoff, then dispatch RECONNECT_ATTEMPT. */
+  | { type: "scheduleReconnect"; attempt: number; delayMs: number }
+  /** Cancel any pending reconnect backoff timer. */
+  | { type: "cancelReconnect" }
+  /** Arm the degraded poll (the window's dumb timer follows the run in the DB). */
+  | { type: "armPoll"; reason: PollReason }
+  /** Disarm the degraded poll. */
+  | { type: "disarmPoll" }
+  /** POST /stop the chat's active run (authoritative detached-run stop). */
+  | { type: "stopRun" }
+  /** POST /stream { supersede: { runId } } — the CAS "interrupt and send now". */
+  | { type: "supersede"; targetRunId: string }
+  /** Abort the in-flight attach/reconnect GET controller (dispose / observer stop). */
+  | { type: "abortAttach" };
+
+// ---------------------------------------------------------------------------
+// Events. An OUTCOME event MAY carry `epoch`; if it does and it does not equal
+// the current epoch, the reducer drops it (I1). Trigger events (user actions,
+// fresh disconnects) carry no epoch and are never dropped.
+// ---------------------------------------------------------------------------
+
+export type Event =
+  // -- local turn --
+  | { type: "SEND_LOCAL" }
+  | { type: "STREAM_START"; runId?: string; epoch?: number }
+  /** An OBSERVER's attached stream ended WITHOUT reaching terminal (a starved
+   *  clean replay, or a torn resume) — fall to the degraded poll to drive the row
+   *  to its real terminal state. (A live-follow drop uses FINISH_DISCONNECT.) */
+  | { type: "STREAM_INCOMPLETE"; reason: PollReason; epoch?: number }
+  | { type: "FINISH_CLEAN"; epoch?: number }
+  | { type: "FINISH_ABORT"; epoch?: number }
+  | { type: "FINISH_DISCONNECT"; hasVisibleContent: boolean; epoch?: number }
+  | { type: "FINISH_ERROR"; kind: ErrorKind; epoch?: number }
+  // -- mount attach (resume) --
+  | { type: "ATTACH_START"; runId?: string }
+  | { type: "ATTACH_LIVE"; epoch?: number }
+  | { type: "ATTACH_NONE"; epoch?: number }
+  // -- reconnect after a live disconnect (entered by FINISH_DISCONNECT, #488 c2) --
+  | { type: "RECONNECT_ATTEMPT"; attempt: number; epoch?: number }
+  | { type: "RECONNECT_ATTACHED"; epoch?: number }
+  | { type: "RECONNECT_NONE"; epoch?: number }
+  | { type: "RETRY" }
+  // -- degraded poll --
+  | { type: "POLL_TERMINAL" }
+  | { type: "POLL_IDLE_CAP" }
+  // -- run-fact (server-confirmed active run) --
+  | { type: "RUN_FACT"; runFact: RunFact; epoch?: number }
+  // -- stop --
+  | { type: "STOP_REQUESTED" }
+  // -- supersede (CAS) --
+  | { type: "SUPERSEDE_REQUESTED"; targetRunId: string }
+  | { type: "SUPERSEDE_READY"; runId?: string; epoch?: number }
+  | { type: "SUPERSEDE_MISMATCH"; currentRunId?: string; epoch?: number }
+  | { type: "SUPERSEDE_TIMEOUT"; epoch?: number }
+  | { type: "SUPERSEDE_INVALID"; epoch?: number }
+  | { type: "RUN_ALREADY_ACTIVE"; activeRunId?: string }
+  // -- lifecycle --
+  | { type: "DISPOSE" };
+
+export const RECONNECT_MAX_ATTEMPTS = 5;
+export const RECONNECT_BASE_DELAY_MS = 1000;
+/** Backoff before attempt N (1-based): 1s, 2s, 4s, 8s, 16s. */
+export function reconnectDelayMs(attempt: number): number {
+  return RECONNECT_BASE_DELAY_MS * 2 ** (attempt - 1);
+}
+
+// ---------------------------------------------------------------------------
+// Constructors / helpers.
+// ---------------------------------------------------------------------------
+
+export function initialMachine(overrides?: Partial<Ctx>): Machine {
+  return {
+    phase: { name: "idle" },
+    ctx: { epoch: 0, ownership: "local", runFact: null, liveFollow: false, ...overrides },
+    effects: [],
+  };
+}
+
+/** Build a machine result: a phase, optional ctx patch, and effects. Empty
+ *  effects by default. Never mutates the input. */
+function to(
+  m: Machine,
+  phase: Phase,
+  opts?: { ctx?: Partial<Ctx>; effects?: Effect[] },
+): Machine {
+  return {
+    phase,
+    ctx: { ...m.ctx, ...(opts?.ctx ?? {}) },
+    effects: opts?.effects ?? [],
+  };
+}
+
+/** No transition: keep the phase, clear effects (so a re-run does not re-fire). */
+function stay(m: Machine): Machine {
+  return { phase: m.phase, ctx: m.ctx, effects: [] };
+}
+
+/** A command-transition: same as `to` but bumps the epoch (I1). Any outcome
+ *  event issued under the old epoch is dropped once this lands. */
+function command(
+  m: Machine,
+  phase: Phase,
+  effects: Effect[],
+  ctx?: Partial<Ctx>,
+): Machine {
+  return {
+    phase,
+    ctx: { ...m.ctx, ...(ctx ?? {}), epoch: m.ctx.epoch + 1 },
+    effects,
+  };
+}
+
+// ---------------------------------------------------------------------------
+// The pure reducer.
+// ---------------------------------------------------------------------------
+
+/** The terminal stream-finish events (one turn's stream ended). */
+function isFinishEvent(event: Event): boolean {
+  return (
+    event.type === "FINISH_ABORT" ||
+    event.type === "FINISH_CLEAN" ||
+    event.type === "FINISH_DISCONNECT" ||
+    event.type === "FINISH_ERROR" ||
+    event.type === "STREAM_INCOMPLETE"
+  );
+}
+
+export function reduce(m: Machine, event: Event): Machine {
+  // MEDIUM (#488 re-review): honor ANY stream finish in `stopping` regardless of
+  // generation. A plain user Stop has NO successor stream — the aborted stream's
+  // finish IS the expected end of the stop, so exit `stopping -> idle` by that DATA
+  // (I4). The epoch filter below must NOT drop it: STOP_REQUESTED bumped the epoch,
+  // but the finish carries the PRE-stop generation (the runtime stamps it with the
+  // stream's start epoch), so I1 would otherwise strand the machine in `stopping`
+  // forever (no idle-cap covers `stopping`). The epoch filter stays in force for
+  // `superseding` (a successor B owns) — that is the F1 supersede drop.
+  if (m.phase.name === "stopping" && isFinishEvent(event)) {
+    return to(m, { name: "idle" }, {
+      // Reset ownership to local on this terminal transition (review #2): otherwise
+      // an observer-stop leaves ownership 'observer' and hides "Send now" forever.
+      ctx: { runFact: null, liveFollow: false, ownership: "local" },
+      effects: [{ type: "disarmPoll" }, { type: "cancelReconnect" }],
+    });
+  }
+
+  // I1: drop a stale outcome (an event issued under a superseded epoch).
+  if ("epoch" in event && event.epoch !== undefined && event.epoch !== m.ctx.epoch) {
+    return stay(m);
+  }
+
+  switch (event.type) {
+    // ---- local turn ----------------------------------------------------
+    case "SEND_LOCAL":
+      // A local send owns the view: leave any recovery, become the local
+      // streamer, disarm poll/reconnect. epoch++ so a late recovery outcome
+      // from the previous phase is dropped.
+      return command(
+        m,
+        { name: "sending" },
+        [{ type: "cancelReconnect" }, { type: "disarmPoll" }],
+        { ownership: "local", liveFollow: false },
+      );
+
+    case "STREAM_INCOMPLETE":
+      // An OBSERVER's attached stream ended incomplete (starved / torn) — follow
+      // the run to terminal via the degraded poll.
+      return to(m, { name: "polling", reason: event.reason }, {
+        effects: [{ type: "armPoll", reason: event.reason }],
+      });
+
+    case "STREAM_START": {
+      // First frame arrived. Adopt the run-fact runId if present. sending ->
+      // streaming; a reconnect/attach that just went live also lands here.
+      const runFact = event.runId ? { runId: event.runId } : m.ctx.runFact;
+      return to(m, { name: "streaming" }, {
+        ctx: { runFact },
+        effects: [{ type: "cancelReconnect" }, { type: "disarmPoll" }],
+      });
+    }
+
+    case "FINISH_CLEAN":
+      // A clean terminal outcome. The run is done — clear the run-fact and go
+      // idle. (The queue flush is a component concern gated by ownership; the
+      // FSM only models the phase.) Review #2: reset ownership to local so a
+      // just-finished observer-attach turn re-exposes "Send now" for the queue.
+      return to(m, { name: "idle" }, {
+        ctx: { runFact: null, liveFollow: false, ownership: "local" },
+        effects: [{ type: "disarmPoll" }, { type: "cancelReconnect" }],
+      });
+
+    case "FINISH_ABORT":
+      // A user Stop / intentional abort finished. If we were stopping, the
+      // terminal data has now arrived (I4) — go idle. The run-fact is cleared.
+      return to(m, { name: "idle" }, {
+        ctx: { runFact: null, liveFollow: false, ownership: "local" },
+        effects: [{ type: "disarmPoll" }, { type: "cancelReconnect" }],
+      });
+
+    case "FINISH_DISCONNECT":
+      // A LIVE SSE drop. Recovery depends on WHO we are (I2 + liveFollow):
+      //  - a mount-attach OBSERVER (a one-shot resume, NOT live-follow) that drops
+      //    -> the degraded poll drives the row to terminal from the DB.
+      if (m.ctx.ownership === "observer" && !m.ctx.liveFollow) {
+        return to(m, { name: "polling", reason: "disconnect-visible" }, {
+          effects: [{ type: "armPoll", reason: "disconnect-visible" }],
+        });
+      }
+      //  - a LOCAL live turn (first drop) OR a live-follow re-attach (a SUBSEQUENT
+      //    drop) -> (re-)enter the reconnect ladder. #488 commit 3: allowed
+      //    REPEATEDLY — `liveFollow` is kept across a successful re-attach, so the
+      //    second break reconnects again instead of falling to silent poll.
+      // #488 commit 2: gated on the RUN-FACT (or an existing live-follow), NOT on
+      // the presence of an assistant message — a setup-phase break still recovers.
+      //  - visible content already on screen -> keep it, ALSO poll to terminal
+      //    (a full replay could clobber the fuller live tail);
+      //  - no visible content -> the reconnect ladder rebuilds it.
+      if (m.ctx.runFact || m.ctx.liveFollow) {
+        const effects: Effect[] = [
+          { type: "scheduleReconnect", attempt: 1, delayMs: reconnectDelayMs(1) },
+        ];
+        if (event.hasVisibleContent) effects.push({ type: "armPoll", reason: "disconnect-visible" });
+        return command(m, { name: "reconnecting", attempt: 1, failed: false }, effects, {
+          ownership: "observer",
+          liveFollow: true,
+        });
+      }
+      // No run to recover: a plain disconnect. Surface the terminal notice.
+      return to(m, { name: "idle" }, {
+        ctx: { runFact: null, liveFollow: false, ownership: "local" },
+      });
+
+    case "FINISH_ERROR":
+      return to(m, { name: "error", kind: event.kind }, {
+        ctx: { runFact: null, liveFollow: false, ownership: "local" },
+        effects: [{ type: "disarmPoll" }, { type: "cancelReconnect" }],
+      });
+
+    // ---- mount attach (resume) ----------------------------------------
+    case "ATTACH_START":
+      // A reopened tab attaches to a still-running run: observer ownership.
+      // #488 F2: ONLY from idle. The mount `getRun` round-trip resolves async, and
+      // a local send may have started meanwhile (phase `sending`, ownership local);
+      // a late ATTACH_START must NOT hijack that local turn into an observer-attach
+      // (queue would stop flushing, "Send now" would hide). Guarding in the reducer
+      // covers every dispatch source.
+      if (m.phase.name !== "idle") return stay(m);
+      return command(m, { name: "attaching" }, [{ type: "resumeStream" }], {
+        ownership: "observer",
+        runFact: event.runId ? { runId: event.runId } : m.ctx.runFact,
+      });
+
+    case "ATTACH_LIVE":
+      // The attach GET returned a live 2xx stream — follow it as an observer.
+      // Review #1: guard by SOURCE phase. The epoch filter alone is not enough — a
+      // POLL_TERMINAL uses to() (no epoch bump) and does not abort the in-flight
+      // GET, so a slow 2xx landing after the machine already left `attaching` (e.g.
+      // the armed poll saw the terminal row -> idle) would resurrect a settled run
+      // into a phantom `streaming`. Only enter streaming FROM `attaching`.
+      if (m.phase.name !== "attaching") return stay(m);
+      return to(m, { name: "streaming" });
+
+    case "ATTACH_NONE":
+      // 204 / non-2xx / throw: nothing live to attach. Arm the degraded poll to
+      // follow the run to terminal from the DB. This is a soft-negative run-fact
+      // (204 on a non-stripped path is authoritative-negative; the runtime may
+      // pass a RUN_FACT null separately). Keep the run-fact as-is here.
+      // Review #1: guard by source phase for consistency (a late outcome after the
+      // machine already left `attaching` must not re-arm a poll).
+      if (m.phase.name !== "attaching") return stay(m);
+      return to(m, { name: "polling", reason: "attach-none" }, {
+        effects: [{ type: "armPoll", reason: "attach-none" }],
+      });
+
+    // ---- reconnect after a live disconnect ----------------------------
+    case "RECONNECT_ATTEMPT":
+      // A scheduled backoff fired — fire the attach GET. epoch++ so the previous
+      // attempt's late outcome cannot drive this one.
+      if (m.phase.name !== "reconnecting") return stay(m);
+      return command(
+        m,
+        { name: "reconnecting", attempt: event.attempt, failed: false },
+        [{ type: "resumeStream" }],
+      );
+
+    case "RECONNECT_ATTACHED":
+      // #488 commit 3: a live re-attach succeeded. Reset to streaming — the
+      // attempt counter is dropped, so a LATER disconnect can start a fresh
+      // ladder from attempt 1 (the old one-shot `!wasResumed` gate forbade a
+      // second cycle, sending the second break to silent poll).
+      // Review #1: guard by SOURCE phase. The armed degraded poll can reach the
+      // terminal row (POLL_TERMINAL -> idle, via to(), NO epoch bump, GET not
+      // aborted) BEFORE a slow reconnect GET returns 2xx; without this guard that
+      // late RECONNECT_ATTACHED (same epoch) would resurrect a settled run into a
+      // phantom `streaming`. Only re-enter streaming FROM `reconnecting`.
+      if (m.phase.name !== "reconnecting") return stay(m);
+      return to(m, { name: "streaming" }, {
+        effects: [{ type: "cancelReconnect" }, { type: "disarmPoll" }],
+      });
+
+    case "RECONNECT_NONE": {
+      // 204 / error during a reconnect attempt. Arm the degraded poll as the
+      // belt-and-suspenders fallback, then either back off to the next attempt
+      // or, at the cap, surface the manual Retry ("failed").
+      if (m.phase.name !== "reconnecting") return stay(m);
+      const attempt = m.phase.attempt;
+      if (attempt < RECONNECT_MAX_ATTEMPTS) {
+        return command(
+          m,
+          { name: "reconnecting", attempt: attempt + 1, failed: false },
+          [
+            { type: "armPoll", reason: "attach-none" },
+            { type: "scheduleReconnect", attempt: attempt + 1, delayMs: reconnectDelayMs(attempt + 1) },
+          ],
+        );
+      }
+      return to(m, { name: "reconnecting", attempt, failed: true }, {
+        effects: [{ type: "armPoll", reason: "reconnect-exhausted" }],
+      });
+    }
+
+    case "RETRY":
+      // Manual Retry from the "failed" reconnect banner OR the stalled banner.
+      if (m.phase.name === "reconnecting" && m.phase.failed) {
+        return command(
+          m,
+          { name: "reconnecting", attempt: 1, failed: false },
+          [{ type: "resumeStream" }],
+        );
+      }
+      if (m.phase.name === "stalled") {
+        // Re-arm the poll to try to catch the run up again.
+        return command(m, { name: "polling", reason: "attach-none" }, [
+          { type: "armPoll", reason: "attach-none" },
+        ]);
+      }
+      return stay(m);
+
+    // ---- degraded poll -------------------------------------------------
+    case "POLL_TERMINAL":
+      // The run reached a terminal row via the poll (or the reconcile merge). Go
+      // idle and disarm everything (I4: this is a DATA-driven exit, incl. exit
+      // from `stopping`). Review #2: reset ownership to local.
+      return to(m, { name: "idle" }, {
+        ctx: { runFact: null, liveFollow: false, ownership: "local" },
+        effects: [{ type: "disarmPoll" }, { type: "cancelReconnect" }],
+      });
+
+    case "POLL_IDLE_CAP":
+      // Review #4: `stopping` also arms the poll (STOP_REQUESTED) but has NO other
+      // backstop — an observer-stop with no SDK stream to fire onFinish, whose
+      // server stop never drives the run terminal, would poll the DB forever. Give
+      // it a bounded exit: cap -> idle + disarm (NOT `stalled`; Stop was already
+      // pressed, so there is nothing for the user to retry).
+      if (m.phase.name === "stopping") {
+        return to(m, { name: "idle" }, {
+          ctx: { runFact: null, liveFollow: false, ownership: "local" },
+          effects: [{ type: "disarmPoll" }, { type: "cancelReconnect" }],
+        });
+      }
+      // #488 commit 4a: the poll hit the inactivity cap. Instead of going SILENT
+      // (the old "forever half-done answer"), surface a stalled banner + Retry.
+      if (m.phase.name !== "polling" && m.phase.name !== "reconnecting") return stay(m);
+      return to(m, { name: "stalled" }, {
+        effects: [{ type: "disarmPoll" }, { type: "cancelReconnect" }],
+      });
+
+    // ---- run-fact ------------------------------------------------------
+    case "RUN_FACT": {
+      const runFact = event.runFact;
+      // A fresh NEGATIVE fact (no active run) cancels recovery immediately (I3):
+      // there is nothing to reconnect to / poll for.
+      if (!runFact) {
+        if (
+          m.phase.name === "reconnecting" ||
+          m.phase.name === "attaching" ||
+          m.phase.name === "polling" ||
+          m.phase.name === "stopping"
+        ) {
+          return to(m, { name: "idle" }, {
+            // Review #2: reset ownership to local on this terminal transition.
+            ctx: { runFact: null, liveFollow: false, ownership: "local" },
+            effects: [{ type: "cancelReconnect" }, { type: "disarmPoll" }],
+          });
+        }
+        return to(m, m.phase, { ctx: { runFact: null } });
+      }
+      // A positive fact just updates the context (pessimism toward an attempt: a
+      // stale-but-positive fact permits entering recovery; a 204 will cut it).
+      return to(m, m.phase, { ctx: { runFact } });
+    }
+
+    // ---- stop ----------------------------------------------------------
+    case "STOP_REQUESTED":
+      // Authoritative stop of a detached run. Enter `stopping` and fire stopRun +
+      // abort the local/attach reader. ALSO arm the poll so the terminal row is
+      // observed — the exit is by DATA (I4: a terminal row / negative run-fact),
+      // never by the stopRun HTTP response (which returns after abort, before
+      // finalization). For a local turn the aborted stream's onFinish (ANY finish)
+      // is HONORED in `stopping` at the top of reduce() — regardless of generation
+      // — and exits to idle; the armed poll is the fallback for an observer stop
+      // with no local onFinish.
+      return command(
+        m,
+        { name: "stopping" },
+        [
+          { type: "stopRun" },
+          { type: "abortAttach" },
+          { type: "cancelReconnect" },
+          { type: "armPoll", reason: "attach-none" },
+        ],
+      );
+
+    // ---- supersede (CAS) ----------------------------------------------
+    case "SUPERSEDE_REQUESTED":
+      // "Interrupt and send now": CAS POST /stream { supersede }. epoch++ so a
+      // late outcome of the interrupted run is dropped.
+      return command(
+        m,
+        { name: "superseding" },
+        [{ type: "supersede", targetRunId: event.targetRunId }, { type: "cancelReconnect" }, { type: "disarmPoll" }],
+      );
+
+    case "SUPERSEDE_READY": {
+      // CAS succeeded (old run stopped/settled, slot taken, new run begun). We
+      // are now the local streamer of the NEW run. Adopt its runId if provided.
+      const runFact = event.runId ? { runId: event.runId } : m.ctx.runFact;
+      return to(m, { name: "streaming" }, {
+        ctx: { ownership: "local", runFact, liveFollow: false },
+      });
+    }
+
+    case "SUPERSEDE_MISMATCH":
+      // The active run moved between the click and the CAS. Per the spec: verify
+      // via /run rather than blindly banner — the mismatch may be our own already-
+      // superseded run. Surface a classified error AND fire a run-fact verify.
+      return to(m, { name: "error", kind: "supersede-mismatch" }, {
+        ctx: { runFact: event.currentRunId ? { runId: event.currentRunId } : m.ctx.runFact },
+        effects: [{ type: "postRun", reason: "verify" }],
+      });
+
+    case "SUPERSEDE_TIMEOUT":
+      // The old run did not settle within W. Nothing persisted; the composer keeps
+      // its text. Classified error, NO auto-retry (the old client retry ladder is
+      // removed in #488 commit 5).
+      return to(m, { name: "error", kind: "supersede-timeout" });
+
+    case "SUPERSEDE_INVALID":
+      return to(m, { name: "error", kind: "supersede-invalid" });
+
+    case "RUN_ALREADY_ACTIVE":
+      // A plain POST hit the one-active-run gate. NO auto-retry — the composer
+      // offers "interrupt and send" (supersede) instead. #497/S4: adopt the
+      // server's activeRunId as the run-fact so that supersede can TARGET the
+      // (possibly foreign-tab) active run via the CAS, rather than a blind
+      // promote+abort that just 409s again. A stale/absent id keeps the prior fact.
+      return to(m, { name: "error", kind: "run-already-active" }, {
+        ctx: { runFact: event.activeRunId ? { runId: event.activeRunId } : m.ctx.runFact },
+      });
+
+    // ---- lifecycle -----------------------------------------------------
+    case "DISPOSE":
+      // Unmount: abort in-flight controllers, drop timers, and bump the epoch so
+      // NO late callback can drive this (now dead) machine (I5).
+      return command(
+        m,
+        { name: "idle" },
+        [
+          { type: "abortAttach" },
+          { type: "cancelReconnect" },
+          { type: "disarmPoll" },
+        ],
+        { liveFollow: false },
+      );
+
+    default: {
+      // Exhaustiveness guard.
+      const _never: never = event;
+      void _never;
+      return stay(m);
+    }
+  }
+}

apps/client/src/features/ai-chat/utils/adopt-chat-id.test.ts

@@ -3,6 +3,7 @@ import {
   resolveAdoptedChatId,
   newlyAddedChatIds,
   extractServerChatId,
+  extractRunId,
 } from "./adopt-chat-id";
 
 describe("resolveAdoptedChatId", () => {
@@ -70,3 +71,17 @@ describe("extractServerChatId", () => {
     expect(extractServerChatId(undefined)).toBeUndefined();
   });
 });
+
+describe("extractRunId", () => {
+  it("reads a string runId from the start metadata", () => {
+    expect(extractRunId({ metadata: { runId: "run-1" } })).toBe("run-1");
+  });
+  it("returns undefined when runId is absent", () => {
+    expect(extractRunId({ metadata: { chatId: "c" } })).toBeUndefined();
+    expect(extractRunId({})).toBeUndefined();
+    expect(extractRunId(undefined)).toBeUndefined();
+  });
+  it("returns undefined for a non-string runId", () => {
+    expect(extractRunId({ metadata: { runId: 7 } })).toBeUndefined();
+  });
+});

apps/client/src/features/ai-chat/utils/adopt-chat-id.ts

@@ -56,6 +56,20 @@ export function extractServerChatId(
   return typeof m?.chatId === "string" ? m.chatId : undefined;
 }
 
+/**
+ * #488: read the authoritative RUN id off a streaming assistant message. The
+ * server attaches it as `message.metadata.runId` on the `start` part when a run
+ * wraps the turn (see server `chatStreamMetadata`, #184/#487). This is the live
+ * run-fact update the client FSM adopts (mirrors `extractServerChatId`). Returns
+ * it only when it is a string; undefined otherwise.
+ */
+export function extractRunId(
+  message: { metadata?: unknown } | undefined,
+): string | undefined {
+  const m = message?.metadata as { runId?: string } | undefined;
+  return typeof m?.runId === "string" ? m.runId : undefined;
+}
+
 /**
  * The deduped set of ids present in `afterIds` but not in `beforeIds`. A
  * paginated/flatMapped list can repeat the same id, so dedupe: one genuinely-new

apps/client/src/features/ai-chat/utils/collapse-blank-lines.test.ts

@@ -33,29 +33,44 @@ describe("collapseBlankLines", () => {
   });
 });
 
-describe("collapseBlankLines + renderChatMarkdown (tight reasoning rendering)", () => {
+describe("collapseBlankLines + renderChatMarkdown (canonical converter)", () => {
-  it("renders a blank-line-separated list as a TIGHT list (no <li><p>)", () => {
+  // Chat markdown now renders through @docmost/prosemirror-markdown (issue #347):
+  // the SAME converter the editor/import use. Its list items are schema-shaped —
+  // each <li>'s content is wrapped in a <p> (listItem content is `paragraph+`) —
+  // so the HTML always carries `<li><p>…</p></li>` regardless of blank-line
+  // looseness in the source (the converter has no tight/loose distinction). The
+  // visual tightness that `collapseBlankLines` used to buy is now provided by
+  // CSS (`.markdown li p { margin: 0 }`), not the HTML shape.
+  it("renders a blank-line-separated bullet list as a real <ul> list", () => {
     const loose =
       "Intro paragraph.\n\n- item one\n\n- item two\n\n- item three";
     const html = renderChatMarkdown(collapseBlankLines(loose), {});
-    // Tight list: each <li> holds the text directly, not wrapped in a <p>.
+    // Clean, un-namespaced HTML (DOMSerializer, not XMLSerializer) — no xmlns.
-    expect(html).toContain("<li>item one</li>");
-    expect(html).not.toContain("<li><p>");
-    // The list still parses as a list after the paragraph (not a paragraph+<br>).
     expect(html).toContain("<ul>");
+    expect(html).not.toMatch(/<ul[^>]*xmlns/);
+    // The item text is present (inside the schema's <li><p> wrapper).
+    expect(html).toContain("item one");
+    // The intro paragraph renders as its own paragraph before the list.
     expect(html).toContain("<p>Intro paragraph.</p>");
   });
 
-  it("renders an ordered list (1. 2.) as tight after collapsing", () => {
+  it("renders an ordered list (1. 2.) as a real <ol> list", () => {
     const loose = "Intro.\n\n1. first\n\n2. second";
     const html = renderChatMarkdown(collapseBlankLines(loose), {});
     expect(html).toContain("<ol>");
-    expect(html).toContain("<li>first</li>");
+    expect(html).not.toMatch(/<ol[^>]*xmlns/);
-    expect(html).not.toContain("<li><p>");
+    expect(html).toContain("first");
+    expect(html).toContain("second");
   });
 
-  it("the loose source WOULD render <li><p> without collapsing (control)", () => {
+  it("wraps list-item content in <p> (schema shape; tightness is CSS)", () => {
+    // The canonical converter always wraps a list item's content in a paragraph,
+    // whether or not the source had blank lines between items.
     const loose = "- a\n\n- b";
     expect(renderChatMarkdown(loose, {})).toContain("<li><p>");
+    // And a "tight" source produces the identical wrapping (no distinction).
+    expect(renderChatMarkdown(collapseBlankLines(loose), {})).toContain(
+      "<li><p>",
+    );
   });
 });

apps/client/src/features/ai-chat/utils/count-stream-tokens.test.ts

@@ -6,10 +6,13 @@ describe("estimateTokens", () => {
     expect(estimateTokens("")).toBe(0);
   });
 
-  it("ceils chars/4 so any non-empty text is at least 1 token", () => {
+  // #490: migrated onto the shared @docmost/token-estimate module (chars/2.5, up
+  // from the old client-only chars/4) so the client counter and the server replay
+  // budgeter can never diverge.
+  it("ceils chars/2.5 so any non-empty text is at least 1 token", () => {
     expect(estimateTokens("a")).toBe(1);
-    expect(estimateTokens("abcd")).toBe(1);
+    expect(estimateTokens("ab")).toBe(1);
-    expect(estimateTokens("abcde")).toBe(2);
+    expect(estimateTokens("abcde")).toBe(2); // 5 / 2.5 = 2
-    expect(estimateTokens("12345678")).toBe(2);
+    expect(estimateTokens("x".repeat(10))).toBe(4); // 10 / 2.5 = 4
   });
 });

apps/client/src/features/ai-chat/utils/count-stream-tokens.ts

@@ -2,18 +2,10 @@
  * Rough client-side token estimation for AI-chat UI affordances.
  *
  * No provider streams exact per-token usage mid-stream, so any in-flight figure
- * is a CLIENT ESTIMATE (chars/≈4 heuristic). Pure + unit-testable: it never runs
+ * is a CLIENT ESTIMATE. This re-exports the SHARED estimator from
- * a real BPE tokenizer (that would be O(n²) on the hot path, bloat the bundle,
+ * `@docmost/token-estimate` (chars/2.5) so the in-body counter and the server's
- * and be wrong for Gemini/Ollama anyway). Used by the in-body reasoning counter
+ * replay budgeter use the SAME heuristic — two divergent estimators would mean
- * ("Thinking · N tokens").
+ * "the badge shows 60%" while "the budgeter already trimmed" (#490). Used by the
+ * in-body reasoning counter ("Thinking · N tokens").
  */
-
+export { estimateTokens } from "@docmost/token-estimate";
-/**
- * Rough token estimate for a piece of text using the standard chars/≈4 heuristic.
- * Returns 0 for empty/whitespace-free-of-content input, and ceils so any
- * non-empty text counts as at least one token.
- */
-export function estimateTokens(text: string): number {
-  if (!text) return 0;
-  return Math.ceil(text.length / 4);
-}

apps/client/src/features/ai-chat/utils/error-message.test.ts

@@ -23,6 +23,89 @@ describe("describeChatError", () => {
     });
   });
 
+  it("classifies an A_RUN_BEGIN_FAILED 503 as a temporary run-start failure, NOT provider-not-configured (#486)", () => {
+    // The FULL real body the server writes for a beginRun failure: a
+    // ServiceUnavailableException(object) whose response is serialized verbatim
+    // onto the raw socket, self-describing statusCode 503 + the run-start code.
+    const body =
+      '{"message":"Could not start the agent run. This is usually temporary — please try again.","code":"A_RUN_BEGIN_FAILED","statusCode":503}';
+    expect(describeChatError(body, t)).toEqual({
+      title: "Could not start the run",
+      detail:
+        "The agent run could not be started. This is usually temporary — please try again.",
+    });
+    // ORDER GUARD: even though the body ALSO carries statusCode 503 (which the
+    // generic branch matches), the A_RUN_BEGIN_FAILED branch runs first, so it is
+    // never mislabeled "AI provider not configured".
+    expect(describeChatError(body, t).title).not.toBe(
+      "AI provider not configured",
+    );
+  });
+
+  // #488 commit 5: the #487 concurrency-gate / supersede 409s. FULL real bodies:
+  // a ConflictException(object) whose response is serialized verbatim, carrying a
+  // `code` and statusCode 409. Each must classify to a human text, not raw JSON.
+  it("classifies A_RUN_ALREADY_ACTIVE (409) as already-answering, not raw JSON", () => {
+    const body =
+      '{"message":"A run is already active for this chat","code":"A_RUN_ALREADY_ACTIVE","statusCode":409}';
+    expect(describeChatError(body, t).title).toBe(
+      "The agent is already answering",
+    );
+    // Never leaks the raw code as the detail.
+    expect(describeChatError(body, t).detail).not.toContain("A_RUN_ALREADY_ACTIVE");
+  });
+
+  it("classifies SUPERSEDE_TARGET_MISMATCH (409) as run-changed", () => {
+    // Real server body shape: the current run id is `activeRunId` (NOT `runId`) —
+    // see ai-chat.controller.ts. describeChatError classifies off `code` only.
+    const body =
+      '{"message":"active run does not match the supersede target","code":"SUPERSEDE_TARGET_MISMATCH","activeRunId":"run-x","statusCode":409}';
+    expect(describeChatError(body, t).title).toBe(
+      "Couldn't interrupt — the run changed",
+    );
+  });
+
+  it("classifies SUPERSEDE_TIMEOUT (409) as couldn't-interrupt-in-time", () => {
+    const body =
+      '{"message":"the run did not settle within the supersede window","code":"SUPERSEDE_TIMEOUT","statusCode":409}';
+    expect(describeChatError(body, t).title).toBe("Couldn't interrupt in time");
+  });
+
+  it("classifies SUPERSEDE_INVALID (409) as couldn't-interrupt-that-run", () => {
+    const body =
+      '{"message":"supervise requires chatId","code":"SUPERSEDE_INVALID","statusCode":409}';
+    expect(describeChatError(body, t).title).toBe(
+      "Couldn't interrupt that run",
+    );
+  });
+
+  it("ORDER GUARD: A_RUN_ALREADY_ACTIVE wins over any generic status branch", () => {
+    // Even though the body could superficially look 4xx-ish, the code branch runs
+    // first, so it is never mislabeled by a generic status heading.
+    const body =
+      '{"message":"conflict","code":"A_RUN_ALREADY_ACTIVE","statusCode":409}';
+    const view = describeChatError(body, t);
+    expect(view.title).not.toBe("Something went wrong");
+    expect(view.title).not.toBe("AI provider not configured");
+  });
+
+  it("classifies a token-degeneration abort under the SAME 'Response stopped.' marker the live view shows (#495)", () => {
+    // The exact reason the server persists in metadata.error on a degeneration
+    // abort (ai-chat.service OUTPUT_DEGENERATION_ERROR). Live, this event shows
+    // the neutral "Response stopped." notice; the persisted banner MUST match it
+    // so live and refetch never disagree.
+    const view = describeChatError(
+      "Output degeneration detected (repeated token loop)",
+      t,
+    );
+    expect(view.title).toBe("Response stopped.");
+    expect(view.detail).toBe(
+      "The answer was stopped automatically because the model fell into a repeated output loop.",
+    );
+    // Regression guard: it must NOT fall through to the generic heading.
+    expect(view.title).not.toBe("Something went wrong");
+  });
+
   it("classifies a dropped connection (ECONNRESET) as a lost-connection error", () => {
     expect(
       describeChatError("Cannot connect to API: read ECONNRESET", t).title,

apps/client/src/features/ai-chat/utils/error-message.ts

@@ -24,6 +24,75 @@ export function describeChatError(
 ): ChatErrorView {
   const msg = message ?? "";
 
+  // Our own "could not start the run" gate (A_RUN_BEGIN_FAILED, #486): a 503
+  // whose body carries this code is a TEMPORARY server-side failure while
+  // starting the run (e.g. a DB-pool blip), NOT an unconfigured provider. It MUST
+  // be matched STRICTLY BEFORE the generic 503 branch below, which would
+  // otherwise mislabel it "The AI provider is not configured" and tell the user
+  // to call an admin instead of just retrying.
+  if (/"code"\s*:\s*"A_RUN_BEGIN_FAILED"/.test(msg)) {
+    return {
+      title: t("Could not start the run"),
+      detail: t(
+        "The agent run could not be started. This is usually temporary — please try again.",
+      ),
+    };
+  }
+
+  // #488 commit 5: the #487 concurrency-gate / supersede 409s. These arrive as a
+  // ConflictException(object) body carrying a `code` (and statusCode 409). They
+  // MUST be classified by `code` STRICTLY BEFORE any generic status branch, or the
+  // user sees the raw JSON `{"code":"A_RUN_ALREADY_ACTIVE",…}`. The code strings
+  // are the real #487 server contract (ai-chat.controller.ts) — do not invent.
+  if (/"code"\s*:\s*"A_RUN_ALREADY_ACTIVE"/.test(msg)) {
+    return {
+      title: t("The agent is already answering"),
+      detail: t(
+        "This chat already has a run in progress. Wait for it to finish, or interrupt it and send now.",
+      ),
+    };
+  }
+  if (/"code"\s*:\s*"SUPERSEDE_TARGET_MISMATCH"/.test(msg)) {
+    return {
+      title: t("Couldn't interrupt — the run changed"),
+      detail: t(
+        "The run you tried to interrupt is no longer the active one. Check the latest answer and try again.",
+      ),
+    };
+  }
+  if (/"code"\s*:\s*"SUPERSEDE_TIMEOUT"/.test(msg)) {
+    return {
+      title: t("Couldn't interrupt in time"),
+      detail: t(
+        "The previous run didn't stop in time. Nothing was sent — try sending again.",
+      ),
+    };
+  }
+  if (/"code"\s*:\s*"SUPERSEDE_INVALID"/.test(msg)) {
+    return {
+      title: t("Couldn't interrupt that run"),
+      detail: t(
+        "The run to interrupt doesn't belong to this chat. Reload and try again.",
+      ),
+    };
+  }
+
+  // Our own token-degeneration abort (#444): the server aborts a runaway
+  // repetition loop and persists this exact reason in metadata.error. LIVE, the
+  // same abort surfaces as the neutral "Response stopped." notice (the client
+  // cannot tell it from a manual Stop mid-stream), so the persisted banner must
+  // read the SAME "Response stopped." marker — otherwise the live view and a
+  // later refetch show two different texts for one event. The detail explains the
+  // loop-guard cause without contradicting the shared heading.
+  if (/output degeneration detected|repeated token loop/i.test(msg)) {
+    return {
+      title: t("Response stopped."),
+      detail: t(
+        "The answer was stopped automatically because the model fell into a repeated output loop.",
+      ),
+    };
+  }
+
   if (/"statusCode"\s*:\s*403\b/.test(msg)) {
     return {
       title: t("AI chat is disabled"),

apps/client/src/features/ai-chat/utils/markdown.ts

@@ -1,6 +1,37 @@
-import { markdownToHtml } from "@docmost/editor-ext";
+import {
+  markdownToProseMirrorSync,
+  docmostExtensions,
+} from "@docmost/prosemirror-markdown/browser";
+import { getSchema } from "@tiptap/core";
+import { Node as PMNode, DOMSerializer } from "@tiptap/pm/model";
 import DOMPurify from "dompurify";
 
+// The Docmost editor schema, built once. Chat markdown is rendered through the
+// SAME schema the editor/import use (issue #347), so chat output matches how the
+// page would render the same markdown.
+const chatSchema = getSchema(docmostExtensions);
+
+/**
+ * Markdown -> HTML for chat display, via the canonical converter. We serialize
+ * the ProseMirror doc with `DOMSerializer` into a real element and read its
+ * `innerHTML` (rather than `@tiptap/html`'s `generateHTML`, whose browser path
+ * uses `XMLSerializer` and stamps a `xmlns` on every block) so the markup is
+ * clean HTML. `li > p` wrapping is inherent to the schema (listItem content is
+ * `paragraph+`); the chat CSS zeroes those paragraph margins so lists still
+ * render tight.
+ */
+function markdownToChatHtml(markdown: string): string {
+  const doc = markdownToProseMirrorSync(markdown);
+  const node = PMNode.fromJSON(chatSchema, doc);
+  const div = document.createElement("div");
+  DOMSerializer.fromSchema(chatSchema).serializeFragment(
+    node.content,
+    { document },
+    div,
+  );
+  return div.innerHTML;
+}
+
 export interface RenderChatMarkdownOptions {
   /**
    * Neutralize INTERNAL links so they render as inert text (no `href`/`target`).
@@ -63,22 +94,32 @@ function neutralizeInternalLinksHook(node: Element): void {
 
 /**
  * Render AI markdown to sanitized HTML for read-only display. We reuse the
- * app's `markdownToHtml` (the same `marked` pipeline used for paste/import) so
+ * canonical converter (issue #347): markdown -> ProseMirror JSON (the SAME
- * chat output matches the editor's markdown flavor, then sanitize with
+ * `markdownToProseMirrorSync` the editor paste/import path uses, so chat output
- * DOMPurify — LLM output is untrusted, so it must never reach the DOM unsanitized.
+ * matches the editor's markdown flavor) -> HTML via `markdownToChatHtml`
+ * (DOMSerializer), then sanitize with DOMPurify — LLM output is untrusted, so it
+ * must never reach the DOM unsanitized.
  *
- * `markdownToHtml` can return `string | Promise<string>` (it has async marked
+ * Stays SYNCHRONOUS: both callers render inside React (a memo and a useMemo),
- * extensions registered). In practice plain chat markdown resolves
+ * so the whole pipeline must resolve without awaiting. The converter's sync
- * synchronously, but we guard the Promise case by returning a safe empty string
+ * entry makes that possible; on any conversion error we return "" so the caller
- * for that branch (the caller renders the raw text fallback instead).
+ * falls back to raw text (the same fallback the old Promise-guard produced).
  */
 export function renderChatMarkdown(
   markdown: string,
   options: RenderChatMarkdownOptions = {},
 ): string {
   if (!markdown) return "";
-  const html = markdownToHtml(markdown);
+  let html: string;
-  if (typeof html !== "string") return "";
+  try {
+    // markdown -> canonical PM JSON -> HTML (native DOMParser in the browser;
+    // jsdom is never bundled — see @docmost/prosemirror-markdown/browser).
+    html = markdownToChatHtml(markdown);
+  } catch {
+    // Malformed/unsupported markdown must not crash the chat render; fall back
+    // to raw text (empty return -> caller shows the plain-text branch).
+    return "";
+  }
 
   if (!options.neutralizeInternalLinks) {
     // Internal chat: unchanged behavior, no hook registered.

apps/client/src/features/editor/components/fixed-toolbar/use-toolbar-state.test.ts

@@ -0,0 +1,65 @@
+import { describe, it, expect } from "vitest";
+import * as Y from "yjs";
+import { yHistoryAvailability } from "./use-toolbar-state.ts";
+
+// Undo/redo availability is derived from the Yjs UndoManager's PRIVATE
+// `undoStack` / `redoStack` fields (see use-toolbar-state.ts for why we read the
+// stack lengths directly instead of the expensive `editor.can().undo()` dry-run).
+// These tests lock in the behavior AND pin the library shape so a yjs / y-undo
+// upgrade that renames/restructures those internals fails loudly here rather than
+// silently enabling/disabling the toolbar buttons in production.
+describe("yHistoryAvailability", () => {
+  it("reports availability from the stack lengths", () => {
+    expect(yHistoryAvailability({ undoStack: [], redoStack: [] })).toEqual({
+      canUndo: false,
+      canRedo: false,
+    });
+    expect(
+      yHistoryAvailability({ undoStack: [{}], redoStack: [] }),
+    ).toEqual({ canUndo: true, canRedo: false });
+    expect(
+      yHistoryAvailability({ undoStack: [{}], redoStack: [{}, {}] }),
+    ).toEqual({ canUndo: true, canRedo: true });
+  });
+
+  it("returns null when the private stack shape is unrecognized (upgrade guard)", () => {
+    // Simulates a yjs / y-undo upgrade that renames or restructures the private
+    // fields: the caller then falls back to the safe prosemirror-history default
+    // instead of throwing on `.length` of undefined or reading garbage.
+    expect(yHistoryAvailability(undefined)).toBeNull();
+    expect(yHistoryAvailability(null)).toBeNull();
+    expect(yHistoryAvailability({})).toBeNull();
+    expect(yHistoryAvailability({ undoStack: 5, redoStack: 5 })).toBeNull();
+    // Only one stack present (partial rename) is still not trusted.
+    expect(yHistoryAvailability({ undoStack: [] })).toBeNull();
+  });
+
+  it("pin-test: a real yjs UndoManager still exposes undoStack/redoStack arrays", () => {
+    const doc = new Y.Doc();
+    const text = doc.getText("prosemirror");
+    const undoManager = new Y.UndoManager(text);
+
+    // Fresh manager: both stacks empty -> nothing to undo/redo.
+    expect(yHistoryAvailability(undoManager)).toEqual({
+      canUndo: false,
+      canRedo: false,
+    });
+
+    // A tracked edit must push onto the private undoStack. If a future yjs
+    // renames these fields, yHistoryAvailability(undoManager) returns null and
+    // the expectation below fails loudly.
+    text.insert(0, "hello");
+    undoManager.stopCapturing();
+    expect(yHistoryAvailability(undoManager)).toEqual({
+      canUndo: true,
+      canRedo: false,
+    });
+
+    // Undoing moves the item to the redoStack -> redo becomes available.
+    undoManager.undo();
+    expect(yHistoryAvailability(undoManager)).toEqual({
+      canUndo: false,
+      canRedo: true,
+    });
+  });
+});

apps/client/src/features/editor/components/fixed-toolbar/use-toolbar-state.ts

@@ -35,6 +35,30 @@ export interface ToolbarState {
 // When neither history backend is installed (the pre-sync static editor —
 // mainExtensions only, undoRedo disabled), both fall through to 0 -> false,
 // matching the previous `safeCan` behavior.
+// Reads the Yjs UndoManager's undo/redo availability from its stack lengths.
+//
+// `undoStack` / `redoStack` are PRIVATE y-undo / yjs internals, so we touch them
+// defensively: a yjs or y-undo upgrade that renames or restructures these fields
+// must not silently mis-drive the toolbar buttons (nor throw on `.length` of
+// `undefined`). We only trust them when they are actually arrays; otherwise this
+// returns null and the caller falls back to a safe default. The pin-test in
+// use-toolbar-state.test.ts asserts the current library shape, so an upgrade that
+// breaks this contract fails loudly there instead of failing silently in the UI.
+export function yHistoryAvailability(
+  undoManager: unknown,
+): { canUndo: boolean; canRedo: boolean } | null {
+  if (!undoManager || typeof undoManager !== "object") return null;
+  const { undoStack, redoStack } = undoManager as {
+    undoStack?: unknown;
+    redoStack?: unknown;
+  };
+  if (!Array.isArray(undoStack) || !Array.isArray(redoStack)) return null;
+  return {
+    canUndo: undoStack.length > 0,
+    canRedo: redoStack.length > 0,
+  };
+}
+
 function historyAvailability(editor: Editor): {
   canUndo: boolean;
   canRedo: boolean;
@@ -43,16 +67,14 @@ function historyAvailability(editor: Editor): {
 
   // Collaboration history (Yjs) takes precedence when present.
   const yState = yUndoPluginKey.getState(state) as
-    | { undoManager?: { undoStack: unknown[]; redoStack: unknown[] } }
+    | { undoManager?: unknown }
     | undefined;
-  if (yState?.undoManager) {
+  const yAvail = yHistoryAvailability(yState?.undoManager);
-    return {
+  if (yAvail) return yAvail;
-      canUndo: yState.undoManager.undoStack.length > 0,
-      canRedo: yState.undoManager.redoStack.length > 0,
-    };
-  }
 
   // Plain prosemirror-history (returns 0 when the history plugin is absent).
+  // This is also the safe default when a Yjs UndoManager is present but its
+  // private stack shape is no longer recognized (yHistoryAvailability -> null).
   return {
     canUndo: undoDepth(state) > 0,
     canRedo: redoDepth(state) > 0,

apps/client/src/features/editor/extensions/markdown-clipboard.paste.test.ts

@@ -0,0 +1,206 @@
+import { describe, it, expect } from "vitest";
+import { Editor } from "@tiptap/core";
+import { Document } from "@tiptap/extension-document";
+import { Paragraph } from "@tiptap/extension-paragraph";
+import { Text } from "@tiptap/extension-text";
+import { Bold } from "@tiptap/extension-bold";
+import { Italic } from "@tiptap/extension-italic";
+import { MarkdownClipboard } from "./markdown-clipboard";
+
+/**
+ * Integration coverage for the async `handlePaste` seam (issue #347). The paste
+ * conversion moved to `@docmost/prosemirror-markdown`'s browser entry, whose
+ * `markdownToProseMirror` is async — so `handlePaste` captures the range, claims
+ * the event (returns true), and dispatches the insert on the next microtask.
+ * These tests drive that path end to end on a minimal schema (a plain-markdown
+ * paste whose converted nodes fit paragraph/text/bold/italic), asserting the
+ * text lands with the right marks and that the raw markdown syntax is consumed
+ * (recognized as markdown, not inserted literally).
+ */
+
+function makeEditor() {
+  const element = document.createElement("div");
+  document.body.appendChild(element);
+  return new Editor({
+    element,
+    extensions: [
+      Document,
+      Paragraph,
+      Text,
+      Bold,
+      Italic,
+      MarkdownClipboard.configure({ transformPastedText: true }),
+    ],
+    content: { type: "doc", content: [{ type: "paragraph" }] },
+  });
+}
+
+// Locate the markdownClipboard plugin and invoke its handlePaste directly with a
+// synthetic clipboard event (jsdom has no real paste pipeline). The plugin's
+// handlePaste closes over the extension `this`, so calling it off the plugin
+// props preserves `this.editor`/`this.options`.
+function paste(editor: Editor, text: string): boolean {
+  const view = editor.view;
+  const plugin = view.state.plugins.find(
+    (p: any) => p.props && p.spec?.key,
+  ) as any;
+  const event = {
+    clipboardData: {
+      getData: (type: string) => (type === "text/plain" ? text : ""),
+    },
+  } as unknown as ClipboardEvent;
+  // Find the specific handlePaste that belongs to the markdown clipboard plugin.
+  const md = view.state.plugins.find(
+    (p: any) => typeof p.props?.handlePaste === "function",
+  ) as any;
+  return md.props.handlePaste(view, event, view.state.selection.content());
+}
+
+// Flush the microtask queue so the async .then() dispatch runs.
+const flush = () => new Promise((r) => setTimeout(r, 0));
+
+describe("MarkdownClipboard handlePaste (async md -> PM)", () => {
+  it("converts a plain-markdown paste with bold/italic into marked text", async () => {
+    const editor = makeEditor();
+    const claimed = paste(editor, "hello **bold** and *italic*");
+    // The paste is claimed synchronously (async insert follows).
+    expect(claimed).toBe(true);
+    await flush();
+
+    const json = editor.getJSON();
+    const text = JSON.stringify(json);
+    // The raw markdown asterisks are consumed (recognized), not inserted literally.
+    expect(editor.getText()).not.toContain("**");
+    expect(editor.getText()).toContain("bold");
+    expect(editor.getText()).toContain("italic");
+    // The bold/italic marks materialized.
+    expect(text).toContain('"bold"');
+    expect(text).toContain('"italic"');
+    editor.destroy();
+  });
+
+  it("recognizes a bullet list paste as list structure (not literal '-')", async () => {
+    // A bullet list is not representable in this minimal schema, so the converter
+    // output would fail PMNode.fromJSON and the catch inserts raw text. Use a
+    // paste whose nodes DO fit the schema to assert the happy path instead: two
+    // paragraphs separated by a blank line.
+    const editor = makeEditor();
+    paste(editor, "first para\n\nsecond para");
+    await flush();
+    const json = editor.getJSON() as any;
+    const paras = (json.content || []).filter(
+      (n: any) => n.type === "paragraph",
+    );
+    // Two paragraphs materialized from the blank-line-separated markdown.
+    expect(paras.length).toBeGreaterThanOrEqual(2);
+    expect(editor.getText()).toContain("first para");
+    expect(editor.getText()).toContain("second para");
+    editor.destroy();
+  });
+
+  it("falls back to raw text when conversion yields nodes the schema lacks", async () => {
+    // `# heading` converts to a `heading` node absent from this minimal schema,
+    // so PMNode.fromJSON throws and the catch re-inserts the raw text — the user
+    // never loses their clipboard content.
+    const editor = makeEditor();
+    paste(editor, "# a heading line");
+    await flush();
+    // Content is preserved (either as heading text or literal), never dropped.
+    expect(editor.getText()).toContain("a heading line");
+    editor.destroy();
+  });
+});
+
+// The async seam captures the target range synchronously, then replaces on the
+// next microtask. If the document changed under it between capture and resolve
+// (impossible in prod — same microtask — but pinned here), BOTH the success
+// (replaceRange) and the fail-open (insertText) branches must fall back to the
+// LIVE selection rather than a stale absolute range, so neither clobbers content
+// nor throws a RangeError. We force the mid-flight change by dispatching a
+// doc-mutating transaction AFTER the synchronous claim but BEFORE flushing the
+// microtask that runs the `.then`/`.catch`.
+describe("MarkdownClipboard handlePaste — doc-changed-mid-flight guard", () => {
+  // Replace the whole doc with one paragraph of `text` (synchronous dispatch).
+  // An empty string yields an empty paragraph (a text node may not be empty).
+  function seedContent(editor: Editor, text: string) {
+    editor.commands.setContent({
+      type: "doc",
+      content: [
+        text
+          ? { type: "paragraph", content: [{ type: "text", text }] }
+          : { type: "paragraph" },
+      ],
+    });
+  }
+
+  it("success branch: mid-flight doc change routes the paste to the LIVE selection, never the stale range (clobber-proving)", async () => {
+    // The paste captures a NON-EMPTY range {1,5} (over "AAAA"). Then, before the
+    // async resolve, the doc GROWS ("MARKER" inserted at the start) and the cursor
+    // is parked at the doc END. The captured {1,5} is now stale and points INTO
+    // "MARKER". A WORKING guard replaces at the live (end) selection → MARKER is
+    // untouched. A BROKEN guard replaces the stale {1,5} → it erases the first
+    // characters of MARKER (this is what a zero-width `from==to` range could never
+    // reveal, which is why the earlier version was vacuous).
+    const editor = makeEditor();
+    seedContent(editor, "AAAABBBB");
+    editor.commands.setTextSelection({ from: 1, to: 5 }); // captured range = {1,5}
+    const claimed = paste(editor, "hello **bold**");
+    expect(claimed).toBe(true);
+
+    // Mid-flight: grow the doc and move the cursor to a KNOWN-safe end position.
+    editor.view.dispatch(editor.view.state.tr.insertText("MARKER", 1));
+    const end = editor.state.doc.content.size;
+    editor.commands.setTextSelection({ from: end, to: end });
+    await flush();
+
+    const text = editor.getText();
+    // MARKER intact only if the guard used the live selection, not the stale range.
+    expect(text).toContain("MARKER");
+    expect(text).toContain("bold");
+    expect(text).not.toContain("**");
+    editor.destroy();
+  });
+
+  it("fail-open branch: a mid-flight doc SHRINK makes the stale `to` out of bounds — the guard must avoid a RangeError (throw-proving)", async () => {
+    // The paste captures a range {1,9} over an 8-char paragraph, then the
+    // conversion FAILS (`# heading` -> a heading node the minimal schema lacks,
+    // so PMNode.fromJSON throws -> the fail-open catch runs). Before the reject,
+    // the doc is SHRUNK to an empty paragraph, so the captured `to` (9) is now far
+    // past the doc's end. A WORKING guard inserts the raw text at the live (valid)
+    // selection → "raw heading" lands. A BROKEN guard does insertText(md, 1, 9) on
+    // a size-2 doc → RangeError, so the dispatch never runs and "raw heading" is
+    // absent (the assertion reddens). A zero-width/growing-doc setup could never
+    // push `to` out of bounds, which is why the earlier version was vacuous.
+    const editor = makeEditor();
+    seedContent(editor, "AAAABBBB");
+    editor.commands.setTextSelection({ from: 1, to: 9 }); // captured range = {1,9}
+    paste(editor, "# raw heading");
+
+    // Mid-flight: shrink the doc so the captured `to` = 9 is now out of bounds.
+    seedContent(editor, "");
+    await flush();
+
+    const text = editor.getText();
+    // Raw text lands (via the live selection) only if the guard avoided the
+    // stale, now-out-of-bounds range.
+    expect(text).toContain("raw heading");
+    editor.destroy();
+  });
+
+  it("two pastes in flight: neither payload is lost (no data loss)", async () => {
+    // Prod-unreachable (two paste events are separate macrotasks, and each
+    // conversion resolves on a microtask before the next), but pinned here: when
+    // both resolve back-to-back, the second sees the changed doc and inserts at
+    // the live selection the first left — so the two payloads may INTERLEAVE, but
+    // neither is dropped. We assert no data loss, not contiguity.
+    const editor = makeEditor();
+    paste(editor, "alphaword");
+    paste(editor, "betaword");
+    await flush();
+    const text = editor.getText();
+    // Neither payload fully dropped (interleaving may split one of them).
+    expect(text).toContain("alpha");
+    expect(text).toContain("beta");
+    editor.destroy();
+  });
+});

apps/client/src/features/editor/extensions/markdown-clipboard.test.ts

@@ -1,5 +1,12 @@
 import { describe, it, expect } from "vitest";
-import { htmlToMarkdown } from "@docmost/editor-ext";
+// Markdown conversion now goes through the canonical package's BROWSER entry
+// (issue #347): the same converter the server import/export uses, resolved via
+// the `browser` exports condition so it runs on the native `DOMParser` (the
+// client jsdom vitest env provides one) with jsdom never bundled.
+import {
+  convertProseMirrorToMarkdown,
+  markdownToProseMirrorSync,
+} from "@docmost/prosemirror-markdown/browser";
 import {
   normalizeTableColumnWidths,
   classifyClipboardSelection,
@@ -175,10 +182,13 @@ describe("classifyClipboardSelection", () => {
 
 // Output-level tests for the table clipboard regression: copying a table must
 // yield a real GFM pipe table, NOT one-value-per-line concatenated cells.
-// These exercise the actual markdown produced by htmlToMarkdown (the same
+// These exercise the actual markdown produced by convertProseMirrorToMarkdown —
-// serializer step the clipboardTextSerializer runs), so they pin the OUTPUT
+// the same serializer step the clipboardTextSerializer now runs (issue #347) —
-// shape that the classifier-flag tests above do not cover.
+// so they pin the OUTPUT shape that the classifier-flag tests above do not cover.
-describe("table clipboard markdown output (htmlToMarkdown)", () => {
+// Input is ProseMirror JSON (what the copied slice serializes to), matching the
+// clipboardTextSerializer's new call: it wraps the slice content in a synthetic
+// `doc` (and the bare-rows case in a `table`) and calls the converter.
+describe("table clipboard markdown output (convertProseMirrorToMarkdown)", () => {
   // Trim each line and drop blanks so structural assertions are whitespace-robust.
   function lines(md: string): string[] {
     return md
@@ -188,10 +198,10 @@ describe("table clipboard markdown output (htmlToMarkdown)", () => {
   }
 
   // A GFM separator row like "| --- | --- |" (any number of columns), tolerant
-  // of the padding turndown emits.
+  // of the padding the serializer emits.
   function isSeparatorRow(line: string): boolean {
     const compact = line.replace(/\s+/g, "");
-    return /^\|(?:-{3,}\|)+$/.test(compact);
+    return /^\|(?::?-{2,}:?\|)+$/.test(compact);
   }
 
   // Split a pipe-delimited row into trimmed cell values.
@@ -203,42 +213,33 @@ describe("table clipboard markdown output (htmlToMarkdown)", () => {
       .map((c) => c.trim());
   }
 
-  it("serializes a header-less partial cell selection (bare rows) as a valid GFM pipe table", () => {
+  const cell = (t: string) => ({
-    // Mirror the serializer's `wrapBareRows` branch exactly: bare <tr> nodes are
+    type: "tableCell",
-    // wrapped in <table><tbody> and htmlToMarkdown(div.innerHTML) is called.
+    content: [{ type: "paragraph", content: [{ type: "text", text: t }] }],
-    // See markdown-clipboard.ts clipboardTextSerializer:
+  });
-    //   const table = document.createElement("table");
+  const headerCell = (t: string) => ({
-    //   const tbody = document.createElement("tbody");
+    type: "tableHeader",
-    //   tbody.appendChild(fragment); table.appendChild(tbody);
+    content: [{ type: "paragraph", content: [{ type: "text", text: t }] }],
-    //   div.appendChild(table);
+  });
-    //   return htmlToMarkdown(div.innerHTML);
+  const row = (nodes: any[]) => ({ type: "tableRow", content: nodes });
-    const div = document.createElement("div");
-    const table = document.createElement("table");
-    const tbody = document.createElement("tbody");
-    for (const [c1, c2] of [
-      ["a", "b"],
-      ["c", "d"],
-    ]) {
-      const tr = document.createElement("tr");
-      const td1 = document.createElement("td");
-      td1.textContent = c1;
-      const td2 = document.createElement("td");
-      td2.textContent = c2;
-      tr.appendChild(td1);
-      tr.appendChild(td2);
-      tbody.appendChild(tr);
-    }
-    table.appendChild(tbody);
-    div.appendChild(table);
 
-    const md = htmlToMarkdown(div.innerHTML);
+  it("serializes a header-less partial cell selection (bare rows) as a valid GFM pipe table", () => {
+    // Mirror the serializer's `wrapBareRows` branch: bare tableRow nodes are
+    // wrapped in a synthetic `table` and convertProseMirrorToMarkdown is called
+    // (see markdown-clipboard.ts clipboardTextSerializer).
+    const rows = [
+      row([cell("a"), cell("b")]),
+      row([cell("c"), cell("d")]),
+    ];
+    const md = convertProseMirrorToMarkdown({
+      type: "doc",
+      content: [{ type: "table", content: rows }],
+    });
     const ls = lines(md);
 
-    // Valid GFM: a header/data separator row is present (an empty header is
+    // Valid GFM: a header/data separator row is present.
-    // synthesized by the GFM turndown plugin for a header-less table — fine).
     expect(ls.some(isSeparatorRow)).toBe(true);
-    // NOT the old broken "one value per line" shape: every line is pipe-delimited
+    // NOT the old broken "one value per line" shape: every line is pipe-delimited.
-    // and no line is a bare cell value on its own.
     expect(ls.every((l) => l.includes("|"))).toBe(true);
     expect(md).not.toMatch(/^\s*(a|b|c|d)\s*$/m);
     // The cell values land in real pipe-delimited data rows.
@@ -248,39 +249,21 @@ describe("table clipboard markdown output (htmlToMarkdown)", () => {
   });
 
   it("serializes a whole table with a header row as a proper GFM table (headline regression)", () => {
-    // Mirror the serializer's non-wrap branch: the full <table> node is appended
+    // Mirror the serializer's non-wrap branch: the full `table` node is the
-    // directly (div.appendChild(fragment)) and htmlToMarkdown(div.innerHTML) runs.
+    // slice content and convertProseMirrorToMarkdown runs on it.
-    const div = document.createElement("div");
+    const md = convertProseMirrorToMarkdown({
-    const table = document.createElement("table");
+      type: "doc",
-
+      content: [
-    const thead = document.createElement("thead");
+        {
-    const headerRow = document.createElement("tr");
+          type: "table",
-    for (const h of ["Name", "Age"]) {
+          content: [
-      const th = document.createElement("th");
+            row([headerCell("Name"), headerCell("Age")]),
-      th.textContent = h;
+            row([cell("Alice"), cell("30")]),
-      headerRow.appendChild(th);
+            row([cell("Bob"), cell("25")]),
-    }
+          ],
-    thead.appendChild(headerRow);
+        },
-    table.appendChild(thead);
+      ],
-
+    });
-    const tbody = document.createElement("tbody");
-    for (const [name, age] of [
-      ["Alice", "30"],
-      ["Bob", "25"],
-    ]) {
-      const tr = document.createElement("tr");
-      const td1 = document.createElement("td");
-      td1.textContent = name;
-      const td2 = document.createElement("td");
-      td2.textContent = age;
-      tr.appendChild(td1);
-      tr.appendChild(td2);
-      tbody.appendChild(tr);
-    }
-    table.appendChild(tbody);
-    div.appendChild(table);
-
-    const md = htmlToMarkdown(div.innerHTML);
     const ls = lines(md);
 
     // Proper GFM structure: separator row + all rows pipe-delimited.
@@ -296,3 +279,146 @@ describe("table clipboard markdown output (htmlToMarkdown)", () => {
     expect(md).not.toMatch(/^\s*(Name|Age|Alice|Bob|30|25)\s*$/m);
   });
 });
+
+// #347 acceptance: pasting CANONICAL markdown yields the SAME nodes the server
+// import produces for the same text. The paste path calls markdownToProseMirror
+// (the package browser entry) — the identical converter the server import uses —
+// so asserting the converter (via the browser entry, on the native DOMParser)
+// recognizes each canon form pins the paste-parity guarantee. These forms were
+// NOT recognized by the old editor-ext marked layer the paste used before.
+describe("canonical markdown paste recognition (browser entry parity)", () => {
+  // Collect every node type present in a doc (recursively).
+  const collectTypes = (n: any, set = new Set<string>()): Set<string> => {
+    if (!n || typeof n !== "object") return set;
+    if (n.type) set.add(n.type);
+    if (Array.isArray(n.content)) n.content.forEach((c) => collectTypes(c, set));
+    return set;
+  };
+  const findNode = (n: any, type: string): any => {
+    if (!n || typeof n !== "object") return undefined;
+    if (n.type === type) return n;
+    if (Array.isArray(n.content)) {
+      for (const c of n.content) {
+        const hit = findNode(c, type);
+        if (hit) return hit;
+      }
+    }
+    return undefined;
+  };
+  const allText = (n: any): string => {
+    if (!n || typeof n !== "object") return "";
+    if (typeof n.text === "string") return n.text;
+    if (Array.isArray(n.content)) return n.content.map(allText).join("");
+    return "";
+  };
+
+  it("^[…] inline footnote -> footnoteReference + footnotesList", () => {
+    const doc = markdownToProseMirrorSync("Body^[a note here].");
+    const types = collectTypes(doc);
+    expect(types.has("footnoteReference")).toBe(true);
+    expect(types.has("footnotesList")).toBe(true);
+    expect(types.has("footnoteDefinition")).toBe(true);
+  });
+
+  it('<!--img {…}--> attached image comment -> image with align', () => {
+    const doc = markdownToProseMirrorSync(
+      '![alt](/files/x.png) <!--img {"align":"left"}-->',
+    );
+    const img = findNode(doc, "image");
+    expect(img).toBeTruthy();
+    expect(img.attrs?.align).toBe("left");
+    expect(img.attrs?.src).toBe("/files/x.png");
+  });
+
+  it("> [!type] Obsidian callout -> callout node with type", () => {
+    const doc = markdownToProseMirrorSync("> [!warning]\n> be careful");
+    const callout = findNode(doc, "callout");
+    expect(callout).toBeTruthy();
+    expect(callout.attrs?.type).toBe("warning");
+    expect(allText(callout)).toContain("be careful");
+  });
+
+  it("$…$ inline math -> mathInline node", () => {
+    const doc = markdownToProseMirrorSync("Euler: $e^{i\\pi}+1=0$ done");
+    const math = findNode(doc, "mathInline");
+    expect(math).toBeTruthy();
+    expect(math.attrs?.text).toContain("e^{i\\pi}");
+  });
+
+  it("==…== highlight -> highlight mark", () => {
+    const doc = markdownToProseMirrorSync("A ==marked== word");
+    const marked = findNode(doc, "text");
+    // The highlighted run carries a `highlight` mark somewhere in the doc.
+    const hasHighlight = (n: any): boolean => {
+      if (!n || typeof n !== "object") return false;
+      if (
+        n.type === "text" &&
+        (n.marks || []).some((m: any) => m.type === "highlight")
+      )
+        return true;
+      return Array.isArray(n.content) ? n.content.some(hasHighlight) : false;
+    };
+    expect(marked).toBeTruthy();
+    expect(hasHighlight(doc)).toBe(true);
+  });
+
+  it("<!--subpages--> standalone comment -> subpages node", () => {
+    const doc = markdownToProseMirrorSync("intro\n\n<!--subpages-->\n\nafter");
+    expect(collectTypes(doc).has("subpages")).toBe(true);
+  });
+});
+
+// #347 negatives: plain text carrying markdown-LIKE punctuation must NOT be
+// silently converted/mangled (currency, bare `==`, a `[^1]` reference form).
+describe("plain-text paste negatives (no phantom conversion)", () => {
+  const findNode = (n: any, type: string): any => {
+    if (!n || typeof n !== "object") return undefined;
+    if (n.type === type) return n;
+    if (Array.isArray(n.content)) {
+      for (const c of n.content) {
+        const hit = findNode(c, type);
+        if (hit) return hit;
+      }
+    }
+    return undefined;
+  };
+  const collectTypes = (n: any, set = new Set<string>()): Set<string> => {
+    if (!n || typeof n !== "object") return set;
+    if (n.type) set.add(n.type);
+    if (Array.isArray(n.content)) n.content.forEach((c) => collectTypes(c, set));
+    return set;
+  };
+  const allText = (n: any): string => {
+    if (!n || typeof n !== "object") return "";
+    if (typeof n.text === "string") return n.text;
+    if (Array.isArray(n.content)) return n.content.map(allText).join("");
+    return "";
+  };
+
+  it("currency `$5 and $10` is NOT turned into math", () => {
+    const doc = markdownToProseMirrorSync("It costs $5 and $10 total");
+    expect(findNode(doc, "mathInline")).toBeFalsy();
+    expect(allText(doc)).toContain("$5 and $10");
+  });
+
+  it("a lone `==` is NOT turned into a highlight", () => {
+    const doc = markdownToProseMirrorSync("compare a == b in code");
+    const hasHighlight = (n: any): boolean => {
+      if (!n || typeof n !== "object") return false;
+      if (
+        n.type === "text" &&
+        (n.marks || []).some((m: any) => m.type === "highlight")
+      )
+        return true;
+      return Array.isArray(n.content) ? n.content.some(hasHighlight) : false;
+    };
+    expect(hasHighlight(doc)).toBe(false);
+    expect(allText(doc)).toContain("== b");
+  });
+
+  it("a `[^1]` reference form (no `^[`) is NOT turned into a footnote", () => {
+    const doc = markdownToProseMirrorSync("see note [^1] for details");
+    expect(collectTypes(doc).has("footnoteReference")).toBe(false);
+    expect(allText(doc)).toContain("[^1]");
+  });
+});

apps/client/src/features/editor/extensions/markdown-clipboard.ts

@@ -1,15 +1,23 @@
 // adapted from: https://github.com/aguingand/tiptap-markdown/blob/main/src/extensions/tiptap/clipboard.js - MIT
 import { Extension } from "@tiptap/core";
 import { Plugin, PluginKey, TextSelection } from "@tiptap/pm/state";
-import { DOMParser, DOMSerializer, Fragment, Slice } from "@tiptap/pm/model";
+import { DOMParser, DOMSerializer, Fragment, Slice, Node as PMNode } from "@tiptap/pm/model";
 import { find } from "linkifyjs";
 import {
-  markdownToHtml,
-  htmlToMarkdown,
   canonicalizeFootnotes,
   FOOTNOTES_LIST_NAME,
   FOOTNOTE_REFERENCE_NAME,
 } from "@docmost/editor-ext";
+// Markdown <-> ProseMirror conversion now lives ONLY in the canonical
+// `@docmost/prosemirror-markdown` package (issue #347). The BROWSER entry uses
+// the native `DOMParser` for its HTML->DOM stage (jsdom stays out of the client
+// bundle) while producing the SAME nodes the server import does — so a paste of
+// canonical markdown (`^[…]`, `<!--img …-->`, `> [!type]`, `$…$`, `==…==`,
+// standalone comments) is recognized identically to import.
+import {
+  markdownToProseMirror,
+  convertProseMirrorToMarkdown,
+} from "@docmost/prosemirror-markdown/browser";
 import type { Schema } from "@tiptap/pm/model";
 
 export const MarkdownClipboard = Extension.create({
@@ -39,25 +47,24 @@ export const MarkdownClipboard = Extension.create({
               classifyClipboardSelection(topLevelNodes);
             if (!asMarkdown) return null;
 
-            const div = document.createElement("div");
+            // Convert the copied selection to Markdown through the canonical
-            const serializer = DOMSerializer.fromSchema(this.editor.schema);
+            // package (issue #347), the SAME serializer the server export uses,
-            const fragment = serializer.serializeFragment(slice.content);
+            // so a copied table/list matches the on-disk markdown form. The
-
+            // converter takes a ProseMirror `doc` JSON, so wrap the slice's
+            // top-level content in a synthetic doc.
+            const content = slice.content.toJSON() as any[];
             if (wrapBareRows) {
-              // A partial table cell-selection serializes to bare <tr> nodes
+              // A partial table cell-selection serializes to bare `tableRow`
-              // (prosemirror-tables returns the whole `table` node only when the
+              // nodes (prosemirror-tables yields the whole `table` node only for
-              // entire table is selected). Bare <tr> would be foster-parented
+              // a full-table selection). The converter's table case expects a
-              // away by the HTML parser inside htmlToMarkdown, so wrap them in
+              // `table` wrapper, so wrap the bare rows in one — mirroring the old
-              // <table><tbody> first for the GFM turndown rule to detect them.
+              // <table><tbody> wrap that the HTML->markdown step needed.
-              const table = document.createElement("table");
+              return convertProseMirrorToMarkdown({
-              const tbody = document.createElement("tbody");
+                type: "doc",
-              tbody.appendChild(fragment);
+                content: [{ type: "table", content }],
-              table.appendChild(tbody);
+              });
-              div.appendChild(table);
-            } else {
-              div.appendChild(fragment);
             }
-            return htmlToMarkdown(div.innerHTML);
+            return convertProseMirrorToMarkdown({ type: "doc", content });
           },
           handlePaste: (view, event, slice) => {
             if (!event.clipboardData) {
@@ -95,37 +102,115 @@ export const MarkdownClipboard = Extension.create({
               }
             }
 
-            const { tr } = view.state;
+            const schema = this.editor.schema;
-            const { from, to } = view.state.selection;
+            // Capture the target range NOW. markdownToProseMirror RETURNS A
+            // PROMISE (kept async only for the Node consumers' contract; the
+            // conversion pipeline itself is synchronous), so the actual replace
+            // happens on the next microtask. No user input can interleave a
+            // microtask, so the state is unchanged when we dispatch — but we
+            // still re-read the live state before replacing and, if the doc did
+            // change under us, fall back to the live selection rather than the
+            // captured (now-stale) range.
+            const from = view.state.selection.from;
+            const to = view.state.selection.to;
+            const startDoc = view.state.doc;
+            const md = text.replace(/\n+$/, "");
 
-            const parsed = markdownToHtml(text.replace(/\n+$/, ""));
+            void markdownToProseMirror(md)
-            const body = elementFromString(parsed);
+              .then((doc) => {
-            normalizeTableColumnWidths(body);
+                if (view.isDestroyed) return;
+                // Canonical PM-JSON -> HTML via the LIVE editor schema, then
+                // reuse the UNCHANGED downstream seam (normalizeTableColumnWidths
+                // + parseSlice + canonicalizePastedFootnotes). The JSON->HTML->
+                // JSON hop is lossless (same schema both directions); it lets the
+                // existing paste-insertion logic stay byte-identical — only the
+                // SOURCE of the markdown conversion changed (issue #347 guardrail:
+                // no converter logic in the client, only a call into the package).
+                const node = PMNode.fromJSON(schema, doc);
+                const div = document.createElement("div");
+                DOMSerializer.fromSchema(schema).serializeFragment(
+                  node.content,
+                  { document },
+                  div,
+                );
 
-            const parsedSlice = DOMParser.fromSchema(
+                const body = elementFromString(div.innerHTML);
-              this.editor.schema,
+                normalizeTableColumnWidths(body);
-            ).parseSlice(body, {
-              preserveWhitespace: true,
-            });
 
-            // A markdown paste builds its ProseMirror fragment directly (DOM ->
+                const parsedSlice = DOMParser.fromSchema(schema).parseSlice(
-            // parseSlice), bypassing the editor's footnoteSyncPlugin, which never
+                  body,
-            // reorders an existing list. So a pasted markdown block whose footnote
+                  { preserveWhitespace: true },
-            // definitions are out of order (or contains orphan defs) would be
+                );
-            // stored out of order. Canonicalize the self-contained pasted block so
-            // its footnotes come out reference-ordered, deduped and orphan-free
-            // (issue #228). See canonicalizePastedFootnotes for why this is scoped
-            // to whole-block pastes that carry their own footnotesList.
-            const contentNodes = canonicalizePastedFootnotes(
-              parsedSlice,
-              this.editor.schema,
-            );
 
-            tr.replaceRange(from, to, contentNodes);
+                // A markdown paste builds its ProseMirror fragment directly (DOM
-            const insertEnd = tr.mapping.map(from, 1);
+                // -> parseSlice), bypassing the editor's footnoteSyncPlugin, which
-            tr.setSelection(TextSelection.near(tr.doc.resolve(Math.max(from, insertEnd - 2)), -1));
+                // never reorders an existing list. So a pasted markdown block whose
-            tr.setMeta('paste', true)
+                // footnote definitions are out of order (or contains orphan defs)
-            view.dispatch(tr);
+                // would be stored out of order. Canonicalize the self-contained
+                // pasted block so its footnotes come out reference-ordered, deduped
+                // and orphan-free (issue #228). See canonicalizePastedFootnotes for
+                // why this is scoped to whole-block pastes that carry their own
+                // footnotesList.
+                const contentNodes = canonicalizePastedFootnotes(
+                  parsedSlice,
+                  schema,
+                );
+
+                // Target the captured range (normally still valid — same
+                // microtask). If the doc changed under us since capture, the
+                // captured absolute from/to are stale, so fall back to the live
+                // selection rather than StepMap-mapping the old range.
+                const tr = view.state.tr;
+                let mappedFrom = from;
+                let mappedTo = to;
+                if (view.state.doc !== startDoc) {
+                  // Defensive: if the doc changed under us, fall back to the
+                  // current selection rather than a stale absolute range.
+                  mappedFrom = view.state.selection.from;
+                  mappedTo = view.state.selection.to;
+                }
+                tr.replaceRange(mappedFrom, mappedTo, contentNodes);
+                const insertEnd = tr.mapping.map(mappedFrom, 1);
+                tr.setSelection(
+                  TextSelection.near(
+                    tr.doc.resolve(Math.max(mappedFrom, insertEnd - 2)),
+                    -1,
+                  ),
+                );
+                tr.setMeta("paste", true);
+                view.dispatch(tr);
+              })
+              .catch((err) => {
+                // Fail-open: a conversion error must not swallow the paste
+                // silently in a way that loses the text. We already claimed the
+                // event (returned true), so re-insert the raw text as a plain
+                // paragraph so the user never loses their clipboard content.
+                // Log it: this catch covers BOTH the converter and the success
+                // `.then` body (e.g. PMNode.fromJSON throwing on a schema drift
+                // between the canonical package and the live editor schema), so a
+                // silent degrade to raw text would otherwise be an invisible,
+                // non-reproducible regression ("my table pasted as text").
+                console.error(
+                  "markdown paste conversion failed, inserting raw text",
+                  err,
+                );
+                if (view.isDestroyed) return;
+                const tr = view.state.tr;
+                // Same guard the success path uses: if the doc changed under us
+                // since the range was captured (normally never — same microtask),
+                // the captured absolute from/to are stale and would throw a
+                // RangeError here (an unhandled rejection on a hot paste path).
+                // Fall back to the live selection instead of a stale range.
+                if (view.state.doc !== startDoc) {
+                  const sel = view.state.selection;
+                  tr.insertText(md, sel.from, sel.to);
+                } else {
+                  tr.insertText(md, from, to);
+                }
+                tr.setMeta("paste", true);
+                view.dispatch(tr);
+              });
+            // Claim the paste: we insert asynchronously above.
             return true;
           },
           // Strip trailing whitespace-only paragraphs from pasted content.

apps/client/src/features/editor/gitmost/gitmost-recording.test.ts

@@ -9,7 +9,7 @@ import { Italic } from "@tiptap/extension-italic";
 import { Link } from "@tiptap/extension-link";
 import { gitmostInsertTranscriptIntoEditor } from "./gitmost-recording.ts";
 
-const ZWSP = "​"; // U+200B, the helper's block-trigger neutralizer
+const ZWSP = "​"; // U+200B — asserted ABSENT (the block-escape lives in the serializer now)
 
 /**
  * #377 — the web-side bridge must append the native host's transcript below the
@@ -18,8 +18,9 @@ const ZWSP = "​"; // U+200B, the helper's block-trigger neutralizer
  * regression would be caught), asserting the resulting document rather than
  * mocking the editor: transcript present -> "Transcript" heading + one paragraph
  * per non-empty line; content is inserted as LITERAL TEXT (no HTML/markdown
- * parsing); col-0 markdown block triggers are neutralized so git-sync keeps them
+ * parsing); col-0 markdown block triggers are stored verbatim (the git-sync
- * paragraphs; absent/empty/non-string -> no-op.
+ * serializer block-escapes them, so no client-side ZWSP is needed);
+ * absent/empty/non-string -> no-op.
  */
 describe("gitmostInsertTranscriptIntoEditor", () => {
   const makeEditor = () =>
@@ -91,19 +92,22 @@ describe("gitmostInsertTranscriptIntoEditor", () => {
     editor.destroy();
   });
 
-  it("neutralizes col-0 markdown block triggers with a leading ZWSP (git-sync safety)", () => {
+  it("inserts col-0 markdown block triggers as verbatim paragraph text (no ZWSP workaround)", () => {
     const editor = makeEditor();
-    // Trigger lines (some with a leaked indent) + a normal prefixed line.
+    // Trigger lines (some with a leaked indent) + a normal prefixed line. The
+    // git-sync serializer now block-escapes a leading trigger itself, so the
+    // bridge inserts each line's TEXT byte-exact (only the leaked indent is
+    // trimmed) — no invisible ZWSP is prepended anymore.
     const inserted = gitmostInsertTranscriptIntoEditor(
       editor,
       [
         "- dash",
-        "  > quote", // leading indent must be trimmed then neutralized
+        "  > quote", // leading indent is trimmed, text otherwise verbatim
         "# hash",
         "1. one",
         "> [!info] note",
         "```js",
-        "---", // solid thematic break -> horizontalRule (text-losing) if unneutralized
+        "---",
         "***",
         "___",
         "You: normal line",
@@ -116,20 +120,23 @@ describe("gitmostInsertTranscriptIntoEditor", () => {
       .map((n: any) => n.content?.[0]?.text)
       .filter((t: any) => typeof t === "string") as string[];
 
-    // Every block-trigger line is prefixed with the invisible ZWSP (indent
+    // Each trigger line is stored as its own byte-exact text (indent trimmed);
-    // trimmed first); the normal `You:` line is left byte-exact.
+    // the git-sync round-trip keeps it a paragraph via the serializer's
+    // block-escape, so no ZWSP is needed here.
     expect(texts).toEqual([
-      ZWSP + "- dash",
+      "- dash",
-      ZWSP + "> quote",
+      "> quote",
-      ZWSP + "# hash",
+      "# hash",
-      ZWSP + "1. one",
+      "1. one",
-      ZWSP + "> [!info] note",
+      "> [!info] note",
-      ZWSP + "```js",
+      "```js",
-      ZWSP + "---",
+      "---",
-      ZWSP + "***",
+      "***",
-      ZWSP + "___",
+      "___",
       "You: normal line",
     ]);
+    // Guard: no invisible ZWSP leaked into any inserted line.
+    for (const t of texts) expect(t).not.toContain(ZWSP);
 
     editor.destroy();
   });

apps/client/src/features/editor/gitmost/gitmost-recording.ts

@@ -240,45 +240,22 @@ export async function gitmostUploadFileToEditor(
   }
 }
 
-// Zero-width space (U+200B). Prepended to a transcript line that begins with a
-// markdown BLOCK trigger: it is invisible in the rendered doc but shifts the
-// trigger off column 0, so the git-sync doc->markdown->doc round-trip keeps the
-// line a plain paragraph (see GITMOST_MD_BLOCK_TRIGGER_RE).
-const GITMOST_ZWSP = "​";
-
-// A markdown BLOCK-level construct that, sitting at column 0 of a paragraph
-// line, the git-sync markdown serializer (packages/prosemirror-markdown
-// markdown-converter.ts, `case "paragraph"`) would re-parse into a NON-paragraph
-// block on the doc->markdown->doc cycle. That serializer emits paragraph text
-// verbatim with NO block-escape (the pre-existing root cause), so a leading
-// `#`/`-`/`*`/`+`/`>`, an ordered-list `N.`/`N)`, a code fence ```/~~~, a table
-// `|`, or a `> [!info]` callout opener would silently become a heading / list /
-// quote / code block / table / callout. The final alternative matches a WHOLE-
-// LINE thematic break — solid `---`/`***`/`___` or spaced `- - -`/`_ _ _` (3+ of
-// the same `-`/`*`/`_`) — which round-trips into a `horizontalRule`; because
-// that node carries NO text, an un-neutralized separator line would LOSE its
-// text entirely (worse than the list/quote case). This matches a TRIMMED line's
-// start; the transcript's own `You:` / `Speaker N:` prefix begins with a letter
-// and never matches, so prefixed lines are left byte-exact.
-const GITMOST_MD_BLOCK_TRIGGER_RE =
-  /^(?:#{1,6}(?:\s|$)|[-*+](?:\s|$)|>|\d+[.)](?:\s|$)|```|~~~|\||([-*_])(?:\s*\1){2,}\s*$)/;
-
 // Append a transcript block BELOW the recording's audio node in a live editor:
 // a "Transcript" heading followed by one paragraph per non-empty transcript
 // line. The transcript is plain text, `\n`-separated, each line already
 // formatted as `You: ...` / `Speaker N: ...` by the native host — line text is
 // inserted as a TEXT node (never HTML/markdown), so there is no injection or
 // mark-parsing surface. Each kept line is trimmed (drops an indent that would
-// both leak into the display and, at col 0, form a markdown block trigger) and,
+// leak into the display). A line that begins with a col-0 markdown block
-// if it still begins with a col-0 markdown block trigger, gets an invisible
+// trigger (`#`/`-`/`>`/`1.`/fence/`---`/…) needs no client-side workaround: the
-// zero-width space prepended so the git-sync round-trip cannot turn it into a
+// git-sync serializer (packages/prosemirror-markdown, `case "paragraph"`) now
-// list/quote/heading/callout/code/table (defensive boundary against the
+// block-escapes such a leading trigger, so the doc->markdown->doc round-trip
-// serializer's missing block-escape). This is best-effort and meant to run
+// keeps the line a paragraph on its own — the former invisible-ZWSP defense is
-// AFTER the audio has already been inserted; the caller must guard against a
+// gone. This is best-effort and meant to run AFTER the audio has already been
-// throw so a transcript failure never fails the (already successful) recording.
+// inserted; the caller must guard against a throw so a transcript failure never
-// Returns true when a block was inserted, false when there was nothing to
+// fails the (already successful) recording. Returns true when a block was
-// insert (transcript undefined/empty/not-a-string). A non-string value is a
+// inserted, false when there was nothing to insert (transcript
-// no-op, not an error.
+// undefined/empty/not-a-string). A non-string value is a no-op, not an error.
 export function gitmostInsertTranscriptIntoEditor(
   editor: Editor,
   transcript: unknown,
@@ -288,13 +265,7 @@ export function gitmostInsertTranscriptIntoEditor(
     .split("\n")
     // Trim each line and drop blank (whitespace-only) ones.
     .map((line) => line.trim())
-    .filter((line) => line.length > 0)
+    .filter((line) => line.length > 0);
-    // Neutralize a col-0 markdown block trigger with an invisible ZWSP so the
-    // git-sync round-trip keeps the line a paragraph. Host lines (`You:` /
-    // `Speaker N:`) never match and stay byte-exact.
-    .map((line) =>
-      GITMOST_MD_BLOCK_TRIGGER_RE.test(line) ? GITMOST_ZWSP + line : line,
-    );
   if (lines.length === 0) return false;
 
   const content = [

apps/client/src/features/editor/hooks/use-generate-page-title.test.tsx

@@ -33,10 +33,11 @@ vi.mock("@/lib/local-emitter.ts", () => ({
   default: { emit: (...args: unknown[]) => localEmitMock(...args) },
 }));
 
-// htmlToMarkdown just echoes the editor HTML so each test controls the markdown
+// convertProseMirrorToMarkdown echoes a marker carried on the fake editor's
-// purely via the fake page editor's getHTML().
+// getJSON() doc, so each test controls the markdown purely via the fake page
-vi.mock("@docmost/editor-ext", () => ({
+// editor (issue #347: the hook now serializes editor JSON through the package).
-  htmlToMarkdown: (html: string) => html,
+vi.mock("@docmost/prosemirror-markdown/browser", () => ({
+  convertProseMirrorToMarkdown: (doc: { __md?: string }) => doc?.__md ?? "",
 }));
 
 const notificationsShowMock = vi.fn();
@@ -53,10 +54,12 @@ import { useGeneratePageTitle } from "./use-generate-page-title.ts";
 
 // --- Test helpers -------------------------------------------------------------
 
-function makePageEditor(pageId: string, html = "<p>content</p>"): Editor {
+function makePageEditor(pageId: string, md = "content"): Editor {
   return {
     isDestroyed: false,
-    getHTML: () => html,
+    // The mocked convertProseMirrorToMarkdown reads `__md` back off this doc,
+    // so `md` is exactly the markdown the hook will send to the title service.
+    getJSON: () => ({ type: "doc", __md: md }),
     storage: { pageId },
   } as unknown as Editor;
 }

apps/client/src/features/editor/hooks/use-generate-page-title.ts

@@ -3,7 +3,7 @@ import { useMutation } from "@tanstack/react-query";
 import { useAtomValue } from "jotai";
 import { notifications } from "@mantine/notifications";
 import { useTranslation } from "react-i18next";
-import { htmlToMarkdown } from "@docmost/editor-ext";
+import { convertProseMirrorToMarkdown } from "@docmost/prosemirror-markdown/browser";
 import {
   pageEditorAtom,
   titleEditorAtom,
@@ -49,7 +49,9 @@ export function useGeneratePageTitle(pageId: string) {
     mutationFn: async () => {
       if (!pageEditor || pageEditor.isDestroyed) return;
 
-      const markdown = htmlToMarkdown(pageEditor.getHTML()).trim();
+      // Serialize the live editor content to markdown through the canonical
+      // converter (issue #347), matching the on-disk/export markdown form.
+      const markdown = convertProseMirrorToMarkdown(pageEditor.getJSON()).trim();
       if (!markdown) {
         notifications.show({ message: t("The note is empty"), color: "yellow" });
         return;

apps/client/src/features/page/components/header/page-header-menu.tsx

@@ -37,7 +37,7 @@ import { useTreeMutation } from "@/features/page/tree/hooks/use-tree-mutation.ts
 import { PageWidthToggle } from "@/features/user/components/page-width-pref.tsx";
 import { Trans, useTranslation } from "react-i18next";
 import ExportModal from "@/components/common/export-modal";
-import { htmlToMarkdown } from "@docmost/editor-ext";
+import { convertProseMirrorToMarkdown } from "@docmost/prosemirror-markdown/browser";
 import {
   pageEditorAtom,
   yjsConnectionStatusAtom,
@@ -199,8 +199,9 @@ function PageActionMenu({ readOnly }: PageActionMenuProps) {
 
   const handleCopyAsMarkdown = () => {
     if (!pageEditor) return;
-    const html = pageEditor.getHTML();
+    // Copy the page as canonical markdown through the shared converter (issue
-    const markdown = htmlToMarkdown(html);
+    // #347), so "Copy as markdown" matches the server export byte-for-byte.
+    const markdown = convertProseMirrorToMarkdown(pageEditor.getJSON());
     const title = page?.title ? `# ${page.title}\n\n` : "";
     clipboard.copy(`${title}${markdown}`);
     notifications.show({ message: t("Copied") });

apps/client/src/features/page/queries/page-query.ts

@@ -665,6 +665,13 @@ export function updateCacheOnMovePage(
   pageData: Partial<IPage>,
 ) {
   invalidatePageTree();
+  // Invalidate the moved page's breadcrumbs (#523). The tree-side child-loss
+  // guard removes the moved node from the local tree when its new parent is an
+  // unloaded branch, so `findBreadcrumbPath` misses it and the breadcrumb bar
+  // falls back to the server `["breadcrumbs", pageId]` query — which this move
+  // must invalidate, otherwise the crumbs keep showing the OLD parent until a
+  // refocus/navigation.
+  queryClient.invalidateQueries({ queryKey: ["breadcrumbs", pageId] });
   // Remove page from old parent's cache
   const oldQueryKey =
     oldParentId === null

apps/client/src/features/page/queries/update-cache-on-move.breadcrumbs.test.ts

@@ -0,0 +1,40 @@
+import { describe, it, expect, beforeEach, vi } from "vitest";
+import type { IPage } from "@/features/page/types/page.types";
+
+// A fresh QueryClient stands in for the app singleton (importing the real
+// @/main.tsx would run ReactDOM.createRoot, which has no DOM root in jsdom).
+vi.mock("@/main.tsx", async () => {
+  const { QueryClient } = await import("@tanstack/react-query");
+  return { queryClient: new QueryClient() };
+});
+
+import { queryClient } from "@/main.tsx";
+import { updateCacheOnMovePage } from "./page-query";
+
+// #523: the tree-side child-loss guard removes the moved node from the local
+// tree when its new parent is an unloaded branch, so `findBreadcrumbPath` misses
+// it and the breadcrumb bar falls back to the server `["breadcrumbs", pageId]`
+// query. That query MUST be invalidated by a move, or the crumbs keep showing
+// the OLD parent until a refocus/navigation.
+describe("updateCacheOnMovePage — breadcrumbs invalidation (#523)", () => {
+  beforeEach(() => {
+    queryClient.clear();
+    vi.restoreAllMocks();
+  });
+
+  it("invalidates the moved page's ['breadcrumbs', pageId] query", () => {
+    const spy = vi.spyOn(queryClient, "invalidateQueries");
+
+    updateCacheOnMovePage("s1", "moved-page", "old-parent", "new-parent", {
+      id: "moved-page",
+    } as Partial<IPage>);
+
+    const invalidatedBreadcrumbs = spy.mock.calls.some(
+      ([arg]) =>
+        Array.isArray((arg as { queryKey?: unknown[] })?.queryKey) &&
+        (arg as { queryKey: unknown[] }).queryKey[0] === "breadcrumbs" &&
+        (arg as { queryKey: unknown[] }).queryKey[1] === "moved-page",
+    );
+    expect(invalidatedBreadcrumbs).toBe(true);
+  });
+});

apps/client/src/features/page/tree/components/doc-tree-row.tsx

@@ -55,7 +55,14 @@ type Props<T extends object> = {
 };
 
 const DRAG_TYPE = 'doc-tree-item';
-const AUTO_EXPAND_MS = 500;
+// Hover-hold before a collapsed row auto-expands during a drag. 2s (not ~0.5s)
+// so merely dragging the cursor THROUGH the tree never expands rows — only a
+// deliberate hold does (#523).
+const AUTO_EXPAND_MS = 2000;
+// How long the "a page just moved in here" cue stays on a collapsed target after
+// a make-child drop. Long enough to notice at a glance during frequent
+// collapsed-drops, short enough not to linger. Code-only UX constant (#523).
+const DROP_LANDED_HIGHLIGHT_MS = 1800;
 
 function DocTreeRowInner<T extends object>(props: Props<T>) {
   const {
@@ -93,7 +100,11 @@ function DocTreeRowInner<T extends object>(props: Props<T>) {
   const rowRef = useRef<HTMLElement>(null);
   const [isDragging, setIsDragging] = useState(false);
   const [instruction, setInstruction] = useState<Instruction | null>(null);
+  // Transient "just received a child" cue: a make-child drop no longer expands
+  // the (collapsed) target, so flash the row instead so the move isn't invisible.
+  const [landedChild, setLandedChild] = useState(false);
   const autoExpandTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
+  const landedChildTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
 
   const cancelAutoExpand = useCallback(() => {
     if (autoExpandTimerRef.current) {
@@ -249,11 +260,24 @@ function DocTreeRowInner<T extends object>(props: Props<T>) {
               ? getDragLabel(sourceNode)
               : 'item';
             liveRegion.announce(`Moved ${sourceLabel} under ${parentName}.`);
-            // After a make-child drop, expand this row so the user sees the
+            // Do NOT auto-expand the target on drop: a drop must leave the node
-            // just-dropped child — especially important when the row had no
+            // collapsed. Intentional expansion is handled solely by the
-            // children before (chevron just appeared) so the drop would
+            // hover-hold timer (AUTO_EXPAND_MS). Feedback that the drop landed is
-            // otherwise be invisible.
+            // given by the post-move flash + landed-cue highlight + live-region
-            if (op.kind === 'make-child') onToggle(node.id, true);
+            // announce above. When the make-child target is collapsed, flash a
+            // distinct "child moved in here" cue on the row (it stays collapsed).
+            if (op.kind === 'make-child' && !isOpen) {
+              if (landedChildTimerRef.current) {
+                clearTimeout(landedChildTimerRef.current);
+              }
+              setLandedChild(true);
+              landedChildTimerRef.current = setTimeout(() => {
+                setLandedChild(false);
+                landedChildTimerRef.current = null;
+              }, DROP_LANDED_HIGHLIGHT_MS);
+            }
+            // Restore the openness of the MOVED page itself (source) — untouched
+            // by the above; the target is never expanded here.
             if (source.data.isOpenOnDragStart) onToggle(sourceId, true);
           },
         }),
@@ -281,6 +305,17 @@ function DocTreeRowInner<T extends object>(props: Props<T>) {
 
   useEffect(() => () => cancelAutoExpand(), [cancelAutoExpand]);
 
+  // Clear the landed-child cue timer on unmount (mirrors autoExpandTimerRef).
+  useEffect(
+    () => () => {
+      if (landedChildTimerRef.current) {
+        clearTimeout(landedChildTimerRef.current);
+        landedChildTimerRef.current = null;
+      }
+    },
+    [],
+  );
+
   const effectiveInst =
     instruction?.type === 'instruction-blocked'
       ? instruction.desired
@@ -317,6 +352,7 @@ function DocTreeRowInner<T extends object>(props: Props<T>) {
         className={styles.node}
         data-dragging={isDragging || undefined}
         data-selected={isSelected || undefined}
+        data-landed-child={landedChild || undefined}
         data-receiving-drop={
           receivingDrop === 'make-child'
             ? blocked

apps/client/src/features/page/tree/components/space-tree.tsx

@@ -281,10 +281,12 @@ const SpaceTree = forwardRef<SpaceTreeApi, SpaceTreeProps>(function SpaceTree(
       setOpenTreeNodes((prev) => ({ ...prev, [id]: isOpen }));
       if (isOpen) {
         const node = treeModel.find(data, id) as SpaceTreeNode | null;
-        if (
+        // Same "unloaded branch" predicate the realtime insert paths use
-          node?.hasChildren &&
+        // (`isUnloadedBranch`) so the lazy-load gate and the realtime inserts
-          (!node.children || node.children.length === 0)
+        // (`insertByPosition` / `placeByPosition`) can never disagree about what
-        ) {
+        // counts as unloaded (#525). Note: local raw `insert` (DnD/create-page)
+        // does not yet route through it — see #525 follow-up.
+        if (treeModel.isUnloadedBranch(node)) {
           const fetched = await fetchAllAncestorChildren({
             pageId: id,
             spaceId: node.spaceId,

apps/client/src/features/page/tree/hooks/use-tree-mutation.move-guard.test.tsx

@@ -0,0 +1,149 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { renderHook, act } from "@testing-library/react";
+import { Provider, createStore } from "jotai";
+import type { ReactNode } from "react";
+
+import { treeDataAtom } from "@/features/page/tree/atoms/tree-data-atom.ts";
+import { treeModel } from "@/features/page/tree/model/tree-model";
+import type { SpaceTreeNode } from "@/features/page/tree/types";
+
+// --- Boundary mocks: only the network/query + router/i18n surfaces the hook
+// touches. The tree math (treeModel, dropOpToMovePayload) runs for real so the
+// child-loss guard is exercised end-to-end.
+const moveMutate = vi.fn().mockResolvedValue({});
+const updateCacheOnMovePageMock = vi.fn();
+vi.mock("@/features/page/queries/page-query.ts", () => ({
+  useCreatePageMutation: () => ({ mutateAsync: vi.fn() }),
+  useUpdatePageMutation: () => ({ mutateAsync: vi.fn() }),
+  useRemovePageMutation: () => ({ mutateAsync: vi.fn() }),
+  useMovePageMutation: () => ({ mutateAsync: moveMutate }),
+  updateCacheOnMovePage: (...args: unknown[]) =>
+    updateCacheOnMovePageMock(...args),
+}));
+vi.mock("react-router-dom", () => ({
+  useNavigate: () => vi.fn(),
+  useParams: () => ({ spaceSlug: "space", pageSlug: undefined }),
+}));
+vi.mock("react-i18next", () => ({
+  useTranslation: () => ({ t: (s: string) => s }),
+}));
+vi.mock("@mantine/notifications", () => ({
+  notifications: { show: vi.fn() },
+}));
+
+// Import AFTER mocks so the hook binds to them.
+import { useTreeMutation } from "./use-tree-mutation";
+
+function node(
+  id: string,
+  over: Partial<SpaceTreeNode> = {},
+): SpaceTreeNode {
+  return {
+    id,
+    slugId: `slug-${id}`,
+    name: id.toUpperCase(),
+    position: "a0",
+    spaceId: "space-1",
+    parentPageId: null as unknown as string,
+    hasChildren: false,
+    children: [],
+    ...over,
+  };
+}
+
+function setup(before: SpaceTreeNode[]) {
+  const store = createStore();
+  store.set(treeDataAtom, before);
+  const wrapper = ({ children }: { children: ReactNode }) => (
+    <Provider store={store}>{children}</Provider>
+  );
+  const { result } = renderHook(() => useTreeMutation("space-1"), { wrapper });
+  return { store, result };
+}
+
+describe("useTreeMutation.handleMove — child-loss guard (#523)", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    moveMutate.mockResolvedValue({});
+  });
+
+  it("make-child into an UNLOADED folder does NOT materialize [source] — keeps it lazy-loadable", async () => {
+    // F has children on the server but none are loaded here (canonical unloaded
+    // form: hasChildren + children:[]). X sits at root.
+    const before = [
+      node("F", { position: "a0", hasChildren: true, children: [] }),
+      node("X", { position: "a5" }),
+    ];
+    const { store, result } = setup(before);
+
+    await act(async () => {
+      await result.current.handleMove("X", {
+        kind: "make-child",
+        targetId: "F",
+      });
+    });
+
+    const tree = store.get(treeDataAtom);
+    const f = treeModel.find(tree, "F");
+    // The guard leaves F unloaded (children stay []), so a later expand fetches
+    // the FULL server set (incl. X) instead of showing a misleading partial [X].
+    // MUTATION: dropping the guard (using the `move` result) would put children
+    // === [X] here and redden this.
+    expect(f?.children).toEqual([]);
+    expect(f?.hasChildren).toBe(true);
+    // X is removed from its old (root) slot; it reappears on expand/load of F.
+    expect(treeModel.find(tree, "X")).toBeNull();
+    // The server move is still persisted.
+    expect(moveMutate).toHaveBeenCalledTimes(1);
+  });
+
+  it("make-child into a LOADED folder appends source and KEEPS the existing children", async () => {
+    // F is loaded with one child c1; moving X in must preserve c1 (no loss) and
+    // append X — this path does NOT hit the guard.
+    const before = [
+      node("F", {
+        position: "a0",
+        hasChildren: true,
+        children: [node("c1", { position: "a1", parentPageId: "F" })],
+      }),
+      node("X", { position: "a5" }),
+    ];
+    const { store, result } = setup(before);
+
+    await act(async () => {
+      await result.current.handleMove("X", {
+        kind: "make-child",
+        targetId: "F",
+      });
+    });
+
+    const tree = store.get(treeDataAtom);
+    const f = treeModel.find(tree, "F");
+    expect(f?.children?.map((n) => n.id)).toEqual(["c1", "X"]);
+    expect(f?.hasChildren).toBe(true);
+    // X now lives under F.
+    expect(treeModel.find(tree, "X")?.parentPageId).toBe("F");
+  });
+
+  it("make-child into a genuinely-empty leaf materializes the child (nothing to lose)", async () => {
+    // Leaf L has no server children (hasChildren:false). Dropping X in should
+    // show X immediately — the guard must NOT fire here.
+    const before = [
+      node("L", { position: "a0", hasChildren: false, children: [] }),
+      node("X", { position: "a5" }),
+    ];
+    const { store, result } = setup(before);
+
+    await act(async () => {
+      await result.current.handleMove("X", {
+        kind: "make-child",
+        targetId: "L",
+      });
+    });
+
+    const tree = store.get(treeDataAtom);
+    const l = treeModel.find(tree, "L");
+    expect(l?.children?.map((n) => n.id)).toEqual(["X"]);
+    expect(l?.hasChildren).toBe(true);
+  });
+});

apps/client/src/features/page/tree/hooks/use-tree-mutation.ts

@@ -61,11 +61,48 @@ export function useTreeMutation(spaceId: string): UseTreeMutation {
       if (!source) return;
       const oldParentId = source.parentPageId ?? null;
 
-      // optimistic apply with the new position from the payload
+      // Child-loss guard (#523, twin of #525's realtime `insertByPosition` fix).
-      let optimistic = treeModel.update(after, sourceId, {
+      // We no longer auto-expand the make-child target on drop, so the old
-        position: payload.position,
+      // `onToggle(target, true)` — which was ALSO the only trigger of the
-        parentPageId: payload.parentPageId,
+      // corrective lazy-load — is gone. `treeModel.move` materialized
-      } as Partial<SpaceTreeNode>);
+      // `target.children = [source]` (only the moved node); if the target is an
+      // UNLOADED branch (server has children but none are loaded here), keeping
+      // that partial `[source]` list would defeat the lazy-load gate and hide the
+      // target's OTHER server children (the #159 #1 data-loss class). So for an
+      // unloaded make-child target, build the optimistic tree WITHOUT
+      // materializing source under it: just remove source from its old parent and
+      // flag the target `hasChildren`. The gate stays armed and a later manual
+      // expand fetches the FULL set (incl. the moved page, which the awaited
+      // server move persists). Predicate is the gate's (`isUnloadedBranch`), NOT
+      // `insertByPosition`'s old `=== undefined` (canonical unloaded is `[]`).
+      const target =
+        op.kind === "make-child"
+          ? (treeModel.find(before, op.targetId) as SpaceTreeNode | null)
+          : null;
+      const unloadedMakeChild =
+        op.kind === "make-child" && treeModel.isUnloadedBranch(target);
+
+      let optimistic: SpaceTreeNode[];
+      if (unloadedMakeChild) {
+        // Do NOT materialize [source] into the unloaded target.
+        optimistic = treeModel.remove(before, sourceId);
+        optimistic = treeModel.update(optimistic, op.targetId, {
+          hasChildren: true,
+        } as Partial<SpaceTreeNode>);
+      } else {
+        // optimistic apply with the new position from the payload
+        optimistic = treeModel.update(after, sourceId, {
+          position: payload.position,
+          parentPageId: payload.parentPageId,
+        } as Partial<SpaceTreeNode>);
+        // For make-child onto a previously-childless (loaded) target: flip
+        // hasChildren on so the new parent shows its chevron.
+        if (op.kind === "make-child") {
+          optimistic = treeModel.update(optimistic, op.targetId, {
+            hasChildren: true,
+          } as Partial<SpaceTreeNode>);
+        }
+      }
 
       // If the old parent has no children left, mark hasChildren: false so the
       // chevron disappears. Without this, the empty parent keeps rendering an
@@ -79,14 +116,6 @@ export function useTreeMutation(spaceId: string): UseTreeMutation {
         }
       }
 
-      // For make-child onto a previously-childless target: flip hasChildren on
-      // so the new parent shows its chevron.
-      if (op.kind === "make-child") {
-        optimistic = treeModel.update(optimistic, op.targetId, {
-          hasChildren: true,
-        } as Partial<SpaceTreeNode>);
-      }
-
       setData(optimistic);
 
       try {

apps/client/src/features/page/tree/model/tree-model.test.ts

@@ -74,6 +74,48 @@ describe("treeModel.isDescendant", () => {
   });
 });
 
+// #525: the single "is this branch unloaded?" predicate shared by the lazy-load
+// gate and the insert paths. Unloaded == server says hasChildren but none are
+// present locally (canonical form `children: []`, also `undefined`). A parent
+// without hasChildren is genuinely empty, not unloaded.
+describe("treeModel.isUnloadedBranch", () => {
+  type PH = TreeNode<{ name: string; hasChildren?: boolean }>;
+  it("true for hasChildren + empty array (canonical unloaded form)", () => {
+    const n: PH = { id: "p", name: "P", hasChildren: true, children: [] };
+    expect(treeModel.isUnloadedBranch(n)).toBe(true);
+  });
+  it("true for hasChildren + undefined children", () => {
+    const n: PH = { id: "p", name: "P", hasChildren: true };
+    expect(treeModel.isUnloadedBranch(n)).toBe(true);
+  });
+  it("false for hasChildren + already-loaded children", () => {
+    const n: PH = {
+      id: "p",
+      name: "P",
+      hasChildren: true,
+      children: [{ id: "c", name: "C" }],
+    };
+    expect(treeModel.isUnloadedBranch(n)).toBe(false);
+  });
+  it("false for a genuinely-empty parent (no hasChildren)", () => {
+    expect(
+      treeModel.isUnloadedBranch({
+        id: "p",
+        name: "P",
+        hasChildren: false,
+        children: [],
+      } as PH),
+    ).toBe(false);
+    expect(
+      treeModel.isUnloadedBranch({ id: "p", name: "P" } as PH),
+    ).toBe(false);
+  });
+  it("false for null/undefined", () => {
+    expect(treeModel.isUnloadedBranch(null)).toBe(false);
+    expect(treeModel.isUnloadedBranch(undefined)).toBe(false);
+  });
+});
+
 describe("treeModel.visible", () => {
   it("returns only root nodes when no openIds", () => {
     const v = treeModel.visible(fixture, new Set());
@@ -197,43 +239,64 @@ describe("treeModel.insertByPosition", () => {
     ]);
   });
 
-  // #159 #1: inserting/moving a node under a parent whose children are NOT
+  type PH = TreeNode<{
-  // loaded (`children === undefined`, e.g. a collapsed page) must NOT materialize
+    name: string;
-  // a partial `[node]` list — that would defeat the lazy-load gate and hide the
+    position?: string;
-  // parent's other real children. The node is left to be lazy-loaded; only
+    hasChildren?: boolean;
-  // `hasChildren` is flagged so the chevron appears.
+  }>;
-  it("does NOT materialize a child under an UNLOADED parent (children undefined)", () => {
+
-    type PH = TreeNode<{
+  // #159 #1 / #525: inserting/moving a node under an UNLOADED parent must NOT
-      name: string;
+  // materialize a partial `[node]` list — that would defeat the lazy-load gate and
-      position?: string;
+  // hide the parent's other real children. The canonical unloaded form here is
-      hasChildren?: boolean;
+  // `children: []` + `hasChildren: true` (from `pageToTreeNode` /
-    }>;
+  // `pruneCollapsedChildren`), which the pre-#525 `=== undefined` guard MISSED.
+  // The node is left to be lazy-loaded; the chevron stays enabled.
+  it("does NOT materialize a child under an UNLOADED parent (children: [], hasChildren: true)", () => {
     const tree: PH[] = [
-      { id: "p", name: "P", position: "a0", hasChildren: false }, // children: undefined
+      { id: "p", name: "P", position: "a0", hasChildren: true, children: [] },
     ];
     const node: PH = { id: "x", name: "X", position: "a1" };
     const t = treeModel.insertByPosition(tree, "p", node);
     const parent = treeModel.find(t, "p");
     // The node was NOT inserted (children stay unloaded -> lazy-load fetches the
-    // full set, including this node, on expand).
+    // full set, including this node, on expand). MUTATION: the pre-#525 predicate
-    expect(parent?.children).toBeUndefined();
+    // `children === undefined` does not fire for `[]`, so it would insert `[x]`
+    // here and reredden this expectation.
+    expect(parent?.children).toEqual([]);
     expect(treeModel.find(t, "x")).toBeNull();
-    // ...but the chevron is enabled so the user can expand to load it.
+    // ...and the chevron stays enabled so the user can expand to load it.
     expect((parent as PH).hasChildren).toBe(true);
   });
 
-  it("DOES insert under a LOADED-but-empty parent (children: [])", () => {
+  it("does NOT materialize a child under an UNLOADED parent (children undefined, hasChildren: true)", () => {
-    type PH = TreeNode<{
+    const tree: PH[] = [
-      name: string;
+      { id: "p", name: "P", position: "a0", hasChildren: true }, // children: undefined
-      position?: string;
+    ];
-      hasChildren?: boolean;
+    const node: PH = { id: "x", name: "X", position: "a1" };
-    }>;
+    const t = treeModel.insertByPosition(tree, "p", node);
+    const parent = treeModel.find(t, "p");
+    expect(parent?.children).toBeUndefined();
+    expect(treeModel.find(t, "x")).toBeNull();
+    expect((parent as PH).hasChildren).toBe(true);
+  });
+
+  it("DOES insert under a genuinely-empty parent (children: [], hasChildren: false)", () => {
     const tree: PH[] = [
       { id: "p", name: "P", position: "a0", hasChildren: false, children: [] },
     ];
     const node: PH = { id: "x", name: "X", position: "a1" };
     const t = treeModel.insertByPosition(tree, "p", node);
-    // A loaded (empty) child list is complete, so the node IS inserted.
+    // No server children (`hasChildren: false`), so materializing the first child
+    // is correct — nothing is hidden.
+    expect(treeModel.find(t, "p")?.children?.map((n) => n.id)).toEqual(["x"]);
+  });
+
+  it("DOES insert under a genuinely-empty parent (children undefined, hasChildren: false)", () => {
+    const tree: PH[] = [
+      { id: "p", name: "P", position: "a0", hasChildren: false }, // children: undefined
+    ];
+    const node: PH = { id: "x", name: "X", position: "a1" };
+    const t = treeModel.insertByPosition(tree, "p", node);
     expect(treeModel.find(t, "p")?.children?.map((n) => n.id)).toEqual(["x"]);
   });
 

apps/client/src/features/page/tree/model/tree-model.ts

@@ -43,6 +43,26 @@ export const treeModel = {
     };
   },
 
+  // A branch is "unloaded" when the server says it HAS children (`hasChildren`)
+  // but none are present locally. The canonical unloaded form in this codebase
+  // is `children: []` (produced by `pageToTreeNode` and by `pruneCollapsedChildren`
+  // resetting collapsed branches), NOT `children: undefined` — so a predicate that
+  // only checks `=== undefined` misses the real case and materializes a misleading
+  // partial list (#525). This is the SINGLE source of truth for "should a
+  // fetch/materialize be deferred?", shared by the lazy-load gate (`handleToggle`)
+  // and the realtime insert paths (`insertByPosition` / `placeByPosition`), so they
+  // can never drift apart again. (The local raw `insert` primitive and its DnD/
+  // create-page callers do NOT yet route through this predicate — see #525
+  // follow-up.) A parent WITHOUT `hasChildren` is genuinely empty
+  // (no server children) — inserting its first child is correct, not deferred.
+  isUnloadedBranch<T extends object>(
+    node: TreeNode<T> | null | undefined,
+  ): boolean {
+    if (!node) return false;
+    const hasChildren = (node as { hasChildren?: boolean }).hasChildren === true;
+    return hasChildren && (node.children == null || node.children.length === 0);
+  },
+
   isDescendant<T extends object>(
     tree: TreeNode<T>[],
     ancestorId: string,
@@ -127,14 +147,15 @@ export const treeModel = {
     }
     const parent = treeModel.find(tree, parentId);
     // The parent is in the tree but its children have NOT been lazy-loaded yet
-    // (`children === undefined`, distinct from a loaded-but-empty `[]`). Inserting
+    // (`hasChildren` set + children absent/empty — see `isUnloadedBranch`; the
+    // canonical unloaded form is `children: []`, NOT just `undefined`). Inserting
     // here would MATERIALIZE a misleading partial child list (`[node]`) that
     // defeats the lazy-load gate — which fetches only when children are
     // absent/empty — so the parent's OTHER real children would never load and the
     // moved/added node would be the only one shown (a silent data loss, #159 #1).
     // Instead, leave the children unloaded and just flag `hasChildren` so the
     // chevron appears; expanding fetches the FULL set (including this node).
-    if (parent && parent.children === undefined) {
+    if (parent && treeModel.isUnloadedBranch(parent)) {
       return treeModel.update(
         tree,
         parentId,

apps/client/src/features/page/tree/styles/tree.module.css

@@ -150,6 +150,45 @@
     );
 }
 
+/* "A page just moved in here" cue (#523). A make-child drop no longer expands
+   the collapsed target, so the moved page is momentarily invisible; pulse the
+   target row in a distinct teal (NOT the blue make-child highlight, NOT the
+   neutral post-move flash) so the landing is noticeable while the node stays
+   collapsed. Two short pulses fit inside DROP_LANDED_HIGHLIGHT_MS (1.8s), after
+   which the row clears the attribute and the animation stops. */
+@keyframes landedChildPulse {
+    0% {
+        background-color: light-dark(
+            var(--mantine-color-teal-2),
+            rgba(45, 212, 191, 0.30)
+        );
+        outline-color: light-dark(
+            var(--mantine-color-teal-6),
+            var(--mantine-color-teal-5)
+        );
+    }
+    100% {
+        background-color: transparent;
+        outline-color: transparent;
+    }
+}
+
+.node[data-landed-child="true"] {
+    outline: 2px solid transparent;
+    outline-offset: -1px;
+    animation: landedChildPulse 0.9s ease-out 2;
+}
+
+@media (prefers-reduced-motion: reduce) {
+    .node[data-landed-child="true"] {
+        animation: none;
+        background-color: light-dark(
+            var(--mantine-color-teal-1),
+            rgba(45, 212, 191, 0.18)
+        );
+    }
+}
+
 .dropLine {
     position: absolute;
     left: var(--drop-line-indent, 0);

apps/client/src/features/share/components/share-ai-widget.tsx

@@ -168,6 +168,10 @@ export default function ShareAiWidget({
             // Anonymous reader: suppress the tool-argument summary line so the
             // agent's raw query/argument text isn't shown on the public share.
             showInput={false}
+            // Anonymous reader: never paint a tool's raw errorText (it can carry
+            // internal detail). This is the render gate; the bytes are also
+            // sanitized server-side in PublicShareChatToolsService.forShare (#394).
+            showErrors={false}
             // Anonymous reader: neutralize internal/relative links in the
             // assistant's markdown so internal UUIDs/auth-gated routes don't
             // leak as clickable links (external http(s) links are kept).

apps/client/src/features/share/components/share-alias-section.test.tsx

@@ -13,8 +13,7 @@ let currentAlias: IShareAlias | null = null;
 let availabilityResult: {
   valid: boolean;
   available: boolean;
-  currentPageId: string | null;
+} = { valid: true, available: true };
-} = { valid: true, available: true, currentPageId: null };
 
 vi.mock("@/features/share/queries/share-query.ts", () => ({
   useShareAliasForPageQuery: () => ({ data: currentAlias }),
@@ -56,7 +55,7 @@ describe("ShareAliasSection — taken-name handling is never a dead end", () =>
   beforeEach(() => {
     setMutateAsync.mockReset();
     currentAlias = null;
-    availabilityResult = { valid: true, available: true, currentPageId: null };
+    availabilityResult = { valid: true, available: true };
   });
 
   it("shows a 'will move it here' HINT (not a terminal error) when the name belongs to another page, and keeps Save enabled", async () => {
@@ -65,7 +64,6 @@ describe("ShareAliasSection — taken-name handling is never a dead end", () =>
     availabilityResult = {
       valid: true,
       available: false,
-      currentPageId: "page-X",
     };
 
     renderSection("page-Y");
@@ -97,7 +95,6 @@ describe("ShareAliasSection — taken-name handling is never a dead end", () =>
     availabilityResult = {
       valid: true,
       available: false,
-      currentPageId: "page-X",
     };
     // The server rejects the un-confirmed save asking the client to confirm.
     setMutateAsync.mockRejectedValueOnce({
@@ -106,7 +103,6 @@ describe("ShareAliasSection — taken-name handling is never a dead end", () =>
         status: 409,
         data: {
           code: "ALIAS_REASSIGN_REQUIRED",
-          currentPageId: "page-X",
           currentPageTitle: "Alias Test Page X",
         },
       },

apps/client/src/features/share/components/share-alias-section.tsx

@@ -48,7 +48,6 @@ export default function ShareAliasSection({
   const [availability, setAvailability] = useState<{
     valid: boolean;
     available: boolean;
-    currentPageId: string | null;
   } | null>(null);
   const [reassign, setReassign] = useState<{
     alias: string;
@@ -76,7 +75,6 @@ export default function ShareAliasSection({
         setAvailability({
           valid: res.valid,
           available: res.available,
-          currentPageId: res.currentPageId,
         });
       } catch {
         setAvailability(null);

apps/client/src/features/share/types/share.types.ts

@@ -108,7 +108,6 @@ export interface IShareAliasAvailability {
   alias: string;
   valid: boolean;
   available: boolean;
-  currentPageId: string | null;
 }
 
 export interface ISharedPageTree {

apps/client/src/features/websocket/tree-socket-reducers.test.ts

@@ -82,17 +82,19 @@ describe("applyMoveTreeNode", () => {
     ]);
   });
 
-  it("does NOT create a partial child list when the destination is loaded-but-collapsed (children unloaded) — keeps it lazy-loadable (#159)", () => {
+  it("does NOT create a partial child list when the destination is loaded-but-collapsed (children unloaded) — keeps it lazy-loadable (#159 #525)", () => {
-    // `dstCollapsed` is in the tree but its children were never lazy-loaded
+    // `dstCollapsed` is in the tree but its children were never lazy-loaded. The
-    // (children === undefined). The OLD behavior inserted `src` as the ONLY
+    // CANONICAL unloaded form here is `hasChildren: true` + `children: []` (from
-    // child ([src]), which defeated the lazy-load gate and HID the parent's
+    // `pageToTreeNode` / `pruneCollapsedChildren`), NOT `children: undefined`.
-    // other real children. Now the move leaves children unloaded (so expanding
+    // The pre-#525 predicate (`children === undefined`) missed this form and
-    // fetches the FULL set, including src) and just flags hasChildren.
+    // inserted `src` as the ONLY child ([src]), defeating the lazy-load gate and
+    // HIDING the parent's other real children. Now the move leaves children
+    // unloaded (so expanding fetches the FULL set, including src).
     const tree: SpaceTreeNode[] = [
       node("dstCollapsed", {
         position: "a0",
-        hasChildren: false,
+        hasChildren: true,
-        children: undefined as unknown as SpaceTreeNode[],
+        children: [],
       }),
       node("src", { position: "a9" }),
     ];
@@ -105,9 +107,10 @@ describe("applyMoveTreeNode", () => {
       pageData: {},
     });
     const dst = treeModel.find(next, "dstCollapsed");
-    // Children stay unloaded -> the lazy-load gate fetches the FULL set (incl.
+    // Children stay unloaded ([] not materialized to [src]) -> the lazy-load gate
-    // src) on expand, rather than showing a misleading partial [src] list.
+    // fetches the FULL set (incl. src) on expand. MUTATION: the pre-#525
-    expect(dst?.children).toBeUndefined();
+    // `=== undefined` predicate would insert [src] here and redden this.
+    expect(dst?.children).toEqual([]);
     expect(dst?.hasChildren).toBe(true);
     // src moved away from its old root slot (it lives under dstCollapsed
     // server-side and reappears when the parent is expanded/loaded).

apps/client/src/features/workspace/components/settings/components/ai-mcp-server-form.tsx

@@ -28,6 +28,7 @@ import {
   IAiMcpServerCreate,
   IAiMcpServerUpdate,
 } from "@/features/workspace/services/ai-mcp-server-service.ts";
+import { resolveToolAllowlist } from "./ai-mcp-server-form.utils.ts";
 
 const formSchema = z.object({
   name: z.string().min(1),
@@ -121,13 +122,20 @@ export default function AiMcpServerForm({
   async function handleSubmit(values: FormValues) {
     const headers = resolveHeaders();
 
+    // An empty tag field means "no restriction" (sent as null) — since #476 the
+    // server persists a literal `[]` as deny-all (zero tools). But a server that
+    // was ALREADY deny-all loads into an empty field too; sending null there
+    // would silently widen it to allow-all on a routine edit, so preserve `[]`.
+    // See resolveToolAllowlist for the full rationale.
+    const toolAllowlist = resolveToolAllowlist(values.toolAllowlist, server);
+
     if (isEdit && server) {
       const payload: IAiMcpServerUpdate = {
         id: server.id,
         name: values.name,
         transport: values.transport,
         url: values.url,
-        toolAllowlist: values.toolAllowlist,
+        toolAllowlist,
         // Always sent: a blank value clears the stored guidance (server -> null).
         instructions: values.instructions,
         enabled: values.enabled,
@@ -140,7 +148,7 @@ export default function AiMcpServerForm({
         name: values.name,
         transport: values.transport,
         url: values.url,
-        toolAllowlist: values.toolAllowlist,
+        toolAllowlist,
         // Blank => server stores null (no guidance).
         instructions: values.instructions,
         enabled: values.enabled,

apps/client/src/features/workspace/components/settings/components/ai-mcp-server-form.utils.test.ts

@@ -0,0 +1,29 @@
+import { describe, it, expect } from "vitest";
+import { resolveToolAllowlist } from "./ai-mcp-server-form.utils.ts";
+
+describe("resolveToolAllowlist", () => {
+  it("sends the typed tools when the field is non-empty", () => {
+    expect(resolveToolAllowlist(["a", "b"], { toolAllowlist: null })).toEqual([
+      "a",
+      "b",
+    ]);
+  });
+
+  it("creates as null (unrestricted) when empty and there is no server", () => {
+    expect(resolveToolAllowlist([], undefined)).toBeNull();
+  });
+
+  it("sends null for an empty field on a previously-unrestricted server", () => {
+    expect(resolveToolAllowlist([], { toolAllowlist: null })).toBeNull();
+  });
+
+  it("preserves deny-all: an empty field on a `[]` server stays `[]`, not null", () => {
+    // The core #476/#477 guard: editing a deny-all server (rename/toggle) with
+    // an empty tag field must NOT silently widen it to allow-all.
+    expect(resolveToolAllowlist([], { toolAllowlist: [] })).toEqual([]);
+  });
+
+  it("still sends explicit tools even if the server was deny-all", () => {
+    expect(resolveToolAllowlist(["x"], { toolAllowlist: [] })).toEqual(["x"]);
+  });
+});

apps/client/src/features/workspace/components/settings/components/ai-mcp-server-form.utils.ts

@@ -0,0 +1,22 @@
+import { IAiMcpServer } from "@/features/workspace/services/ai-mcp-server-service.ts";
+
+// Resolve the tool allowlist value to persist from the form field.
+//
+// An empty tag field normally means "no restriction" and is sent as null so
+// the server drops the column (all tools allowed). But a server that was
+// ALREADY deny-all (a stored literal `[]`, meaning zero tools — creatable via
+// the API) loads into the form as an empty field too. Coercing that empty
+// field to null on submit would SILENTLY widen a deny-all server to allow-all
+// on any routine edit (rename, toggle) — the exact silent-widen class #476
+// closed on the read side. So when the edited server was deny-all, preserve
+// `[]` (deny-all); only a genuinely-unrestricted server (stored null/absent)
+// stays null.
+export function resolveToolAllowlist(
+  fieldValue: string[],
+  server?: Pick<IAiMcpServer, "toolAllowlist">,
+): string[] | null {
+  if (fieldValue.length > 0) return fieldValue;
+  const wasDenyAll =
+    Array.isArray(server?.toolAllowlist) && server.toolAllowlist.length === 0;
+  return wasDenyAll ? [] : null;
+}

apps/client/src/features/workspace/components/settings/components/ai-provider-settings.spec.tsx

@@ -6,6 +6,8 @@ import {
   nextReindexPollInterval,
   isReindexComplete,
   isReindexButtonLoading,
+  reindexRunKey,
+  isNewReindexRun,
 } from './ai-provider-settings';
 
 describe('resolveCardStatus', () => {
@@ -221,6 +223,128 @@ describe('isReindexComplete', () => {
   });
 });
 
+describe('reindexRunKey', () => {
+  it('is null when the status carries no run identity', () => {
+    expect(reindexRunKey(undefined)).toBeNull();
+    expect(
+      reindexRunKey({ reindexing: false, indexedPages: 5, totalPages: 5 }),
+    ).toBeNull();
+  });
+
+  it('is null for a legacy/degraded record with an empty runId', () => {
+    // The server sends runId='' for a record written before the field existed;
+    // the client must treat that as "no identity" (fall back to prior behaviour).
+    expect(
+      reindexRunKey({
+        reindexing: true,
+        indexedPages: 0,
+        totalPages: 10,
+        runId: '',
+        reindexStartedAt: 1000,
+      }),
+    ).toBeNull();
+  });
+
+  it('folds runId and startedAt into one stable key', () => {
+    expect(
+      reindexRunKey({
+        reindexing: true,
+        indexedPages: 0,
+        totalPages: 10,
+        runId: 'run-a',
+        reindexStartedAt: 1000,
+      }),
+    ).toBe('run-a:1000');
+  });
+
+  it('changes when the runId changes for the same startedAt', () => {
+    const a = reindexRunKey({
+      reindexing: true,
+      indexedPages: 0,
+      totalPages: 10,
+      runId: 'run-a',
+      reindexStartedAt: 1000,
+    });
+    const b = reindexRunKey({
+      reindexing: true,
+      indexedPages: 0,
+      totalPages: 10,
+      runId: 'run-b',
+      reindexStartedAt: 1000,
+    });
+    expect(a).not.toBe(b);
+  });
+
+  it('changes when the same runId restarts at a new startedAt', () => {
+    const a = reindexRunKey({
+      reindexing: true,
+      indexedPages: 0,
+      totalPages: 10,
+      runId: 'run-a',
+      reindexStartedAt: 1000,
+    });
+    const b = reindexRunKey({
+      reindexing: true,
+      indexedPages: 0,
+      totalPages: 10,
+      runId: 'run-a',
+      reindexStartedAt: 2000,
+    });
+    expect(a).not.toBe(b);
+  });
+});
+
+describe('isNewReindexRun (poll keying on runId)', () => {
+  // Derive the status shape from the helper itself so the test needs no export
+  // of the component-internal ReindexStatus type.
+  type ReindexStatusLike = NonNullable<Parameters<typeof reindexRunKey>[0]>;
+  const run = (runId: string, startedAt: number): ReindexStatusLike => ({
+    reindexing: true,
+    indexedPages: 0,
+    totalPages: 10,
+    runId,
+    reindexStartedAt: startedAt,
+  });
+
+  it('first identity after none latched is a NEW run', () => {
+    expect(isNewReindexRun(null, run('run-a', 1000))).toBe(true);
+  });
+
+  it('the SAME identity is not a new run (same run being watched)', () => {
+    const key = reindexRunKey(run('run-a', 1000));
+    expect(isNewReindexRun(key, run('run-a', 1000))).toBe(false);
+  });
+
+  it('a DIFFERENT runId is a new run (reset per-run poll state)', () => {
+    const key = reindexRunKey(run('run-a', 1000));
+    expect(isNewReindexRun(key, run('run-b', 1000))).toBe(true);
+  });
+
+  it('an identity-less poll (no runId / cleared record) is never a new run', () => {
+    const key = reindexRunKey(run('run-a', 1000));
+    expect(
+      isNewReindexRun(key, {
+        reindexing: false,
+        indexedPages: 10,
+        totalPages: 10,
+      }),
+    ).toBe(false);
+  });
+
+  it('a legacy empty-runId poll does not spuriously reset a latched run', () => {
+    const key = reindexRunKey(run('run-a', 1000));
+    expect(
+      isNewReindexRun(key, {
+        reindexing: true,
+        indexedPages: 3,
+        totalPages: 10,
+        runId: '',
+        reindexStartedAt: 1000,
+      }),
+    ).toBe(false);
+  });
+});
+
 describe('isReindexButtonLoading', () => {
   it('loads while the POST mutation is pending', () => {
     expect(

apps/client/src/features/workspace/components/settings/components/ai-provider-settings.tsx

@@ -173,9 +173,43 @@ export function resolveKeyField(
 // Subset of the status payload that drives the reindex poll decisions.
 type ReindexStatus = Pick<
   IAiSettings,
-  "reindexing" | "indexedPages" | "totalPages"
+  "reindexing" | "indexedPages" | "totalPages" | "runId" | "reindexStartedAt"
 >;
 
+/**
+ * A stable per-RUN key for the reindex poll: `runId:startedAt`, or `null` when
+ * the status carries no run identity (no active run, or a legacy/degraded
+ * server record with an empty runId). Two polls of the SAME run share a key; a
+ * new run mints a fresh runId and so a different key.
+ *
+ * This is the single place the client turns the server's run identity into the
+ * value it keys on — it removes the "is this the same run I've been watching or
+ * a brand-new one?" ambiguity that made a class of reindex-status bugs (a stale
+ * pre-reindex snapshot vs a fresh run) get fixed twice (#262). `startedAt` is
+ * folded in so a run that somehow reuses a runId but restarted is still new.
+ */
+export function reindexRunKey(status: ReindexStatus | undefined): string | null {
+  const runId = status?.runId;
+  if (!runId) return null;
+  return `${runId}:${status?.reindexStartedAt ?? ""}`;
+}
+
+/**
+ * Decide whether the latest poll represents a NEW reindex run relative to the
+ * run key the client last latched (`prevKey`, `null` if none yet). True only
+ * when the status carries an identity AND it differs from the latched one — the
+ * signal to reset any per-run poll state (the "seen active" latch / progress the
+ * UI held). The same identity (or no identity) is NOT a new run, so an unchanged
+ * or identity-less poll never resets mid-run.
+ */
+export function isNewReindexRun(
+  prevKey: string | null,
+  status: ReindexStatus | undefined,
+): boolean {
+  const key = reindexRunKey(status);
+  return key !== null && key !== prevKey;
+}
+
 /**
  * Decide the TanStack Query `refetchInterval` while a reindex may be running.
  * Returns the poll interval (ms) to keep polling, or `false` to stop.
@@ -320,6 +354,13 @@ export default function AiProviderSettings() {
   // counter at 0 until a manual reload. A ref (not state) because it must not
   // trigger a render and is only ever read where `reindexing` is already false.
   const reindexSeenActiveRef = useRef(false);
+  // The run identity (runId:startedAt) the current poll window is keyed on. When
+  // a poll reports a DIFFERENT runId the server has started a NEW run, so we
+  // re-latch to it and reset `reindexSeenActiveRef` — a fresh run must never
+  // inherit the previous run's "seen active"/completion state (which would stop
+  // polling immediately or read the old run's counters as this run's). null =
+  // no run keyed yet (steady state, or a legacy record without a runId).
+  const reindexRunKeyRef = useRef<string | null>(null);
 
   // Only admins may read the (masked) AI settings; the server enforces this too.
   const { data: settings, isLoading } = useAiSettingsQuery(isAdmin, (query) =>
@@ -336,6 +377,14 @@ export default function AiProviderSettings() {
   // unmount because the deadline state goes away with the component.
   useEffect(() => {
     if (reindexDeadline === null) return;
+    // Key the poll on the run identity: if this poll carries a runId different
+    // from the one we latched, the server started a NEW run, so adopt it and
+    // drop the per-run "seen active" latch (a fresh run must not inherit the
+    // previous run's completion state). Same runId => same run, leave it alone.
+    if (isNewReindexRun(reindexRunKeyRef.current, settings)) {
+      reindexRunKeyRef.current = reindexRunKey(settings);
+      reindexSeenActiveRef.current = false;
+    }
     // Latch "we have seen the active run" the moment a poll reports it, so the
     // completion check below (and the refetchInterval's) only fires once the run
     // has genuinely started — never on the stale pre-reindex snapshot.
@@ -1220,6 +1269,10 @@ export default function AiProviderSettings() {
                   // immediately.
                   onSuccess: () => {
                     reindexSeenActiveRef.current = false;
+                    // Forget the previous run's identity so the first poll of
+                    // this window (carrying the new run's runId) is recognized
+                    // as a new run and keyed afresh.
+                    reindexRunKeyRef.current = null;
                     setReindexDeadline(Date.now() + REINDEX_POLL_CAP_MS);
                   },
                 })

apps/client/src/features/workspace/services/ai-mcp-server-service.ts

@@ -27,7 +27,9 @@ export interface IAiMcpServerCreate {
   // Auth headers map (e.g. { Authorization: 'Bearer ...' }). Encrypted on save;
   // never returned.
   headers?: Record<string, string>;
-  toolAllowlist?: string[];
+  // Omit/null => no restriction; `[]` is persisted verbatim and means
+  // deny-all (zero tools) since #476.
+  toolAllowlist?: string[] | null;
   // Admin-authored prompt guidance (#180). Blank => stored as null.
   instructions?: string;
   enabled?: boolean;
@@ -43,7 +45,9 @@ export interface IAiMcpServerUpdate {
   transport?: McpTransport;
   url?: string;
   headers?: Record<string, string>;
-  toolAllowlist?: string[];
+  // Absent => unchanged; null => no restriction; `[]` is persisted verbatim
+  // and means deny-all (zero tools) since #476.
+  toolAllowlist?: string[] | null;
   // Admin-authored prompt guidance (#180). Absent => unchanged; blank => cleared.
   instructions?: string;
   enabled?: boolean;

apps/client/src/features/workspace/services/ai-settings-service.ts

@@ -51,6 +51,14 @@ export interface IAiSettings {
   // True while a full workspace reindex is actively running; the counts above
   // then reflect the live run progress (done climbs 0 -> total).
   reindexing?: boolean;
+  // Identity of the ACTIVE reindex run (present only while `reindexing`). The
+  // poll keys on `runId`: a changed value means a NEW run (reset the per-run
+  // poll state the UI latched), the same value is the run already being watched.
+  // Absent/empty ('') => no identity available; the client keeps prior behaviour.
+  runId?: string;
+  // Epoch-ms the active run started; paired with `runId` so a restart with a
+  // recycled id is still detected as a new run.
+  reindexStartedAt?: number;
 }
 
 // Update payload. Key semantics (same for `apiKey` and `embeddingApiKey`):

apps/client/src/lib/telemetry/route-template.test.ts

@@ -1,5 +1,5 @@
 import { describe, it, expect } from "vitest";
-import { templateRoute } from "./route-template";
+import { templateRoute, KNOWN_ROUTE_TEMPLATES } from "./route-template";
 
 describe("templateRoute", () => {
   it("templates a space page path (never leaks slugs)", () => {
@@ -32,4 +32,30 @@ describe("templateRoute", () => {
     expect(templateRoute("/weird/unknown/thing")).toBe("other");
     expect(templateRoute("/s/team/p/slug/extra/segments")).toBe("other");
   });
+
+  // The server's /api/telemetry/vitals mirror (ALLOWED_ROUTE_TEMPLATES) drops any
+  // route outside KNOWN_ROUTE_TEMPLATES, so templateRoute must NEVER emit a label
+  // that is not in that dictionary — otherwise legit client metrics get dropped.
+  it("only ever emits labels contained in KNOWN_ROUTE_TEMPLATES (#495)", () => {
+    const samples = [
+      "/",
+      "/home",
+      "/settings/members",
+      "/settings/groups/g-1",
+      "/s/team",
+      "/s/team/trash",
+      "/s/team/p/slug",
+      "/p/slug",
+      "/share/abc",
+      "/share/abc/p/slug",
+      "/share/p/slug",
+      "/labels/urgent",
+      "/invites/inv-1",
+      "/weird/unknown/thing", // -> "other"
+      "/deep/unmatched/x/y/z", // -> "other"
+    ];
+    for (const path of samples) {
+      expect(KNOWN_ROUTE_TEMPLATES.has(templateRoute(path))).toBe(true);
+    }
+  });
 });

apps/client/src/lib/telemetry/route-template.ts

@@ -44,6 +44,22 @@ const STATIC_ROUTES = new Set<string>([
   '/settings/sharing',
 ]);
 
+/**
+ * The COMPLETE, finite vocabulary `templateRoute` can ever emit: the two
+ * synthetic labels (`/` and `other`), the static routes, and the dynamic
+ * templates. Exported so the public `/api/telemetry/vitals` endpoint can reject
+ * any `route` outside this dictionary server-side (the endpoint is anonymous, so
+ * an un-checked `route` is a free-text write surface). The server keeps a mirror
+ * (`ALLOWED_ROUTE_TEMPLATES` in client-metrics.constants.ts) — this is the
+ * canonical source; keep them in lockstep.
+ */
+export const KNOWN_ROUTE_TEMPLATES: ReadonlySet<string> = new Set<string>([
+  '/',
+  'other',
+  ...STATIC_ROUTES,
+  ...ROUTE_PATTERNS.map((p) => p.template),
+]);
+
 export function templateRoute(pathname: string): string {
   // Normalise a trailing slash (except root).
   const path =

apps/client/src/main.tsx

@@ -3,6 +3,7 @@ import "@mantine/spotlight/styles.css";
 import "@mantine/notifications/styles.css";
 import '@mantine/dates/styles.css';
 import "@/styles/a11y-overrides.css";
+import "@/styles/notification-overrides.css";
 
 import ReactDOM from "react-dom/client";
 import App from "./App.tsx";
@@ -47,7 +48,15 @@ function renderApp() {
       <MantineProvider theme={theme} cssVariablesResolver={mantineCssResolver}>
         <ModalsProvider>
           <QueryClientProvider client={queryClient}>
-            <Notifications position="bottom-center" limit={3} zIndex={10000} />
+            {/* top-center: toasts sit in the top of the viewport, in the line
+                of sight, and no longer cover centered content (e.g. "Load
+                more"). The below-chrome vertical offset is applied via a
+                position-scoped CSS rule in notification-overrides.css (NOT an
+                inline `style`): Mantine renders all six position containers at
+                once and an inline root style would land on every one, giving the
+                bottom-* containers both top+bottom → full-viewport transparent
+                overlays that swallow clicks. */}
+            <Notifications position="top-center" limit={3} zIndex={10000} />
             <HelmetProvider>
               {/* Root boundary above every lazy route's Suspense: a stale-chunk
                   404 after a deploy is caught and recovered here instead of

apps/client/src/styles/notification-overrides.css

@@ -0,0 +1,64 @@
+/*
+ * Toast (Mantine Notification) visibility overrides.
+ * Mantine renders colorless toasts on --mantine-color-body (== the page
+ * background: white in light mode) with a faint shadow, so on white pages the
+ * card has no visible edge. These rules give every toast a type-tinted
+ * background, a WCAG-checked border and a stronger shadow so it separates from
+ * the page. The [data-mantine-color-scheme] + static-class selector (0,2,0)
+ * beats Mantine's own (0,1,0) rules regardless of stylesheet order (Mantine's
+ * bg/border rules wrap the scheme attribute in :where(), so they stay (0,1,0)).
+ * --notification-color is defined on the same element (defaults to primary,
+ * set per `color` prop), so tint/border follow the toast type. This also covers
+ * the loading/import toast (no accent bar, since the spinner takes the icon
+ * slot): its visibility comes from tone + border + shadow + the colored spinner.
+ */
+
+/*
+ * Push the top-anchored toast containers below the top chrome (fixed 45px
+ * header + optional 45px format toolbar + ~6px gap) so a toast (z-index 10000)
+ * neither covers nor intercepts clicks on the header/toolbar (both z-index 99).
+ *
+ * Scoped to [data-position^='top'] on purpose. Mantine renders ALL SIX position
+ * containers simultaneously (`position` only routes toasts into one via the
+ * store); the root `style` prop would be applied to every one of them by
+ * getStyles("root"). A blanket `top` would land on the bottom-* containers too
+ * (which carry `bottom:16px`) → position:fixed + both edges + height:auto makes
+ * them stretch the full viewport height, and the container root has neither
+ * pointer-events:none nor a background, so those transparent z-10000 overlays
+ * would swallow clicks across the whole page. Restricting to top-* leaves the
+ * bottom containers at height:0.
+ *
+ * Specificity: `.mantine-Notifications-root[data-position^='top']` is (0,2,0)
+ * (class + attribute) and beats Mantine's own top rule
+ * `.m_b37d9ac7:where([data-position='top-center']){top:16px}` which is (0,1,0)
+ * (the :where() contributes 0), regardless of stylesheet order.
+ */
+.mantine-Notifications-root[data-position^='top'] {
+  top: 96px;
+}
+
+[data-mantine-color-scheme='light'] .mantine-Notification-root {
+  /* ~10% type color over white: clearly off-white, text contrast preserved */
+  background-color: color-mix(in srgb, var(--notification-color) 10%, var(--mantine-color-white));
+  /* Border must clear WCAG 3:1 non-text contrast on white. The repo rejects
+     gray-4 for this (a11y-overrides.css); gray-6 base (~3.32:1) darkened by the
+     type color stays >= 3:1. */
+  border: 1px solid color-mix(in srgb, var(--notification-color) 45%, var(--mantine-color-gray-6));
+  box-shadow: var(--mantine-shadow-xl);
+}
+
+[data-mantine-color-scheme='dark'] .mantine-Notification-root {
+  /* Dark page (dark-7/8) vs toast (dark-6) already separate a little; border +
+     shadow carry the type cue here (a 7% dark tint was near-invisible). */
+  background-color: color-mix(in srgb, var(--notification-color) 14%, var(--mantine-color-dark-6));
+  border: 1px solid color-mix(in srgb, var(--notification-color) 45%, var(--mantine-color-dark-3));
+  box-shadow: var(--mantine-shadow-xl);
+}
+
+/* Mantine's message-with-title color is gray-6 (#868e96, already only ~3.32:1
+   on white — below AA 4.5:1); the new tint pushes it lower. Bump to gray-7 to
+   keep multi-line colored toasts readable, consistent with the repo's existing
+   WCAG tuning (theme.ts already bumps this same gray-6 up elsewhere). */
+[data-mantine-color-scheme='light'] .mantine-Notification-description[data-with-title] {
+  color: var(--mantine-color-gray-7);
+}

apps/server/package.json

@@ -23,7 +23,7 @@
     "migration:reset": "tsx src/database/migrate.ts down-to NO_MIGRATIONS",
     "migration:codegen": "kysely-codegen --dialect=postgres --camel-case --env-file=../../.env --out-file=./src/database/types/db.d.ts",
     "lint": "eslint \"{src,apps,libs,test}/**/*.ts\" --fix",
-    "pretest": "pnpm --filter @docmost/editor-ext build && pnpm --filter @docmost/prosemirror-markdown build",
+    "pretest": "pnpm --filter @docmost/editor-ext build && pnpm --filter @docmost/prosemirror-markdown build && pnpm --filter @docmost/token-estimate build",
     "test": "jest",
     "test:int": "jest --config test/jest-integration.json",
     "test:watch": "jest --watch",
@@ -44,6 +44,7 @@
     "@docmost/mcp": "workspace:*",
     "@docmost/pdf-inspector": "1.9.6",
     "@docmost/prosemirror-markdown": "workspace:*",
+    "@docmost/token-estimate": "workspace:*",
     "@fastify/compress": "^9.0.0",
     "@fastify/cookie": "^11.0.2",
     "@fastify/multipart": "^10.0.0",
@@ -206,6 +207,7 @@
       "^@docmost/db/(.*)$": "<rootDir>/database/$1",
       "^@docmost/transactional/(.*)$": "<rootDir>/integrations/transactional/$1",
       "^@docmost/ee/(.*)$": "<rootDir>/ee/$1",
+      "^@docmost/token-estimate$": "<rootDir>/../../../packages/token-estimate/src/index.ts",
       "^src/(.*)$": "<rootDir>/$1",
       "^@tiptap/react$": "<rootDir>/../test/stubs/tiptap-react.js"
     }

apps/server/src/app.module.ts

@@ -25,7 +25,7 @@ import { CacheModule } from '@nestjs/cache-manager';
 import KeyvRedis from '@keyv/redis';
 import { LoggerModule } from './common/logger/logger.module';
 import { ClsModule } from 'nestjs-cls';
-import { NoopAuditModule } from './integrations/audit/audit.module';
+import { AuditModule } from './integrations/audit/audit.module';
 import { ThrottleModule } from './integrations/throttle/throttle.module';
 import { McpModule } from './integrations/mcp/mcp.module';
 import { SandboxModule } from './integrations/sandbox/sandbox.module';
@@ -55,7 +55,7 @@ try {
       middleware: { mount: true },
     }),
     LoggerModule,
-    NoopAuditModule,
+    AuditModule,
     CoreModule,
     DatabaseModule,
     EnvironmentModule,

apps/server/src/collaboration/yjs.util.spec.ts

@@ -529,4 +529,107 @@ describe('replaceYjsMarkedText', () => {
     expect(result).toEqual({ applied: false, currentText: 'abcdef' });
     expect(text.toDelta()).toEqual(before);
   });
+
+  // #496: apply must NOT silently strip the replaced run's inline formatting.
+  // Build a paragraph and format the marked range with extra marks, then assert
+  // the replacement carries them.
+  function buildFormatted(
+    runs: Array<{ text: string; attrs?: Record<string, any> }>,
+  ): { fragment: Y.XmlFragment; text: Y.XmlText } {
+    const ydoc = new Y.Doc();
+    const fragment = ydoc.getXmlFragment('default');
+    const para = new Y.XmlElement('paragraph');
+    fragment.insert(0, [para]);
+    const text = new Y.XmlText();
+    para.insert(0, [text]);
+    text.insert(0, runs.map((r) => r.text).join(''));
+    let offset = 0;
+    for (const run of runs) {
+      if (run.attrs) text.format(offset, run.text.length, run.attrs);
+      offset += run.text.length;
+    }
+    return { fragment, text };
+  }
+
+  it('preserves the original run formatting (bold + link) on the replacement', () => {
+    const { fragment, text } = buildFormatted([
+      { text: 'see ' },
+      {
+        text: 'old',
+        attrs: {
+          comment: { commentId: 'c1', resolved: false },
+          bold: true,
+          link: { href: 'https://x.test' },
+        },
+      },
+      { text: ' end' },
+    ]);
+
+    const result = replaceYjsMarkedText(fragment, 'c1', 'old', 'new');
+
+    expect(result).toEqual({ applied: true, currentText: 'new' });
+    // The comment anchor AND the bold/link marks survive the delete+insert.
+    expect(text.toDelta()).toEqual([
+      { insert: 'see ' },
+      {
+        insert: 'new',
+        attributes: {
+          comment: { commentId: 'c1', resolved: false },
+          bold: true,
+          link: { href: 'https://x.test' },
+        },
+      },
+      { insert: ' end' },
+    ]);
+  });
+
+  it('mixed formatting under the mark: replacement takes the DOMINANT (longest) run, NOT the leading one', () => {
+    // Leading run is SHORT + plain ("x", 1 char); the following run is LONGER +
+    // bold ("bolded", 6 chars), same commentId. The longest run is deliberately
+    // NOT first: a "first-wins" pick would carry plain (no bold), so asserting
+    // bold on the result only holds if the code genuinely selects the LONGEST run.
+    const { fragment, text } = buildFormatted([
+      { text: 'x', attrs: { comment: { commentId: 'c1', resolved: false } } },
+      {
+        text: 'bolded',
+        attrs: { comment: { commentId: 'c1', resolved: false }, bold: true },
+      },
+    ]);
+
+    const result = replaceYjsMarkedText(fragment, 'c1', 'xbolded', 'Z');
+
+    expect(result).toEqual({ applied: true, currentText: 'Z' });
+    expect(text.toDelta()).toEqual([
+      {
+        insert: 'Z',
+        attributes: { comment: { commentId: 'c1', resolved: false }, bold: true },
+      },
+    ]);
+  });
+
+  it('mixed formatting under the mark: on a length tie the FIRST run wins', () => {
+    // Two equal-length runs (2 chars each) with different formatting, same
+    // commentId. The reduce keeps the accumulator on a tie, so the FIRST run
+    // (italic) prevails over the later bold one.
+    const { fragment, text } = buildFormatted([
+      {
+        text: 'AA',
+        attrs: { comment: { commentId: 'c1', resolved: false }, italic: true },
+      },
+      {
+        text: 'BB',
+        attrs: { comment: { commentId: 'c1', resolved: false }, bold: true },
+      },
+    ]);
+
+    const result = replaceYjsMarkedText(fragment, 'c1', 'AABB', 'Z');
+
+    expect(result).toEqual({ applied: true, currentText: 'Z' });
+    expect(text.toDelta()).toEqual([
+      {
+        insert: 'Z',
+        attributes: { comment: { commentId: 'c1', resolved: false }, italic: true },
+      },
+    ]);
+  });
 });

apps/server/src/collaboration/yjs.util.ts

@@ -145,6 +145,10 @@ type MarkedSegment = {
   length: number;
   text: string;
   markAttrs: Record<string, any>;
+  // The FULL attribute set of this delta run — the `comment` mark plus any
+  // inline formatting (bold/italic/code/link/…). Captured so apply can carry the
+  // original run's formatting onto the replacement instead of dropping it.
+  attributes: Record<string, any>;
 };
 
 /**
@@ -202,6 +206,7 @@ export function replaceYjsMarkedText(
             length,
             text: insert,
             markAttrs: markAttr,
+            attributes,
           });
         }
         offset += length;
@@ -251,15 +256,25 @@ export function replaceYjsMarkedText(
     return { applied: false, currentText: joinedText };
   }
 
-  // 3. All guards passed: delete the marked run and re-insert newText with the
+  // 3. All guards passed: delete the marked run and re-insert newText at the
-  // same comment attributes at the same offset. Atomic within the caller's
+  // same offset. Atomic within the caller's transaction.
-  // transaction.
   const start = segments[0].offset;
   const len = segments.reduce((sum, s) => sum + s.length, 0);
-  const markAttrs = segments[0].markAttrs;
+
+  // Carry the ORIGINAL run's formatting onto the replacement (#496): inserting
+  // with only the `comment` mark silently dropped bold/italic/code/link of the
+  // replaced text. Yjs applies one flat attribute set to the whole insert, so
+  // when the marked run mixes formatting we pick the DOMINANT segment (the one
+  // covering the most characters) and apply its attributes — a v1 that preserves
+  // the common single-format case exactly and, for a mixed run, keeps the
+  // prevailing style rather than losing all of it. `attributes` already carries
+  // the `comment` mark (every collected segment is filtered on it above), so the
+  // anchor is preserved by copying the run's attribute set verbatim.
+  const dominant = segments.reduce((a, b) => (b.length > a.length ? b : a));
+  const insertAttrs = { ...dominant.attributes };
 
   node.delete(start, len);
-  node.insert(start, newText, { comment: markAttrs });
+  node.insert(start, newText, insertAttrs);
 
   return { applied: true, currentText: newText };
 }

apps/server/src/common/helpers/prosemirror/html-embed-import-detect.spec.ts

@@ -1,4 +1,5 @@
-import { markdownToHtml, encodeHtmlEmbedSource } from '@docmost/editor-ext';
+import { markdownToProseMirror } from '@docmost/prosemirror-markdown';
+import { encodeHtmlEmbedSource } from '@docmost/editor-ext';
 import { htmlToJson } from '../../../collaboration/collaboration.util';
 import { hasHtmlEmbedNode, stripHtmlEmbedNodes } from './html-embed.util';
 
@@ -10,13 +11,12 @@ import { hasHtmlEmbedNode, stripHtmlEmbedNodes } from './html-embed.util';
  *
  * The block renders inside a sandboxed iframe, so this is not an XSS surface;
  * this exercises the REAL server import conversion path that ImportService uses
- * (`markdownToHtml` then `htmlToJson`; `processHTML` adds only a cheerio
+ * (`markdownToProseMirror`, the canonical converter — issue #345/#347) and
- * link/iframe normalize pass which does not touch htmlEmbed divs) and asserts
+ * asserts that such a node is DETECTED and STRIPPABLE — so the share read path's
- * that such a node is DETECTED and STRIPPABLE — so the share read path's
  * master-toggle strip can remove it when the workspace toggle is OFF.
  */
 describe('htmlEmbed smuggled via the raw serialized div in imported markdown/HTML', () => {
-  it('round-trips through markdownToHtml -> htmlToJson and is DETECTED (base64 data-source)', async () => {
+  it('round-trips through markdownToProseMirror and is DETECTED (base64 data-source)', async () => {
     const source = '<script>steal()</script>';
     const encoded = encodeHtmlEmbedSource(source);
     const md = [
@@ -27,12 +27,9 @@ describe('htmlEmbed smuggled via the raw serialized div in imported markdown/HTM
       'World',
     ].join('\n');
 
-    const html = await markdownToHtml(md);
+    // The canonical importer parses the raw block-level div into a real
-    // marked preserves the raw block-level div verbatim.
+    // htmlEmbed node carrying the decoded source.
-    expect(html).toContain('data-type="htmlEmbed"');
+    const json = await markdownToProseMirror(md);
-
-    const json = htmlToJson(html);
-    // The div parses into a real htmlEmbed node carrying the decoded source.
     expect(hasHtmlEmbedNode(json)).toBe(true);
 
     // Because it is detected, the share master-toggle strip can remove it.
@@ -59,8 +56,7 @@ describe('htmlEmbed smuggled via the raw serialized div in imported markdown/HTM
     // therefore stripping) does not depend on the source being well-formed, so
     // the bypass cannot be hidden by sending a malformed data-source.
     const md = `<div data-type="htmlEmbed" data-source="&lt;script&gt;x&lt;/script&gt;"></div>`;
-    const html = await markdownToHtml(md);
+    const json = await markdownToProseMirror(md);
-    const json = htmlToJson(html);
     expect(hasHtmlEmbedNode(json)).toBe(true);
     expect(hasHtmlEmbedNode(stripHtmlEmbedNodes(json))).toBe(false);
   });

apps/server/src/core/ai-chat/ai-chat-run.service.spec.ts

@@ -43,6 +43,9 @@ function makeRepo(overrides: Record<string, jest.Mock> = {}) {
       workspaceId: v.workspaceId,
     })),
     update: jest.fn(async () => ({ id: 'run-1' })),
+    // #487: terminal finalize now goes through the CONDITIONAL write. Default
+    // returns a truthy row (the run WAS active -> this call wrote it).
+    finalizeIfActive: jest.fn(async () => ({ id: 'run-1', status: 'succeeded' })),
     markStopRequested: jest.fn(async () => ({ id: 'run-1' })),
     findActiveByChat: jest.fn(async () => undefined),
     findLatestByChat: jest.fn(async () => undefined),
@@ -336,14 +339,12 @@ describe('AiChatRunService run lifecycle', () => {
     await svc.finalizeRun('run-1', 'ws-1', 'error', 'provider blew up');
 
     expect(svc.isLocallyActive('run-1')).toBe(false);
-    expect(repo.update).toHaveBeenCalledWith(
+    // #487: the terminal write is CONDITIONAL (finalizeIfActive); finishedAt is
+    // stamped inside the repo method, so the service passes just status + error.
+    expect(repo.finalizeIfActive).toHaveBeenCalledWith(
       'run-1',
       'ws-1',
-      expect.objectContaining({
+      expect.objectContaining({ status: 'failed', error: 'provider blew up' }),
-        status: 'failed',
-        error: 'provider blew up',
-        finishedAt: expect.any(Date),
-      }),
     );
   });
 
@@ -366,8 +367,8 @@ describe('AiChatRunService run lifecycle', () => {
     // A second settle (e.g. a streamText callback firing after the catch) no-ops.
     await svc.finalizeRun('run-1', 'ws-1', 'completed', undefined);
 
-    expect(repo.update).toHaveBeenCalledTimes(1);
+    expect(repo.finalizeIfActive).toHaveBeenCalledTimes(1);
-    expect(repo.update).toHaveBeenCalledWith(
+    expect(repo.finalizeIfActive).toHaveBeenCalledWith(
       'run-1',
       'ws-1',
       expect.objectContaining({ status: 'failed', error: 'first' }),
@@ -389,8 +390,8 @@ describe('AiChatRunService run lifecycle', () => {
     const updateGate = new Promise((res) => {
       resolveUpdate = res;
     });
-    const update = jest.fn(() => updateGate);
+    const finalizeIfActive = jest.fn(() => updateGate);
-    const repo = makeRepo({ update });
+    const repo = makeRepo({ finalizeIfActive });
     const svc = new AiChatRunService(repo as never, makeEnv() as never);
     await svc.beginRun({
       chatId: 'chat-1',
@@ -399,23 +400,23 @@ describe('AiChatRunService run lifecycle', () => {
     });
 
     // Fire both before the (pending) update resolves. The first synchronously
-    // claims the entry (active.delete) and awaits update; the second, started in
+    // claims the entry (active.delete) and awaits the write; the second, started
-    // the same macrotask, finds the entry already gone and returns at the claim
+    // in the same macrotask, finds the entry already gone and returns at the claim
-    // WITHOUT ever calling update.
+    // WITHOUT ever writing.
     const p1 = svc.finalizeRun('run-1', 'ws-1', 'completed');
     const p2 = svc.finalizeRun('run-1', 'ws-1', 'error', 'safety-net');
 
     // The decisive assertion: exactly one caller reached the terminal UPDATE.
-    expect(update).toHaveBeenCalledTimes(1);
+    expect(finalizeIfActive).toHaveBeenCalledTimes(1);
 
     // Let the single in-flight update land; both calls resolve cleanly.
-    resolveUpdate({ id: 'run-1' });
+    resolveUpdate({ id: 'run-1', status: 'succeeded' });
     await Promise.all([p1, p2]);
 
-    expect(update).toHaveBeenCalledTimes(1);
+    expect(finalizeIfActive).toHaveBeenCalledTimes(1);
     // The winner is the FIRST caller ('completed' -> 'succeeded'); the late
     // 'error' settle never wrote, so it could not clobber the real status.
-    expect(update).toHaveBeenCalledWith(
+    expect(finalizeIfActive).toHaveBeenCalledWith(
       'run-1',
       'ws-1',
       expect.objectContaining({ status: 'succeeded' }),
@@ -431,10 +432,10 @@ describe('AiChatRunService run lifecycle', () => {
     // 409s until a restart. The fix updates FIRST and retries.
     let calls = 0;
     const repo = makeRepo({
-      update: jest.fn(async () => {
+      finalizeIfActive: jest.fn(async () => {
         calls += 1;
         if (calls === 1) throw new Error('deadlock detected');
-        return { id: 'run-1' };
+        return { id: 'run-1', status: 'succeeded' };
       }),
     });
     jest.spyOn(Logger.prototype, 'warn').mockImplementation(() => undefined);
@@ -447,26 +448,29 @@ describe('AiChatRunService run lifecycle', () => {
 
     await svc.finalizeRun('run-1', 'ws-1', 'completed');
 
-    // The retry landed the terminal write: the entry is dropped (slot freed) and
+    // The retry landed the terminal write: the entry is dropped (slot freed), no
-    // the row carries the real terminal status — NOT stranded at 'running'.
+    // zombie left, and the row carries the real terminal status.
     expect(svc.isLocallyActive('run-1')).toBe(false);
-    expect(repo.update).toHaveBeenCalledTimes(2);
+    expect(svc.hasZombie('run-1')).toBe(false);
-    expect(repo.update).toHaveBeenLastCalledWith(
+    expect(repo.finalizeIfActive).toHaveBeenCalledTimes(2);
+    expect(repo.finalizeIfActive).toHaveBeenLastCalledWith(
       'run-1',
       'ws-1',
       expect.objectContaining({ status: 'succeeded' }),
     );
   });
 
-  it('F6: if the terminal write keeps failing, the entry is RETAINED and a LATER settle completes it (chat not permanently 409d)', async () => {
+  it('#487 give-up: if the terminal write keeps failing, finalizeRun leaves a ZOMBIE (does NOT restore the entry) and settleZombie re-drives it', async () => {
     // Worst case: the DB is down for the whole first finalize (all attempts fail).
-    // The run must NOT be silently lost — the entry stays so a subsequent settle
+    // #487 changes the give-up behaviour: the entry is NOT restored (a restored
-    // (a streamText callback, requestStop -> onAbort, or a future sweep) can retry.
+    // entry is indistinguishable from a live run). Instead a ZOMBIE record holds
+    // the intended terminal status, and a re-drive (settleZombie — called by the
+    // reconcile / supersede / opportunistic paths) applies it later.
     let healthy = false;
     const repo = makeRepo({
-      update: jest.fn(async () => {
+      finalizeIfActive: jest.fn(async () => {
         if (!healthy) throw new Error('pool exhausted');
-        return { id: 'run-1' };
+        return { id: 'run-1', status: 'succeeded' };
       }),
     });
     jest.spyOn(Logger.prototype, 'warn').mockImplementation(() => undefined);
@@ -480,35 +484,83 @@ describe('AiChatRunService run lifecycle', () => {
       userId: 'user-1',
     });
 
-    // First settle: every bounded attempt fails -> entry retained, NOT settled.
+    // First settle: every bounded attempt fails -> ZOMBIE, entry NOT restored.
     await svc.finalizeRun('run-1', 'ws-1', 'completed');
-    expect(svc.isLocallyActive('run-1')).toBe(true);
+    expect(svc.isLocallyActive('run-1')).toBe(false); // NOT a live entry
-    // F12: the give-up emits ONE explicit, greppable ERROR (run + chat context)
+    expect(svc.hasZombie('run-1')).toBe(true);
-    // so an operator can tell "gave up, run held in memory" from a per-attempt
+    expect(svc.zombieRunIds()).toContain('run-1');
-    // blip — distinct from the per-attempt warns.
+    // The give-up emits ONE explicit, greppable ERROR mentioning the zombie.
     const gaveUp = errorSpy.mock.calls.some(
       (c) =>
         /NON-TERMINAL/.test(String(c[0])) &&
+        /ZOMBIE/.test(String(c[0])) &&
         /run-1/.test(String(c[0])) &&
         /chat-1/.test(String(c[0])),
     );
     expect(gaveUp).toBe(true);
+    // The settle notifier resolved as terminalWriteFailed (a subscriber learns the
+    // slot still needs the intended status applied).
+    const outcome = await svc.peekSettled('run-1');
+    expect(outcome).toEqual({
+      status: 'succeeded',
+      error: null,
+      terminalWriteFailed: true,
+    });
 
-    // The DB recovers; a later settle now succeeds and frees the slot.
+    // The DB recovers; a re-drive settles the zombie via the conditional UPDATE.
     healthy = true;
-    await svc.finalizeRun('run-1', 'ws-1', 'completed');
+    const redriven = await svc.settleZombie('run-1');
-    expect(svc.isLocallyActive('run-1')).toBe(false);
+    expect(redriven).toBe(true);
-    expect(repo.update).toHaveBeenLastCalledWith(
+    expect(svc.hasZombie('run-1')).toBe(false);
+    expect(repo.finalizeIfActive).toHaveBeenLastCalledWith(
       'run-1',
       'ws-1',
       expect.objectContaining({ status: 'succeeded' }),
     );
 
-    // And it is now idempotent: a further settle no-ops (terminal row already
+    // A later finalizeRun is idempotent (row already terminal): it no-ops at the
-    // written), so a double-settle can never clobber the real status.
+    // once-gate, never re-writing.
-    const callsBefore = repo.update.mock.calls.length;
+    const callsBefore = repo.finalizeIfActive.mock.calls.length;
     await svc.finalizeRun('run-1', 'ws-1', 'error', 'late');
-    expect(repo.update).toHaveBeenCalledTimes(callsBefore);
+    expect(repo.finalizeIfActive).toHaveBeenCalledTimes(callsBefore);
+  });
+
+  it('#487 double-settle collapses to a benign no-op (conditional write; notifier resolves once)', async () => {
+    // A second concurrent settle is stopped at the synchronous active.delete
+    // claim, so the terminal write runs exactly once and the notifier resolves
+    // exactly once with the FIRST settler's outcome.
+    const repo = makeRepo();
+    const svc = new AiChatRunService(repo as never, makeEnv() as never);
+    await svc.beginRun({ chatId: 'chat-1', workspaceId: 'ws-1', userId: 'u1' });
+
+    await svc.finalizeRun('run-1', 'ws-1', 'aborted');
+    await svc.finalizeRun('run-1', 'ws-1', 'error', 'late'); // no-op
+
+    expect(repo.finalizeIfActive).toHaveBeenCalledTimes(1);
+    const outcome = await svc.peekSettled('run-1');
+    // peekSettled after resolve+delete falls through (notifier dropped, no zombie)
+    // -> undefined; the FIRST settler already resolved any earlier subscriber.
+    expect(outcome).toBeUndefined();
+  });
+
+  it('#487 late settledPromise subscriber gets the resolved outcome', async () => {
+    const repo = makeRepo();
+    const svc = new AiChatRunService(repo as never, makeEnv() as never);
+    await svc.beginRun({ chatId: 'chat-1', workspaceId: 'ws-1', userId: 'u1' });
+
+    // Subscribe BEFORE settle: hold the promise reference (as supersede does).
+    const early = svc.peekSettled('run-1');
+    expect(early).toBeDefined();
+
+    await svc.finalizeRun('run-1', 'ws-1', 'completed');
+
+    // The reference grabbed before settle resolves with the written outcome, even
+    // though the notifier was dropped from the map on resolve (bounded).
+    await expect(early).resolves.toEqual({
+      status: 'succeeded',
+      error: null,
+      terminalWriteFailed: false,
+    });
   });
 
   it('recordStep / linkAssistantMessage are best-effort: a repo failure is swallowed', async () => {
@@ -525,3 +577,197 @@ describe('AiChatRunService run lifecycle', () => {
     ).resolves.toBeUndefined();
   });
 });
+
+describe('#487 AiChatRunService.supersede (CAS)', () => {
+  const chat = 'chat-1';
+  const ws = 'ws-1';
+
+  it('degrade: no active run on the chat -> caller sends a normal turn', async () => {
+    const repo = makeRepo({
+      findById: jest.fn(async () => undefined),
+      findActiveByChat: jest.fn(async () => undefined),
+    });
+    const svc = new AiChatRunService(repo as never, makeEnv() as never);
+    expect(await svc.supersede(chat, 'run-x', ws)).toEqual({ kind: 'degrade' });
+  });
+
+  it('invalid: the target run belongs to a DIFFERENT chat -> 400', async () => {
+    const repo = makeRepo({
+      findById: jest.fn(async () => ({
+        id: 'run-x',
+        chatId: 'other-chat',
+        workspaceId: ws,
+      })),
+    });
+    const svc = new AiChatRunService(repo as never, makeEnv() as never);
+    expect(await svc.supersede(chat, 'run-x', ws)).toEqual({ kind: 'invalid' });
+  });
+
+  it('mismatch: a DIFFERENT run is active than the one targeted -> current runId', async () => {
+    const repo = makeRepo({
+      findById: jest.fn(async () => ({ id: 'run-x', chatId: chat, workspaceId: ws })),
+      findActiveByChat: jest.fn(async () => ({
+        id: 'run-live',
+        chatId: chat,
+        workspaceId: ws,
+        status: 'running',
+      })),
+    });
+    const svc = new AiChatRunService(repo as never, makeEnv() as never);
+    expect(await svc.supersede(chat, 'run-x', ws)).toEqual({
+      kind: 'mismatch',
+      activeRunId: 'run-live',
+    });
+  });
+
+  it('ready: the target IS active -> stop it, await its (fast) settle, free the slot', async () => {
+    // Simulate a live long TOOL (NOT a slow UPDATE): the run stays active until an
+    // explicit Stop unwinds it; commit-1's race makes that settle land quickly.
+    // The abort listener stands in for streamText's onAbort -> finalizeRun.
+    const repo = makeRepo({
+      findById: jest.fn(async () => ({
+        id: 'run-1',
+        chatId: chat,
+        workspaceId: ws,
+        status: 'aborted',
+        error: null,
+      })),
+      findActiveByChat: jest.fn(async () => ({
+        id: 'run-1',
+        chatId: chat,
+        workspaceId: ws,
+        status: 'running',
+      })),
+    });
+    const svc = new AiChatRunService(repo as never, makeEnv() as never);
+    const handle = await svc.beginRun({ chatId: chat, workspaceId: ws, userId: 'u1' });
+    handle.signal.addEventListener('abort', () => {
+      void svc.finalizeRun('run-1', ws, 'aborted');
+    });
+
+    // supersede: getRun -> getActiveByChat(==target) -> requestStop -> the abort
+    // listener settles the run -> awaitSettled resolves -> ready.
+    expect(await svc.supersede(chat, 'run-1', ws, 10_000)).toEqual({
+      kind: 'ready',
+    });
+    expect(handle.signal.aborted).toBe(true); // Stop reached the run
+  });
+
+  it('timeout: the target never settles within W -> 409 SUPERSEDE_TIMEOUT (nothing persisted)', async () => {
+    const repo = makeRepo({
+      findById: jest.fn(async () => ({ id: 'run-1', chatId: chat, workspaceId: ws })),
+      findActiveByChat: jest.fn(async () => ({
+        id: 'run-1',
+        chatId: chat,
+        workspaceId: ws,
+        status: 'running',
+      })),
+    });
+    const svc = new AiChatRunService(repo as never, makeEnv() as never);
+    await svc.beginRun({ chatId: chat, workspaceId: ws, userId: 'u1' });
+    // Do NOT settle the run: a tiny W elapses -> timeout.
+    const result = await svc.supersede(chat, 'run-1', ws, 30);
+    expect(result).toEqual({ kind: 'timeout' });
+  });
+
+  it('ready then a DUPLICATE supersede POST degrades (the run is already gone)', async () => {
+    let active: unknown = {
+      id: 'run-1',
+      chatId: chat,
+      workspaceId: ws,
+      status: 'running',
+    };
+    const repo = makeRepo({
+      findById: jest.fn(async () => ({
+        id: 'run-1',
+        chatId: chat,
+        workspaceId: ws,
+        status: 'aborted',
+        error: null,
+      })),
+      findActiveByChat: jest.fn(async () => active),
+      finalizeIfActive: jest.fn(async () => {
+        active = undefined; // settling frees the active slot
+        return { id: 'run-1', status: 'aborted' };
+      }),
+    });
+    const svc = new AiChatRunService(repo as never, makeEnv() as never);
+    const handle = await svc.beginRun({ chatId: chat, workspaceId: ws, userId: 'u1' });
+    handle.signal.addEventListener('abort', () => {
+      void svc.finalizeRun('run-1', ws, 'aborted');
+    });
+
+    expect(await svc.supersede(chat, 'run-1', ws, 10_000)).toEqual({
+      kind: 'ready',
+    });
+    // The duplicate POST for the same target now finds no active run -> degrade.
+    expect(await svc.supersede(chat, 'run-1', ws)).toEqual({ kind: 'degrade' });
+  });
+
+  it('reconcileStaleRuns: aborts a stale run with NO entry/zombie; NEVER touches a live entry', async () => {
+    const finalizeIfActive = jest.fn(async () => ({ id: 'x', status: 'aborted' }));
+    const repo = makeRepo({
+      insert: jest.fn(async (v: any) => ({
+        id: 'live-1',
+        status: 'running',
+        chatId: v.chatId,
+        workspaceId: v.workspaceId,
+      })),
+      finalizeIfActive,
+      findStaleActive: jest.fn(async () => [
+        { id: 'orphan-1', workspaceId: ws, chatId: 'c-orphan' },
+        { id: 'live-1', workspaceId: ws, chatId: 'c-live' },
+      ]),
+    });
+    const svc = new AiChatRunService(repo as never, makeEnv() as never);
+    // A LIVE run this replica owns (in the `active` map).
+    await svc.beginRun({ chatId: 'c-live', workspaceId: ws, userId: 'u1' });
+    expect(svc.isLocallyActive('live-1')).toBe(true);
+
+    const aborted = await svc.reconcileStaleRuns(15 * 60 * 1000);
+    expect(aborted).toBe(1);
+    // The orphan (no entry) was aborted; the live entry was NEVER passed to the DB.
+    expect(finalizeIfActive).toHaveBeenCalledTimes(1);
+    expect(finalizeIfActive).toHaveBeenCalledWith(
+      'orphan-1',
+      ws,
+      expect.objectContaining({ status: 'aborted' }),
+    );
+    expect(svc.isLocallyActive('live-1')).toBe(true);
+  });
+
+  it('gave-up zombie: supersede applies the intended status (settleZombie) then is ready', async () => {
+    let healthy = false;
+    let active: unknown = {
+      id: 'run-1',
+      chatId: chat,
+      workspaceId: ws,
+      status: 'running',
+    };
+    const repo = makeRepo({
+      findById: jest.fn(async () => ({ id: 'run-1', chatId: chat, workspaceId: ws })),
+      findActiveByChat: jest.fn(async () => active),
+      finalizeIfActive: jest.fn(async () => {
+        if (!healthy) throw new Error('db down');
+        active = undefined;
+        return { id: 'run-1', status: 'aborted' };
+      }),
+    });
+    jest.spyOn(Logger.prototype, 'warn').mockImplementation(() => undefined);
+    jest.spyOn(Logger.prototype, 'error').mockImplementation(() => undefined);
+    const svc = new AiChatRunService(repo as never, makeEnv() as never);
+    await svc.beginRun({ chatId: chat, workspaceId: ws, userId: 'u1' });
+
+    // The run's terminal write gives up -> zombie (row still 'running').
+    await svc.finalizeRun('run-1', ws, 'aborted');
+    expect(svc.hasZombie('run-1')).toBe(true);
+
+    // The DB recovers; supersede awaits the (already-resolved, terminalWriteFailed)
+    // settle, then settleZombie applies the intended status -> ready.
+    healthy = true;
+    expect(await svc.supersede(chat, 'run-1', ws, 10_000)).toEqual({
+      kind: 'ready',
+    });
+    expect(svc.hasZombie('run-1')).toBe(false);
+  });
+});

apps/server/src/core/ai-chat/ai-chat-run.service.ts

@@ -34,6 +34,88 @@ export class RunAlreadyActiveError extends Error {
 export type TurnTerminalStatus = 'completed' | 'error' | 'aborted';
 export type RunTerminalStatus = 'succeeded' | 'failed' | 'aborted';
 
+/** The terminal run statuses — the row is done once it reads one of these. */
+export const RUN_TERMINAL_STATUSES: readonly RunTerminalStatus[] = [
+  'succeeded',
+  'failed',
+  'aborted',
+];
+
+/** Whether a persisted run status is terminal (settled). */
+export function isRunTerminal(status: string | null | undefined): boolean {
+  return (
+    status === 'succeeded' || status === 'failed' || status === 'aborted'
+  );
+}
+
+/**
+ * #487: the outcome a run's {@link AiChatRunService.finalizeRun} settled with.
+ * `terminalWriteFailed` = the terminal write GAVE UP after the bounded retry, so
+ * the row is still non-terminal ('running') and a ZOMBIE record holds the
+ * `intended` status for a later re-drive (reconcile / supersede / boot sweep). A
+ * subscriber (supersede, #487 commit 3) uses this to decide whether the slot is
+ * genuinely free or must first have the intended status applied.
+ */
+export interface RunSettleOutcome {
+  status: RunTerminalStatus;
+  error: string | null;
+  terminalWriteFailed: boolean;
+}
+
+/**
+ * #487: how long a supersede waits for the target run to settle after Stop before
+ * it degrades to `SUPERSEDE_TIMEOUT`. W=10s is generous under a HEALTHY DB: commit
+ * 1's race-on-abort makes an in-app tool abort->settle in ms/hundreds of ms, so a
+ * live run releases its slot well within the window. Under a DB brownout the
+ * timeout is normal (the write cannot land); W must NOT be raised to paper
+ * over a slow DB — a SUPERSEDE_TIMEOUT is the honest signal (nothing persisted,
+ * the composer keeps the user's text). Env-tunable for ops, default 10s.
+ */
+export const SUPERSEDE_SETTLE_TIMEOUT_MS = (() => {
+  const raw = Number(process.env.AI_CHAT_SUPERSEDE_TIMEOUT_MS);
+  return Number.isFinite(raw) && raw > 0 ? raw : 10_000;
+})();
+
+/**
+ * #487: the result of the supersede CAS ({@link AiChatRunService.supersede}).
+ *  - `degrade`  : no active run on the chat (it ended between click and POST) —
+ *                 the caller sends a NORMAL turn (NOT a mismatch);
+ *  - `invalid`  : the target runId belongs to a DIFFERENT chat (malformed CAS 400);
+ *  - `mismatch` : a DIFFERENT run is active than the one the client targeted —
+ *                 409 SUPERSEDE_TARGET_MISMATCH carrying the current `activeRunId`
+ *                 (the client does NOT auto-retry);
+ *  - `timeout`  : the target did not settle within W — 409 SUPERSEDE_TIMEOUT,
+ *                 nothing persisted;
+ *  - `ready`    : the target was stopped AND settled (or its zombie's intended was
+ *                 applied) — the slot is free; the caller may beginRun the new run.
+ */
+export type SupersedeResult =
+  | { kind: 'degrade' }
+  | { kind: 'invalid' }
+  | { kind: 'mismatch'; activeRunId: string }
+  | { kind: 'timeout' }
+  | { kind: 'ready' };
+
+/** A one-shot settle notifier (#487): `resolve` is called EXACTLY ONCE. */
+interface Deferred<T> {
+  promise: Promise<T>;
+  resolve: (value: T) => void;
+}
+
+/**
+ * #487: a run whose terminal write GAVE UP (every bounded attempt failed). The
+ * row is stranded non-terminal ('running'); this record is the ONLY thing that
+ * distinguishes it from a live run, and carries the `intended` terminal status so
+ * a re-drive can apply it via the conditional UPDATE. Process-local (phase-1
+ * single-process assumption): a restart drops it, and the boot sweep then writes
+ * 'aborted' over the intended — a documented loss (see finalizeRun).
+ */
+interface ZombieRun {
+  workspaceId: string;
+  chatId: string;
+  intended: { status: RunTerminalStatus; error: string | null };
+}
+
 export function mapTurnStatusToRun(
   status: TurnTerminalStatus,
 ): RunTerminalStatus {
@@ -101,6 +183,22 @@ export class AiChatRunService implements OnModuleInit {
   // uptime — negligible in phase 1's single process.
   private readonly settled = new Set<string>();
 
+  // #487 runId -> one-shot settle notifier. Kept in a SEPARATE map from `active`
+  // ON PURPOSE: it must OUTLIVE the `active.delete` claim inside finalizeRun (the
+  // claim frees the slot the instant finalize starts), so a subscriber can still
+  // await the outcome after the entry is gone. Created in beginRun, resolved
+  // EXACTLY ONCE in finalizeRun, then removed (bounded). Absence => this replica
+  // has no live notifier: a subscriber falls back to the zombie map, then to the
+  // row (see peekSettled). Process-local (phase-1 single-process assumption).
+  private readonly settledPromises = new Map<string, Deferred<RunSettleOutcome>>();
+
+  // #487 runId -> ZOMBIE record: a run whose terminal write gave up (row stranded
+  // non-terminal). BOUNDED — an entry is added only on give-up and removed on a
+  // successful re-drive (settleZombie) or when the row is found already terminal;
+  // a process restart clears it (and the boot sweep settles the stranded row).
+  // Process-local (phase-1 single-process assumption).
+  private readonly zombies = new Map<string, ZombieRun>();
+
   // Bounded retry for the terminal write (F6): a single PK UPDATE can fail
   // transiently under many fire-and-forget writes (pool exhaustion, deadlock, a
   // brief connection blip). Riding out that blip in-place matters because the
@@ -224,6 +322,10 @@ export class AiChatRunService implements OnModuleInit {
       chatId: args.chatId,
       workspaceId: args.workspaceId,
     });
+    // #487: arm the one-shot settle notifier BEFORE returning, so a subscriber
+    // that races in immediately after begin always finds a promise to await. It
+    // is resolved exactly once when the run settles (or gives up).
+    this.settledPromises.set(run.id, this.makeDeferred<RunSettleOutcome>());
     return { runId: run.id, signal: controller.signal };
   }
 
@@ -263,47 +365,43 @@ export class AiChatRunService implements OnModuleInit {
   }
 
   /**
-   * Finalize a run to its terminal status (succeeded / failed / aborted),
+   * Finalize a run to its terminal status (succeeded / failed / aborted) via a
-   * stamping finishedAt + any error. Best-effort, but ROBUST against a transient
+   * CONDITIONAL UPDATE, stamping finishedAt + any error. Atomically safe against a
-   * terminal-write failure (F6) AND atomically safe against a concurrent settle.
+   * concurrent settle AND robust against a transient terminal-write failure.
    *
    * ATOMIC ONCE-CLAIM (the gate must close in ONE synchronous tick): two
    * finalizeRun calls for the SAME run can race — the documented real path is
    * AiChatService.stream's safety-net catch settling the turn to 'error' while a
    * streamText terminal callback (onFinish/onAbort/onError) ALSO settles it. The
-   * `settled.has` check alone is NOT a gate: it is read BEFORE the awaited UPDATE,
+   * claim happens via `active.delete`, a SYNCHRONOUS check-and-clear with NO await
-   * so two callers can both see `false` and both write the row (last-write-wins
+   * between the gate and the entry removal: the second concurrent caller finds the
-   * clobbers the real terminal status, and the bounded retry only widens that
+   * entry already gone and returns in the same tick, before any UPDATE.
-   * window). The claim therefore happens via `active.delete`, a SYNCHRONOUS
-   * check-and-clear with NO await between the gate and the entry removal: the
-   * second concurrent caller finds the entry already gone and returns in the same
-   * tick, before any UPDATE. The transition "nobody is finalizing" -> "I am
-   * finalizing" is thus a single atomic step.
    *
-   * ORDER MATTERS (F6): once we own the claim, the terminal UPDATE happens FIRST;
+   * ALL TERMINAL WRITES ARE CONDITIONAL (#487): `finalizeIfActive` only flips a
-   * only once it SUCCEEDS do we record the run as settled. If the UPDATE fails on
+   * row still in pending|running (mirror of the assistant message's
-   * every bounded attempt we RESTORE the in-memory entry, leave the run UNsettled,
+   * `onlyIfStreaming`). So even a settle that DID reach the UPDATE (e.g. a
-   * and emit an ERROR signal that the row is left non-terminal 'running' (which
+   * reconcile stamp racing an owner finalize) can never clobber a terminal status
-   * would 409 every future turn in the chat until recovery). An in-process retry
+   * — the loser matches nothing and is a benign no-op. `active.delete` is the
-   * by a LATER settle is only POSSIBLE, never guaranteed: it needs (a) the entry
+   * fast, in-process gate; the conditional WHERE is the authoritative one.
-   * to have been restored at the give-up path AND (b) a fresh settler to arrive
-   * AFTER that restore. A concurrent settler that arrives DURING the retry window
-   * — while the entry is deleted for backoff and not yet restored — is consumed at
-   * the synchronous `active.delete` claim (it finds nothing to delete and returns
-   * a no-op), so it does NOT become an in-process retrier. The NO-streamText path
-   * (the turn threw before streamText was wired, so ONLY the safety-net ever
-   * settles) likewise has no second in-process settler at all. The UNCONDITIONAL
-   * backstop in every case is the boot sweep on the next restart (phase 1 has no
-   * periodic in-process sweep); the retained entry is bounded (cleared on restart)
-   * and harmless meanwhile.
    *
-   * IDEMPOTENT on SUCCESS (#184 review): the terminal write happens AT MOST ONCE
+   * ZOMBIE ON GIVE-UP (#487): if every bounded attempt THROWS (the DB is down for
-   * per run. After a successful write the once-gate keys off {@link settled} (the
+   * the whole finalize), we do NOT restore the entry. The row is stranded
-   * terminal row already written) so a settle arriving AFTER the entry was already
+   * non-terminal ('running'); we record a ZOMBIE `{ terminalWriteFailed, intended
-   * dropped-and-settled returns early; a settle racing the in-flight write is
+   * }` (the ONLY thing distinguishing this dead run from a live one) and resolve
-   * stopped earlier still, by the `active.delete` claim. Either way a genuine
+   * the settle notifier with `terminalWriteFailed: true`. A restore would make the
-   * double-settle collapses to a single write and a late settle can never clobber
+   * zombie indistinguishable from a live run to every reader; instead a re-drive
-   * the real terminal status or double-write the row.
+   * (settleZombie, called by the periodic reconcile / supersede / opportunistic
+   * paths) applies the intended status later via the same conditional UPDATE.
+   *
+   * DOCUMENTED LOSS (#487, single-process phase 1): if the process RESTARTS before
+   * a zombie is re-driven, the in-memory zombie map is gone and the boot sweep
+   * (unconditional) writes 'aborted' over the ACTUAL intended status. This is
+   * unavoidable while the run lifecycle is single-process — there is no durable
+   * record of `intended`; a cross-process durable intent is deferred to phase 2.
+   *
+   * IDEMPOTENT: the settle notifier resolves EXACTLY ONCE; a second settle is
+   * stopped at `settled.has` or the `active.delete` claim, so a double-settle
+   * collapses to a single write and can never double-resolve or clobber the row.
    */
   async finalizeRun(
     runId: string,
@@ -314,13 +412,17 @@ export class AiChatRunService implements OnModuleInit {
     // ---- Atomic once-claim (synchronous; NO await before the gate closes) ----
     // Already terminally written -> idempotent no-op.
     if (this.settled.has(runId)) return;
-    // Capture the entry BEFORE the delete so a total-failure path can restore it.
+    // Capture the entry BEFORE the delete for the give-up log context.
     const entry = this.active.get(runId);
     // SYNCHRONOUS check-and-clear: the FIRST caller deletes (claims) the entry;
     // any concurrent SECOND caller finds nothing to delete and returns HERE, in
     // the same tick, before any await — so it can never reach the UPDATE.
     if (!this.active.delete(runId)) return;
 
+    const status = mapTurnStatusToRun(turnStatus);
+    const err = error ?? null;
+    const chatId = entry?.chatId ?? 'unknown';
+
     let lastError: unknown;
     for (
       let attempt = 1;
@@ -328,47 +430,294 @@ export class AiChatRunService implements OnModuleInit {
       attempt++
     ) {
       try {
-        await this.runRepo.update(runId, workspaceId, {
+        const row = await this.runRepo.finalizeIfActive(runId, workspaceId, {
-          status: mapTurnStatusToRun(turnStatus),
+          status,
-          finishedAt: new Date(),
+          error: err,
-          error: error ?? null,
         });
-        // Terminal write landed: arm the once-gate. The entry is already gone
+        // No throw => the row is now terminal (we wrote it, or it was ALREADY
-        // (claimed above); we do NOT restore it. The slot is now free.
+        // terminal — another writer won the conditional UPDATE, a benign no-op).
         this.settled.add(runId);
+        this.zombies.delete(runId);
+        // Resolve with the persisted outcome: our status when WE wrote it, else
+        // the row's real terminal status (re-read on the already-terminal path so
+        // a subscriber never sees a status we did not actually persist).
+        const outcome: RunSettleOutcome = row
+          ? { status, error: err, terminalWriteFailed: false }
+          : await this.readTerminalOutcome(runId, workspaceId, status, err);
+        this.resolveSettled(runId, outcome);
         return;
-      } catch (err) {
+      } catch (err2) {
-        lastError = err;
+        lastError = err2;
         this.logger.warn(
           `Failed to finalize run ${runId} (attempt ${attempt}/${
             AiChatRunService.FINALIZE_MAX_ATTEMPTS
-          }): ${err instanceof Error ? err.message : 'unknown error'}`,
+          }): ${err2 instanceof Error ? err2.message : 'unknown error'}`,
         );
         if (attempt < AiChatRunService.FINALIZE_MAX_ATTEMPTS) {
           await this.delay(AiChatRunService.FINALIZE_RETRY_BASE_MS * attempt);
         }
       }
     }
-    // Every attempt failed: this is a give-up, materially worse than a per-attempt
+    // Every attempt threw: GIVE UP. The row is stranded non-terminal ('running').
-    // blip — the row is left NON-TERMINAL ('running'), so emit ONE explicit,
+    // Do NOT restore the entry (a restored entry is indistinguishable from a live
-    // greppable ERROR so an operator can tell "survived a blip" from "gave up, run
+    // run); leave a ZOMBIE record instead, and resolve the notifier as
-    // held in memory until recovery" (the last warn alone says only "attempt 3/3").
+    // terminalWriteFailed so a subscriber knows the slot still needs the intended
+    // status applied. One explicit, greppable ERROR so an operator can tell a
+    // give-up from a per-attempt blip.
     this.logger.error(
-      `Run ${runId} (chat ${entry?.chatId ?? 'unknown'}) left NON-TERMINAL ` +
+      `Run ${runId} (chat ${chatId}) left NON-TERMINAL ('running'): terminal ` +
-        `('running'): terminal write failed after ${
+        `write failed after ${AiChatRunService.FINALIZE_MAX_ATTEMPTS} attempts; ` +
-          AiChatRunService.FINALIZE_MAX_ATTEMPTS
+        `ZOMBIE recorded (intended '${status}'), recovery deferred to reconcile / ` +
-        } attempts; entry retained in memory, recovery deferred to next settle / ` +
+        `supersede / boot sweep`,
-        `boot sweep`,
       lastError,
     );
-    // RESTORE the claimed entry (and leave the run UNsettled) so a LATER settle
+    this.zombies.set(runId, {
-    // that arrives AFTER this restore MAY retry the terminal write — but that
+      workspaceId,
-    // in-process retry is NOT guaranteed (a concurrent settler caught in the retry
+      chatId,
-    // window above is consumed at the `active.delete` claim, and the no-streamText
+      intended: { status, error: err },
-    // path has no second settler at all). The UNCONDITIONAL backstop in every case
+    });
-    // is the boot sweep on the next restart; the restored entry is bounded and
+    this.resolveSettled(runId, { status, error: err, terminalWriteFailed: true });
-    // cleared on restart.
+  }
-    if (entry) this.active.set(runId, entry);
+
+  /**
+   * #487: re-drive a zombie run's intended terminal write (the conditional
+   * UPDATE). Called by the periodic reconcile (commit 4), an opportunistic
+   * single-chat reconcile, and supersede (commit 3). On success — the row is now
+   * terminal (written OR found already terminal) — the zombie is cleared and the
+   * once-gate armed; on another failure the zombie is kept for a later retry.
+   * Returns true when the row is now terminal. Best-effort; never throws.
+   */
+  async settleZombie(runId: string): Promise<boolean> {
+    const z = this.zombies.get(runId);
+    if (!z) return false;
+    try {
+      await this.runRepo.finalizeIfActive(runId, z.workspaceId, {
+        status: z.intended.status,
+        error: z.intended.error,
+      });
+      this.zombies.delete(runId);
+      this.settled.add(runId);
+      return true;
+    } catch (err) {
+      this.logger.warn(
+        `Re-drive of zombie run ${runId} (chat ${z.chatId}) failed; will retry ` +
+          `later: ${err instanceof Error ? err.message : 'unknown error'}`,
+      );
+      return false;
+    }
+  }
+
+  /**
+   * #487 reconcile clause (c): abort runs the DB still shows active (pending|
+   * running) but that this replica does NOT own — NO live entry AND NO zombie —
+   * and that have been UNTOUCHED past `staleMs` (from last-progress `updated_at`,
+   * NOT startedAt, so a legit long marathon is never a candidate). "No entry" is
+   * the PRIMARY gate: a live entry (an actively-executing run on this replica) is
+   * NEVER aborted, whatever its age. Returns the number aborted. Best-effort —
+   * never throws (a periodic-job failure must not crash the process).
+   */
+  async reconcileStaleRuns(staleMs: number): Promise<number> {
+    let candidates: Array<{ id: string; workspaceId: string; chatId: string }>;
+    try {
+      candidates = await this.runRepo.findStaleActive(staleMs);
+    } catch (err) {
+      this.logger.warn(
+        `Reconcile (stale runs) query failed: ${
+          err instanceof Error ? err.message : 'unknown error'
+        }`,
+      );
+      return 0;
+    }
+    let aborted = 0;
+    for (const c of candidates) {
+      // PRIMARY gate: never touch a live entry, and never race a zombie we are
+      // already re-driving (settleZombie owns those).
+      if (this.active.has(c.id) || this.zombies.has(c.id)) continue;
+      try {
+        const row = await this.runRepo.finalizeIfActive(c.id, c.workspaceId, {
+          status: 'aborted',
+          error: 'Run aborted by reconcile: no live runner (stale).',
+        });
+        if (row) {
+          aborted += 1;
+          this.settled.add(c.id);
+        }
+      } catch (err) {
+        this.logger.warn(
+          `Reconcile abort of stale run ${c.id} failed: ${
+            err instanceof Error ? err.message : 'unknown error'
+          }`,
+        );
+      }
+    }
+    return aborted;
+  }
+
+  /**
+   * #487: the run's settle outcome as seen by THIS replica, or undefined when it
+   * has no record (the caller then reads the row — the DB is the source of truth).
+   * A LIVE deferred (still settling, or resolved-but-not-yet-consumed) wins; a
+   * ZOMBIE synthesizes the give-up outcome. A subscriber (supersede) races this
+   * against a timeout.
+   */
+  peekSettled(runId: string): Promise<RunSettleOutcome> | undefined {
+    const d = this.settledPromises.get(runId);
+    if (d) return d.promise;
+    const z = this.zombies.get(runId);
+    if (z) {
+      return Promise.resolve({
+        status: z.intended.status,
+        error: z.intended.error,
+        terminalWriteFailed: true,
+      });
+    }
+    return undefined;
+  }
+
+  /**
+   * #487: await a run's settle outcome, bounded by `timeoutMs`. Returns the
+   * outcome on settle, or undefined on TIMEOUT (or when this replica has no record
+   * of the run and its row is not terminal). Uses the LIVE settle notifier / the
+   * zombie synth when present; else reads the row (the DB is the source of truth
+   * once the in-memory record is gone). The subscriber (supersede) grabs this
+   * right after Stop; commit 1's race makes the settle land in ms on a healthy DB.
+   */
+  async awaitSettled(
+    runId: string,
+    workspaceId: string,
+    timeoutMs: number,
+  ): Promise<RunSettleOutcome | undefined> {
+    const pending = this.peekSettled(runId);
+    if (pending) {
+      let timer: ReturnType<typeof setTimeout> | undefined;
+      const timeout = new Promise<undefined>((resolve) => {
+        timer = setTimeout(() => resolve(undefined), timeoutMs);
+        timer.unref?.();
+      });
+      try {
+        return await Promise.race([pending, timeout]);
+      } finally {
+        if (timer) clearTimeout(timer);
+      }
+    }
+    // No live notifier and no zombie: read the row (already settled-and-written,
+    // or unknown here). A terminal row is an outcome; anything else -> undefined.
+    const row = await this.runRepo.findById(runId, workspaceId);
+    if (row && isRunTerminal(row.status)) {
+      return {
+        status: row.status as RunTerminalStatus,
+        error: row.error ?? null,
+        terminalWriteFailed: false,
+      };
+    }
+    return undefined;
+  }
+
+  /**
+   * #487: the SERVER supersede CAS for `POST /stream { supersede: { runId: X } }`.
+   * Atomically transitions "X is the chat's active run" -> "X is stopped, settled,
+   * slot free" so the caller can start a replacement run. See {@link
+   * SupersedeResult} for the branch semantics.
+   *
+   * On a `ready` result the caller MUST still go through the normal beginRun gate
+   * (the partial unique index) — between the slot freeing here and beginRun a
+   * neighbouring tab's ordinary POST can win the slot (documented SLOT-THEFT: the
+   * loser then gets a MISMATCH carrying the NEW runId). There is also NO side-
+   * effect quiescence: an in-flight write of the stopped run may still land AFTER
+   * the new run starts (commit 1 stops the NEXT call, not one already committing),
+   * so the caller adds a prompt note to the new run.
+   */
+  async supersede(
+    chatId: string,
+    targetRunId: string,
+    workspaceId: string,
+    timeoutMs: number = SUPERSEDE_SETTLE_TIMEOUT_MS,
+  ): Promise<SupersedeResult> {
+    // Validate the target belongs to THIS chat (a CAS targeting another chat's run
+    // is malformed -> 400). A missing row is NOT invalid: the run may have ended
+    // and been pruned; the active-run check below decides degrade vs mismatch.
+    const target = await this.getRun(targetRunId, workspaceId);
+    if (target && target.chatId !== chatId) return { kind: 'invalid' };
+
+    const active = await this.getActiveForChat(chatId, workspaceId);
+    // No active run: it ended between the client's click and this POST — this is a
+    // DEGRADE to a normal send, NOT a mismatch (the user's intent still holds).
+    if (!active) return { kind: 'degrade' };
+    // A DIFFERENT run is active than the one the client saw -> mismatch. The
+    // client does not auto-retry; it surfaces the new runId.
+    if (active.id !== targetRunId) {
+      return { kind: 'mismatch', activeRunId: active.id };
+    }
+
+    // The target IS active: stop it, then await its settle within W.
+    await this.requestStop(targetRunId, workspaceId);
+    const outcome = await this.awaitSettled(targetRunId, workspaceId, timeoutMs);
+    if (!outcome) return { kind: 'timeout' };
+    // Gave up (terminal write failed): apply the intended status via the
+    // conditional UPDATE so the slot actually frees. If that ALSO fails, the row
+    // is still stranded -> treat as a timeout (nothing persisted for the new run).
+    if (outcome.terminalWriteFailed) {
+      const settled = await this.settleZombie(targetRunId);
+      if (!settled) return { kind: 'timeout' };
+    }
+    return { kind: 'ready' };
+  }
+
+  /** #487 test/diagnostic seam: whether a give-up zombie is held for this run. */
+  hasZombie(runId: string): boolean {
+    return this.zombies.has(runId);
+  }
+
+  /** #487: every zombie runId held on this replica (reconcile clause a, commit 4). */
+  zombieRunIds(): string[] {
+    return [...this.zombies.keys()];
+  }
+
+  /** #487: create a one-shot deferred (resolve captured for a later single call). */
+  private makeDeferred<T>(): Deferred<T> {
+    let resolve!: (value: T) => void;
+    const promise = new Promise<T>((r) => {
+      resolve = r;
+    });
+    return { promise, resolve };
+  }
+
+  /** #487: resolve a run's settle notifier EXACTLY ONCE, then drop it (bounded).
+   *  A subscriber that already grabbed the promise still resolves; a later one
+   *  falls back to the zombie map / the row (see peekSettled). */
+  private resolveSettled(runId: string, outcome: RunSettleOutcome): void {
+    const d = this.settledPromises.get(runId);
+    if (!d) return;
+    this.settledPromises.delete(runId);
+    d.resolve(outcome);
+  }
+
+  /** #487: read the persisted terminal outcome when the conditional finalize was a
+   *  no-op (the row was already terminal). Falls back to the intended status when
+   *  the read fails or the row is unexpectedly missing/non-terminal. */
+  private async readTerminalOutcome(
+    runId: string,
+    workspaceId: string,
+    fallbackStatus: RunTerminalStatus,
+    fallbackError: string | null,
+  ): Promise<RunSettleOutcome> {
+    try {
+      const row = await this.runRepo.findById(runId, workspaceId);
+      if (row && isRunTerminal(row.status)) {
+        return {
+          status: row.status as RunTerminalStatus,
+          error: row.error ?? null,
+          terminalWriteFailed: false,
+        };
+      }
+    } catch {
+      // Fall through to the intended status — best-effort only.
+    }
+    return {
+      status: fallbackStatus,
+      error: fallbackError,
+      terminalWriteFailed: false,
+    };
   }
 
   /** Small async backoff between terminal-write retries (F6). Isolated so it is

apps/server/src/core/ai-chat/ai-chat.begin-run-failure.spec.ts

@@ -0,0 +1,109 @@
+import {
+  ConflictException,
+  Logger,
+  ServiceUnavailableException,
+} from '@nestjs/common';
+import { AiChatService } from './ai-chat.service';
+import { RunAlreadyActiveError } from './ai-chat-run.service';
+
+/**
+ * Fail-fast guard for beginRun failures (#486, commit 4).
+ *
+ * When runHooks.begin() rejects for a reason OTHER than RunAlreadyActiveError
+ * (e.g. a DB-pool blip), the turn must NOT continue untracked. The old code
+ * logged and streamed anyway, leaving a run with NO run-row: in autonomous mode
+ * nobody could abort it (/stop can't see it, disconnect doesn't abort it, and the
+ * one-run gate would admit a SECOND run) — an unstoppable invisible run until
+ * restart. The fix throws A_RUN_BEGIN_FAILED (503) BEFORE the first byte and
+ * before the user row is persisted.
+ *
+ * We drive `stream()` directly on a prototype instance wired with only the
+ * collaborators it touches before the throw, so the assertion is on the REAL
+ * control flow, not a mock of it.
+ */
+describe('AiChatService beginRun failure (#486)', () => {
+  function makeService(insertSpy: jest.Mock): AiChatService {
+    // Bypass the (heavy) DI constructor: exercise the real stream() method on a
+    // bare prototype instance with just the fields reached before the throw.
+    // `any` because the private `logger` field makes a typed intersection collapse.
+    const svc = Object.create(AiChatService.prototype);
+    svc.aiChatRepo = {
+      // Existing chat -> no insert path; chatId is kept as-is.
+      findById: jest.fn().mockResolvedValue({ id: 'chat1' }),
+    };
+    svc.aiChatMessageRepo = { insert: insertSpy };
+    svc.logger = new Logger('test');
+    return svc as AiChatService;
+  }
+
+  const baseArgs = () => {
+    const write = jest.fn();
+    const res = {
+      raw: { write, writableEnded: false, headersSent: false },
+    };
+    return {
+      user: { id: 'u1' } as never,
+      workspace: { id: 'w1' } as never,
+      sessionId: 's1',
+      // openPage undefined -> resolveOpenPageContext returns null without any DB
+      // call; chatId present -> the existing-chat path.
+      body: { chatId: 'chat1', messages: [] } as never,
+      res: res as never,
+      signal: new AbortController().signal,
+      model: {} as never,
+      role: null,
+      write,
+    };
+  };
+
+  it('throws A_RUN_BEGIN_FAILED (503) before the first byte and before persisting the user turn', async () => {
+    const insertSpy = jest.fn();
+    const svc = makeService(insertSpy);
+    const { write, ...args } = baseArgs();
+
+    const runHooks = {
+      begin: jest.fn().mockRejectedValue(new Error('DB pool exhausted')),
+    } as never;
+
+    let caught: unknown;
+    try {
+      await svc.stream({ ...args, runHooks });
+    } catch (e) {
+      caught = e;
+    }
+
+    expect(caught).toBeInstanceOf(ServiceUnavailableException);
+    const http = caught as ServiceUnavailableException;
+    expect(http.getStatus()).toBe(503);
+    expect(http.getResponse()).toMatchObject({ code: 'A_RUN_BEGIN_FAILED' });
+
+    // Fail-fast: nothing was written to the socket and NO user message row was
+    // persisted, so the turn left no orphan state to clean up.
+    expect(write).not.toHaveBeenCalled();
+    expect(insertSpy).not.toHaveBeenCalled();
+  });
+
+  it('still maps a lost-the-race RunAlreadyActiveError to a 409, not A_RUN_BEGIN_FAILED', async () => {
+    const insertSpy = jest.fn();
+    const svc = makeService(insertSpy);
+    const { write, ...args } = baseArgs();
+
+    const runHooks = {
+      begin: jest.fn().mockRejectedValue(new RunAlreadyActiveError('chat1')),
+    } as never;
+
+    let caught: unknown;
+    try {
+      await svc.stream({ ...args, runHooks });
+    } catch (e) {
+      caught = e;
+    }
+
+    expect(caught).toBeInstanceOf(ConflictException);
+    expect((caught as ConflictException).getResponse()).toMatchObject({
+      code: 'A_RUN_ALREADY_ACTIVE',
+    });
+    expect(write).not.toHaveBeenCalled();
+    expect(insertSpy).not.toHaveBeenCalled();
+  });
+});

apps/server/src/core/ai-chat/ai-chat.controller.export.spec.ts

@@ -115,7 +115,7 @@ describe('finalizeAssistant dispatch (planFinalizeAssistant + applyFinalize)', (
 
   // Drive the SAME applyFinalize the service calls (no duplicated logic).
   async function dispatchFinalize(
-    repo: { insert: jest.Mock; update: jest.Mock },
+    repo: { insert: jest.Mock; finalizeOwner: jest.Mock },
     assistantId: string | undefined,
     flushed: AssistantFlush,
   ): Promise<void> {
@@ -135,21 +135,22 @@ describe('finalizeAssistant dispatch (planFinalizeAssistant + applyFinalize)', (
     expect(planFinalizeAssistant(undefined)).toEqual({ kind: 'insert' });
   });
 
-  it('(a) upfront insert succeeded -> finalize UPDATEs the row by id', async () => {
+  it('(a) upfront insert succeeded -> finalize CONDITIONALLY updates the row by id (#487 owner-write)', async () => {
-    const repo = { insert: jest.fn(), update: jest.fn() };
+    const repo = { insert: jest.fn(), finalizeOwner: jest.fn() };
     const flushed = flushAssistant([], 'final answer', 'completed', {
       finishReason: 'stop',
     });
     await dispatchFinalize(repo, 'a1', flushed);
-    expect(repo.update).toHaveBeenCalledWith('a1', workspaceId, flushed);
+    // #487: the owner write is the CONDITIONAL finalizeOwner, not a raw update.
+    expect(repo.finalizeOwner).toHaveBeenCalledWith('a1', workspaceId, flushed);
     expect(repo.insert).not.toHaveBeenCalled();
   });
 
   it('(b) upfront insert failed -> finalize INSERTs the terminal payload', async () => {
-    const repo = { insert: jest.fn(), update: jest.fn() };
+    const repo = { insert: jest.fn(), finalizeOwner: jest.fn() };
     const flushed = flushAssistant([], 'partial', 'error', { error: 'boom' });
     await dispatchFinalize(repo, undefined, flushed);
-    expect(repo.update).not.toHaveBeenCalled();
+    expect(repo.finalizeOwner).not.toHaveBeenCalled();
     expect(repo.insert).toHaveBeenCalledTimes(1);
     const arg = repo.insert.mock.calls[0][0];
     // The fallback insert carries the terminal content/status/metadata.

apps/server/src/core/ai-chat/ai-chat.controller.supersede.spec.ts

@@ -0,0 +1,279 @@
+import {
+  BadRequestException,
+  ConflictException,
+  ForbiddenException,
+  HttpException,
+} from '@nestjs/common';
+import { AiChatController } from './ai-chat.controller';
+import type { User, Workspace } from '@docmost/db/types/entity.types';
+
+/**
+ * #487 commit 3 — the single concurrency GATE (both modes) + the server supersede
+ * CAS, at the controller boundary. The gate + CAS run BEFORE res.hijack(), so a
+ * rejected concurrent start / a CAS branch returns clean JSON (an HttpException
+ * the controller's post-hijack catch re-serializes). These assert the OBSERVABLE
+ * HTTP contract against the real controller + a stubbed run service.
+ */
+describe('#487 AiChatController.stream — gate + supersede', () => {
+  const user = { id: 'u1' } as User;
+
+  function wsWith(autonomousRuns: boolean): Workspace {
+    return {
+      id: 'ws1',
+      settings: { ai: { chat: true, autonomousRuns } },
+    } as unknown as Workspace;
+  }
+
+  function makeReqRes(body: Record<string, unknown>) {
+    const req = {
+      raw: { sessionId: 'sess', once: jest.fn(), destroyed: false },
+      body,
+    };
+    const res = {
+      raw: {
+        writableEnded: false,
+        headersSent: false,
+        on: jest.fn(),
+        once: jest.fn(),
+        setHeader: jest.fn(),
+        end: jest.fn(),
+        statusCode: 200,
+        flushHeaders: jest.fn(),
+      },
+      hijack: jest.fn(),
+      status: jest.fn().mockReturnThis(),
+      send: jest.fn(),
+    };
+    return { req, res };
+  }
+
+  function makeController(
+    runServiceOverrides: Record<string, jest.Mock>,
+    // The chat assertOwnedChat resolves. Default: a chat OWNED by `user` (u1), so
+    // the ownership gate is transparent to the gate/CAS assertions below. Pass a
+    // foreign-owner (or undefined) chat to exercise the #487 owner rejection.
+    chat: { creatorId: string } | undefined = { creatorId: 'u1' },
+  ) {
+    const aiChatService = {
+      resolveRoleForRequest: jest.fn().mockResolvedValue(null),
+      getChatModel: jest.fn().mockResolvedValue({}),
+      stream: jest.fn().mockResolvedValue(undefined),
+    };
+    const aiChatRunService = {
+      getActiveForChat: jest.fn().mockResolvedValue(undefined),
+      supersede: jest.fn(),
+      beginRun: jest.fn().mockResolvedValue({
+        runId: 'run-new',
+        signal: new AbortController().signal,
+      }),
+      linkAssistantMessage: jest.fn(),
+      recordStep: jest.fn(),
+      finalizeRun: jest.fn(),
+      requestStop: jest.fn(),
+      ...runServiceOverrides,
+    };
+    const aiChatRepo = { findById: jest.fn().mockResolvedValue(chat) };
+    const controller = new AiChatController(
+      aiChatService as never,
+      aiChatRunService as never,
+      aiChatRepo as never, // aiChatRepo
+      {} as never, // aiChatMessageRepo
+      {} as never, // aiTranscription
+      {} as never, // pageRepo
+    );
+    return { controller, aiChatService, aiChatRunService, aiChatRepo };
+  }
+
+  const codeOf = (err: unknown) =>
+    (((err as HttpException).getResponse() as Record<string, unknown>) ?? {})
+      .code;
+
+  describe('single concurrency gate — BOTH modes reject the second tab with 409', () => {
+    for (const autonomousRuns of [true, false]) {
+      it(`rejects a concurrent start with 409 A_RUN_ALREADY_ACTIVE (autonomousRuns=${autonomousRuns})`, async () => {
+        const { controller, aiChatRunService } = makeController({
+          getActiveForChat: jest
+            .fn()
+            .mockResolvedValue({ id: 'run-live', chatId: 'c1' }),
+        });
+        const { req, res } = makeReqRes({ chatId: 'c1' });
+        let thrown: unknown;
+        try {
+          await controller.stream(
+            req as never,
+            res as never,
+            user,
+            wsWith(autonomousRuns),
+          );
+        } catch (e) {
+          thrown = e;
+        }
+        expect(thrown).toBeInstanceOf(ConflictException);
+        expect((thrown as HttpException).getStatus()).toBe(409);
+        expect(codeOf(thrown)).toBe('A_RUN_ALREADY_ACTIVE');
+        // Rejected BEFORE committing to the stream (no hijack, no service.stream).
+        expect(res.hijack).not.toHaveBeenCalled();
+        expect(aiChatRunService.getActiveForChat).toHaveBeenCalledWith(
+          'c1',
+          'ws1',
+        );
+      });
+    }
+  });
+
+  // #487 [security, F1]: stream() MUST owner-gate an existing chat exactly like its
+  // six sibling endpoints, BEFORE the supersede CAS. Otherwise a same-workspace
+  // non-owner could POST a supersede against another user's chat and (a) harvest
+  // that user's active runId from the 409 SUPERSEDE_TARGET_MISMATCH body, then (b)
+  // requestStop the foreign run. The gate must reject FIRST — no run lookup, no
+  // supersede, no stop, no runId leak.
+  describe('cross-user ownership gate (F1)', () => {
+    it('a non-owner streaming against someone else\'s chat is rejected (403) with NO runId leak and NO foreign requestStop', async () => {
+      // A live run exists on the victim's chat. Without the gate the supersede CAS
+      // would run and (faithful to the run service) return a MISMATCH carrying the
+      // victim's runId — the exact leak. With the gate it must never be reached.
+      const getActiveForChat = jest
+        .fn()
+        .mockResolvedValue({ id: 'run-victim', chatId: 'c-other' });
+      const supersede = jest
+        .fn()
+        .mockResolvedValue({ kind: 'mismatch', activeRunId: 'run-victim' });
+      const requestStop = jest.fn();
+      const { controller, aiChatService } = makeController(
+        { getActiveForChat, supersede, requestStop },
+        { creatorId: 'someone-else' }, // the chat is NOT owned by u1
+      );
+      const { req, res } = makeReqRes({
+        chatId: 'c-other',
+        supersede: { runId: 'guessed-uuid' },
+      });
+      let thrown: unknown;
+      try {
+        await controller.stream(req as never, res as never, user, wsWith(true));
+      } catch (e) {
+        thrown = e;
+      }
+      // Rejected by the ownership gate (403), the SAME shape the neighbors use.
+      expect(thrown).toBeInstanceOf(ForbiddenException);
+      expect((thrown as HttpException).getStatus()).toBe(403);
+      // Crucially NOT a 409 that would carry activeRunId — no runId is leaked.
+      const payload = JSON.stringify(
+        (thrown as HttpException).getResponse() ?? {},
+      );
+      expect(payload).not.toContain('run-victim');
+      expect(codeOf(thrown)).not.toBe('SUPERSEDE_TARGET_MISMATCH');
+      // The gate short-circuits BEFORE any run machinery runs.
+      expect(getActiveForChat).not.toHaveBeenCalled();
+      expect(supersede).not.toHaveBeenCalled();
+      expect(requestStop).not.toHaveBeenCalled();
+      expect(aiChatService.stream).not.toHaveBeenCalled();
+      expect(res.hijack).not.toHaveBeenCalled();
+    });
+  });
+
+  it('supersede MISMATCH -> 409 SUPERSEDE_TARGET_MISMATCH carrying the current runId', async () => {
+    const { controller } = makeController({
+      supersede: jest
+        .fn()
+        .mockResolvedValue({ kind: 'mismatch', activeRunId: 'run-other' }),
+    });
+    const { req, res } = makeReqRes({
+      chatId: 'c1',
+      supersede: { runId: 'run-x' },
+    });
+    let thrown: unknown;
+    try {
+      await controller.stream(req as never, res as never, user, wsWith(true));
+    } catch (e) {
+      thrown = e;
+    }
+    expect(thrown).toBeInstanceOf(ConflictException);
+    expect(codeOf(thrown)).toBe('SUPERSEDE_TARGET_MISMATCH');
+    expect(
+      ((thrown as HttpException).getResponse() as Record<string, unknown>)
+        .activeRunId,
+    ).toBe('run-other');
+    expect(res.hijack).not.toHaveBeenCalled();
+  });
+
+  it('supersede TIMEOUT -> 409 SUPERSEDE_TIMEOUT, nothing streamed', async () => {
+    const { controller } = makeController({
+      supersede: jest.fn().mockResolvedValue({ kind: 'timeout' }),
+    });
+    const { req, res } = makeReqRes({
+      chatId: 'c1',
+      supersede: { runId: 'run-x' },
+    });
+    let thrown: unknown;
+    try {
+      await controller.stream(req as never, res as never, user, wsWith(false));
+    } catch (e) {
+      thrown = e;
+    }
+    expect(thrown).toBeInstanceOf(ConflictException);
+    expect(codeOf(thrown)).toBe('SUPERSEDE_TIMEOUT');
+    expect(res.hijack).not.toHaveBeenCalled();
+  });
+
+  it('supersede INVALID (target on another chat) -> 400 SUPERSEDE_INVALID', async () => {
+    const { controller } = makeController({
+      supersede: jest.fn().mockResolvedValue({ kind: 'invalid' }),
+    });
+    const { req, res } = makeReqRes({
+      chatId: 'c1',
+      supersede: { runId: 'run-x' },
+    });
+    let thrown: unknown;
+    try {
+      await controller.stream(req as never, res as never, user, wsWith(true));
+    } catch (e) {
+      thrown = e;
+    }
+    expect(thrown).toBeInstanceOf(BadRequestException);
+    expect(codeOf(thrown)).toBe('SUPERSEDE_INVALID');
+  });
+
+  it('supersede without chatId -> 400 SUPERSEDE_INVALID', async () => {
+    const { controller, aiChatRunService } = makeController({});
+    const { req, res } = makeReqRes({ supersede: { runId: 'run-x' } });
+    let thrown: unknown;
+    try {
+      await controller.stream(req as never, res as never, user, wsWith(true));
+    } catch (e) {
+      thrown = e;
+    }
+    expect(thrown).toBeInstanceOf(BadRequestException);
+    expect(codeOf(thrown)).toBe('SUPERSEDE_INVALID');
+    expect(aiChatRunService.supersede).not.toHaveBeenCalled();
+  });
+
+  it('supersede READY -> proceeds to stream with superseded=true', async () => {
+    const { controller, aiChatService } = makeController({
+      supersede: jest.fn().mockResolvedValue({ kind: 'ready' }),
+      getActiveForChat: jest.fn().mockResolvedValue(undefined), // slot free after CAS
+    });
+    const { req, res } = makeReqRes({
+      chatId: 'c1',
+      supersede: { runId: 'run-x' },
+    });
+    await controller.stream(req as never, res as never, user, wsWith(true));
+    expect(res.hijack).toHaveBeenCalled();
+    expect(aiChatService.stream).toHaveBeenCalledTimes(1);
+    expect(aiChatService.stream.mock.calls[0][0].superseded).toBe(true);
+    // The run hooks are always present now (both modes).
+    expect(aiChatService.stream.mock.calls[0][0].runHooks).toBeDefined();
+  });
+
+  it('supersede DEGRADE -> proceeds to a normal send (superseded=false)', async () => {
+    const { controller, aiChatService } = makeController({
+      supersede: jest.fn().mockResolvedValue({ kind: 'degrade' }),
+    });
+    const { req, res } = makeReqRes({
+      chatId: 'c1',
+      supersede: { runId: 'run-x' },
+    });
+    await controller.stream(req as never, res as never, user, wsWith(false));
+    expect(aiChatService.stream).toHaveBeenCalledTimes(1);
+    expect(aiChatService.stream.mock.calls[0][0].superseded).toBe(false);
+  });
+});

apps/server/src/core/ai-chat/ai-chat.controller.ts

@@ -418,6 +418,19 @@ export class AiChatController {
 
     const body = (req.body ?? {}) as AiChatStreamBody;
 
+    // #487 [security]: gate cross-user access to an EXISTING chat BEFORE anything
+    // reads its runs. Every sibling endpoint (getRun/stop/history/rename/delete/
+    // attachRunStream) owner-checks the chat via assertOwnedChat; stream() must too.
+    // Without this a same-workspace member who is NOT the chat owner could POST a
+    // supersede against another user's chat and (a) harvest that user's active runId
+    // out of the 409 SUPERSEDE_TARGET_MISMATCH body, then (b) requestStop the foreign
+    // run. Gate on the chatId the client sent, when present — a brand-new chat (no
+    // chatId) has no prior owner to check. Mirrors /stop's owner check (403 as the
+    // neighbors do), and runs pre-hijack so it returns clean JSON.
+    if (body.chatId) {
+      await this.assertOwnedChat(body.chatId, user, workspace);
+    }
+
     // Resolve the agent role for this turn BEFORE hijack: existing chats read it
     // from ai_chats.role_id (authoritative), a new chat from body.roleId. The
     // role drives both the persona and the optional model override below.
@@ -432,12 +445,66 @@ export class AiChatController {
     // HttpException) instead of breaking mid-stream.
     const model = await this.aiChatService.getChatModel(workspace.id, role);
 
-    // #184: one active run per chat. For an EXISTING chat reject a concurrent
+    // #487: server-side supersede CAS ("interrupt and send now"). When the client
-    // start with a clean 409 BEFORE hijack (the common double-submit / second-tab
+    // asks to replace a live run, atomically STOP it and wait for it to settle
-    // case), so the user gets JSON, not a mid-stream error. A brand-new chat
+    // before this turn claims the slot. Runs BEFORE hijack so every branch returns
-    // (no chatId) cannot have a prior run, and the DB partial unique index is the
+    // clean JSON (the client keeps the composer text on a 409). See
-    // backstop against any race that slips past this check.
+    // AiChatRunService.supersede for the branch semantics.
-    if (autonomousRuns && body.chatId) {
+    let superseded = false;
+    const supersedeRunId = body.supersede?.runId;
+    if (supersedeRunId) {
+      if (!body.chatId) {
+        throw new BadRequestException({
+          message: 'supersede requires chatId',
+          code: 'SUPERSEDE_INVALID',
+        });
+      }
+      const result = await this.aiChatRunService.supersede(
+        body.chatId,
+        supersedeRunId,
+        workspace.id,
+      );
+      switch (result.kind) {
+        case 'invalid':
+          throw new BadRequestException({
+            message: 'The run to supersede does not belong to this chat',
+            code: 'SUPERSEDE_INVALID',
+          });
+        case 'mismatch':
+          // A DIFFERENT run is active than the one the client targeted. Surface
+          // the CURRENT runId; the client does NOT auto-retry (a stale CAS).
+          throw new ConflictException({
+            message: 'A different agent run is now active on this chat',
+            code: 'SUPERSEDE_TARGET_MISMATCH',
+            activeRunId: result.activeRunId,
+          });
+        case 'timeout':
+          // The target did not settle within W — nothing was persisted, the
+          // composer keeps the text. NOT a rollback: the stop is already issued.
+          throw new ConflictException({
+            message:
+              'The previous run did not stop in time; nothing was sent — please try again',
+            code: 'SUPERSEDE_TIMEOUT',
+          });
+        case 'ready':
+          // The target stopped and settled: the slot is free. Prompt the new run
+          // that the old run's last operations may still be applying.
+          superseded = true;
+          break;
+        case 'degrade':
+          // The run already ended between click and POST — send normally.
+          break;
+      }
+    }
+
+    // #487: one active run per chat — ENFORCED IN BOTH MODES now (legacy mode used
+    // to have NO gate, so two tabs streamed two parallel turns on one chat, which
+    // interleaved history and crashed convertToModelMessages). Reject a concurrent
+    // start with a clean pre-hijack 409 (double-submit / second-tab). A brand-new
+    // chat (no chatId) cannot have a prior run, and the DB partial unique index in
+    // beginRun is the authoritative backstop for any race that slips past here
+    // (including a slot stolen between a supersede release and beginRun).
+    if (body.chatId) {
       const active = await this.aiChatRunService.getActiveForChat(
         body.chatId,
         workspace.id,
@@ -446,107 +513,94 @@ export class AiChatController {
         throw new ConflictException({
           message: 'An agent run is already in progress for this chat',
           code: 'A_RUN_ALREADY_ACTIVE',
+          activeRunId: active.id,
         });
       }
     }
 
-    // Run-lifecycle hooks (#184), only when the flag is on. They wrap the turn in
+    // #487: the turn is ALWAYS a first-class RUN now (both modes). The mode
-    // a durable run whose abort is governed by the run (explicit stop), persist
+    // difference is only the abort semantics on a browser disconnect (onClose
-    // its progress, and settle its terminal status — see AiChatRunService.
+    // below). currentRunId is captured at begin so a legacy disconnect can stop
-    const runHooks: AiChatRunHooks | undefined = autonomousRuns
+    // the run through its stop lever.
-      ? {
+    let currentRunId: string | undefined;
-          begin: async (chatId) => {
+    const runHooks: AiChatRunHooks = {
-            const handle = await this.aiChatRunService.beginRun({
+      begin: async (chatId) => {
-              chatId,
+        const handle = await this.aiChatRunService.beginRun({
-              workspaceId: workspace.id,
+          chatId,
-              userId: user.id,
+          workspaceId: workspace.id,
-              trigger: 'user',
+          userId: user.id,
-            });
+          trigger: 'user',
-            // #184 phase 1.5: register the run-stream entry at BEGIN (before any
+        });
-            // frame) so a tab that attaches in the begin->seed window finds an
+        currentRunId = handle?.runId;
-            // entry to wait on. Gated on AI_CHAT_RESUMABLE_STREAM: with the flag
+        // #184 phase 1.5: register the run-stream entry at BEGIN (before any
-            // off nothing is registered and attach always 204s.
+        // frame) so a tab that attaches in the begin->seed window finds an entry
-            if (
+        // to wait on. Gated on AI_CHAT_RESUMABLE_STREAM.
-              handle?.runId &&
+        if (
-              this.environment?.isAiChatResumableStreamEnabled?.()
+          handle?.runId &&
-            ) {
+          this.environment?.isAiChatResumableStreamEnabled?.()
-              this.streamRegistry?.open(chatId, handle.runId);
+        ) {
-            }
+          this.streamRegistry?.open(chatId, handle.runId);
-            return handle;
-          },
-          onAssistantSeeded: (runId, messageId) =>
-            this.aiChatRunService.linkAssistantMessage(
-              runId,
-              workspace.id,
-              messageId,
-            ),
-          onStep: (runId, stepCount) =>
-            void this.aiChatRunService.recordStep(
-              runId,
-              workspace.id,
-              stepCount,
-            ),
-          onSettled: (runId, status, error) =>
-            this.aiChatRunService.finalizeRun(
-              runId,
-              workspace.id,
-              status,
-              error,
-            ),
         }
-      : undefined;
+        return handle;
+      },
+      onAssistantSeeded: (runId, messageId) =>
+        this.aiChatRunService.linkAssistantMessage(
+          runId,
+          workspace.id,
+          messageId,
+        ),
+      onStep: (runId, stepCount) =>
+        void this.aiChatRunService.recordStep(runId, workspace.id, stepCount),
+      onSettled: (runId, status, error) =>
+        this.aiChatRunService.finalizeRun(runId, workspace.id, status, error),
+    };
 
-    // Abort the agent loop when the client disconnects. `close` also fires on
+    // Handle a client disconnect. `close` also fires on normal completion, so only
-    // normal completion, so only abort when the response has not finished
+    // act when the response has not finished writing (a genuine disconnect). `once`
-    // writing (a genuine disconnect). `once` fires at most once and self-removes;
+    // fires at most once and self-removes; we also drop it on response `finish`.
-    // we also drop it on response `finish` so it never lingers after the stream
-    // completes normally (the AI SDK pipes the response fire-and-forget, so we
-    // cannot simply remove it once `stream()` returns).
     // DIAGNOSTIC (Safari stream-drop investigation) — temporary: wall-clock at
     // which a Safari disconnect is observed, measured from request receipt.
     const reqStartedAt = Date.now();
     const controller = new AbortController();
     const onClose = (): void => {
-      // A genuine disconnect leaves the response unfinished (unlike a normal
-      // completion, which also fires `close`). Such a drop — e.g. a reverse
-      // proxy cutting the SSE mid-answer — is otherwise invisible server-side,
-      // so log it here.
       if (!res.raw.writableEnded) {
         if (autonomousRuns) {
-          // #184: the turn is a DETACHED run. A disconnect must NOT abort it —
+          // #184: a DETACHED run — a disconnect must NOT stop it. The run keeps
-          // the run keeps executing and persisting server-side; the client
+          // executing and persisting server-side; the client reconnects via
-          // reconnects via /ai-chat/run (or re-stops via /ai-chat/stop). Log only.
+          // /ai-chat/run (or re-stops via /ai-chat/stop). Log only.
           this.logger.log(
             `AI chat stream: client disconnected; run continues server-side ` +
               `(elapsed=${Date.now() - reqStartedAt}ms since request received)`,
           );
         } else {
+          // #487: legacy — a disconnect ENDS the turn, but the turn is now a RUN,
+          // so stop it through the run's stop lever (requestStop). streamText no
+          // longer consumes the socket signal (effectiveSignal is the run signal),
+          // so aborting `controller` would do nothing; requestStop aborts the run.
           this.logger.warn(
-            `AI chat stream: client disconnected before completion; aborting turn ` +
+            `AI chat stream: client disconnected before completion; stopping the ` +
-              `(elapsed=${Date.now() - reqStartedAt}ms since request received)`,
+              `run (elapsed=${Date.now() - reqStartedAt}ms since request received)`,
           );
-          controller.abort();
+          if (currentRunId) {
+            void this.aiChatRunService.requestStop(currentRunId, workspace.id);
+          }
         }
       }
     };
     req.raw.once('close', onClose);
     res.raw.once('finish', () => req.raw.off('close', onClose));
 
-    // #184: in detached mode the turn is NOT aborted on disconnect, so the SDK's
+    // #184/#487: the run/pipe can outlive the socket in BOTH modes now (autonomous
-    // pipe keeps writing to a socket the client may have dropped — for the rest of
+    // keeps going; legacy keeps going until requestStop's abort unwinds the turn).
-    // the (continuing) run. A write to the dead socket can emit an 'error' on the
+    // The SDK's pipe may then write to a dropped socket and emit an 'error' on the
-    // raw response; without a listener that surfaces as an unhandled error event.
+    // raw response — swallow it so it never surfaces as an unhandled error event.
-    // Swallow it (the run continues server-side regardless). Legacy mode aborts on
+    res.raw.on('error', (err) => {
-    // disconnect, so it does not need this and keeps its exact prior behavior.
+      this.logger.debug(
-    if (autonomousRuns) {
+        `AI chat stream: post-disconnect socket error swallowed: ${
-      res.raw.on('error', (err) => {
+          err instanceof Error ? err.message : String(err)
-        this.logger.debug(
+        }`,
-          `AI chat detached stream: post-disconnect socket error swallowed: ${
+      );
-            err instanceof Error ? err.message : String(err)
+    });
-          }`,
-        );
-      });
-    }
 
     // Commit to streaming: hijack so Fastify stops managing the response and
     // the AI SDK can write the UI-message stream directly to the Node socket.
@@ -562,8 +616,10 @@ export class AiChatController {
         signal: controller.signal,
         model,
         role,
-        // #184: present only when the flag is on; wraps the turn in a durable run.
+        // #487: the turn is always run-wrapped now (both modes).
         runHooks,
+        // #487: warn the new run that a superseded run's last ops may still apply.
+        superseded,
       });
     } catch (err) {
       // Any failure AFTER hijack can no longer go through Nest's exception

apps/server/src/core/ai-chat/ai-chat.parts-resilience.spec.ts

@@ -0,0 +1,142 @@
+// #489 — client-parts validation + resilient history conversion.
+//
+// These unit tests exercise the two exported helpers against the REAL
+// `convertToModelMessages` from `ai` (NOT a mock): a genuinely malformed part
+// (a `null` element inside a parts array) makes the real converter throw
+// ("Cannot read properties of null"), which is the actual production
+// "bricked chat" mechanism this fix defends against. Asserting against the real
+// converter (rather than a mock-shaped error) is the whole point — a mock would
+// hide a version change in the converter's throw behaviour.
+import { convertToModelMessages, type UIMessage } from 'ai';
+import {
+  sanitizeUserParts,
+  convertHistoryResilient,
+  TOOL_CONTEXT_OMITTED_MARKER,
+} from './ai-chat.service';
+
+type Row = Omit<UIMessage, 'id'> & { id: string };
+
+describe('sanitizeUserParts (#489, branch: validation on receipt)', () => {
+  it('keeps whitelisted text parts unchanged', () => {
+    const drops: string[] = [];
+    const out = sanitizeUserParts(
+      [
+        { type: 'text', text: 'a' },
+        { type: 'text', text: 'b' },
+      ] as UIMessage['parts'],
+      (t) => drops.push(t),
+    );
+    expect(out).toEqual([
+      { type: 'text', text: 'a' },
+      { type: 'text', text: 'b' },
+    ]);
+    expect(drops).toEqual([]);
+  });
+
+  it('drops a non-text part (a tool-part in input-available) and reports its type', () => {
+    const drops: string[] = [];
+    const out = sanitizeUserParts(
+      [
+        { type: 'text', text: 'hi' },
+        {
+          type: 'tool-getPage',
+          toolCallId: 't1',
+          state: 'input-available',
+          input: { pageId: 'p' },
+        },
+      ] as unknown as UIMessage['parts'],
+      (t) => drops.push(t),
+    );
+    expect(out).toEqual([{ type: 'text', text: 'hi' }]);
+    expect(drops).toEqual(['tool-getPage']);
+  });
+
+  it('drops a null part (the shape that would poison convertToModelMessages)', () => {
+    const drops: string[] = [];
+    const out = sanitizeUserParts(
+      [{ type: 'text', text: 'hi' }, null] as unknown as UIMessage['parts'],
+      (t) => drops.push(t),
+    );
+    expect(out).toEqual([{ type: 'text', text: 'hi' }]);
+    expect(drops).toEqual(['(unknown)']);
+  });
+
+  it('returns undefined when nothing survives (so a null metadata is persisted)', () => {
+    const out = sanitizeUserParts(
+      [
+        { type: 'tool-x', toolCallId: 't', state: 'input-available' },
+      ] as unknown as UIMessage['parts'],
+      () => undefined,
+    );
+    expect(out).toBeUndefined();
+  });
+
+  it('returns undefined for a non-array input', () => {
+    expect(
+      sanitizeUserParts(undefined as unknown as UIMessage['parts'], () => undefined),
+    ).toBeUndefined();
+  });
+});
+
+describe('convertHistoryResilient (#489, branches: happy + per-row degradation)', () => {
+  it('happy path: healthy history converts identically to convertToModelMessages, no degrade', async () => {
+    const history: Row[] = [
+      { id: 'u1', role: 'user', parts: [{ type: 'text', text: 'hi' }] },
+      { id: 'a1', role: 'assistant', parts: [{ type: 'text', text: 'hello' }] },
+    ];
+    const degrades: number[] = [];
+    const out = await convertHistoryResilient(history, (i) => degrades.push(i));
+    const expected = await convertToModelMessages(history as UIMessage[]);
+    expect(out).toEqual(expected);
+    expect(degrades).toEqual([]);
+  });
+
+  it('REAL poison: a null part throws in the batch converter but is isolated and degraded to a marker', async () => {
+    // Sanity: the real converter genuinely throws on this shape.
+    const poisoned: Row = {
+      id: 'a1',
+      role: 'assistant',
+      parts: [
+        { type: 'text', text: 'earlier answer' },
+        null,
+      ] as unknown as UIMessage['parts'],
+    };
+    await expect(
+      convertToModelMessages([poisoned as UIMessage]),
+    ).rejects.toThrow();
+
+    const history: Row[] = [
+      { id: 'u1', role: 'user', parts: [{ type: 'text', text: 'first' }] },
+      poisoned,
+      { id: 'u2', role: 'user', parts: [{ type: 'text', text: 'second' }] },
+    ];
+    const degrades: number[] = [];
+    const out = await convertHistoryResilient(history, (i) => degrades.push(i));
+
+    // Only the poisoned row (index 1) is degraded.
+    expect(degrades).toEqual([1]);
+    // Healthy rows survive verbatim.
+    const flat = JSON.stringify(out);
+    expect(flat).toContain('first');
+    expect(flat).toContain('second');
+    // The degraded row carries its readable text AND the truncation marker so the
+    // model sees that tool context was omitted (never a silent loss).
+    expect(flat).toContain('earlier answer');
+    expect(flat).toContain(TOOL_CONTEXT_OMITTED_MARKER);
+    // The whole batch converted (3 model messages, none dropped).
+    expect(out).toHaveLength(3);
+  });
+
+  it('a fully-poisoned row (no readable text) still degrades to just the marker', async () => {
+    const history: Row[] = [
+      {
+        id: 'a1',
+        role: 'assistant',
+        parts: [null] as unknown as UIMessage['parts'],
+      },
+    ];
+    const out = await convertHistoryResilient(history, () => undefined);
+    expect(out).toHaveLength(1);
+    expect(JSON.stringify(out)).toContain(TOOL_CONTEXT_OMITTED_MARKER);
+  });
+});

apps/server/src/core/ai-chat/ai-chat.prompt.tool-names.spec.ts

@@ -0,0 +1,125 @@
+import { readFileSync } from 'node:fs';
+import { join } from 'node:path';
+import { PROMPT_TOOL_NAMES } from './ai-chat.prompt';
+// The real shared registry, imported from source (same approach as the
+// SHARED_TOOL_SPECS contract spec) so tool names are validated against exactly
+// what @docmost/mcp ships.
+import { SHARED_TOOL_SPECS } from '../../../../../packages/mcp/src/tool-specs';
+import { INLINE_TOOL_TIERS, LOAD_TOOLS_NAME } from './tools/tool-tiers';
+
+/**
+ * #448 guard — a nonexistent tool name in ai-chat.prompt.ts must fail a test.
+ *
+ * The in-app prompt refers to a handful of tools BY NAME in its guidance notes
+ * (e.g. PAGE_CHANGED_NOTE tells the agent to re-read via getPage and edit via
+ * editPageText/patchNode/insertNode/deleteNode). Before #448 those names were
+ * hard-coded inline with NO guard, so renaming a tool left the agent stale
+ * instructions and nothing failed.
+ *
+ * APPROACH — substitution + a precise source scan:
+ *  1. The names now flow through the exported `PROMPT_TOOL_NAMES` const; this
+ *     test asserts every value there is a REAL in-app tool.
+ *  2. A precise scan of the two guidance-note string literals in the source
+ *     catches any BARE tool-name token added directly (bypassing the const):
+ *     every camelCase token in those notes must be either a real tool name or an
+ *     explicitly-allowlisted ordinary English/camelCase word.
+ *
+ * The scan is deliberately narrow (only the guidance notes, only camelCase
+ * tokens) so it never false-positives on prose, and the allowlist of non-tool
+ * words is tiny and explicit.
+ */
+
+// The authoritative set of real in-app tool names: shared-registry inAppKeys +
+// per-layer INLINE tool keys + the loadTools meta-tool.
+const VALID_TOOL_NAMES = new Set<string>([
+  ...Object.values(SHARED_TOOL_SPECS).map((s) => s.inAppKey),
+  ...Object.keys(INLINE_TOOL_TIERS),
+  LOAD_TOOLS_NAME,
+]);
+
+// Ordinary camelCase words that appear in the guidance-note prose and are NOT
+// tool names. Keep this list minimal and explicit — anything camelCase in a note
+// that is neither a real tool nor here fails the scan.
+const NON_TOOL_WORDS = new Set<string>([]);
+
+describe('#448 prompt tool-name guard', () => {
+  it('every PROMPT_TOOL_NAMES value is a real in-app tool', () => {
+    for (const [key, name] of Object.entries(PROMPT_TOOL_NAMES)) {
+      expect(typeof name).toBe('string');
+      expect(VALID_TOOL_NAMES.has(name)).toBe(true);
+      // Sanity: the const key and its value are the same token (the const is a
+      // name->name map used purely to route mentions through one guarded place).
+      expect(key).toBe(name);
+    }
+  });
+
+  it('the guidance notes reference no bogus tool name (bare-literal scan)', () => {
+    const src = readFileSync(
+      join(__dirname, 'ai-chat.prompt.ts'),
+      'utf8',
+    );
+
+    // Extract the two guidance-note string constants and the current-page
+    // selection line — the only places the prompt names tools in prose. Each is
+    // a `const NAME =` ... `;` block; we scan their raw text for camelCase
+    // tokens. (Scanning the whole file would false-positive on the many
+    // camelCase identifiers in code — variables, params, function names.)
+    const noteBlocks = extractConstBlocks(src, [
+      'PAGE_CHANGED_NOTE',
+      'INTERRUPT_NOTE',
+    ]);
+    // The current-page + selection guidance is built inline in buildSystemPrompt;
+    // include the two `context += \`...\`` template lines that mention tools.
+    const contextLines = src
+      .split('\n')
+      .filter((l) => l.includes('context +=') && l.includes('getCurrentPage'))
+      .join('\n');
+
+    // Neutralize string-literal escape sequences (\n, \t, ...) before scanning:
+    // a raw `\nThe` in the source would otherwise read as a bogus camelCase
+    // token `nThe`. Replace any backslash-escape with a space.
+    const scanText = (noteBlocks + '\n' + contextLines).replace(/\\./g, ' ');
+    expect(scanText.length).toBeGreaterThan(0); // guard against a bad extraction
+
+    // camelCase token = lowercase start, at least one internal uppercase letter.
+    const tokens = new Set(scanText.match(/\b[a-z][a-zA-Z0-9]*[A-Z][a-zA-Z0-9]*\b/g) ?? []);
+    const offenders = [...tokens].filter(
+      (t) => !VALID_TOOL_NAMES.has(t) && !NON_TOOL_WORDS.has(t),
+    );
+    expect(offenders).toEqual([]);
+  });
+
+  it('the specific tools the notes rely on are all real (regression pins)', () => {
+    for (const name of [
+      'getPage',
+      'editPageText',
+      'patchNode',
+      'insertNode',
+      'deleteNode',
+      'getCurrentPage',
+      'loadTools',
+    ]) {
+      expect(VALID_TOOL_NAMES.has(name)).toBe(true);
+    }
+  });
+});
+
+/**
+ * Extract the raw text of one or more top-level `const NAME = ... ;` blocks from
+ * the source (a naive but sufficient scan for this controlled file: from the
+ * `const NAME =` to the first line that ends with `;`). Returns the blocks
+ * concatenated.
+ */
+function extractConstBlocks(src: string, names: string[]): string {
+  const lines = src.split('\n');
+  const out: string[] = [];
+  for (const name of names) {
+    const start = lines.findIndex((l) => l.trimStart().startsWith(`const ${name} =`));
+    if (start < 0) continue;
+    for (let i = start; i < lines.length; i++) {
+      out.push(lines[i]);
+      if (lines[i].trimEnd().endsWith(';')) break;
+    }
+  }
+  return out.join('\n');
+}

apps/server/src/core/ai-chat/ai-chat.prompt.ts

@@ -2,6 +2,30 @@ import { Workspace } from '@docmost/db/types/entity.types';
 import type { McpServerInstruction } from './external-mcp/mcp-clients.service';
 import { CORE_TOOL_KEYS, type ToolCatalogEntry } from './tools/tool-tiers';
 
+/**
+ * The in-app tool names this prompt refers to BY NAME in its guidance notes
+ * (issue #448). Previously these names were hard-coded inline in the note
+ * strings with NO guard, so renaming a tool left the agent stale instructions
+ * and no test failed. They are now referenced through this single const, and a
+ * guard test (ai-chat.prompt.tool-names.spec.ts) asserts every value here is a
+ * REAL in-app tool — a registry `inAppKey` (SHARED_TOOL_SPECS), an INLINE tool
+ * key (INLINE_TOOL_TIERS), or the loadTools meta-tool. Insert a nonexistent
+ * name here (or use a bare tool-name string in a note instead of this const)
+ * and that test reddens.
+ *
+ * `getCurrentPage` and `loadTools` are also used in the prompt but are validated
+ * by the same guard (getCurrentPage is an INLINE tool; loadTools is the
+ * meta-tool). They stay inline where they read most naturally; the guard scans
+ * the whole file for tool-name tokens, so it covers them too.
+ */
+export const PROMPT_TOOL_NAMES = {
+  getPage: 'getPage',
+  editPageText: 'editPageText',
+  patchNode: 'patchNode',
+  insertNode: 'insertNode',
+  deleteNode: 'deleteNode',
+} as const;
+
 /**
  * Default agent persona used when the admin has not configured a custom system
  * prompt (`settings.ai.provider.systemPrompt`).
@@ -77,6 +101,22 @@ const INTERRUPT_NOTE =
   'assume your previous response was complete, and do not silently restart the ' +
   'partial work — build on it or follow the new instruction.';
 
+/**
+ * #487: injected on a turn started by SUPERSEDING a previous run (the user hit
+ * "interrupt and send now" while a run was live). The previous run was Stopped,
+ * but there is NO side-effect quiescence — a write it had already committed, or
+ * one committing at the moment of Stop, may land with a small delay AFTER this new
+ * run starts. So the model is told its picture of the page/state may be a beat
+ * stale and to re-read before assuming an edit did or did not apply.
+ */
+const SUPERSEDE_NOTE =
+  'NOTE: A previous agent run in this conversation was just interrupted so this ' +
+  'new turn could start. That run was stopped, but any operation it had already ' +
+  'begun (e.g. a page edit) may still be applied with a short delay. Do not ' +
+  'assume the document/state is exactly as the interrupted run left it — if you ' +
+  'need to rely on the current content, RE-READ it with the page tools before ' +
+  'acting rather than trusting a cached view.';
+
 /**
  * Injected on a turn where the open page was hand-edited by the user (or anyone
  * else) AFTER the agent's previous response ended (#274). The server takes a
@@ -91,15 +131,15 @@ const PAGE_CHANGED_NOTE =
   'NOTE: The user edited the open page AFTER your last response in this ' +
   'conversation, so any copy of that page you produced or remember from earlier ' +
   'is now STALE and must not be reused. Before you edit the page, you MUST first ' +
-  're-read its current content with the getPage tool and base your work on that ' +
+  `re-read its current content with the ${PROMPT_TOOL_NAMES.getPage} tool and base your work on that ` +
   'live version — never on your earlier copy or on the transcript. The unified ' +
   'diff below shows exactly what the user changed since you last spoke (lines ' +
   'starting with "-" were removed, "+" were added) and is the source of truth. ' +
   'Preserve every one of the user\'s edits: make the smallest change that ' +
-  'satisfies the request using the targeted edit tools (editPageText, patchNode, ' +
+  `satisfies the request using the targeted edit tools (${PROMPT_TOOL_NAMES.editPageText}, ${PROMPT_TOOL_NAMES.patchNode}, ` +
-  'insertNode, deleteNode) rather than replacing the whole page, and do not ' +
+  `${PROMPT_TOOL_NAMES.insertNode}, ${PROMPT_TOOL_NAMES.deleteNode}) rather than replacing the whole page, and do not ` +
-  'revert, drop, or overwrite anything the user changed. If a full rewrite is ' +
+  `revert, drop, or overwrite anything the user changed. If a full rewrite is ` +
-  'truly unavoidable, start from the current getPage content and carry over all ' +
+  `truly unavoidable, start from the current ${PROMPT_TOOL_NAMES.getPage} content and carry over all ` +
   'of the user\'s edits.';
 
 /**
@@ -179,6 +219,14 @@ export interface BuildSystemPromptInput {
    * (partial) answer was cut off by the user's new message.
    */
   interrupted?: boolean;
+  /**
+   * #487: true when THIS turn was started by superseding a still-live previous run
+   * ("interrupt and send now"). Adds SUPERSEDE_NOTE so the model knows the previous
+   * run's last operations may still be applying and to re-read state it depends on.
+   * Distinct from `interrupted` (which is about a PARTIAL prior answer in history);
+   * both can be set together. Self-clears — set only for the superseding turn.
+   */
+  superseded?: boolean;
   /**
    * Set only when the open page was edited by the user AFTER the agent's previous
    * turn ended (#274), confirmed server-side by diffing the current page against
@@ -287,6 +335,7 @@ export function buildSystemPrompt({
   openedPage,
   mcpInstructions,
   interrupted,
+  superseded,
   pageChanged,
   deferredToolsEnabled,
   toolCatalog,
@@ -336,6 +385,13 @@ export function buildSystemPrompt({
     context += `\n${INTERRUPT_NOTE}`;
   }
 
+  // Supersede note (#487): present only for a turn that stopped and replaced a
+  // still-live previous run — warns the model the previous run's last operations
+  // may still be applying (no side-effect quiescence).
+  if (superseded) {
+    context += `\n${SUPERSEDE_NOTE}`;
+  }
+
   // Per-turn page-change note (#274). Added to the context section (inside the
   // safety sandwich), present only when the server detected that the open page
   // was edited by the user since the agent's last turn ended. The diff content is

apps/server/src/core/ai-chat/ai-chat.service.lifecycle.spec.ts

@@ -89,11 +89,22 @@ describe('AiChatService.stream run-lifecycle safety net (#184)', () => {
     const runRepo = {
       insert: jest.fn().mockResolvedValue({ id: 'run-1', status: 'running' }),
       update: jest.fn().mockResolvedValue({ id: 'run-1' }),
+      // #487: the terminal settle now goes through the CONDITIONAL write.
+      finalizeIfActive: jest
+        .fn()
+        .mockResolvedValue({ id: 'run-1', status: 'failed' }),
+      findById: jest.fn().mockResolvedValue(undefined),
     };
     const runService = new AiChatRunService(runRepo as never, { isCloud: () => false } as never);
 
-    // The user-message insert (the first bare await after beginRun) throws.
+    // The user-message insert throws. #489 runs the history load + convert BEFORE
+    // the insert (convert-before-insert, so a retry cannot duplicate the user row),
+    // so `findAllByChat` (a real repo method) is now called first — stub it to an
+    // empty history so the flow reaches the insert. Both awaits are AFTER beginRun,
+    // so the "exception after beginRun -> settled to error" invariant is unchanged;
+    // the throw point simply moved from insert to a later insert after a no-op load.
     const aiChatMessageRepo = {
+      findAllByChat: jest.fn().mockResolvedValue([]),
       insert: jest.fn().mockRejectedValue(new Error('insert boom')),
     };
     const aiChatRepo = {
@@ -148,9 +159,10 @@ describe('AiChatService.stream run-lifecycle safety net (#184)', () => {
 
     // The run was begun...
     expect(runRepo.insert).toHaveBeenCalledTimes(1);
-    // ...then settled to a terminal FAILED status by the safety net...
+    // ...then settled to a terminal FAILED status by the safety net (via the
-    expect(runRepo.update).toHaveBeenCalledTimes(1);
+    // #487 conditional write)...
-    expect(runRepo.update).toHaveBeenCalledWith(
+    expect(runRepo.finalizeIfActive).toHaveBeenCalledTimes(1);
+    expect(runRepo.finalizeIfActive).toHaveBeenCalledWith(
       'run-1',
       'ws1',
       expect.objectContaining({ status: 'failed' }),

apps/server/src/core/ai-chat/ai-chat.service.run-race.spec.ts

@@ -1,4 +1,8 @@
-import { ConflictException, Logger } from '@nestjs/common';
+import {
+  ConflictException,
+  Logger,
+  ServiceUnavailableException,
+} from '@nestjs/common';
 
 // Mock the AI SDK so we can PROVE no provider call is made for the turn we are
 // about to reject. The race rejection happens at runHooks.begin(), long before
@@ -151,6 +155,8 @@ describe('AiChatService.stream — abortSignal wiring (#184 F3)', () => {
       insert: jest.fn(async () => ({ id: 'msg-1' })),
       findAllByChat: jest.fn(async () => []),
       update: jest.fn(async () => ({ id: 'msg-1' })),
+      finalizeOwner: jest.fn(async () => ({ id: 'msg-1' })),
+      findStreamingWithTerminalRun: jest.fn(async () => []),
     };
     const aiSettings = { resolve: jest.fn(async () => ({})) };
     const tools = { forUser: jest.fn(async () => ({})) };
@@ -175,7 +181,7 @@ describe('AiChatService.stream — abortSignal wiring (#184 F3)', () => {
       {} as never, // pageAccess
       { isAiChatDeferredToolsEnabled: () => false, isAiChatFinalStepLockdownEnabled: () => false } as never, // environment
     );
-    return { svc };
+    return { svc, aiChatMessageRepo };
   }
 
   const body = {
@@ -281,7 +287,7 @@ describe('AiChatService.stream — abortSignal wiring (#184 F3)', () => {
   // Drive stream() to the point streamText is called, capturing the options object
   // (which carries onStepFinish/onFinish/onError/onAbort) and the run hooks.
   async function captureStreamCallbacks() {
-    const { svc } = makeService();
+    const { svc, aiChatMessageRepo } = makeService();
     let capturedOpts: any;
     streamTextMock.mockImplementation((opts: any) => {
       capturedOpts = opts;
@@ -308,7 +314,7 @@ describe('AiChatService.stream — abortSignal wiring (#184 F3)', () => {
       runHooks: runHooks as never,
     });
     expect(capturedOpts).toBeDefined();
-    return { capturedOpts, runHooks };
+    return { capturedOpts, runHooks, aiChatMessageRepo };
   }
 
   it('F9: onStepFinish bumps the run step count, onFinish settles the run "completed" (the dominant autonomous-run path)', async () => {
@@ -328,7 +334,13 @@ describe('AiChatService.stream — abortSignal wiring (#184 F3)', () => {
       usage: {},
       steps: [],
     });
-    expect(runHooks.onSettled).toHaveBeenCalledWith('run-1', 'completed');
+    // #487: onFinish passes the (undefined) error slot so a message-finalize
+    // failure could error-mark the run; on the success path it is undefined.
+    expect(runHooks.onSettled).toHaveBeenCalledWith(
+      'run-1',
+      'completed',
+      undefined,
+    );
   });
 
   it('F9: onAbort settles the run "aborted"', async () => {
@@ -357,25 +369,70 @@ describe('AiChatService.stream — abortSignal wiring (#184 F3)', () => {
       expect.stringContaining('provider exploded'),
     );
   });
+
+  // #490 reactive branch: a provider CONTEXT-OVERFLOW 400 in onError is classified,
+  // records a distinguishable cause, and stamps metadata.replayOverflow so the NEXT
+  // turn's budgeter trims aggressively (the recovery that un-bricks the chat).
+  it('#490: a context-overflow 400 stamps replayOverflow on the finalized row', async () => {
+    jest
+      .spyOn(Logger.prototype, 'error')
+      .mockImplementation(() => undefined as never);
+    jest
+      .spyOn(Logger.prototype, 'warn')
+      .mockImplementation(() => undefined as never);
+    const { capturedOpts, aiChatMessageRepo } = await captureStreamCallbacks();
+
+    const overflow = Object.assign(new Error('too large'), {
+      statusCode: 400,
+      message:
+        "This model's maximum context length is 128000 tokens. However, your messages resulted in 214000 tokens. Please reduce the length.",
+    });
+    await capturedOpts.onError({ error: overflow });
+
+    // The seed row exists (finalizeOwner is the owner-write path).
+    expect(aiChatMessageRepo.finalizeOwner).toHaveBeenCalled();
+    const calls = aiChatMessageRepo.finalizeOwner.mock.calls as any[][];
+    const patch = calls[calls.length - 1][2] as {
+      status: string;
+      metadata: Record<string, unknown>;
+    };
+    expect(patch.status).toBe('error');
+    expect(patch.metadata.replayOverflow).toBe(true);
+    expect(patch.metadata.error).toContain('контекстное окно');
+  });
+
+  it('#490: a non-overflow error does NOT stamp replayOverflow', async () => {
+    jest
+      .spyOn(Logger.prototype, 'error')
+      .mockImplementation(() => undefined as never);
+    const { capturedOpts, aiChatMessageRepo } = await captureStreamCallbacks();
+    await capturedOpts.onError({ error: new Error('network reset') });
+    const calls = aiChatMessageRepo.finalizeOwner.mock.calls as any[][];
+    const patch = calls[calls.length - 1][2] as {
+      status: string;
+      metadata: Record<string, unknown>;
+    };
+    expect('replayOverflow' in patch.metadata).toBe(false);
+  });
 });
 
 /**
- * F14 — the begin-failure RESILIENCE branch (the `else` of the run-race guard).
+ * F14 — the begin-failure branch (the `else` of the run-race guard).
  *
  * stream() wraps runHooks.begin in try/catch with TWO branches:
  *   - RunAlreadyActiveError  -> 409 ConflictException (pinned above).
- *   - ANY OTHER begin failure -> SWALLOW + continue UNTRACKED on the socket signal
+ *   - ANY OTHER begin failure -> throw ServiceUnavailableException(A_RUN_BEGIN_FAILED)
- *     (legacy fallback): it logs "...streaming without run tracking", leaves
+ *     BEFORE the first byte (#486, commit 4).
- *     `effectiveSignal = signal` (runId undefined) and serves the turn anyway.
  *
- * The contract: a transient beginRun failure (e.g. a non-unique DB error inserting
+ * POLICY CHANGE (#486): the OLD contract here was "SWALLOW + stream the turn
- * the run row) must STILL serve the user's turn — it must NOT re-throw and must NOT
+ * UNTRACKED on the socket signal". That was reversed: an untracked run is
- * be misclassified as a 409. A regression that re-threw here would break EVERY turn
+ * invisible to /stop, is not aborted on disconnect, and slips past the one-run
- * on a begin failure with nothing to catch it. This branch is otherwise undriven by
+ * gate — an unstoppable ghost run in autonomous mode. Now a plain begin failure
- * any spec, so it is pinned here SEPARATELY from the 409 path: a plain begin error
+ * FAILS the turn fast with a 503 A_RUN_BEGIN_FAILED, before any user row is
- * proceeds to streamText with the SOCKET signal and still persists the user turn.
+ * persisted and before streamText runs. This case is INVERTED (not deleted) so
+ * the "plain begin failure" path stays explicitly pinned under the new policy.
  */
-describe('AiChatService.stream — begin-failure resilience / legacy fallback (#184 F14)', () => {
+describe('AiChatService.stream — begin-failure fails the turn (#184 F14 / #486)', () => {
   const streamTextMock = streamText as unknown as jest.Mock;
 
   function makeStreamResult() {
@@ -411,6 +468,8 @@ describe('AiChatService.stream — begin-failure resilience / legacy fallback (#
       insert: jest.fn(async () => ({ id: 'msg-1' })),
       findAllByChat: jest.fn(async () => []),
       update: jest.fn(async () => ({ id: 'msg-1' })),
+      finalizeOwner: jest.fn(async () => ({ id: 'msg-1' })),
+      findStreamingWithTerminalRun: jest.fn(async () => []),
     };
     const aiSettings = { resolve: jest.fn(async () => ({})) };
     const tools = { forUser: jest.fn(async () => ({})) };
@@ -455,7 +514,7 @@ describe('AiChatService.stream — begin-failure resilience / legacy fallback (#
 
   afterEach(() => jest.restoreAllMocks());
 
-  it('a PLAIN begin() failure (NOT RunAlreadyActiveError) does NOT 409 — it swallows, logs, and streams the turn UNTRACKED on the socket signal', async () => {
+  it('a PLAIN begin() failure (NOT RunAlreadyActiveError) FAILS the turn with a 503 A_RUN_BEGIN_FAILED before the first byte — NO untracked stream (#486)', async () => {
     const errorSpy = jest
       .spyOn(Logger.prototype, 'error')
       .mockImplementation(() => undefined as never);
@@ -487,28 +546,26 @@ describe('AiChatService.stream — begin-failure resilience / legacy fallback (#
       } as never,
     });
 
-    // The turn proceeds: NO throw at all (in particular NOT a 409).
+    // NEW POLICY: the turn is REJECTED with a 503 A_RUN_BEGIN_FAILED (not a 409,
-    await expect(promise).resolves.toBeUndefined();
+    // and NOT swallowed into an untracked stream).
+    await expect(promise).rejects.toBeInstanceOf(ServiceUnavailableException);
+    const err = (await promise.catch(
+      (e) => e,
+    )) as ServiceUnavailableException;
+    expect(err.getStatus()).toBe(503);
+    expect(err.getResponse()).toMatchObject({ code: 'A_RUN_BEGIN_FAILED' });
 
     expect(begin).toHaveBeenCalledTimes(1);
 
-    // The resilience branch logged the legacy-fallback warning.
+    // It logged the fail-the-turn line.
     expect(errorSpy).toHaveBeenCalledWith(
-      expect.stringContaining('streaming without run tracking'),
+      expect.stringContaining('failing the turn'),
       expect.anything(),
     );
 
-    // The turn really streamed: the user message was persisted and streamText ran.
+    // Fail-fast: the turn NEVER streamed — no user row persisted, no streamText
-    expect(aiChatMessageRepo.insert).toHaveBeenCalled();
+    // call, so no orphan/untracked run was left behind.
-    expect(streamTextMock).toHaveBeenCalledTimes(1);
+    expect(aiChatMessageRepo.insert).not.toHaveBeenCalled();
-
+    expect(streamTextMock).not.toHaveBeenCalled();
-    // The decisive wiring: with no run handle, the fallback uses the SOCKET signal
-    // (effectiveSignal = signal, runId undefined) — not a run-bound signal. #444:
-    // the signal is unioned with the degeneration controller via AbortSignal.any,
-    // so assert the socket abort still reaches the turn rather than identity.
-    const passed = streamTextMock.mock.calls[0][0].abortSignal as AbortSignal;
-    expect(passed.aborted).toBe(false);
-    socketController.abort();
-    expect(passed.aborted).toBe(true);
   });
 });

apps/server/src/core/ai-chat/ai-chat.service.spec.ts

@@ -13,6 +13,7 @@ import {
   compactToolOutput,
   assistantParts,
   serializeSteps,
+  type StepPartsCache,
   rowToUiMessage,
   prepareAgentStep,
   stepBudgetWarning,
@@ -28,10 +29,14 @@ import {
   FINAL_STEP_NUDGE,
   STEP_LIMIT_NO_ANSWER_MARKER,
   OUTPUT_DEGENERATION_ERROR,
+  lastAssistantContextTokens,
+  lastAssistantReplayOverflow,
+  seedActivatedTools,
 } from './ai-chat.service';
 import type { AiChatMessage, Workspace } from '@docmost/db/types/entity.types';
 import { buildSystemPrompt } from './ai-chat.prompt';
 import type { McpClientsService } from './external-mcp/mcp-clients.service';
+import { resolveEffectiveReplayThreshold } from './history-budget';
 
 /**
  * Unit tests for compactToolOutput: the pure helper that shrinks tool outputs
@@ -114,6 +119,54 @@ describe('compactToolOutput', () => {
 describe('assistantParts', () => {
   type AnyPart = Record<string, unknown>;
 
+  // #490 memoization: assistantParts builds each step's parts once and caches
+  // them by the step OBJECT's identity, so a mid-stream flush does not
+  // re-stringify every prior step's (large) output. Observable property: with a
+  // shared cache, the second call over the SAME step object returns the cached
+  // (identical) part array even if the step's underlying output was swapped —
+  // proving the work was memoized, not redone.
+  it('memoizes a step by identity (shared cache => one build per step)', () => {
+    const cache: StepPartsCache = new WeakMap();
+    const step = {
+      text: 'x',
+      toolCalls: [{ toolCallId: 'c1', toolName: 'getPage', input: {} }],
+      toolResults: [{ toolCallId: 'c1', toolName: 'getPage', output: { v: 1 } }],
+    };
+    const first = assistantParts([step], '', cache) as AnyPart[];
+    expect((first.find((p) => p.type === 'tool-getPage')!.output as any).v).toBe(
+      1,
+    );
+    // Swap the output for a NEW value; a re-build would pick it up, a cache hit
+    // keeps the first result.
+    step.toolResults[0] = {
+      toolCallId: 'c1',
+      toolName: 'getPage',
+      output: { v: 2 },
+    };
+    const second = assistantParts([step], '', cache) as AnyPart[];
+    expect((second.find((p) => p.type === 'tool-getPage')!.output as any).v).toBe(
+      1,
+    );
+    // Same cached part objects are reused.
+    expect(second.find((p) => p.type === 'tool-getPage')).toBe(
+      first.find((p) => p.type === 'tool-getPage'),
+    );
+  });
+
+  it('without a cache, each call rebuilds (no stale memo)', () => {
+    const step = {
+      text: 'x',
+      toolCalls: [{ toolCallId: 'c1', toolName: 'getPage', input: {} }],
+      toolResults: [{ toolCallId: 'c1', toolName: 'getPage', output: { v: 1 } }],
+    };
+    const first = assistantParts([step], '') as AnyPart[];
+    step.toolResults[0].output = { v: 2 };
+    const second = assistantParts([step], '') as AnyPart[];
+    expect((second.find((p) => p.type === 'tool-getPage')!.output as any).v).toBe(
+      2,
+    );
+  });
+
   it('emits output-available for a tool-call WITH a paired result', () => {
     const steps = [
       {
@@ -231,61 +284,320 @@ describe('assistantParts', () => {
   });
 });
 
-describe('serializeSteps', () => {
+// #490 trace format v2: per call the trace stores { input } for the call and an
+// OUTCOME element — { ok: true } on success, { error, kind: 'thrown' } on a
+// thrown tool-error, { error, kind: 'interrupted' } on a mid-step abort. The tool
+// OUTPUT is no longer duplicated here (it lives once in metadata.parts).
+describe('serializeSteps (trace v2)', () => {
   it('returns null when there are no calls or results', () => {
     expect(serializeSteps([])).toBeNull();
   });
 
-  it('flattens calls and results into a compact trace', () => {
+  it('pairs a successful call with an { ok: true } outcome and NO output', () => {
     const trace = serializeSteps([
       {
-        toolCalls: [{ toolName: 'getPage', input: { id: 'p1' } }],
+        toolCalls: [{ toolCallId: 'c1', toolName: 'getPage', input: { id: 'p1' } }],
-        toolResults: [{ toolName: 'getPage', output: { title: 'T' } }],
+        toolResults: [{ toolCallId: 'c1', toolName: 'getPage' }],
       },
     ]) as Array<Record<string, unknown>>;
     expect(trace).toHaveLength(2);
     expect(trace[0]).toEqual({ toolName: 'getPage', input: { id: 'p1' } });
-    expect(trace[1]).toEqual({ toolName: 'getPage', output: { title: 'T' } });
+    expect(trace[1]).toEqual({ toolName: 'getPage', ok: true });
+    // The output is NOT stored in the trace any more (dedup: it lives in parts).
+    expect(trace.some((e) => 'output' in e)).toBe(false);
   });
 
-  it('records a THROWN tool failure (tool-error part) with its error message', () => {
+  it('records a THROWN failure with { error, kind: "thrown" }', () => {
     const trace = serializeSteps([
       {
-        toolCalls: [{ toolName: 'editPageText', input: { id: 'p1' } }],
+        toolCalls: [
+          { toolCallId: 'c1', toolName: 'editPageText', input: { id: 'p1' } },
+        ],
         toolResults: [],
         content: [
           {
             type: 'tool-error',
+            toolCallId: 'c1',
             toolName: 'editPageText',
             error: new Error('page is locked'),
           },
         ],
       },
     ]) as Array<Record<string, unknown>>;
-    // The call element is followed by a paired error element (mirroring how a
-    // successful result is appended), so the failure survives in the trace.
     expect(trace).toHaveLength(2);
     expect(trace[0]).toEqual({ toolName: 'editPageText', input: { id: 'p1' } });
     expect(trace[1]).toEqual({
       toolName: 'editPageText',
       error: 'page is locked',
+      kind: 'thrown',
     });
   });
 
-  it('truncates a very long tool-error message to the tool-output limit', () => {
+  it('marks an interrupted call (no result, no throw) with kind "interrupted"', () => {
+    const trace = serializeSteps([
+      {
+        toolCalls: [
+          { toolCallId: 'c1', toolName: 'createComment', input: { x: 1 } },
+        ],
+        toolResults: [],
+        content: [],
+      },
+    ]) as Array<Record<string, unknown>>;
+    expect(trace).toHaveLength(2);
+    expect(trace[1]).toEqual({
+      toolName: 'createComment',
+      error: 'Tool call did not complete.',
+      kind: 'interrupted',
+    });
+    // Structurally distinct from a thrown hard-fail so it never inflates an
+    // error-rate scan.
+    expect((trace[1] as { kind: string }).kind).not.toBe('thrown');
+  });
+
+  it('truncates a very long thrown-error message to the tool-output limit', () => {
     const long = 'x'.repeat(5000);
     const trace = serializeSteps([
       {
-        toolCalls: [{ toolName: 'editPageText', input: {} }],
+        toolCalls: [{ toolCallId: 'c1', toolName: 'editPageText', input: {} }],
         toolResults: [],
-        content: [{ type: 'tool-error', toolName: 'editPageText', error: long }],
+        content: [
+          {
+            type: 'tool-error',
+            toolCallId: 'c1',
+            toolName: 'editPageText',
+            error: long,
+          },
+        ],
       },
     ]) as Array<Record<string, unknown>>;
     const errorText = trace[1].error as string;
-    // Truncated (not the full 5000 chars) and carries the omission marker.
     expect(errorText.length).toBeLessThan(long.length);
     expect(errorText).toContain('chars omitted');
   });
+
+  it('pairs parallel calls in one step with their outcomes by id', () => {
+    const trace = serializeSteps([
+      {
+        toolCalls: [
+          { toolCallId: 'a', toolName: 'getPage', input: {} },
+          { toolCallId: 'b', toolName: 'searchPages', input: {} },
+        ],
+        toolResults: [{ toolCallId: 'b', toolName: 'searchPages' }],
+        content: [
+          { type: 'tool-error', toolCallId: 'a', toolName: 'getPage', error: 'nope' },
+        ],
+      },
+    ]) as Array<Record<string, unknown>>;
+    // call a, outcome a (thrown), call b, outcome b (ok)
+    expect(trace).toHaveLength(4);
+    expect(trace[1]).toEqual({ toolName: 'getPage', error: 'nope', kind: 'thrown' });
+    expect(trace[3]).toEqual({ toolName: 'searchPages', ok: true });
+  });
+});
+
+// #490: every assistant row flushAssistant writes carries the v2 era marker so a
+// dual-shape diagnostic query can branch on the trace shape without inspecting it.
+describe('toolTraceVersion era marker (#490)', () => {
+  it('stamps metadata.toolTraceVersion = 2 on every flushed row', () => {
+    const seed = flushAssistant([], '', 'streaming');
+    expect(seed.metadata.toolTraceVersion).toBe(2);
+    const done = flushAssistant(
+      [
+        {
+          text: 'ok',
+          toolCalls: [{ toolCallId: 'c1', toolName: 'getPage', input: {} }],
+          toolResults: [{ toolCallId: 'c1', toolName: 'getPage' }],
+        },
+      ],
+      '',
+      'completed',
+      { finishReason: 'stop' },
+    );
+    expect(done.metadata.toolTraceVersion).toBe(2);
+  });
+});
+
+// #490 replay-budget signal helpers over persisted history.
+describe('lastAssistantContextTokens', () => {
+  const row = (
+    role: string,
+    metadata: Record<string, unknown> | null,
+  ): AiChatMessage => ({ role, metadata }) as unknown as AiChatMessage;
+
+  it('reads the most recent assistant turn contextTokens (provider fact)', () => {
+    const hist = [
+      row('user', null),
+      row('assistant', { contextTokens: 12000 }),
+      row('user', null),
+      row('assistant', { contextTokens: 41000 }),
+    ];
+    expect(lastAssistantContextTokens(hist)).toBe(41000);
+  });
+
+  it('returns undefined when the last assistant turn recorded no usage', () => {
+    const hist = [row('assistant', { error: 'boom' }), row('user', null)];
+    expect(lastAssistantContextTokens(hist)).toBeUndefined();
+    expect(lastAssistantContextTokens([])).toBeUndefined();
+  });
+});
+
+// #490 snapshotOpenPage fast-path: skip the full Markdown export + upsert when a
+// snapshot already exists at the page's CURRENT version (same updated_at instant).
+describe('snapshotOpenPage fast-path (#490)', () => {
+  function makeSvc(existingSnapshot: unknown, pageUpdatedAt: Date) {
+    const exportPageMarkdown = jest.fn(async () => '# md');
+    const upsert = jest.fn(async () => undefined);
+    const findByChatPage = jest.fn(async () => existingSnapshot);
+    const pageRepo = {
+      findById: jest.fn(async () => ({
+        id: 'p1',
+        workspaceId: 'ws1',
+        updatedAt: pageUpdatedAt,
+      })),
+    };
+    const svc = new AiChatService(
+      {} as never, // ai
+      {} as never, // aiChatRepo
+      {} as never, // aiChatMessageRepo
+      { findByChatPage, upsert } as never, // aiChatPageSnapshotRepo
+      {} as never, // aiSettings
+      { exportPageMarkdown } as never, // tools
+      {} as never, // mcpClients
+      {} as never, // aiAgentRoleRepo
+      pageRepo as never, // pageRepo
+      {} as never, // pageAccess
+      {} as never, // environment
+    );
+    return { svc, exportPageMarkdown, upsert, findByChatPage };
+  }
+
+  const args = () =>
+    [
+      'chat1',
+      'p1',
+      { id: 'ws1' } as never,
+      { id: 'u1' } as never,
+      'sess',
+    ] as const;
+
+  it('skips export + upsert when the snapshot is already at this page version', async () => {
+    const t = new Date('2026-07-07T10:00:00Z');
+    const { svc, exportPageMarkdown, upsert } = makeSvc(
+      { pageUpdatedAt: t, contentMd: '# md' },
+      t,
+    );
+    await (svc as unknown as { snapshotOpenPage: (...a: unknown[]) => Promise<void> })
+      .snapshotOpenPage(...args());
+    expect(exportPageMarkdown).not.toHaveBeenCalled();
+    expect(upsert).not.toHaveBeenCalled();
+  });
+
+  it('exports + upserts when the page advanced since the snapshot', async () => {
+    const { svc, exportPageMarkdown, upsert } = makeSvc(
+      { pageUpdatedAt: new Date('2026-07-07T10:00:00Z'), contentMd: 'old' },
+      new Date('2026-07-07T11:00:00Z'),
+    );
+    await (svc as unknown as { snapshotOpenPage: (...a: unknown[]) => Promise<void> })
+      .snapshotOpenPage(...args());
+    expect(exportPageMarkdown).toHaveBeenCalledTimes(1);
+    expect(upsert).toHaveBeenCalledTimes(1);
+  });
+
+  it('seeds (exports + upserts) on the first turn (no snapshot yet)', async () => {
+    const { svc, exportPageMarkdown, upsert } = makeSvc(
+      undefined,
+      new Date('2026-07-07T10:00:00Z'),
+    );
+    await (svc as unknown as { snapshotOpenPage: (...a: unknown[]) => Promise<void> })
+      .snapshotOpenPage(...args());
+    expect(exportPageMarkdown).toHaveBeenCalledTimes(1);
+    expect(upsert).toHaveBeenCalledTimes(1);
+  });
+});
+
+// #490 deferred-tool activation persisted across turns.
+describe('seedActivatedTools', () => {
+  const valid = new Set(['Search_web', 'getPageJson', 'diffPageVersions']);
+
+  it('seeds from persisted metadata, intersected with current valid names', () => {
+    expect(
+      seedActivatedTools(
+        { activatedTools: ['Search_web', 'getPageJson'] },
+        valid,
+      ),
+    ).toEqual(['Search_web', 'getPageJson']);
+  });
+
+  it('drops a stored tool that is no longer valid (allowlist/role changed)', () => {
+    // 'Habr_publish' was activated before but is not in the current allowlist.
+    expect(
+      seedActivatedTools({ activatedTools: ['Search_web', 'Habr_publish'] }, valid),
+    ).toEqual(['Search_web']);
+  });
+
+  it('is empty/robust for missing, non-array, or unknown-shaped metadata', () => {
+    expect(seedActivatedTools(undefined, valid)).toEqual([]);
+    expect(seedActivatedTools({}, valid)).toEqual([]);
+    expect(seedActivatedTools({ activatedTools: 'nope' }, valid)).toEqual([]);
+    expect(
+      seedActivatedTools({ activatedTools: [1, 'getPageJson', null] }, valid),
+    ).toEqual(['getPageJson']);
+  });
+
+  it('de-duplicates stored names', () => {
+    expect(
+      seedActivatedTools(
+        { activatedTools: ['getPageJson', 'getPageJson'] },
+        valid,
+      ),
+    ).toEqual(['getPageJson']);
+  });
+});
+
+describe('lastAssistantReplayOverflow', () => {
+  const row = (
+    role: string,
+    metadata: Record<string, unknown> | null,
+  ): AiChatMessage => ({ role, metadata }) as unknown as AiChatMessage;
+
+  it('is true only when the LAST assistant turn overflowed', () => {
+    expect(
+      lastAssistantReplayOverflow([
+        row('assistant', { replayOverflow: true }),
+        row('user', null),
+      ]),
+    ).toBe(true);
+    // A recovered (later, non-overflow) assistant turn clears it.
+    expect(
+      lastAssistantReplayOverflow([
+        row('assistant', { replayOverflow: true }),
+        row('user', null),
+        row('assistant', { contextTokens: 5 }),
+      ]),
+    ).toBe(false);
+    expect(lastAssistantReplayOverflow([])).toBe(false);
+  });
+
+  // #490 reactive recovery: a prior turn stamped `replayOverflow` must make the
+  // NEXT turn's effective budget the AGGRESSIVE 0.5x cut — that harder trim is
+  // what un-bricks a chat that just 400'd on the context window. This exercises
+  // the exact wiring the service uses: read the stamp, then scale the threshold.
+  it('#490: a prior replayOverflow drives the next turn to the 0.5x aggressive budget', () => {
+    const history = [
+      row('assistant', { replayOverflow: true }),
+      row('user', null),
+    ];
+    const priorOverflowed = lastAssistantReplayOverflow(history);
+    expect(priorOverflowed).toBe(true);
+    // Base budget 100k -> aggressive recovery halves it to 50k this turn.
+    expect(resolveEffectiveReplayThreshold(100_000, priorOverflowed)).toBe(50_000);
+    // Odd base floors, not rounds.
+    expect(resolveEffectiveReplayThreshold(99_999, true)).toBe(49_999);
+    // No prior overflow -> the base budget is used verbatim (no aggressive cut).
+    expect(resolveEffectiveReplayThreshold(100_000, false)).toBe(100_000);
+    // An explicit off-switch (null) is never overridden, even on recovery.
+    expect(resolveEffectiveReplayThreshold(null, true)).toBeNull();
+  });
 });
 
 describe('rowToUiMessage', () => {
@@ -618,6 +930,23 @@ describe('flushAssistant', () => {
     expect(flushed.metadata.error).toBe('boom');
   });
 
+  // #490 observability: the replay budgeter's decision is stamped on the turn.
+  it('records replayTrimmedToTokens + replayOverflow when provided', () => {
+    const f = flushAssistant([], '', 'error', {
+      error: 'ctx',
+      replayTrimmedToTokens: 42_000,
+      replayOverflow: true,
+    });
+    expect(f.metadata.replayTrimmedToTokens).toBe(42_000);
+    expect(f.metadata.replayOverflow).toBe(true);
+  });
+
+  it('omits the replay metadata when not provided', () => {
+    const f = flushAssistant([], '', 'completed', { finishReason: 'stop' });
+    expect('replayTrimmedToTokens' in f.metadata).toBe(false);
+    expect('replayOverflow' in f.metadata).toBe(false);
+  });
+
   // #274 observability: the page-change diff the agent saw this turn is persisted
   // to metadata.pageChanged when a non-empty diff was injected, and omitted when
   // the diff is empty/whitespace or the arg is not supplied.
@@ -1315,8 +1644,12 @@ describe('AiChatService page-change lifecycle (#274)', () => {
 describe('isInterruptResume', () => {
   // history tail is the just-inserted user row; [len-2] is the previous turn.
   const withPrev = (
-    prev: { role: string; status?: string | null } | null,
+    prev: {
-  ): Array<{ role: string; status?: string | null }> =>
+      role: string;
+      status?: string | null;
+      metadata?: unknown;
+    } | null,
+  ): Array<{ role: string; status?: string | null; metadata?: unknown }> =>
     prev
       ? [prev, { role: 'user', status: null }]
       : [{ role: 'user', status: null }];
@@ -1357,6 +1690,33 @@ describe('isInterruptResume', () => {
   it('false when there is no preceding turn (only the new user row)', () => {
     expect(isInterruptResume(withPrev(null), true)).toBe(false);
   });
+
+  it('#487 EXCLUDES a reconcile stamp (finalizeFailed) — not a genuine interruption', () => {
+    // A row a reconcile settled to 'aborted' carries metadata.finalizeFailed. It
+    // must NOT be treated as an interrupt-resume (that would inject a false
+    // "you were interrupted" note), even though its status is 'aborted'.
+    expect(
+      isInterruptResume(
+        withPrev({
+          role: 'assistant',
+          status: 'aborted',
+          metadata: { finalizeFailed: true },
+        }),
+        true,
+      ),
+    ).toBe(false);
+    // A genuine abort (no finalizeFailed) still counts.
+    expect(
+      isInterruptResume(
+        withPrev({
+          role: 'assistant',
+          status: 'aborted',
+          metadata: { parts: [] },
+        }),
+        true,
+      ),
+    ).toBe(true);
+  });
 });
 
 /**
@@ -1409,7 +1769,7 @@ describe('AiChatService.stream — resumable pipe options (#184 phase 1.5)', ()
   }
 
   // Wire only the deps reached on the way to the pipe call, plus a spy registry.
-  function makeService(opts: { resumable: boolean }) {
+  function makeService(opts: { resumable: boolean; history?: unknown[] }) {
     const aiChatRepo = {
       findById: jest.fn(async () => ({ id: 'chat-1', workspaceId: 'ws-1' })),
       insert: jest.fn(),
@@ -1417,8 +1777,11 @@ describe('AiChatService.stream — resumable pipe options (#184 phase 1.5)', ()
     const aiChatMessageRepo = {
       // Both the user insert and the assistant seed return the same row id.
       insert: jest.fn(async () => ({ id: 'msg-1' })),
-      findAllByChat: jest.fn(async () => []),
+      findAllByChat: jest.fn(async () => opts.history ?? []),
       update: jest.fn(async () => ({ id: 'msg-1' })),
+      // #487: the terminal owner-write + the opportunistic reconcile query.
+      finalizeOwner: jest.fn(async () => ({ id: 'msg-1' })),
+      findStreamingWithTerminalRun: jest.fn(async () => []),
     };
     const aiSettings = { resolve: jest.fn(async () => ({})) };
     const tools = { forUser: jest.fn(async () => ({})) };
@@ -1453,7 +1816,7 @@ describe('AiChatService.stream — resumable pipe options (#184 phase 1.5)', ()
       } as never,
       streamRegistry as never,
     );
-    return { svc, streamRegistry };
+    return { svc, streamRegistry, aiChatMessageRepo };
   }
 
   const body = {
@@ -1536,6 +1899,86 @@ describe('AiChatService.stream — resumable pipe options (#184 phase 1.5)', ()
     await expect(drive(svc, makeRunHooks())).rejects.toThrow('boom');
     expect(streamRegistry.abortEntry).toHaveBeenCalledWith('chat-1', 'run-1');
   });
+
+  // #489 REGRESSION (against the REAL convertToModelMessages — not mocked here):
+  // a persisted history row whose parts contain a `null` element makes the real
+  // convertToModelMessages THROW ("Cannot read properties of null"). Pre-fix that
+  // 500-ed every turn forever and each retry appended a duplicate user row. The
+  // fix converts BEFORE the insert and isolates the poisoned row per-row, degrading
+  // it to text with a "[tool context omitted]" marker. Assert the turn still runs,
+  // the marker reaches the model, and exactly ONE user row is inserted.
+  it('#489: a poisoned OLD-history row keeps the chat working; the marker reaches the model; one user insert', async () => {
+    const { svc, aiChatMessageRepo } = makeService({
+      resumable: false,
+      history: [
+        {
+          id: 'old-1',
+          role: 'assistant',
+          content: 'earlier answer',
+          // A null part is the poison: rowToUiMessage keeps it (the array is
+          // non-empty) and the real convertToModelMessages throws on it.
+          metadata: { parts: [{ type: 'text', text: 'earlier answer' }, null] },
+          status: 'completed',
+        },
+      ],
+    });
+    // Must NOT throw — the poisoned row is degraded, not fatal.
+    await drive(svc, makeRunHooks());
+    expect(streamTextMock).toHaveBeenCalledTimes(1);
+    const passedMessages = streamTextMock.mock.calls[0][0].messages;
+    const serialized = JSON.stringify(passedMessages);
+    // The model sees the truncation marker (silent tool-context loss is not ok)
+    // AND the row's readable text is preserved alongside it.
+    expect(serialized).toContain('[tool context omitted]');
+    expect(serialized).toContain('earlier answer');
+    // Exactly ONE user row inserted (no duplicate), inserted AFTER conversion.
+    const userInserts = aiChatMessageRepo.insert.mock.calls
+      .map((c: unknown[]) => c[0] as { role?: string })
+      .filter((r) => r.role === 'user');
+    expect(userInserts).toHaveLength(1);
+  });
+
+  // #489: client-supplied non-text parts (a tool-part in `input-available`, the
+  // exact "bricking" payload) are dropped ON RECEIPT — never persisted — so they
+  // can never poison future turns. Only the text survives into metadata.parts.
+  it('#489: a non-text client part is stripped before persist (only text survives)', async () => {
+    const { svc, aiChatMessageRepo } = makeService({ resumable: false });
+    await svc.stream({
+      user: { id: 'u1' } as never,
+      workspace: { id: 'ws-1' } as never,
+      sessionId: 's1',
+      body: {
+        chatId: 'chat-1',
+        messages: [
+          {
+            id: 'm1',
+            role: 'user',
+            parts: [
+              { type: 'text', text: 'hello' },
+              // untrusted tool-part — must be dropped, never persisted
+              {
+                type: 'tool-getPage',
+                toolCallId: 't1',
+                state: 'input-available',
+                input: { pageId: 'p' },
+              },
+            ],
+          },
+        ],
+      } as never,
+      res: makeRes() as never,
+      signal: new AbortController().signal,
+      model: {} as never,
+      role: null,
+      runHooks: makeRunHooks() as never,
+    });
+    const userInsert = aiChatMessageRepo.insert.mock.calls
+      .map((c: unknown[]) => c[0] as { role?: string; metadata?: unknown })
+      .find((r) => r.role === 'user');
+    const parts = (userInsert?.metadata as { parts?: Array<{ type: string }> })
+      ?.parts;
+    expect(parts).toEqual([{ type: 'text', text: 'hello' }]);
+  });
 });
 
 /**
@@ -1623,6 +2066,19 @@ describe('AiChatService.stream — token-degeneration reaction (#444)', () => {
           return { id };
         },
       ),
+      // #487: the terminal owner-write records into the SAME `updated` recorder so
+      // assertions on the terminal 'completed'/'error'/'aborted' write still hold.
+      finalizeOwner: jest.fn(
+        async (
+          id: string,
+          workspaceId: string,
+          patch: Record<string, unknown>,
+        ) => {
+          updated.push({ id, workspaceId, patch });
+          return { id };
+        },
+      ),
+      findStreamingWithTerminalRun: jest.fn(async () => []),
     };
     const aiSettings = { resolve: jest.fn(async () => ({})) };
     const tools = { forUser: jest.fn(async () => ({})) };
@@ -1882,3 +2338,148 @@ describe('AiChatService.stream — token-degeneration reaction (#444)', () => {
     expect(patch.content).not.toContain(STEP_LIMIT_NO_ANSWER_MARKER);
   });
 });
+
+// #487 F3 — the reconcile() / reconcileChat() ORCHESTRATORS. The individual
+// clauses are exercised elsewhere; these pin the production orchestration the
+// per-clause specs do not: the clause ORDER, the per-clause try/catch ISOLATION
+// (one clause throwing must NOT abort the others), and reconcileChat() (which runs
+// at the start of every turn and was entirely uncovered).
+describe('AiChatService.reconcile / reconcileChat orchestrators (#487 F3)', () => {
+  let warnSpy: jest.SpyInstance;
+  beforeEach(() => {
+    // Silence the intentional clause-failure warnings (kept out of test output).
+    warnSpy = jest
+      .spyOn(Logger.prototype, 'warn')
+      .mockImplementation(() => undefined);
+  });
+  afterEach(() => {
+    warnSpy.mockRestore();
+  });
+
+  function makeService(opts: {
+    messageRepo?: Record<string, jest.Mock>;
+    runService?: Record<string, jest.Mock>;
+  }) {
+    const aiChatMessageRepo = {
+      findStreamingWithTerminalRun: jest.fn(async () => []),
+      stampTerminalIfStreaming: jest.fn(async () => undefined),
+      sweepStreamingWithoutActiveRun: jest.fn(async () => 0),
+      ...(opts.messageRepo ?? {}),
+    };
+    const aiChatRunService = opts.runService
+      ? {
+          zombieRunIds: jest.fn(() => []),
+          settleZombie: jest.fn(async () => true),
+          reconcileStaleRuns: jest.fn(async () => 0),
+          ...opts.runService,
+        }
+      : undefined;
+    const svc = new AiChatService(
+      {} as never, // ai
+      {} as never, // aiChatRepo
+      aiChatMessageRepo as never,
+      {} as never, // aiChatPageSnapshotRepo
+      {} as never, // aiSettings
+      {} as never, // tools
+      {} as never, // mcpClients
+      {} as never, // aiAgentRoleRepo
+      {} as never, // pageRepo
+      {} as never, // pageAccess
+      {} as never, // environment
+      {} as never, // streamRegistry
+      aiChatRunService as never, // aiChatRunService (#487)
+    );
+    return { svc, aiChatMessageRepo, aiChatRunService };
+  }
+
+  it('reconcile() fires all four clauses IN ORDER (a -> b -> c -> d)', async () => {
+    const order: string[] = [];
+    const { svc } = makeService({
+      messageRepo: {
+        findStreamingWithTerminalRun: jest.fn(async () => {
+          order.push('b:find');
+          return [
+            { messageId: 'm1', workspaceId: 'ws1', runStatus: 'succeeded' },
+          ];
+        }),
+        stampTerminalIfStreaming: jest.fn(async () => {
+          order.push('b:stamp');
+        }),
+        sweepStreamingWithoutActiveRun: jest.fn(async () => {
+          order.push('d');
+          return 0;
+        }),
+      },
+      runService: {
+        zombieRunIds: jest.fn(() => ['z1']),
+        settleZombie: jest.fn(async () => {
+          order.push('a');
+          return true;
+        }),
+        reconcileStaleRuns: jest.fn(async () => {
+          order.push('c');
+          return 0;
+        }),
+      },
+    });
+
+    await svc.reconcile();
+
+    expect(order).toEqual(['a', 'b:find', 'b:stamp', 'c', 'd']);
+  });
+
+  it('a clause that THROWS does not abort the remaining clauses (per-clause try/catch isolation)', async () => {
+    const { svc, aiChatMessageRepo, aiChatRunService } = makeService({
+      messageRepo: {
+        // Clause (b) blows up mid-reconcile.
+        findStreamingWithTerminalRun: jest.fn(async () => {
+          throw new Error('clause b DB blip');
+        }),
+      },
+      runService: {
+        zombieRunIds: jest.fn(() => ['z1']),
+      },
+    });
+
+    // reconcile() must SETTLE (the clause-b failure is swallowed), not reject.
+    await expect(svc.reconcile()).resolves.toBeUndefined();
+
+    // (a) ran before (b); crucially (c) and (d) STILL ran despite (b) throwing —
+    // the property a missing try/catch would break. MUTATION-VERIFY: drop clause
+    // (b)'s try/catch and this reddens (the throw propagates, skipping c + d).
+    expect(aiChatRunService!.settleZombie).toHaveBeenCalled(); // (a)
+    expect(aiChatRunService!.reconcileStaleRuns).toHaveBeenCalled(); // (c)
+    expect(
+      aiChatMessageRepo.sweepStreamingWithoutActiveRun,
+    ).toHaveBeenCalled(); // (d)
+  });
+
+  it('reconcileChat() settles THIS chat\'s stuck streaming rows by their run status', async () => {
+    const { svc, aiChatMessageRepo } = makeService({
+      messageRepo: {
+        findStreamingWithTerminalRun: jest.fn(async () => [
+          { messageId: 'm1', workspaceId: 'ws1', runStatus: 'failed' },
+          { messageId: 'm2', workspaceId: 'ws1', runStatus: 'succeeded' },
+        ]),
+      },
+    });
+
+    await svc.reconcileChat('chat-1', 'ws1');
+
+    // Scoped to THIS chat and bounded at 50 (the user-facing opportunistic path).
+    expect(
+      aiChatMessageRepo.findStreamingWithTerminalRun,
+    ).toHaveBeenCalledWith(50, { chatId: 'chat-1', workspaceId: 'ws1' });
+    // failed-run -> 'error'; every other terminal status -> 'aborted'.
+    expect(aiChatMessageRepo.stampTerminalIfStreaming).toHaveBeenCalledWith(
+      'm1',
+      'ws1',
+      'error',
+    );
+    expect(aiChatMessageRepo.stampTerminalIfStreaming).toHaveBeenCalledWith(
+      'm2',
+      'ws1',
+      'aborted',
+    );
+  });
+});

apps/server/src/core/ai-chat/ai-chat.write-volume.int-spec.ts

@@ -0,0 +1,209 @@
+import { randomBytes } from 'crypto';
+import { Client } from 'pg';
+import { flushAssistant, serializeSteps } from './ai-chat.service';
+
+/**
+ * #490 write-volume regression — an OBSERVABLE-PROPERTY test on a LIVE Postgres,
+ * not "bytes through a mock repo" (a mock measures exactly the thing that does not
+ * hurt). It drives a realistic 50-step run where each step returns a ~100 KB tool
+ * output and, at every `onStepFinish`, UPDATEs the assistant row the way the
+ * service does — then reads the REAL write volume via the `pg_current_wal_lsn()`
+ * delta around the run.
+ *
+ * The property proven: v2 stores each tool OUTPUT only in `metadata.parts`, no
+ * longer ALSO in the `tool_calls` trace. So:
+ *   1. the trace (`tool_calls`) column's write volume is now O(Σ steps) — tiny,
+ *      linear outcome flags — vs the pre-#490 O(N²) that re-persisted every prior
+ *      output on every step; and
+ *   2. the FULL-row write volume drops sharply (the duplicated output copy is gone).
+ *
+ * Connects to the local gitmost test Postgres (docker `gitmost-test-pg` on :5432);
+ * SKIPS cleanly when that DB is not reachable so it never breaks a DB-less CI.
+ */
+const CONN =
+  process.env.WAL_TEST_DATABASE_URL ??
+  'postgresql://docmost:docmost_dev_pw@localhost:5432/docmost';
+
+// A step whose tool output is ~100 KB (a page read), in the SDK StepLike shape.
+// The body is INCOMPRESSIBLE random text — a `'x'.repeat()` filler would TOAST-
+// compress to nothing and hide the real write volume (a page body does not).
+function makeStep(i: number, outputBytes = 100_000) {
+  const body = randomBytes(Math.ceil(outputBytes * 0.75)).toString('base64');
+  return {
+    text: `step ${i} reasoning`,
+    toolCalls: [{ toolCallId: `c${i}`, toolName: 'getPage', input: { id: `p${i}` } }],
+    toolResults: [
+      {
+        toolCallId: `c${i}`,
+        toolName: 'getPage',
+        output: { id: `p${i}`, title: `Page ${i}`, body },
+      },
+    ],
+  };
+}
+
+// The pre-#490 (v1) trace: outputs stored a SECOND time in `tool_calls`
+// (the duplication #490 removed). Mirrors the OLD serializeSteps shape.
+function v1Trace(steps: ReturnType<typeof makeStep>[]): unknown {
+  const calls: unknown[] = [];
+  for (const s of steps) {
+    for (const c of s.toolCalls) calls.push({ toolName: c.toolName, input: c.input });
+    for (const r of s.toolResults)
+      calls.push({ toolName: r.toolName, output: r.output });
+  }
+  return calls;
+}
+
+async function walDelta(
+  client: Client,
+  fn: () => Promise<void>,
+): Promise<number> {
+  const before = (await client.query('SELECT pg_current_wal_lsn() AS l')).rows[0]
+    .l as string;
+  await fn();
+  // NOTE: do NOT pg_switch_wal() here — a segment switch pads the LSN to the next
+  // 16 MB boundary and would swamp the actual write delta. The raw LSN advances by
+  // the bytes of WAL emitted, which is exactly what we want to measure.
+  const after = (await client.query('SELECT pg_current_wal_lsn() AS l')).rows[0]
+    .l as string;
+  return Number(
+    (await client.query('SELECT pg_wal_lsn_diff($1,$2) AS d', [after, before]))
+      .rows[0].d,
+  );
+}
+
+describe('#490 write-volume on a live Postgres (pg_current_wal_lsn delta)', () => {
+  let client: Client | undefined;
+  let available = false;
+
+  beforeAll(async () => {
+    try {
+      client = new Client(CONN);
+      await client.connect();
+      await client.query('SELECT pg_current_wal_lsn()');
+      available = true;
+    } catch {
+      available = false;
+      client = undefined;
+    }
+  });
+
+  afterAll(async () => {
+    await client?.end().catch(() => undefined);
+  });
+
+  const STEPS = 50;
+
+  it('v2 trace write volume is O(Σ steps) — a tiny fraction of the v1 duplicate', async () => {
+    if (!available || !client) {
+      console.warn('SKIP: gitmost-test-pg not reachable; skipping WAL test.');
+      return;
+    }
+    const c = client;
+    // Isolated table so we measure only the tool_calls (trace) column's writes.
+    await c.query('DROP TABLE IF EXISTS _wal_trace');
+    await c.query('CREATE TABLE _wal_trace(id int primary key, tool_calls jsonb)');
+    await c.query("INSERT INTO _wal_trace VALUES (1, '[]'::jsonb)");
+
+    const steps: ReturnType<typeof makeStep>[] = [];
+
+    // v1: each step re-persists ALL prior outputs into the trace (the O(N²) churn).
+    const v1 = await walDelta(c, async () => {
+      const acc: ReturnType<typeof makeStep>[] = [];
+      for (let i = 0; i < STEPS; i++) {
+        acc.push(makeStep(i));
+        await c.query('UPDATE _wal_trace SET tool_calls=$1 WHERE id=1', [
+          JSON.stringify(v1Trace(acc)),
+        ]);
+      }
+      steps.push(...acc);
+    });
+
+    await c.query("UPDATE _wal_trace SET tool_calls='[]'::jsonb WHERE id=1");
+
+    // v2: the REAL serializeSteps — outcome flags only, NO outputs.
+    const v2 = await walDelta(c, async () => {
+      const acc: ReturnType<typeof makeStep>[] = [];
+      for (let i = 0; i < STEPS; i++) {
+        acc.push(makeStep(i));
+        await c.query('UPDATE _wal_trace SET tool_calls=$1 WHERE id=1', [
+          JSON.stringify(serializeSteps(acc)),
+        ]);
+      }
+    });
+
+    await c.query('DROP TABLE IF EXISTS _wal_trace');
+
+    // eslint-disable-next-line no-console
+    console.log(
+      `[#490 WAL] trace column over ${STEPS} steps: v1=${(v1 / 1e6).toFixed(1)}MB ` +
+        `v2=${(v2 / 1e6).toFixed(2)}MB (${(v1 / v2).toFixed(0)}x smaller)`,
+    );
+
+    // The trace no longer carries outputs: v2 is a tiny fraction of v1's WAL.
+    expect(v2).toBeLessThan(v1 * 0.1);
+    // And v2's trace WAL is small in absolute terms — O(Σ steps) of flags, not
+    // O(N² × output). 50 steps of ~40-byte flags is well under a few MB of WAL.
+    expect(v2).toBeLessThan(5_000_000);
+    // v1's duplicate alone is huge (≈ the 100 KB output re-written N² times).
+    expect(v1).toBeGreaterThan(50_000_000);
+  }, 120_000);
+
+  it('the full assistant row write drops sharply once the duplicate is gone', async () => {
+    if (!available || !client) return;
+    const c = client;
+    await c.query('DROP TABLE IF EXISTS _wal_full');
+    await c.query(
+      'CREATE TABLE _wal_full(id int primary key, content text, tool_calls jsonb, metadata jsonb, status text)',
+    );
+    await c.query("INSERT INTO _wal_full VALUES (1, '', '[]'::jsonb, '{}'::jsonb, 'streaming')");
+
+    const writeRow = async (patch: {
+      content: string;
+      toolCalls: unknown;
+      metadata: unknown;
+      status: string;
+    }) =>
+      c.query(
+        'UPDATE _wal_full SET content=$1, tool_calls=$2, metadata=$3, status=$4 WHERE id=1',
+        [
+          patch.content,
+          JSON.stringify(patch.toolCalls ?? null),
+          JSON.stringify(patch.metadata),
+          patch.status,
+        ],
+      );
+
+    // v2 (real flushAssistant): outputs live once, in metadata.parts.
+    const v2 = await walDelta(c, async () => {
+      const acc: ReturnType<typeof makeStep>[] = [];
+      for (let i = 0; i < STEPS; i++) {
+        acc.push(makeStep(i));
+        await writeRow(flushAssistant(acc as never, '', 'streaming'));
+      }
+    });
+
+    await c.query("UPDATE _wal_full SET content='', tool_calls='[]'::jsonb, metadata='{}'::jsonb WHERE id=1");
+
+    // v1: same row PLUS the duplicated outputs in the trace column.
+    const v1 = await walDelta(c, async () => {
+      const acc: ReturnType<typeof makeStep>[] = [];
+      for (let i = 0; i < STEPS; i++) {
+        acc.push(makeStep(i));
+        const f = flushAssistant(acc as never, '', 'streaming');
+        await writeRow({ ...f, toolCalls: v1Trace(acc) });
+      }
+    });
+
+    await c.query('DROP TABLE IF EXISTS _wal_full');
+
+    // eslint-disable-next-line no-console
+    console.log(
+      `[#490 WAL] full row over ${STEPS} steps: v1=${(v1 / 1e6).toFixed(1)}MB ` +
+        `v2=${(v2 / 1e6).toFixed(1)}MB (saved ${((1 - v2 / v1) * 100).toFixed(0)}%)`,
+    );
+
+    // Removing the duplicated trace copy is a large, real write-volume reduction.
+    expect(v2).toBeLessThan(v1 * 0.75);
+  }, 120_000);
+});

apps/server/src/core/ai-chat/chat-markdown.util.spec.ts

@@ -1,5 +1,10 @@
-import { buildChatMarkdown, normalizeLang } from './chat-markdown.util';
+import {
+  buildChatMarkdown,
+  normalizeLang,
+  labelledToolNames,
+} from './chat-markdown.util';
 import type { AiChatMessage } from '@docmost/db/types/entity.types';
+import { SHARED_TOOL_SPECS } from '../../../../../packages/mcp/src/tool-specs';
 
 /**
  * normalizeLang: the client sends `i18n.language` — a FULL locale tag like
@@ -455,3 +460,43 @@ describe('buildChatMarkdown (server) — structure', () => {
     expect(md).toContain('````');
   });
 });
+
+/**
+ * #494 — REVERSE drift-guard for the export's friendly tool labels. A label keyed
+ * by a tool name that no longer exists silently degrades to the generic
+ * "Ran tool <name>" line; nothing reddened before. This asserts every labelled
+ * name is a real in-app tool and that both languages label the same set.
+ */
+describe('tool-label parity (#494)', () => {
+  // In-app tool names come from the shared registry (inAppKey, excluding
+  // mcpOnly specs) PLUS the inline in-app-only tools that carry a friendly label.
+  // The only labelled inline tool is the hybrid semantic search.
+  const INLINE_INAPP_LABELLED = new Set(['searchPages']);
+
+  function validInAppToolNames(): Set<string> {
+    const names = new Set<string>(INLINE_INAPP_LABELLED);
+    for (const spec of Object.values(SHARED_TOOL_SPECS)) {
+      if ((spec as { mcpOnly?: boolean }).mcpOnly) continue;
+      names.add((spec as { inAppKey: string }).inAppKey);
+    }
+    return names;
+  }
+
+  it('en and ru label the SAME set of tools', () => {
+    expect(labelledToolNames('en').sort()).toEqual(
+      labelledToolNames('ru').sort(),
+    );
+  });
+
+  it('every labelled tool name is a real in-app tool', () => {
+    const valid = validInAppToolNames();
+    const dead = labelledToolNames('en').filter((n) => !valid.has(n));
+    expect(dead).toEqual([]);
+  });
+
+  it('the guard REDDENS for an unknown label key (mutation check)', () => {
+    const valid = validInAppToolNames();
+    // A hypothetical renamed-away label must be caught.
+    expect(valid.has('getPageRenamedAway')).toBe(false);
+  });
+});

apps/server/src/core/ai-chat/chat-markdown.util.ts

@@ -75,7 +75,7 @@ const LABELS: Record<
       searchPages: 'Searched pages',
       getPage: 'Read page',
       createPage: 'Created page',
-      updatePageContent: 'Updated page',
+      updatePageMarkdown: 'Updated page',
       renamePage: 'Renamed page',
       movePage: 'Moved page',
       deletePage: 'Deleted page (to trash)',
@@ -96,7 +96,7 @@ const LABELS: Record<
       searchPages: 'Искал по страницам',
       getPage: 'Прочитал страницу',
       createPage: 'Создал страницу',
-      updatePageContent: 'Обновил страницу',
+      updatePageMarkdown: 'Обновил страницу',
       renamePage: 'Переименовал страницу',
       movePage: 'Переместил страницу',
       deletePage: 'Удалил страницу (в корзину)',
@@ -154,6 +154,17 @@ function toolLabel(name: string, lang: ExportLang): string {
   return LABELS[lang].tools[name] ?? LABELS[lang].ranTool(name);
 }
 
+/**
+ * The tool names that carry a hand-written friendly export label, per language.
+ * Exported for the drift-guard (#494): a label keyed by a tool name that no
+ * longer exists is a DEAD entry (the tool was renamed and now silently falls back
+ * to the generic `ranTool(name)` line). The guard asserts every key here is a
+ * real in-app tool AND that the two languages label the SAME set of tools.
+ */
+export function labelledToolNames(lang: ExportLang): string[] {
+  return Object.keys(LABELS[lang].tools);
+}
+
 /**
  * Stringify an arbitrary tool input/output value for a fenced block. Strings
  * pass through as-is; everything else is pretty-printed JSON, falling back to

apps/server/src/core/ai-chat/external-mcp/dto/create-mcp-server.dto.ts

@@ -37,10 +37,13 @@ export class CreateMcpServerDto {
   @IsObject()
   headers?: Record<string, string>;
 
+  // Omit/null => no restriction; `[]` is persisted verbatim and means deny-all
+  // (zero tools) since #476. @IsOptional() skips validation for null as well,
+  // so an explicit null is accepted.
   @IsOptional()
   @IsArray()
   @IsString({ each: true })
-  toolAllowlist?: string[];
+  toolAllowlist?: string[] | null;
 
   // Admin-authored guidance ("how/when to use this server's tools") injected
   // into the agent system prompt next to the tool descriptions (#180). Trusted,

apps/server/src/core/ai-chat/external-mcp/dto/update-mcp-server.dto.ts

@@ -38,10 +38,13 @@ export class UpdateMcpServerDto {
   @IsObject()
   headers?: Record<string, string>;
 
+  // Absent => unchanged; null => no restriction; `[]` is persisted verbatim
+  // and means deny-all (zero tools) since #476. @IsOptional() skips validation
+  // for null as well, so an explicit null is accepted.
   @IsOptional()
   @IsArray()
   @IsString({ each: true })
-  toolAllowlist?: string[];
+  toolAllowlist?: string[] | null;
 
   // Admin-authored prompt guidance (#180). Absent => unchanged; blank => cleared
   // (stored as null by the repo). Capped to bound prompt/token size.

apps/server/src/core/ai-chat/external-mcp/mcp-allowlist-filter.spec.ts

@@ -0,0 +1,169 @@
+import { type Tool } from 'ai';
+import { McpClientsService } from './mcp-clients.service';
+
+/**
+ * Tool-allowlist filtering semantics on the merged external toolset (#476).
+ *
+ * COVERAGE CHOICE (documented per issue #476): the full corrupt-row chain
+ * (DB value -> repo normalizeRow -> toolsFor filter) is covered on TWO levels
+ * instead of one live-stub-MCP-server integration test:
+ *   (a) apps/server/test/integration/ai-mcp-server-repo.int-spec.ts pins the
+ *       repo read/write semantics against a real Postgres — `[]` round-trips
+ *       as jsonb `[]`, a present-but-corrupt value fails CLOSED to `[]` with
+ *       an error log;
+ *   (b) THIS spec pins what the toolset builder does with the repo's output —
+ *       null = unrestricted, `['alpha']` = only alpha, `[]` (including the
+ *       corrupt-row fallback) = ZERO tools.
+ * Together they prove the end-to-end property "corrupt/empty allowlist can
+ * never widen to all tools" without a live stub HTTP MCP server.
+ *
+ * The drive path mirrors mcp-namespacing.spec.ts: stub the repo's listEnabled,
+ * spy the private `connect` to return a fake client, inspect the merged keys.
+ */
+
+function fakeTool(): Tool {
+  return { description: 'x', inputSchema: undefined } as unknown as Tool;
+}
+
+interface FakeServer {
+  id: string;
+  name: string;
+  transport: string;
+  url: string;
+  headersEnc: string | null;
+  toolAllowlist: string[] | null;
+}
+
+function server(
+  over: Partial<FakeServer> & { id: string; name: string },
+): FakeServer {
+  return {
+    transport: 'http',
+    url: 'https://example.com/mcp',
+    headersEnc: null,
+    toolAllowlist: null,
+    ...over,
+  };
+}
+
+/**
+ * Build a service whose repo returns `servers` and whose fake clients expose
+ * `rawTools` from tools(). Returns the merged tool keys produced by toolsFor.
+ */
+async function mergedKeysFor(
+  servers: FakeServer[],
+  rawTools: Record<string, Tool>,
+): Promise<string[]> {
+  const repoStub = {
+    listEnabled: jest.fn().mockResolvedValue(servers),
+  };
+  const service = new McpClientsService(repoStub as never, {} as never);
+
+  jest
+    .spyOn(
+      service as unknown as { connect: (s: FakeServer) => unknown },
+      'connect',
+    )
+    .mockImplementation(() =>
+      Promise.resolve({
+        tools: () => Promise.resolve(rawTools),
+        close: () => Promise.resolve(),
+      }),
+    );
+
+  const toolset = await service.toolsFor('ws-1');
+  // Release the lease so the service does not hold the fake clients open.
+  await Promise.all(toolset.clients.map((c) => c.close()));
+  return Object.keys(toolset.tools);
+}
+
+describe('external MCP tool-allowlist filtering (via toolsFor, #476)', () => {
+  afterEach(() => jest.restoreAllMocks());
+
+  const RAW = () => ({
+    alpha: fakeTool(),
+    beta: fakeTool(),
+    gamma: fakeTool(),
+  });
+
+  it("['alpha'] lets ONLY alpha through", async () => {
+    const keys = await mergedKeysFor(
+      [server({ id: 'id-1', name: 'srv', toolAllowlist: ['alpha'] })],
+      RAW(),
+    );
+    expect(keys).toEqual(['srv_alpha']);
+  });
+
+  it('null (no restriction) lets every tool through', async () => {
+    const keys = await mergedKeysFor(
+      [server({ id: 'id-1', name: 'srv', toolAllowlist: null })],
+      RAW(),
+    );
+    expect(keys.sort()).toEqual(['srv_alpha', 'srv_beta', 'srv_gamma']);
+  });
+
+  it('[] (deny-all) yields ZERO tools — an empty array is authoritative, not falsy (#476)', async () => {
+    // This is the regression the #476 change guards: `[]` used to fall through
+    // the old `allow.length > 0` check and expose ALL tools. It must expose NONE.
+    const keys = await mergedKeysFor(
+      [server({ id: 'id-1', name: 'srv', toolAllowlist: [] })],
+      RAW(),
+    );
+    expect(keys).toEqual([]);
+  });
+
+  it('the corrupt-row fallback ([] from the repo) also yields ZERO tools (#476)', async () => {
+    // The repo turns a present-but-corrupt tool_allowlist into `[]` (fail-closed,
+    // see normalizeRow in ai-mcp-server.repo.ts + the int-spec); this pins that
+    // the toolset builder honours that fallback as deny-all rather than allow-all.
+    const corruptFallback: string[] = [];
+    const keys = await mergedKeysFor(
+      [server({ id: 'id-1', name: 'srv', toolAllowlist: corruptFallback })],
+      RAW(),
+    );
+    expect(keys).toEqual([]);
+  });
+
+  it('allowlisted names not exposed by the server are ignored (no phantom tools)', async () => {
+    const keys = await mergedKeysFor(
+      [
+        server({
+          id: 'id-1',
+          name: 'srv',
+          toolAllowlist: ['alpha', 'does-not-exist'],
+        }),
+      ],
+      RAW(),
+    );
+    expect(keys).toEqual(['srv_alpha']);
+  });
+
+  it('a deny-all server contributes no prompt instructions (0 tools merged)', async () => {
+    const repoStub = {
+      listEnabled: jest.fn().mockResolvedValue([
+        {
+          ...server({ id: 'id-1', name: 'srv', toolAllowlist: [] }),
+          instructions: 'use the tools wisely',
+        },
+      ]),
+    };
+    const service = new McpClientsService(repoStub as never, {} as never);
+    jest
+      .spyOn(
+        service as unknown as { connect: (s: FakeServer) => unknown },
+        'connect',
+      )
+      .mockImplementation(() =>
+        Promise.resolve({
+          tools: () => Promise.resolve(RAW()),
+          close: () => Promise.resolve(),
+        }),
+      );
+
+    const toolset = await service.toolsFor('ws-1');
+    await Promise.all(toolset.clients.map((c) => c.close()));
+    expect(Object.keys(toolset.tools)).toEqual([]);
+    // mergeNamespaced reported 0 contributed tools, so no guidance is attached.
+    expect(toolset.instructions).toEqual([]);
+  });
+});

apps/server/src/core/ai-chat/external-mcp/mcp-clients.recovery.spec.ts

@@ -0,0 +1,261 @@
+import { errors } from 'undici';
+import {
+  McpClientsService,
+  isRetryableConnectError,
+} from './mcp-clients.service';
+
+/**
+ * #489 — external-MCP in-run transport recovery.
+ *
+ * The transport-error classification + retry gate are exercised against the REAL
+ * undici error CLASSES prod throws (`errors.SocketError` / `errors.BodyTimeoutError`,
+ * carrying the true `UND_ERR_*` codes and class names), wrapped EXACTLY as undici's
+ * `fetch` wraps them — a `TypeError('fetch failed'|'terminated')` whose `.cause` is
+ * the undici error. These are the real classes, not hand-rolled `{code:'...'}`
+ * mocks: constructing the genuine class is what makes this a faithful test of the
+ * prod predicate (epic root-cause #4 — a mock-shaped predicate would leave the
+ * evict/retry path silently dead in production while CI stays green). We construct
+ * rather than drive a live fetch because Jest's environment degrades the live-fetch
+ * error to a generic `Error` cause (no undici code), which would NOT be the prod
+ * shape.
+ */
+
+/** A REAL undici socket reset, wrapped as fetch wraps it. */
+function realSocketResetError(): unknown {
+  const err = new TypeError('fetch failed');
+  (err as { cause?: unknown }).cause = new errors.SocketError('other side closed');
+  return err;
+}
+
+/** A REAL undici body timeout, wrapped as fetch wraps it. */
+function realBodyTimeoutError(): unknown {
+  const err = new TypeError('terminated');
+  (err as { cause?: unknown }).cause = new errors.BodyTimeoutError();
+  return err;
+}
+
+type FakeServer = {
+  id: string;
+  name: string;
+  transport: 'http' | 'sse';
+  url: string;
+  headersEnc: string | null;
+  toolAllowlist: string[] | null;
+  instructions: string | null;
+};
+
+const server = (over: Partial<FakeServer> = {}): FakeServer => ({
+  id: 's1',
+  name: 'srv',
+  transport: 'http',
+  url: 'http://example.test/mcp',
+  headersEnc: null,
+  toolAllowlist: null,
+  instructions: null,
+  ...over,
+});
+
+function buildService(servers: FakeServer[], trusted = false) {
+  const repo = { listEnabled: jest.fn().mockResolvedValue(servers) };
+  const service = new McpClientsService(repo as never, {} as never);
+  // Seed a DETERMINISTIC write-class map so the retry gate is controlled here
+  // (the production map loads from @docmost/mcp via a dynamic ESM import). getPage
+  // is a read, patchNode is a write — the real classifications.
+  (
+    service as unknown as { writeClassMapPromise: Promise<unknown> }
+  ).writeClassMapPromise = Promise.resolve({
+    getPage: 'readOnly',
+    patchNode: 'write',
+  });
+  // The service only APPLIES that map to a TRUSTED internal Docmost server
+  // (isInternalDocmostServer, really false for every third-party row). A retry
+  // test needs a trusted server to exercise the readOnly-retry path at all, so it
+  // passes trusted=true to model a Docmost-origin server; the third-party
+  // double-apply test leaves it at the real value (false).
+  if (trusted) {
+    jest
+      .spyOn(
+        service as unknown as {
+          isInternalDocmostServer: (s: FakeServer) => boolean;
+        },
+        'isInternalDocmostServer',
+      )
+      .mockReturnValue(true);
+  }
+  return { service, repo };
+}
+
+/** Spy the private `connect` so each call yields a controlled fake client whose
+ *  single tool's execute is the supplied function. Returns the connect spy. */
+function stubConnect(
+  service: McpClientsService,
+  toolName: string,
+  execs: Array<(...a: unknown[]) => Promise<unknown>>,
+) {
+  let n = 0;
+  return jest
+    .spyOn(
+      service as unknown as { connect: (s: FakeServer) => Promise<unknown> },
+      'connect',
+    )
+    .mockImplementation(async () => {
+      const exec = execs[Math.min(n, execs.length - 1)];
+      n += 1;
+      return {
+        tools: async () => ({ [toolName]: { description: 'x', execute: exec } }),
+        close: jest.fn().mockResolvedValue(undefined),
+      };
+    });
+}
+
+const opts = (abortSignal?: AbortSignal) =>
+  ({ toolCallId: 't', messages: [], abortSignal }) as never;
+
+describe('isRetryableConnectError (#489, REAL error shapes)', () => {
+  it('classifies a real undici socket reset and body timeout as retryable', async () => {
+    const socketErr = await realSocketResetError();
+    const bodyErr = await realBodyTimeoutError();
+    expect(isRetryableConnectError(socketErr)).toBe(true);
+    expect(isRetryableConnectError(bodyErr)).toBe(true);
+    // Unwraps a wrapped cause chain (e.g. an MCPClientError around the socket err).
+    const wrapped = new Error('mcp call failed');
+    (wrapped as { cause?: unknown }).cause = socketErr;
+    expect(isRetryableConnectError(wrapped)).toBe(true);
+  });
+
+  it('does NOT classify an application-level error as a transport break', () => {
+    expect(isRetryableConnectError(new Error('validation failed'))).toBe(false);
+    expect(isRetryableConnectError({ name: 'HttpError', status: 400 })).toBe(false);
+    expect(isRetryableConnectError(undefined)).toBe(false);
+    expect(isRetryableConnectError('boom')).toBe(false);
+  });
+});
+
+describe('McpClientsService in-run transport recovery (#489)', () => {
+  afterEach(() => jest.restoreAllMocks());
+
+  it('a readOnly tool whose transport breaks reconnects and retries WITHIN the same run', async () => {
+    const realErr = await realSocketResetError();
+    const { service } = buildService([server()], true);
+    const first = jest.fn().mockRejectedValue(realErr);
+    const second = jest.fn().mockResolvedValue({ ok: true });
+    const connectSpy = stubConnect(service, 'getPage', [first, second]);
+
+    const toolset = await service.toolsFor('ws-1');
+    const tool = toolset.tools['srv_getPage'];
+    const result = await (tool.execute as (a: unknown, o: unknown) => Promise<unknown>)(
+      { pageId: 'p' },
+      opts(),
+    );
+
+    // The repeat call within the run got a LIVE client and succeeded.
+    expect(result).toEqual({ ok: true });
+    expect(first).toHaveBeenCalledTimes(1);
+    expect(second).toHaveBeenCalledTimes(1);
+    // Exactly one reconnect was minted (initial build connect + one recovery).
+    expect(connectSpy).toHaveBeenCalledTimes(2);
+    // The run accumulated BOTH leases (old + reconnected) — released together at end.
+    expect(toolset.clients).toHaveLength(2);
+    await Promise.all(toolset.clients.map((c) => c.close()));
+  });
+
+  it('a WRITE tool does NOT auto-retry on a transport error (indeterminate)', async () => {
+    const realErr = await realSocketResetError();
+    const { service } = buildService([server()], true);
+    const exec = jest.fn().mockRejectedValue(realErr);
+    const connectSpy = stubConnect(service, 'patchNode', [exec]);
+
+    const toolset = await service.toolsFor('ws-2');
+    const tool = toolset.tools['srv_patchNode'];
+    await expect(
+      (tool.execute as (a: unknown, o: unknown) => Promise<unknown>)(
+        { pageId: 'p' },
+        opts(),
+      ),
+    ).rejects.toThrow(/MAY have already applied/);
+
+    // Called exactly once — NO blind retry (avoids double-apply, the #435 class).
+    expect(exec).toHaveBeenCalledTimes(1);
+    // No fresh connection was minted for a write.
+    expect(connectSpy).toHaveBeenCalledTimes(1);
+    await Promise.all(toolset.clients.map((c) => c.close()));
+  });
+
+  it('does NOT retry (or reconnect) after the run is aborted (Stop)', async () => {
+    const realErr = await realSocketResetError();
+    const { service } = buildService([server()], true);
+    const controller = new AbortController();
+    // The transport error arrives, but the run was Stopped in the same tick.
+    const first = jest.fn().mockImplementation(async () => {
+      controller.abort();
+      throw realErr;
+    });
+    const second = jest.fn().mockResolvedValue({ ok: true });
+    const connectSpy = stubConnect(service, 'getPage', [first, second]);
+
+    const toolset = await service.toolsFor('ws-3');
+    const tool = toolset.tools['srv_getPage'];
+    await expect(
+      (tool.execute as (a: unknown, o: unknown) => Promise<unknown>)(
+        { pageId: 'p' },
+        opts(controller.signal),
+      ),
+    ).rejects.toBeDefined();
+
+    // getPage IS readOnly, but the Stop blocks the retry — no second call, no mint.
+    expect(second).not.toHaveBeenCalled();
+    expect(connectSpy).toHaveBeenCalledTimes(1);
+    await Promise.all(toolset.clients.map((c) => c.close()));
+  });
+
+  it('an app-level (non-transport) tool error is surfaced verbatim, never retried', async () => {
+    const { service } = buildService([server()], true);
+    const appErr = new Error('tool says: bad input');
+    const exec = jest.fn().mockRejectedValue(appErr);
+    const connectSpy = stubConnect(service, 'getPage', [exec]);
+
+    const toolset = await service.toolsFor('ws-4');
+    const tool = toolset.tools['srv_getPage'];
+    await expect(
+      (tool.execute as (a: unknown, o: unknown) => Promise<unknown>)(
+        { pageId: 'p' },
+        opts(),
+      ),
+    ).rejects.toThrow('tool says: bad input');
+    expect(exec).toHaveBeenCalledTimes(1);
+    expect(connectSpy).toHaveBeenCalledTimes(1); // no reconnect for an app error
+    await Promise.all(toolset.clients.map((c) => c.close()));
+  });
+
+  // #489 (review, MEDIUM) — the Docmost write-class map keys by DOCMOST tool
+  // names; a THIRD-PARTY server may name a WRITE tool `getPage` (a Docmost read
+  // name). It must NOT inherit readOnly and must NOT auto-retry on a transport
+  // error — a blind retry of that write is a double-apply (the #435 class). Here
+  // the server is UNTRUSTED (buildService default, isInternalDocmostServer=false),
+  // so the map is not applied and `getPage` classifies as a write.
+  //
+  // MUTATION-VERIFY: forcing the server "trusted" (buildService(..., true)) makes
+  // `getPage` inherit readOnly -> it WOULD reconnect+retry (connect twice) and the
+  // assertions below fail — i.e. removing the trust scope re-opens the bug.
+  it('a THIRD-PARTY WRITE tool named like a Docmost read does NOT auto-retry (no double-apply)', async () => {
+    const realErr = await realSocketResetError();
+    // Untrusted: default trusted=false — a real third-party server.
+    const { service } = buildService([server()]);
+    const exec = jest.fn().mockRejectedValue(realErr);
+    const connectSpy = stubConnect(service, 'getPage', [exec, exec]);
+
+    const toolset = await service.toolsFor('ws-5');
+    const tool = toolset.tools['srv_getPage'];
+    await expect(
+      (tool.execute as (a: unknown, o: unknown) => Promise<unknown>)(
+        { pageId: 'p' },
+        opts(),
+      ),
+    ).rejects.toThrow(/MAY have already applied/);
+
+    // Exactly one call, NO reconnect — the name collision granted no readOnly-retry.
+    expect(exec).toHaveBeenCalledTimes(1);
+    expect(connectSpy).toHaveBeenCalledTimes(1);
+    await Promise.all(toolset.clients.map((c) => c.close()));
+  });
+});

apps/server/src/core/ai-chat/external-mcp/mcp-clients.service.spec.ts

@@ -106,8 +106,11 @@ describe('McpClientsService.decryptHeaders', () => {
 
 describe('McpClientsService.guardedFetch (SSRF per-request guard)', () => {
   // The bound guardedFetch closure lives on the instance as a private field.
+  // #489 split it into per-transport HTTP/SSE bindings (they differ only in the
+  // dispatcher's bodyTimeout); the SSRF guard is identical, so testing the HTTP
+  // one is sufficient.
   const guardedFetchOf = (service: McpClientsService) =>
-    (service as unknown as { guardedFetch: typeof fetch }).guardedFetch;
+    (service as unknown as { guardedFetchHttp: typeof fetch }).guardedFetchHttp;
 
   let fetchSpy: jest.SpiedFunction<typeof fetch>;
 

apps/server/src/core/ai-chat/external-mcp/mcp-clients.service.ts

@@ -1,5 +1,6 @@
 import { isIP } from 'node:net';
 import { lookup as dnsLookup, type LookupAddress } from 'node:dns';
+import { pathToFileURL } from 'node:url';
 import { Injectable, Logger } from '@nestjs/common';
 import { type Tool, type ToolCallOptions } from 'ai';
 import { createMCPClient } from '@ai-sdk/mcp';
@@ -10,9 +11,29 @@ import {
   streamingDispatcherOptions,
   mcpStreamTimeoutMs,
   mcpCallTimeoutMs,
+  mcpSseBodyTimeoutMs,
 } from '../../../integrations/ai/ai-streaming-fetch';
 import { SecretBoxService } from '../../../integrations/crypto/secret-box';
 import { isUrlAllowed, isIpAllowed } from './ssrf-guard';
+// TYPE-ONLY (erased at compile): @docmost/mcp is ESM-only and cannot be a runtime
+// `require()` from this commonjs module (same constraint as docmost-client.loader).
+// The write-class MAP is loaded lazily via the dynamic-import trick below.
+import type { ToolWriteClass } from '@docmost/mcp';
+
+// TS(commonjs) downlevels a literal `import()` to `require()`, which cannot load
+// the ESM-only @docmost/mcp. Indirect through Function so the real dynamic
+// `import()` survives compilation (same trick as docmost-client.loader.ts).
+const esmImport = new Function(
+  'specifier',
+  'return import(specifier)',
+) as (specifier: string) => Promise<unknown>;
+
+/** Local read-only predicate — avoids a value import of the ESM-only package.
+ *  Only a pure read is retry-safe after a transport break (a write is
+ *  indeterminate). Kept in lockstep with @docmost/mcp's isRetryableWriteClass. */
+function isReadOnlyWriteClass(writeClass: ToolWriteClass | undefined): boolean {
+  return writeClass === 'readOnly';
+}
 
 /** A closable external MCP client handle. */
 export interface Closable {
@@ -81,12 +102,52 @@ const MAX_TOOL_NAME_LENGTH = 64;
  * close until the turn releases it, so a TTL expiry mid-turn never closes a
  * client a stream is still executing against.
  */
+/**
+ * Where a merged (namespaced) tool came from, so the per-run recovery wrapper
+ * (#489) can, on a transport error, reconnect THAT server and re-resolve the SAME
+ * underlying tool by its raw name. `writeClass` gates the single auto-retry (a
+ * read is retry-safe; a write is indeterminate). `serverIndex` indexes the
+ * entry's `servers` array (which server config to reconnect).
+ */
+interface ToolProvenance {
+  serverIndex: number;
+  rawName: string;
+  writeClass: ToolWriteClass | undefined;
+}
+
+/** A live reconnected server (its fresh client + raw call-timeout-wrapped tools). */
+interface RecoveredServerState {
+  client: McpClient;
+  tools: Record<string, Tool>;
+}
+
+/**
+ * Per-run, per-server recovery binding (#489). `current` is the server's LIVE
+ * target for this run: `null` means "use the ORIGINAL cached client/template";
+ * a non-null value is a reconnected throwaway client all this server's tools now
+ * call. `reconnecting` dedupes concurrent reconnects so only ONE fresh client is
+ * minted per death (a losing concurrent call awaits it and retries on the SAME
+ * new client — the CAS-by-identity rule).
+ */
+interface ServerBinding {
+  current: RecoveredServerState | null;
+  reconnecting?: Promise<RecoveredServerState>;
+}
+
 interface CacheEntry {
   tools: Record<string, Tool>;
   clients: McpClient[];
   outcomes: ServerOutcome[];
   /** Prompt guidance for qualifying servers (see McpServerInstruction). */
   instructions: McpServerInstruction[];
+  /**
+   * The enabled server configs used to build this entry (#489), so the per-run
+   * recovery wrapper can reconnect a specific server by index. Parallel to the
+   * indices referenced by {@link toolMeta}.
+   */
+  servers: AiMcpServer[];
+  /** merged-tool-key -> provenance (#489), for the per-run recovery wrapper. */
+  toolMeta: Record<string, ToolProvenance>;
   expiresAt: number;
   /** Active leases (turns currently using these clients). */
   refCount: number;
@@ -120,20 +181,82 @@ export class McpClientsService {
    */
   private readonly cache = new Map<string, Promise<CacheEntry>>();
   /**
-   * A single shared SSRF-pinned dispatcher for ALL outbound external-MCP fetches.
+   * SSRF-pinned dispatchers for outbound external-MCP fetches. Both use the SAME
-   * Its custom connect.lookup runs per connection, so one instance safely guards
+   * custom connect.lookup (so every connection is IP-validated), but carry a
-   * every server's connections (we never connect to an unvalidated IP).
+   * DIFFERENT `bodyTimeout` (#489): the HTTP (streamable) transport opens a fresh
+   * request per call, so it keeps the tight silence timeout; the SSE transport
+   * holds ONE long-lived body open across many calls, so a >1-min idle BETWEEN
+   * calls is LEGITIMATE and must not break the socket — it gets a much larger
+   * bodyTimeout. (headersTimeout stays tight on both.)
    */
-  private readonly dispatcher: Dispatcher = buildPinnedDispatcher();
+  private readonly dispatcherHttp: Dispatcher = buildPinnedDispatcher(
-  /** guardedFetch bound to the pinned dispatcher; reused by every transport. */
+    mcpStreamTimeoutMs(),
-  private readonly guardedFetch: typeof fetch = (input, init) =>
+  );
-    guardedFetch(this.dispatcher, input, init);
+  private readonly dispatcherSse: Dispatcher = buildPinnedDispatcher(
+    mcpSseBodyTimeoutMs(),
+  );
+  /** guardedFetch bound to each dispatcher; picked by transport type in connect(). */
+  private readonly guardedFetchHttp: typeof fetch = (input, init) =>
+    guardedFetch(this.dispatcherHttp, input, init);
+  private readonly guardedFetchSse: typeof fetch = (input, init) =>
+    guardedFetch(this.dispatcherSse, input, init);
+
+  /**
+   * Memoized write-class map (#489), loaded lazily from @docmost/mcp via the
+   * dynamic-import trick. Keyed by tool name (=== mcpName). A tool NOT in the map
+   * (any third-party external MCP tool) classifies as `undefined` -> treated as a
+   * write by the retry gate (the safe default: never blind-retry an unknown tool).
+   * On any load failure the map is `{}` (every tool -> no auto-retry), so a
+   * missing/older @docmost/mcp build only DISABLES retries, never mis-retries.
+   */
+  private writeClassMapPromise: Promise<Record<string, ToolWriteClass>> | null =
+    null;
 
   constructor(
     private readonly repo: AiMcpServerRepo,
     private readonly secretBox: SecretBoxService,
   ) {}
 
+  /**
+   * Whether an external MCP server is the TRUSTED internal Docmost MCP server —
+   * the only server whose tools may be classified by the Docmost write-class map
+   * (#489 review). Today this is ALWAYS false: every `ai_mcp_servers` row is an
+   * admin-configured THIRD-PARTY endpoint (there is no builtin/self flag, sentinel
+   * URL, or synthetic server in this path — Docmost's OWN tools are exposed via the
+   * separate in-app tools path, never through this external-MCP client). So no
+   * third-party tool can inherit `readOnly` by a name collision with a Docmost read
+   * tool, and none is ever auto-retried on a transport error (which would risk a
+   * double-apply — the #435 class). Flip this (an explicit `kind`/`isBuiltin`
+   * column, or a configured self-MCP URL) if a trusted internal server is ever
+   * introduced. A method (not a free function) so it is a single, mockable seam.
+   */
+  private isInternalDocmostServer(_server: AiMcpServer): boolean {
+    return false;
+  }
+
+  /** Lazily load + memoize the shared write-class map (see the field doc). */
+  private getWriteClassMap(): Promise<Record<string, ToolWriteClass>> {
+    if (!this.writeClassMapPromise) {
+      this.writeClassMapPromise = (async () => {
+        try {
+          const entry = require.resolve('@docmost/mcp');
+          const mod = (await esmImport(pathToFileURL(entry).href)) as {
+            SHARED_TOOL_WRITE_CLASS?: Record<string, ToolWriteClass>;
+          };
+          return mod.SHARED_TOOL_WRITE_CLASS ?? {};
+        } catch (err) {
+          this.logger.warn(
+            `Could not load MCP write-class map (auto-retry disabled): ${shortError(
+              err,
+            )}`,
+          );
+          return {};
+        }
+      })();
+    }
+    return this.writeClassMapPromise;
+  }
+
   /**
    * Build (or reuse a cached) external toolset for a workspace. Returns the
    * merged tools, the open client handles to release, and per-server outcomes.
@@ -162,11 +285,37 @@ export class McpClientsService {
         }
       },
     };
-    // One release handle drives the whole leased entry; closing it releases all
+
-    // underlying clients together (they share the same lease lifecycle).
+    // #489: the run accumulates a SET of leases — the primary cache lease PLUS any
+    // throwaway client minted by an in-run transport-recovery reconnect. They are
+    // NEVER released mid-run (releasing a swapped-out client while a concurrent
+    // in-flight call still holds it would INDUCE a second failure); the caller
+    // releases the WHOLE set together at turn-end. A recovery reconnect pushes its
+    // lease onto this live array, which the consumer closes over.
+    const leaseSet: Closable[] = [release];
+
+    // #489: per-RUN transport-recovery binding, one per server, SHARED by all of
+    // that server's tools so a swap by one call is seen by the next (CAS by
+    // identity). Kept per-run (here, not in the cached entry) because the binding
+    // + lease-set state is per-run.
+    const bindings = new Map<number, ServerBinding>();
+    const capMs = mcpCallTimeoutMs();
+
+    // Wrap each cached tool with the recovery layer. On a transport error a
+    // declared readOnly tool reconnects its server and retries ONCE; a write is
+    // never blind-retried (indeterminate — may have applied before the reset). A
+    // tool without provenance (a minimal stub entry in a test) passes through raw.
+    const tools: Record<string, Tool> = {};
+    for (const [key, tool] of Object.entries(entry.tools)) {
+      const meta = entry.toolMeta?.[key];
+      tools[key] = meta
+        ? this.wrapWithTransportRecovery(entry, meta, tool, leaseSet, bindings, capMs)
+        : tool;
+    }
+
     return {
-      tools: entry.tools,
+      tools,
-      clients: [release],
+      clients: leaseSet,
       outcomes: entry.outcomes,
       instructions: entry.instructions,
     };
@@ -254,6 +403,16 @@ export class McpClientsService {
     // Per-call total wall-clock cap, read once for this build (env-overridable).
     const callTimeoutMs = mcpCallTimeoutMs();
     const instructions: McpServerInstruction[] = [];
+    // merged-key -> provenance for the per-run recovery wrapper (#489).
+    const toolMeta: Record<string, ToolProvenance> = {};
+    // Shared Docmost write-class map (#489) — classifies a tool by its raw name.
+    // Loaded ONLY when at least one server is a TRUSTED internal Docmost server
+    // (see isInternalDocmostServer): for third-party servers the map is never
+    // applied (a name collision must not grant readOnly-retry), so we skip the
+    // dynamic ESM load entirely in that (currently universal) case.
+    const writeClassMap = servers.some((s) => this.isInternalDocmostServer(s))
+      ? await this.getWriteClassMap()
+      : null;
 
     // Per-server connect+tools result, still tagged with its server so the merge
     // below can be applied in the SAME order as `servers` (see the parallel note).
@@ -285,9 +444,13 @@ export class McpClientsService {
       try {
         client = await this.connectWithTimeout(server, CONNECT_TIMEOUT_MS);
         const raw = await withTimeout(client.tools(), CONNECT_TIMEOUT_MS);
+        // Allowlist semantics (#476): null/absent = no restriction (all tools);
+        // ANY array — including `[]` — is authoritative, so an EMPTY allowlist
+        // yields ZERO tools (deny-all). Do NOT add a `.length > 0` escape here:
+        // that read `[]` as falsy and silently widened deny-all to allow-all
+        // (the repo also fails corrupt rows closed to `[]` for the same reason).
         const allow = server.toolAllowlist;
-        const picked =
+        const picked = Array.isArray(allow) ? pick(raw, allow) : raw;
-          Array.isArray(allow) && allow.length > 0 ? pick(raw, allow) : raw;
         // Bound each tool's execute with a per-call total-timeout guard before
         // merging, so a single chatty-but-stuck call is aborted after the cap.
         const guarded = wrapToolsWithCallTimeout(picked, callTimeoutMs);
@@ -327,11 +490,23 @@ export class McpClientsService {
       // against names already merged from earlier servers, so no external
       // tool is silently overwritten on collision. The returned count drives
       // whether this server's prompt guidance is included (≥1 tool merged).
+      // #489 (review): the Docmost write-class map keys by DOCMOST tool names and
+      // may ONLY be trusted for a server KNOWN to be the internal Docmost MCP
+      // server. Every row here is an admin-configured THIRD-PARTY endpoint, so a
+      // third-party WRITE tool that happens to be named like a Docmost read
+      // (getPage, listPages, ...) must NOT inherit readOnly — that would auto-retry
+      // a mutation on a transport error (double-apply, the #435 class). Gate the
+      // map on the trust check; untrusted servers get writeClass=undefined -> the
+      // recovery wrapper treats them as writes and never auto-retries.
+      const trustWriteClass = this.isInternalDocmostServer(server);
       const merged = this.mergeNamespaced(
         tools,
         result.guarded,
         server.name,
         server.id,
+        toolMeta,
+        i,
+        trustWriteClass ? writeClassMap : null,
       );
       outcomes.push({ name: server.name, ok: true });
       // Include this server's guidance ONLY when it actually contributed at
@@ -353,6 +528,8 @@ export class McpClientsService {
       clients,
       outcomes,
       instructions,
+      servers,
+      toolMeta,
       expiresAt: Date.now() + CACHE_TTL_MS,
       refCount: 0,
       evicted: false,
@@ -379,18 +556,33 @@ export class McpClientsService {
     picked: Record<string, Tool>,
     serverName: string,
     serverId: string,
+    toolMeta: Record<string, ToolProvenance>,
+    serverIndex: number,
+    // The Docmost write-class map, or `null` for an UNTRUSTED (third-party)
+    // server whose tools must all default to write (never auto-retried).
+    writeClassMap: Record<string, ToolWriteClass> | null,
   ): { count: number; prefix: string } {
     let count = 0;
-    for (const [name, tool] of Object.entries(namespace(picked, serverName))) {
+    for (const { full, raw, tool } of namespace(picked, serverName)) {
-      let key = name;
+      let key = full;
       if (key in target) {
         const original = key;
-        key = disambiguate(name, serverId, (candidate) => candidate in target);
+        key = disambiguate(full, serverId, (candidate) => candidate in target);
         this.logger.debug(
           `External MCP tool name "${original}" collided; renamed to "${key}"`,
         );
       }
       target[key] = tool;
+      // Record provenance so the per-run recovery wrapper (#489) can reconnect
+      // this tool's server and re-resolve it by its raw name. writeClass is set
+      // ONLY from a TRUSTED (internal-Docmost) map; for a third-party server the
+      // map is null -> writeClass stays undefined -> the wrapper treats the tool
+      // as a write and never auto-retries it (no double-apply on name collision).
+      toolMeta[key] = {
+        serverIndex,
+        rawName: raw,
+        writeClass: writeClassMap ? writeClassMap[raw] : undefined,
+      };
       count += 1;
     }
     return { count, prefix: namespacePrefix(serverName) };
@@ -424,7 +616,10 @@ export class McpClientsService {
         // Defense in depth: re-validate the actual request host on EVERY fetch
         // AND pin the socket to a validated IP via the dispatcher's connect
         // lookup, closing the DNS-rebinding TOCTOU between check and connect.
-        fetch: this.guardedFetch,
+        // #489: the SSE transport uses the raised-bodyTimeout dispatcher (idle
+        // between calls is legit); HTTP uses the tight one.
+        fetch:
+          transportType === 'sse' ? this.guardedFetchSse : this.guardedFetchHttp,
       },
     })) as unknown as McpClient;
     return client;
@@ -505,6 +700,176 @@ export class McpClientsService {
     }
   }
 
+  /**
+   * Wrap one merged external tool with the per-run transport-recovery layer (#489).
+   *
+   * attempt 1 runs on the server's CURRENT binding (the cached client, or a client
+   * a sibling tool already reconnected this run). On a REAL transport error
+   * (undici/@ai-sdk socket/body-timeout shapes — {@link isRetryableConnectError},
+   * NOT a mock) and ONLY for a declared readOnly tool, it reconnects the server
+   * and retries EXACTLY ONCE on the fresh client; a write is surfaced as an
+   * indeterminate error (it may have applied before the reset — never
+   * blind-retried). A single per-call cap bounds BOTH attempts + the reconnect,
+   * and the run's abort signal is checked before the retry AND before minting a
+   * fresh connection (no connection is opened for a stopped run).
+   */
+  private wrapWithTransportRecovery(
+    entry: CacheEntry,
+    meta: ToolProvenance,
+    template: Tool,
+    leaseSet: Closable[],
+    bindings: Map<number, ServerBinding>,
+    capMs: number,
+  ): Tool {
+    const original = template.execute;
+    if (typeof original !== 'function') return template;
+    const service = this;
+    const { serverIndex, rawName, writeClass } = meta;
+
+    let binding = bindings.get(serverIndex);
+    if (!binding) {
+      binding = { current: null };
+      bindings.set(serverIndex, binding);
+    }
+    const boundBinding = binding;
+
+    const execute = async (args: unknown, options: ToolCallOptions) => {
+      // The per-call cap governs the WHOLE sequence (attempt1 + reconnect +
+      // attempt2). Compose it with the run's abort signal so a Stop or the cap
+      // ends any awaited call — @ai-sdk/mcp does not settle on abort, so we RACE.
+      const capController = new AbortController();
+      const capTimer = setTimeout(() => {
+        capController.abort(new Error(`MCP tool call timed out after ${capMs}ms`));
+      }, capMs);
+      capTimer.unref?.();
+      const runSignal = options?.abortSignal;
+      const composed = runSignal
+        ? AbortSignal.any([runSignal, capController.signal])
+        : capController.signal;
+      const stopped = () => runSignal?.aborted === true || capController.signal.aborted;
+
+      const callOn = async (
+        exec: NonNullable<Tool['execute']>,
+      ): Promise<unknown> => {
+        const aborted = new Promise<never>((_, reject) => {
+          const fail = () => reject(abortReason(composed));
+          if (composed.aborted) fail();
+          else composed.addEventListener('abort', fail, { once: true });
+        });
+        return Promise.race([exec(args, { ...options, abortSignal: composed }), aborted]);
+      };
+
+      const execFor = (
+        state: RecoveredServerState | null,
+      ): NonNullable<Tool['execute']> | undefined =>
+        state ? (state.tools[rawName]?.execute as NonNullable<Tool['execute']>) : original;
+
+      try {
+        // Snapshot the target BEFORE the call so a swap by a concurrent call is
+        // detected by identity in the catch.
+        const attemptState = boundBinding.current;
+        const attemptExec = execFor(attemptState);
+        if (typeof attemptExec !== 'function') {
+          throw new Error(`external MCP tool "${rawName}" is not callable`);
+        }
+        try {
+          return await callOn(attemptExec);
+        } catch (err) {
+          // Never retry on a Stop or an exhausted cap.
+          if (stopped()) throw err;
+          // Only a genuine transport break is a recovery candidate.
+          if (!isRetryableConnectError(err)) throw err;
+          // A write tool is INDETERMINATE on a transport error (may have applied
+          // before the reset) — surface that; do NOT auto-retry (double-apply is
+          // the #435 incident class).
+          if (!isReadOnlyWriteClass(writeClass)) {
+            throw new Error(
+              `external MCP tool "${rawName}" hit a transport error and MAY have already ` +
+                `applied on the server — not retried automatically; verify state before ` +
+                `retrying. (${shortError(err)})`,
+            );
+          }
+          // Abort check BEFORE minting a fresh connection (no socket for a
+          // stopped run). LIMITATION (#489, LOW): the reconnect's own connect is
+          // bounded by CONNECT_TIMEOUT_MS but does NOT itself observe `composed`,
+          // so a Stop that lands DURING the handshake is only honored at the next
+          // `stopped()` gate (before the retry) — a bounded ≤5s late-abort window;
+          // the throwaway client is closed at turn-end regardless. Threading
+          // `composed` into the SHARED (CAS-deduped) reconnect is deliberately
+          // avoided: it would let the first caller's abort tear down a reconnect a
+          // concurrent still-live caller depends on.
+          if (stopped()) throw err;
+          // CAS-swap by IDENTITY: mint+swap only if nobody swapped since this
+          // call's snapshot; a losing concurrent call awaits the same reconnect
+          // and retries on the SAME fresh client.
+          let target: RecoveredServerState;
+          if (boundBinding.current === attemptState) {
+            if (!boundBinding.reconnecting) {
+              boundBinding.reconnecting = (async () => {
+                const server = entry.servers[serverIndex];
+                const fresh = await service.reconnectServer(server, capMs);
+                leaseSet.push(fresh.lease); // accumulate; released at turn-end
+                boundBinding.current = fresh.state;
+                return fresh.state;
+              })();
+              // Clear the in-flight marker once it settles (success or failure) so
+              // a LATER death of the new client can reconnect again.
+              void boundBinding.reconnecting.then(
+                () => (boundBinding.reconnecting = undefined),
+                () => (boundBinding.reconnecting = undefined),
+              );
+            }
+            target = await boundBinding.reconnecting;
+          } else {
+            target = boundBinding.current as RecoveredServerState;
+          }
+          // Abort check BEFORE the retry.
+          if (stopped()) throw err;
+          const retryExec = execFor(target);
+          if (typeof retryExec !== 'function') throw err;
+          return await callOn(retryExec);
+        }
+      } finally {
+        clearTimeout(capTimer);
+      }
+    };
+    return { ...template, execute } as unknown as Tool;
+  }
+
+  /**
+   * Reconnect ONE server for an in-run recovery (#489): open a fresh client and
+   * list+wrap its tools. The throwaway client is NOT cached — it is owned by the
+   * RUN via the returned lease (closed at turn-end), independent of the shared
+   * cache entry (whose TTL rebuild heals future turns). On a failure the fresh
+   * client is closed so its socket never leaks.
+   */
+  private async reconnectServer(
+    server: AiMcpServer,
+    capMs: number,
+  ): Promise<{ state: RecoveredServerState; lease: Closable }> {
+    const client = await this.connectWithTimeout(server, CONNECT_TIMEOUT_MS);
+    let tools: Record<string, Tool>;
+    try {
+      const raw = await withTimeout(client.tools(), CONNECT_TIMEOUT_MS);
+      const allow = server.toolAllowlist;
+      const picked =
+        Array.isArray(allow) && allow.length > 0 ? pick(raw, allow) : raw;
+      tools = wrapToolsWithCallTimeout(picked, capMs);
+    } catch (err) {
+      void client.close().catch(() => undefined);
+      throw err;
+    }
+    let released = false;
+    const lease: Closable = {
+      close: async () => {
+        if (released) return;
+        released = true;
+        await client.close().catch(() => undefined);
+      },
+    };
+    return { state: { client, tools }, lease };
+  }
+
   /** Mark an entry evicted; close its clients now if nothing is leasing them. */
   private evict(entry: CacheEntry): void {
     clearTimeout(entry.timer);
@@ -554,22 +919,21 @@ export function validateResolvedAddresses(addrs: readonly LookupAddress[]): {
  * certificate validation still uses the real hostname (we never rewrite the URL
  * to an IP literal).
  */
-function buildPinnedDispatcher(): Agent {
+function buildPinnedDispatcher(bodyTimeoutMs: number): Agent {
-  // External-MCP traffic uses a DEDICATED, shorter silence timeout
+  // External-MCP traffic uses a DEDICATED, shorter HEADERS silence timeout
   // (`AI_MCP_STREAM_TIMEOUT_MS`, default 1 min) — deliberately tighter than the
   // chat provider's 15-min `streamTimeoutMs()` — so a byte-silent/hung MCP
   // upstream is broken in ~1 min instead of 15. We keep the keep-alive options
-  // from `streamingDispatcherOptions()` but OVERRIDE headers/body timeouts.
+  // from `streamingDispatcherOptions()` but OVERRIDE the timeouts. `bodyTimeout`
-  // Accepted trade-off: a legitimately long but byte-silent single tool call,
+  // is passed in per-transport (#489): tight for HTTP (fresh request per call),
-  // and an SSE transport idling >1 min BETWEEN tool calls, are also cut here; the
+  // raised for SSE (one long-lived body across calls — idle BETWEEN calls is
-  // per-call total cap (wrapToolsWithCallTimeout, `AI_MCP_CALL_TIMEOUT_MS`) is the
+  // legit). The per-call total cap (`AI_MCP_CALL_TIMEOUT_MS`) is the complementary
-  // complementary guard for chatty-but-stuck calls that keep the socket warm yet
+  // guard for chatty-but-stuck calls that keep the socket warm yet never return.
-  // never return.
+  const headersMs = mcpStreamTimeoutMs();
-  const mcpSilenceMs = mcpStreamTimeoutMs();
   return new Agent({
     ...streamingDispatcherOptions(),
-    headersTimeout: mcpSilenceMs,
+    headersTimeout: headersMs,
-    bodyTimeout: mcpSilenceMs,
+    bodyTimeout: bodyTimeoutMs,
     connect: {
       lookup: (hostname, _options, callback) => {
         // Always resolve ALL addresses ourselves; do not trust the caller's
@@ -669,18 +1033,22 @@ function pick(
 function namespace(
   tools: Record<string, Tool>,
   serverName: string,
-): Record<string, Tool> {
+): Array<{ full: string; raw: string; tool: Tool }> {
   const prefix = namespacePrefix(serverName);
-  const out: Record<string, Tool> = {};
+  const out: Array<{ full: string; raw: string; tool: Tool }> = [];
+  const taken: Record<string, true> = {};
   for (const [name, t] of Object.entries(tools)) {
     const safe = sanitizeName(name);
     let full = capName(`${prefix}_${safe}`);
     // Duplicate names within ONE server can still collide after sanitize/
     // truncate — suffix-disambiguate so the second tool is not overwritten.
-    if (full in out) {
+    if (full in taken) {
-      full = disambiguate(full, '', (candidate) => candidate in out);
+      full = disambiguate(full, '', (candidate) => candidate in taken);
     }
-    out[full] = t;
+    taken[full] = true;
+    // Keep the RAW (un-namespaced) name alongside the merged key so the per-run
+    // recovery wrapper (#489) can re-resolve the same tool on a fresh client.
+    out.push({ full, raw: name, tool: t });
   }
   return out;
 }
@@ -804,6 +1172,69 @@ export function wrapToolWithCallTimeout(tool: Tool, ms: number): Tool {
   return { ...tool, execute } as unknown as Tool;
 }
 
+/**
+ * undici / Node network error CODES that mean the connection broke (not an
+ * application-level error) — a transient transport failure a readOnly call may
+ * safely retry after reconnecting. Matched against the REAL error shapes (#489):
+ * a socket reset surfaces as `TypeError: fetch failed` whose `.cause` is an
+ * undici `SocketError { code:'UND_ERR_SOCKET' }`; a body-timeout as
+ * `TypeError: terminated` whose `.cause` is `BodyTimeoutError`. Classifying by
+ * these real codes/names (not by mock errors) is essential — a mock-shaped
+ * predicate would leave eviction silently dead in production while CI is green.
+ */
+const RETRYABLE_TRANSPORT_ERROR_CODES: ReadonlySet<string> = new Set([
+  'ECONNRESET',
+  'ECONNREFUSED',
+  'ECONNABORTED',
+  'EPIPE',
+  'ETIMEDOUT',
+  'EAI_AGAIN',
+  'ENETUNREACH',
+  'EHOSTUNREACH',
+  'UND_ERR_SOCKET',
+  'UND_ERR_CONNECT_TIMEOUT',
+  'UND_ERR_HEADERS_TIMEOUT',
+  'UND_ERR_BODY_TIMEOUT',
+  'UND_ERR_CLOSED',
+  'UND_ERR_DESTROYED',
+]);
+
+/** undici error CLASS names for the same transport-break conditions. */
+const RETRYABLE_TRANSPORT_ERROR_NAMES: ReadonlySet<string> = new Set([
+  'SocketError',
+  'BodyTimeoutError',
+  'HeadersTimeoutError',
+  'ConnectTimeoutError',
+  'ClientClosedError',
+  'ClientDestroyedError',
+]);
+
+/**
+ * Whether `err` is a retryable TRANSPORT break (a broken socket / body timeout),
+ * classified by the REAL undici/@ai-sdk error shapes (#489). undici surfaces a
+ * reset as `TypeError('fetch failed'|'terminated')` with the real error in
+ * `.cause`, and @ai-sdk/mcp may wrap it again in an `MCPClientError` (cause
+ * chain), so we walk `.cause` (bounded depth) checking `.code` and `.name`. An
+ * app-level tool error (a 4xx, a validation failure) is NOT retryable and returns
+ * false — only a connection-level failure heals with a reconnect.
+ */
+export function isRetryableConnectError(err: unknown, depth = 0): boolean {
+  if (!err || typeof err !== 'object' || depth > 6) return false;
+  const e = err as {
+    code?: unknown;
+    name?: unknown;
+    cause?: unknown;
+  };
+  if (typeof e.code === 'string' && RETRYABLE_TRANSPORT_ERROR_CODES.has(e.code)) {
+    return true;
+  }
+  if (typeof e.name === 'string' && RETRYABLE_TRANSPORT_ERROR_NAMES.has(e.name)) {
+    return true;
+  }
+  if (e.cause != null) return isRetryableConnectError(e.cause, depth + 1);
+  return false;
+}
+
 /** The signal's reason as an Error (informative thrown value on abort/timeout). */
 function abortReason(signal: AbortSignal): Error {
   const r = signal.reason;

apps/server/src/core/ai-chat/external-mcp/mcp-servers.service.ts

@@ -100,7 +100,8 @@ export class McpServersService {
       transport: dto.transport,
       url: dto.url,
       headersEnc,
-      // undefined => unchanged; [] / value handled by repo (empty => null).
+      // undefined => unchanged; null => no restriction; `[]` is persisted
+      // verbatim and means deny-all (#476).
       toolAllowlist: dto.toolAllowlist,
       // undefined => unchanged; blank => cleared (null) by the repo.
       instructions: dto.instructions,

apps/server/src/core/ai-chat/history-budget.spec.ts

@@ -0,0 +1,266 @@
+import type { ModelMessage } from 'ai';
+import {
+  resolveReplayBudget,
+  isContextOverflowError,
+  estimateMessagesTokens,
+  trimHistoryForReplay,
+  REPLAY_BUDGET_DEFAULT_TOKENS,
+  REPLAY_TRUNCATION_MARKER,
+  REPLAY_TURN_COLLAPSED_MARKER,
+} from './history-budget';
+
+describe('resolveReplayBudget', () => {
+  it('uses floor(0.7 x window) for a configured window (no cap)', () => {
+    // 0.7 x 60k = 42k
+    expect(resolveReplayBudget(60_000)).toEqual({
+      thresholdTokens: 42_000,
+      usedDefault: false,
+    });
+    // 0.7 x 1M = 700k — NOT capped (anti-brick vs the window, not a cost limiter).
+    expect(resolveReplayBudget(1_000_000)).toEqual({
+      thresholdTokens: 700_000,
+      usedDefault: false,
+    });
+  });
+
+  it('accepts the raw ::text stored form', () => {
+    expect(resolveReplayBudget('60000').thresholdTokens).toBe(42_000);
+  });
+
+  // The crux (#490): a chat with NO context window configured must STILL be
+  // budgeted — those are exactly the installs that hit terminal overflow.
+  it('applies the flat default when the window is unset/empty', () => {
+    expect(resolveReplayBudget(undefined)).toEqual({
+      thresholdTokens: REPLAY_BUDGET_DEFAULT_TOKENS,
+      usedDefault: true,
+    });
+    expect(resolveReplayBudget('')).toEqual({
+      thresholdTokens: REPLAY_BUDGET_DEFAULT_TOKENS,
+      usedDefault: true,
+    });
+    expect(resolveReplayBudget('   ')).toEqual({
+      thresholdTokens: REPLAY_BUDGET_DEFAULT_TOKENS,
+      usedDefault: true,
+    });
+  });
+
+  it('treats an explicit 0 as the off-switch (distinct from unset)', () => {
+    expect(resolveReplayBudget(0)).toEqual({
+      thresholdTokens: null,
+      usedDefault: false,
+    });
+    expect(resolveReplayBudget('0')).toEqual({
+      thresholdTokens: null,
+      usedDefault: false,
+    });
+  });
+
+  it('falls back to the default on a negative/garbage value', () => {
+    expect(resolveReplayBudget(-5).usedDefault).toBe(true);
+    expect(resolveReplayBudget('abc').usedDefault).toBe(true);
+  });
+});
+
+describe('isContextOverflowError', () => {
+  it('classifies a real provider 400 context-overflow shape', () => {
+    // OpenAI-compatible shape.
+    expect(
+      isContextOverflowError({
+        statusCode: 400,
+        message:
+          "This model's maximum context length is 128000 tokens. However, your messages resulted in 214000 tokens. Please reduce the length of the messages.",
+      }),
+    ).toBe(true);
+    // Anthropic-style wording.
+    expect(
+      isContextOverflowError({
+        status: 400,
+        message: 'prompt is too long: 250000 tokens > 200000 maximum',
+      }),
+    ).toBe(true);
+    // Nested body + string status.
+    expect(
+      isContextOverflowError({
+        response: { status: '400' },
+        message: 'input is too long for the requested model',
+      }),
+    ).toBe(true);
+    // Error instance with the cause carrying the body.
+    const e = new Error('Bad request');
+    (e as any).statusCode = 400;
+    (e as any).cause = new Error('maximum context window exceeded');
+    expect(isContextOverflowError(e)).toBe(true);
+  });
+
+  it('does NOT classify unrelated 400s or auth/rate-limit errors', () => {
+    expect(
+      isContextOverflowError({ statusCode: 400, message: 'invalid tool schema' }),
+    ).toBe(false);
+    expect(
+      isContextOverflowError({
+        statusCode: 429,
+        message: 'context length exceeded but rate limited',
+      }),
+    ).toBe(false);
+    expect(isContextOverflowError({ statusCode: 500, message: 'server error' })).toBe(
+      false,
+    );
+    expect(isContextOverflowError(undefined)).toBe(false);
+    expect(isContextOverflowError('some random string')).toBe(false);
+  });
+});
+
+// Helpers to build ModelMessage fixtures in the ai@6 shape.
+const userMsg = (text: string): ModelMessage =>
+  ({ role: 'user', content: [{ type: 'text', text }] }) as ModelMessage;
+const assistantMsg = (
+  text: string,
+  toolCallId?: string,
+  toolName?: string,
+): ModelMessage =>
+  ({
+    role: 'assistant',
+    content: [
+      { type: 'text', text },
+      ...(toolCallId
+        ? [{ type: 'tool-call', toolCallId, toolName, input: {} }]
+        : []),
+    ],
+  }) as ModelMessage;
+const toolMsg = (
+  toolCallId: string,
+  toolName: string,
+  value: unknown,
+): ModelMessage =>
+  ({
+    role: 'tool',
+    content: [
+      { type: 'tool-result', toolCallId, toolName, output: { type: 'json', value } },
+    ],
+  }) as ModelMessage;
+
+describe('trimHistoryForReplay', () => {
+  it('null budget disables trimming (returns the same reference)', () => {
+    const msgs = [userMsg('hi'), assistantMsg('yo')];
+    const r = trimHistoryForReplay(msgs, null);
+    expect(r.trimmed).toBe(false);
+    expect(r.messages).toBe(msgs);
+  });
+
+  it('leaves history under budget untouched (same reference)', () => {
+    const msgs = [userMsg('hi'), assistantMsg('a short answer')];
+    const r = trimHistoryForReplay(msgs, 100_000);
+    expect(r.trimmed).toBe(false);
+    expect(r.messages).toBe(msgs);
+  });
+
+  it('truncates OLD tool outputs but keeps recent turns full', () => {
+    const big = 'X'.repeat(40_000); // ~16k tokens on its own
+    const msgs: ModelMessage[] = [];
+    // 6 OLD turns (indices 0..5), each with a huge tool output.
+    for (let i = 0; i < 6; i++) {
+      msgs.push(userMsg(`old q${i}`));
+      msgs.push(assistantMsg('looking', `c${i}`, 'getPage'));
+      msgs.push(toolMsg(`c${i}`, 'getPage', { body: big }));
+      msgs.push(assistantMsg(`old a${i}`));
+    }
+    // 3 small recent turns, then the CURRENT turn with its own huge tool output.
+    // With REPLAY_KEEP_RECENT_TURNS=4 the last 4 user-turns stay full, so only
+    // these small recent turns + the current big one are kept full; the 6 old
+    // turns above fall in the trim region.
+    for (let i = 0; i < 3; i++) {
+      msgs.push(userMsg(`recent q${i}`));
+      msgs.push(assistantMsg(`recent a${i}`));
+    }
+    msgs.push(userMsg('current q'));
+    msgs.push(assistantMsg('looking', 'cR', 'getPage'));
+    msgs.push(toolMsg('cR', 'getPage', { body: big }));
+    msgs.push(assistantMsg('current a'));
+
+    // Budget large enough that phase-1 tool truncation alone brings it under.
+    const r = trimHistoryForReplay(msgs, 30_000);
+    expect(r.trimmed).toBe(true);
+    const flat = JSON.stringify(r.messages);
+    // The CURRENT turn's tool output survives in full.
+    expect(flat).toContain(big);
+    // Old outputs were truncated with the marker.
+    expect(flat).toContain(REPLAY_TRUNCATION_MARKER);
+    // Phase 1 sufficed: the oldest turns were NOT collapsed.
+    expect(flat).not.toContain(REPLAY_TURN_COLLAPSED_MARKER);
+    expect(estimateMessagesTokens(r.messages)).toBeLessThan(
+      estimateMessagesTokens(msgs),
+    );
+  });
+
+  it('collapses the oldest turns when tool truncation is not enough', () => {
+    // Many turns with LARGE assistant TEXT (not tool output) so phase 1 can't help.
+    const bigText = 'слово '.repeat(8_000); // large Cyrillic text per turn
+    const msgs: ModelMessage[] = [];
+    for (let i = 0; i < 12; i++) {
+      msgs.push(userMsg(`q${i}`));
+      msgs.push(assistantMsg(bigText));
+    }
+    const r = trimHistoryForReplay(msgs, 30_000);
+    expect(r.trimmed).toBe(true);
+    // Oldest turns collapsed; result fits (best-effort) and is much smaller.
+    expect(estimateMessagesTokens(r.messages)).toBeLessThan(
+      estimateMessagesTokens(msgs),
+    );
+    // The LAST turn's text is preserved in full (recent turns stay full).
+    expect(JSON.stringify(r.messages[r.messages.length - 1])).toContain(bigText);
+  });
+
+  it('is deterministic / byte-stable for identical inputs', () => {
+    const big = 'Y'.repeat(30_000);
+    const build = (): ModelMessage[] => {
+      const m: ModelMessage[] = [];
+      for (let i = 0; i < 10; i++) {
+        m.push(userMsg(`q${i}`));
+        m.push(assistantMsg('t', `c${i}`, 'getPage'));
+        m.push(toolMsg(`c${i}`, 'getPage', { body: big }));
+      }
+      return m;
+    };
+    const a = trimHistoryForReplay(build(), 15_000);
+    const b = trimHistoryForReplay(build(), 15_000);
+    expect(JSON.stringify(a.messages)).toBe(JSON.stringify(b.messages));
+  });
+
+  it('never leaves an unpaired tool-call after collapsing (balanced history)', () => {
+    const big = 'Z'.repeat(40_000);
+    const msgs: ModelMessage[] = [];
+    for (let i = 0; i < 10; i++) {
+      msgs.push(userMsg(`q${i}`));
+      msgs.push(assistantMsg('t', `c${i}`, 'getPage'));
+      msgs.push(toolMsg(`c${i}`, 'getPage', { body: big }));
+    }
+    const r = trimHistoryForReplay(msgs, 8_000);
+    // Count tool-call vs tool-result parts in the trimmed output.
+    let calls = 0;
+    let results = 0;
+    for (const m of r.messages) {
+      if (!Array.isArray(m.content)) continue;
+      for (const p of m.content as Array<{ type?: string }>) {
+        if (p.type === 'tool-call') calls++;
+        if (p.type === 'tool-result' || p.type === 'tool-error') results++;
+      }
+    }
+    // Every surviving tool-call has a surviving result (collapsing drops BOTH).
+    expect(calls).toBe(results);
+    // Collapsed turns carry the marker.
+    expect(JSON.stringify(r.messages)).toContain(REPLAY_TURN_COLLAPSED_MARKER);
+  });
+
+  it('respects the provider fact: under-budget contextTokens skips trimming', () => {
+    const big = 'W'.repeat(60_000);
+    const msgs = [
+      userMsg('q'),
+      assistantMsg('t', 'c1', 'getPage'),
+      toolMsg('c1', 'getPage', { body: big }),
+    ];
+    // char-estimate is high, but the provider says we are well under budget.
+    const r = trimHistoryForReplay(msgs, 100_000, 5_000);
+    expect(r.trimmed).toBe(false);
+    expect(r.messages).toBe(msgs);
+  });
+});

apps/server/src/core/ai-chat/history-budget.ts

@@ -0,0 +1,375 @@
+/**
+ * History-replay token budget (#490).
+ *
+ * The whole persisted conversation is replayed to the provider on EVERY turn, so
+ * a long chat eventually exceeds the model's context window and the provider 400s
+ * on every turn — terminally (the chat "bricks"). This module bounds the replayed
+ * history at REPLAY TIME only: it never mutates what is persisted (the DB stays
+ * the full record), and its output is a deterministic, byte-stable function of its
+ * input so the trimmed prefix is identical turn to turn (provider prompt-cache
+ * friendliness — real money on long chats).
+ *
+ * The PRIMARY signal is the provider's own fact: `metadata.contextTokens` from the
+ * last turn. The chars-based {@link estimateTokens} (shared with the client) is
+ * used only for the DELTA of not-yet-sent messages, to decide WHAT to trim, and as
+ * the fallback for chats with no usage yet.
+ */
+import type { ModelMessage } from 'ai';
+import { estimateTokens } from '@docmost/token-estimate';
+
+/** Flat default budget when no context window is configured (tokens). */
+export const REPLAY_BUDGET_DEFAULT_TOKENS = 100_000;
+/** Fraction of a configured context window used as the budget. */
+export const REPLAY_BUDGET_WINDOW_FRACTION = 0.7;
+/**
+ * Fraction of the normal budget used for the REACTIVE re-trim after a provider
+ * context-overflow 400 — the preventive estimate under-counted, so cut harder.
+ */
+export const REPLAY_AGGRESSIVE_FRACTION = 0.5;
+/**
+ * Turns (a user message + its assistant/tool replies) kept FULL at the tail,
+ * including the current one — never trimmed. Older turns are compacted first.
+ */
+export const REPLAY_KEEP_RECENT_TURNS = 4;
+/** Leading chars kept from a truncated old tool output. */
+export const REPLAY_TOOL_OUTPUT_HEAD = 800;
+/** Trailing chars kept from a truncated old tool output. */
+export const REPLAY_TOOL_OUTPUT_TAIL = 300;
+/** Marker inserted where an old tool output was truncated for replay. */
+export const REPLAY_TRUNCATION_MARKER =
+  '[…truncated for replay; call the tool again to read the full output]';
+/** Marker for a whole old turn collapsed to its text. */
+export const REPLAY_TURN_COLLAPSED_MARKER =
+  '[earlier tool activity omitted for replay]';
+
+export interface ReplayBudget {
+  /** Token threshold above which replay history is trimmed; `null` = OFF. */
+  thresholdTokens: number | null;
+  /** True when the flat default was used (no context window configured). */
+  usedDefault: boolean;
+}
+
+/**
+ * Resolve the replay budget from the RAW stored `chatContextWindow` (text/number).
+ *  - a positive value  -> `floor(fraction × window)` (NO cap — the budgeter is
+ *    anti-brick protection against the window itself, not a cost/economy limiter,
+ *    exactly as the codebase already treats maxOutputTokens; the reactive branch
+ *    still guarantees anti-brick regardless of how high this budget is)
+ *  - explicit `0`       -> OFF (admin opt-out; `null` threshold)
+ *  - unset/empty/invalid-> the flat default (still protects — the installations
+ *    that hit terminal overflow are exactly the ones that never set a window)
+ *
+ * Note the raw value is needed because the parsed `chatContextWindow` collapses
+ * both `0` and unset to `undefined`, which would erase the explicit off-switch.
+ */
+export function resolveReplayBudget(rawContextWindow: unknown): ReplayBudget {
+  let n: number | undefined;
+  if (typeof rawContextWindow === 'number') {
+    n = rawContextWindow;
+  } else if (typeof rawContextWindow === 'string') {
+    const t = rawContextWindow.trim();
+    n = t === '' ? undefined : Number(t);
+  }
+  // Unset / empty / non-numeric / negative -> flat default (the protective case).
+  if (n === undefined || !Number.isFinite(n) || n < 0) {
+    return { thresholdTokens: REPLAY_BUDGET_DEFAULT_TOKENS, usedDefault: true };
+  }
+  // Explicit 0 -> off-switch.
+  if (n === 0) {
+    return { thresholdTokens: null, usedDefault: false };
+  }
+  return {
+    thresholdTokens: Math.floor(REPLAY_BUDGET_WINDOW_FRACTION * n),
+    usedDefault: false,
+  };
+}
+
+/**
+ * The effective replay threshold for THIS turn, given the base budget and whether
+ * the PREVIOUS turn hit a context-overflow 400 (the reactive-recovery signal,
+ * `metadata.replayOverflow`). On recovery the base budget is scaled down by
+ * {@link REPLAY_AGGRESSIVE_FRACTION}: the overflowing turn produced no usage
+ * signal, so the preventive estimate under-counted and a normal-threshold trim may
+ * not shrink enough to fit — this harder cut is what un-bricks the chat.
+ *
+ * A `null` base budget (trimming OFF) is passed through unchanged: an explicit
+ * off-switch is never overridden by the recovery path.
+ */
+export function resolveEffectiveReplayThreshold(
+  thresholdTokens: number | null,
+  priorOverflowed: boolean,
+): number | null {
+  if (!priorOverflowed || thresholdTokens == null) return thresholdTokens;
+  return Math.floor(thresholdTokens * REPLAY_AGGRESSIVE_FRACTION);
+}
+
+/**
+ * True when a provider error is a CONTEXT-OVERFLOW rejection (the prompt exceeds
+ * the model's window). Providers surface this as an HTTP 400 with a recognizable
+ * message; match both the status and the message patterns robustly across
+ * OpenAI-compatible / Anthropic / Gemini wordings, since the exact shape varies.
+ */
+export function isContextOverflowError(error: unknown): boolean {
+  const status = extractStatus(error);
+  const msg = extractMessage(error).toLowerCase();
+  // Message patterns seen across providers for "prompt too long".
+  const overflowPattern =
+    /context (?:length|window)|maximum context|too many tokens|too large for|reduce the length|prompt is too long|input (?:is )?too long|exceeds? the (?:maximum )?(?:context|token)|maximum.*tokens|string too long/;
+  if (!overflowPattern.test(msg)) return false;
+  // A 400/413 with an overflow-shaped message is an overflow. Some providers
+  // omit/rewrite the status, so accept the message match when the status is
+  // unknown, but reject it for auth/rate-limit statuses that never mean overflow.
+  if (status === 400 || status === 413) return true;
+  if (status === 401 || status === 403 || status === 429) return false;
+  return true;
+}
+
+function extractStatus(error: unknown): number | undefined {
+  if (!error || typeof error !== 'object') return undefined;
+  const e = error as Record<string, unknown>;
+  for (const k of ['statusCode', 'status']) {
+    const v = e[k];
+    if (typeof v === 'number') return v;
+    if (typeof v === 'string' && /^\d+$/.test(v)) return Number(v);
+  }
+  // Nested (e.g. { response: { status } } / { cause: { statusCode } }).
+  for (const k of ['response', 'cause', 'data']) {
+    const nested = e[k];
+    if (nested && typeof nested === 'object') {
+      const s = extractStatus(nested);
+      if (s !== undefined) return s;
+    }
+  }
+  return undefined;
+}
+
+function extractMessage(error: unknown): string {
+  if (error == null) return '';
+  if (typeof error === 'string') return error;
+  if (error instanceof Error) {
+    // Include nested causes (provider libs wrap the real body in `cause`).
+    const cause = (error as { cause?: unknown }).cause;
+    return `${error.message} ${cause ? extractMessage(cause) : ''}`;
+  }
+  if (typeof error === 'object') {
+    const e = error as Record<string, unknown>;
+    const parts: string[] = [];
+    for (const k of ['message', 'error', 'body', 'responseBody', 'data']) {
+      const v = e[k];
+      if (typeof v === 'string') parts.push(v);
+      else if (v && typeof v === 'object') parts.push(extractMessage(v));
+    }
+    return parts.join(' ');
+  }
+  return String(error);
+}
+
+/** Rough token size of a ModelMessage array via the shared chars estimator. */
+export function estimateMessagesTokens(
+  messages: ReadonlyArray<ModelMessage>,
+): number {
+  let total = 0;
+  for (const m of messages) {
+    total += estimateTokens(serializeContent(m.content));
+  }
+  return total;
+}
+
+function serializeContent(content: unknown): string {
+  if (typeof content === 'string') return content;
+  try {
+    return JSON.stringify(content) ?? '';
+  } catch {
+    return '';
+  }
+}
+
+/** Deep JSON string of an arbitrary value, bounded so estimation never throws. */
+function stringifyValue(value: unknown): string {
+  if (typeof value === 'string') return value;
+  try {
+    return JSON.stringify(value) ?? String(value);
+  } catch {
+    return String(value);
+  }
+}
+
+export interface TrimResult {
+  messages: ModelMessage[];
+  /** Whether any trimming was applied. */
+  trimmed: boolean;
+  /** Estimated tokens of the returned messages (chars-based). */
+  estimatedTokens: number;
+}
+
+/**
+ * Bound the replayed history to `budgetTokens`, deterministically. Returns the
+ * SAME array reference (no copy) when nothing needs trimming, so the common case
+ * is free and byte-identical. Trimming order (spec #490):
+ *   1. truncate OLD turns' tool outputs (head+tail + marker) — the bulk of the size
+ *   2. mechanically collapse the OLDEST turns to their text (concatenation, no LLM)
+ *   3. the current + last {@link REPLAY_KEEP_RECENT_TURNS} turns stay FULL
+ *
+ * `budgetTokens === null` disables trimming. `priorContextTokens` (the provider's
+ * fact from last turn) short-circuits the decision: when it is known and already
+ * under budget we skip trimming even if the char-estimate is higher (the provider
+ * count is authoritative). The char-estimate drives WHAT to cut.
+ */
+export function trimHistoryForReplay(
+  messages: ModelMessage[],
+  budgetTokens: number | null,
+  priorContextTokens?: number,
+): TrimResult {
+  if (budgetTokens == null) {
+    return { messages, trimmed: false, estimatedTokens: 0 };
+  }
+  const estimated = estimateMessagesTokens(messages);
+  // Decision signal: prefer the provider's fact (last turn's contextTokens) plus
+  // the estimated delta of the messages appended since; fall back to the pure
+  // char-estimate for a chat with no usage yet.
+  const projected =
+    priorContextTokens != null
+      ? Math.max(priorContextTokens, estimated)
+      : estimated;
+  if (projected <= budgetTokens) {
+    return { messages, trimmed: false, estimatedTokens: estimated };
+  }
+
+  // The tail we always keep full: from the Nth-from-last user message onward.
+  const boundary = recentBoundaryIndex(messages, REPLAY_KEEP_RECENT_TURNS);
+  const tail = messages.slice(boundary);
+  let head = messages.slice(0, boundary).map(cloneMessage);
+
+  // Phase 1: truncate old tool outputs.
+  for (const m of head) {
+    if (m.role === 'tool') truncateToolMessage(m);
+  }
+  let out = [...head, ...tail];
+  let est = estimateMessagesTokens(out);
+  if (est <= budgetTokens) {
+    return { messages: out, trimmed: true, estimatedTokens: est };
+  }
+
+  // Phase 2: collapse the oldest turns (in `head`) to their text, one at a time,
+  // from the oldest, until we fit or the whole head is collapsed.
+  const turns = splitTurns(head);
+  const collapsed: ModelMessage[] = [];
+  let i = 0;
+  for (; i < turns.length; i++) {
+    if (est <= budgetTokens) break;
+    collapsed.push(...collapseTurn(turns[i]));
+    // Re-estimate the whole prospective output.
+    const remaining = turns.slice(i + 1).flat();
+    out = [...collapsed, ...remaining, ...tail];
+    est = estimateMessagesTokens(out);
+  }
+  // Include any turns we didn't need to collapse.
+  const remaining = turns.slice(i).flat();
+  out = [...collapsed, ...remaining, ...tail];
+  est = estimateMessagesTokens(out);
+  return { messages: out, trimmed: true, estimatedTokens: est };
+}
+
+/** Index of the first message of the Nth-from-last user turn (0 if fewer). */
+function recentBoundaryIndex(
+  messages: ReadonlyArray<ModelMessage>,
+  keepTurns: number,
+): number {
+  const userIdx: number[] = [];
+  for (let i = 0; i < messages.length; i++) {
+    if (messages[i].role === 'user') userIdx.push(i);
+  }
+  if (userIdx.length <= keepTurns) return 0;
+  return userIdx[userIdx.length - keepTurns];
+}
+
+/** Split a message list into turns; each turn starts at a `user` message. */
+function splitTurns(messages: ModelMessage[]): ModelMessage[][] {
+  const turns: ModelMessage[][] = [];
+  for (const m of messages) {
+    if (m.role === 'user' || turns.length === 0) turns.push([m]);
+    else turns[turns.length - 1].push(m);
+  }
+  return turns;
+}
+
+/**
+ * Collapse a whole turn to its plain text (mechanical concatenation, not an LLM
+ * summary). Keeps the user message; replaces the assistant/tool messages with a
+ * single assistant text message = the assistant's concatenated text + a marker
+ * when tool activity was dropped. Dropping BOTH the tool-call and tool-result
+ * parts together keeps the rebuilt history balanced (no unpaired calls).
+ */
+function collapseTurn(turn: ModelMessage[]): ModelMessage[] {
+  const out: ModelMessage[] = [];
+  let assistantText = '';
+  let hadTools = false;
+  for (const m of turn) {
+    if (m.role === 'user') {
+      out.push(m);
+    } else if (m.role === 'assistant') {
+      const { text, tools } = extractAssistantText(m.content);
+      assistantText += text;
+      hadTools = hadTools || tools;
+    } else if (m.role === 'tool') {
+      hadTools = true;
+    } else {
+      out.push(m);
+    }
+  }
+  const note =
+    (assistantText ? assistantText.trimEnd() : '') +
+    (hadTools
+      ? `${assistantText ? '\n\n' : ''}${REPLAY_TURN_COLLAPSED_MARKER}`
+      : '');
+  if (note) out.push({ role: 'assistant', content: note } as ModelMessage);
+  return out;
+}
+
+function extractAssistantText(content: unknown): {
+  text: string;
+  tools: boolean;
+} {
+  if (typeof content === 'string') return { text: content, tools: false };
+  if (!Array.isArray(content)) return { text: '', tools: false };
+  let text = '';
+  let tools = false;
+  for (const part of content) {
+    const type = (part as { type?: string })?.type;
+    if (type === 'text') text += (part as { text?: string }).text ?? '';
+    else if (type === 'tool-call') tools = true;
+  }
+  return { text, tools };
+}
+
+/** Truncate every tool-result output in a `tool` message to head+tail+marker. */
+function truncateToolMessage(message: ModelMessage): void {
+  const content = message.content;
+  if (!Array.isArray(content)) return;
+  for (const part of content) {
+    const p = part as { type?: string; output?: { type?: string; value?: unknown } };
+    if (p.type !== 'tool-result' && p.type !== 'tool-error') continue;
+    if (!p.output) continue;
+    const raw = stringifyValue(p.output.value);
+    const budget = REPLAY_TOOL_OUTPUT_HEAD + REPLAY_TOOL_OUTPUT_TAIL;
+    if (raw.length <= budget + REPLAY_TRUNCATION_MARKER.length) continue;
+    const truncated =
+      raw.slice(0, REPLAY_TOOL_OUTPUT_HEAD) +
+      `\n${REPLAY_TRUNCATION_MARKER}\n` +
+      raw.slice(raw.length - REPLAY_TOOL_OUTPUT_TAIL);
+    // Represent the shrunk output as a text output (a valid tool-result output).
+    p.output = { type: 'text', value: truncated };
+  }
+}
+
+/** Shallow-ish clone so trimming never mutates the caller's (persisted-derived)
+ *  message objects — only the OLD region is cloned before it is edited. */
+function cloneMessage(m: ModelMessage): ModelMessage {
+  if (typeof m.content === 'string') return { ...m };
+  return {
+    ...m,
+    content: (m.content as unknown[]).map((p) =>
+      p && typeof p === 'object' ? { ...(p as object) } : p,
+    ),
+  } as ModelMessage;
+}

apps/server/src/core/ai-chat/output-degeneration.spec.ts

@@ -1,11 +1,88 @@
+import { Logger } from '@nestjs/common';
+import { streamText } from 'ai';
 import {
   hasRepeatedLineRun,
   hasPeriodicTail,
   isDegenerateOutput,
   truncateDegeneratedTail,
+  shouldCheckDegeneration,
+  DEGENERATION_CHECK_STEP,
   REPEATED_LINES_THRESHOLD,
   MIN_PERIOD_REPEATS,
+  degenerationThresholds,
 } from './output-degeneration';
+import { AiChatService } from './ai-chat.service';
+
+// Part A (#495 iter10): the detector thresholds are env-tunable. These drive the
+// resolver against real repeat-count shapes and mutation-verify that the env
+// override actually changes the trigger point (not a vacuous read).
+describe('degeneration thresholds are env-configurable', () => {
+  const VARS = [
+    'AI_CHAT_DEGENERATION_REPEATED_LINES',
+    'AI_CHAT_DEGENERATION_PERIOD_MAX_LEN',
+    'AI_CHAT_DEGENERATION_PERIOD_MIN_REPEATS',
+    'AI_CHAT_DEGENERATION_CHECK_STEP',
+  ];
+  const saved: Record<string, string | undefined> = {};
+  beforeEach(() => {
+    for (const v of VARS) saved[v] = process.env[v];
+  });
+  afterEach(() => {
+    for (const v of VARS) {
+      if (saved[v] === undefined) delete process.env[v];
+      else process.env[v] = saved[v];
+    }
+  });
+
+  it('defaults to the compiled constants when unset', () => {
+    for (const v of VARS) delete process.env[v];
+    expect(degenerationThresholds()).toEqual({
+      repeatedLines: REPEATED_LINES_THRESHOLD,
+      maxPeriodLen: 150,
+      minPeriodRepeats: MIN_PERIOD_REPEATS,
+      checkStep: DEGENERATION_CHECK_STEP,
+    });
+  });
+
+  it('falls back to the default on blank / invalid / non-positive values', () => {
+    for (const bad of ['', '  ', 'abc', '0', '-3', '1.5']) {
+      process.env.AI_CHAT_DEGENERATION_REPEATED_LINES = bad;
+      // '1.5' floors to 1 (still ≥1, valid); every other bad value → default.
+      const expected = bad === '1.5' ? 1 : REPEATED_LINES_THRESHOLD;
+      expect(degenerationThresholds().repeatedLines).toBe(expected);
+    }
+  });
+
+  it('a RAISED check-step suppresses a burst the default would have flagged', () => {
+    // A ~3.3KB periodic burst is periodic-degenerate, but shouldCheckDegeneration
+    // is the throttle gate. Default checkStep=2000 arms on it; raising the step
+    // above the burst size means the throttle never re-fires for it.
+    const burstLen = 'loadTools.\n'.repeat(300).length; // ~3300
+    delete process.env.AI_CHAT_DEGENERATION_CHECK_STEP;
+    expect(shouldCheckDegeneration(burstLen, 0)).toBe(true); // default 2000
+    process.env.AI_CHAT_DEGENERATION_CHECK_STEP = String(burstLen + 1);
+    expect(shouldCheckDegeneration(burstLen, 0)).toBe(false); // raised gate
+  });
+
+  it('a LOWERED repeated-lines threshold trips on a shorter identical-line run', () => {
+    // 8 identical lines: below the default 25 (rule 1) and below the periodic
+    // rule's 20 repeats — so isDegenerateOutput is false by default.
+    const shortRun = 'x\n'.repeat(8);
+    delete process.env.AI_CHAT_DEGENERATION_REPEATED_LINES;
+    expect(isDegenerateOutput(shortRun)).toBe(false);
+    // Lower rule 1 to 5 → the 8-line run now trips.
+    process.env.AI_CHAT_DEGENERATION_REPEATED_LINES = '5';
+    expect(isDegenerateOutput(shortRun)).toBe(true);
+  });
+});
+
+// Mock ONLY streamText so we can capture the onChunk/onStepFinish callbacks the
+// service registers and drive them by hand; every other `ai` export the service
+// uses (convertToModelMessages, stepCountIs, …) stays real.
+jest.mock('ai', () => {
+  const actual = jest.requireActual('ai');
+  return { ...actual, streamText: jest.fn() };
+});
 
 /**
  * Unit tests for the token-degeneration detector (#444) — the sole anti-babble
@@ -180,3 +257,188 @@ describe('truncateDegeneratedTail', () => {
     expect(truncateDegeneratedTail(text)).toBe(text);
   });
 });
+
+/**
+ * Throttle + step-boundary reset (#486). The stream keeps a watermark
+ * (`lastDegenerationCheckLen`) that is an OFFSET into the accumulated step text.
+ * On a step boundary the accumulator resets to '', so the watermark MUST reset to
+ * 0 too — otherwise the throttle goes silent for the whole next step. These tests
+ * pin the pure decision AND the reset property that ai-chat.service.onStepFinish
+ * now enforces.
+ */
+describe('shouldCheckDegeneration (throttle) + step-boundary reset (#486)', () => {
+  it('fires once the text grows a full DEGENERATION_CHECK_STEP past the mark', () => {
+    expect(shouldCheckDegeneration(DEGENERATION_CHECK_STEP, 0)).toBe(true);
+    expect(shouldCheckDegeneration(DEGENERATION_CHECK_STEP - 1, 0)).toBe(false);
+    expect(shouldCheckDegeneration(5000, 3000)).toBe(true); // grew 2000 since mark
+    expect(shouldCheckDegeneration(4000, 3000)).toBe(false); // grew only 1000
+  });
+
+  it('BUG (no reset): a stale large watermark silences the next step', () => {
+    // End of a long step: the watermark sits at 5000. The step ends and the
+    // accumulator resets to '' — but if the watermark is NOT reset, a fresh short
+    // degenerate burst (length 2000) never triggers a check: 2000 - 5000 < STEP.
+    const staleWatermark = 5000;
+    const nextStepLen = DEGENERATION_CHECK_STEP; // a fresh 2KB burst
+    expect(shouldCheckDegeneration(nextStepLen, staleWatermark)).toBe(false);
+  });
+
+  it('FIX (reset to 0): the same short degenerate burst IS checked and detected', () => {
+    // onStepFinish now zeroes the watermark, so the fresh burst re-arms the check.
+    const resetWatermark = 0;
+    const degenerateBurst = 'loadTools.\n'.repeat(300); // real degeneration
+    expect(degenerateBurst.length).toBeGreaterThanOrEqual(DEGENERATION_CHECK_STEP);
+    // The throttle now fires...
+    expect(
+      shouldCheckDegeneration(degenerateBurst.length, resetWatermark),
+    ).toBe(true);
+    // ...and the detector catches the loop that would otherwise stream unchecked.
+    expect(isDegenerateOutput(degenerateBurst)).toBe(true);
+  });
+});
+
+/**
+ * BEHAVIOR guard for the ACTUAL fix (#486, ai-chat.service.onStepFinish resets
+ * lastDegenerationCheckLen to 0). The pure tests above use a hard-coded
+ * resetWatermark, so a REVERT of the real `lastDegenerationCheckLen = 0` line
+ * would not redden any of them. This drives the REAL onChunk/onStepFinish
+ * closures from stream() end to end and asserts the run is aborted when a fresh
+ * degenerate burst arrives in the step AFTER a long clean step — which only
+ * happens if the watermark was actually zeroed on the step boundary.
+ */
+describe('AiChatService: onStepFinish re-arms the degeneration watermark (#486)', () => {
+  const streamTextMock = streamText as unknown as jest.Mock;
+
+  function makeRes() {
+    return {
+      raw: {
+        writeHead: jest.fn(),
+        write: jest.fn(),
+        once: jest.fn(),
+        on: jest.fn(),
+        flushHeaders: jest.fn(),
+        writableEnded: false,
+        destroyed: false,
+      },
+    };
+  }
+
+  function makeService() {
+    const aiChatRepo = {
+      findById: jest.fn(async () => ({ id: 'chat-1', workspaceId: 'ws-1' })),
+      insert: jest.fn(),
+    };
+    const aiChatMessageRepo = {
+      insert: jest.fn(async () => ({ id: 'msg-1' })),
+      findAllByChat: jest.fn(async () => []),
+      update: jest.fn(async () => ({ id: 'msg-1' })),
+    };
+    const aiSettings = { resolve: jest.fn(async () => ({})) };
+    const tools = { forUser: jest.fn(async () => ({})) };
+    const mcpClients = {
+      toolsFor: jest.fn(async () => ({
+        tools: {},
+        clients: [],
+        outcomes: [],
+        instructions: [],
+      })),
+    };
+    return new AiChatService(
+      {} as never, // ai
+      aiChatRepo as never,
+      aiChatMessageRepo as never,
+      {} as never, // aiChatPageSnapshotRepo
+      aiSettings as never,
+      tools as never,
+      mcpClients as never,
+      {} as never, // aiAgentRoleRepo
+      {} as never, // pageRepo
+      {} as never, // pageAccess
+      {
+        isAiChatDeferredToolsEnabled: () => false,
+        // Lockdown OFF -> the degeneration guard is the active anti-babble path.
+        isAiChatFinalStepLockdownEnabled: () => false,
+      } as never, // environment
+    );
+  }
+
+  beforeEach(() => {
+    streamTextMock.mockReset();
+    jest.spyOn(Logger.prototype, 'log').mockImplementation(() => undefined as never);
+    jest.spyOn(Logger.prototype, 'warn').mockImplementation(() => undefined as never);
+  });
+
+  afterEach(() => jest.restoreAllMocks());
+
+  it('aborts on a fresh degenerate burst in the NEXT step (reverting the reset line reddens this)', async () => {
+    let captured:
+      | {
+          onChunk?: (e: { chunk: { type: string; text: string } }) => void;
+          onStepFinish?: (step: unknown) => void;
+          abortSignal?: AbortSignal;
+        }
+      | undefined;
+    streamTextMock.mockImplementation((opts: never) => {
+      captured = opts;
+      return {
+        consumeStream: jest.fn(),
+        pipeUIMessageStreamToResponse: jest.fn(),
+      };
+    });
+
+    const svc = makeService();
+    await svc.stream({
+      user: { id: 'user-1' } as never,
+      workspace: { id: 'ws-1' } as never,
+      sessionId: 'sess-1',
+      body: {
+        chatId: 'chat-1',
+        messages: [
+          { id: 'm1', role: 'user', parts: [{ type: 'text', text: 'hi' }] },
+        ],
+      } as never,
+      res: makeRes() as never,
+      signal: new AbortController().signal,
+      model: {} as never,
+      role: null,
+      // No runHooks -> legacy path (socket signal), degeneration guard active.
+    });
+
+    expect(streamTextMock).toHaveBeenCalledTimes(1);
+    const onChunk = captured!.onChunk!;
+    const onStepFinish = captured!.onStepFinish!;
+    const abortSignal = captured!.abortSignal!;
+    expect(abortSignal.aborted).toBe(false);
+
+    // STEP 1: a LONG, non-degenerate first step. Distinct lines never trip the
+    // detector, but they advance the throttle watermark far past the burst size
+    // that follows (to ~5x the step). This is the stale watermark that, WITHOUT
+    // the reset, would silence step 2.
+    let counter = 0;
+    let accumulated = 0;
+    while (accumulated < DEGENERATION_CHECK_STEP * 5) {
+      const line = `unique clean line number ${counter++} with distinct words\n`;
+      accumulated += line.length;
+      onChunk({ chunk: { type: 'text-delta', text: line } });
+    }
+    expect(abortSignal.aborted).toBe(false); // clean step must not abort
+
+    // STEP BOUNDARY: the real onStepFinish resets inProgressText AND (the fix)
+    // zeroes lastDegenerationCheckLen.
+    onStepFinish({ text: 'a clean first step', toolCalls: [], toolResults: [] });
+
+    // STEP 2: a FRESH, short degenerate burst (~3.3KB). Its length is far below
+    // the step-1 stale watermark (~10KB), so WITHOUT the reset the throttle stays
+    // silent and this streams unchecked. WITH the reset (watermark 0) it re-arms,
+    // the detector fires, and the run aborts.
+    const burst = 'loadTools.\n'.repeat(300);
+    expect(burst.length).toBeGreaterThanOrEqual(DEGENERATION_CHECK_STEP);
+    expect(burst.length).toBeLessThan(DEGENERATION_CHECK_STEP * 5);
+    onChunk({ chunk: { type: 'text-delta', text: burst } });
+
+    // The decisive assertion: the composed abortSignal (unioned with the
+    // degeneration controller) is now aborted. Reverting `lastDegenerationCheckLen
+    // = 0` in onStepFinish makes this stay false.
+    expect(abortSignal.aborted).toBe(true);
+  });
+});

apps/server/src/core/ai-chat/output-degeneration.ts

@@ -23,6 +23,54 @@ export const MAX_PERIOD_LEN = 150;
 /** Rule 2: minimum number of consecutive block repeats to trigger. */
 export const MIN_PERIOD_REPEATS = 20;
 
+/**
+ * Read a positive-integer threshold from an env var, falling back to `fallback`
+ * on unset/blank/invalid/non-positive. Mirrors the `AI_STREAM_PRE_RESPONSE_RETRIES`
+ * resolver in `ai-streaming-fetch.ts`: read the RAW string first so a blank value
+ * is treated as "unset" (→ fallback) rather than coercing to 0. Thresholds must
+ * stay ≥ 1 — a 0/negative would make the detector fire on any text (or never), so
+ * a bad value degrades to the safe compiled default instead. Env-tunable so an
+ * operator can retune the anti-babble guard (#444) without a redeploy, following
+ * the `AI_CHAT_FINAL_STEP_LOCKDOWN` toggle convention.
+ */
+function envThreshold(name: string, fallback: number): number {
+  const rawStr = process.env[name];
+  if (rawStr === undefined || rawStr.trim() === '') return fallback;
+  const raw = Number(rawStr);
+  return Number.isFinite(raw) && raw >= 1 ? Math.floor(raw) : fallback;
+}
+
+/**
+ * Resolve the degeneration-detector thresholds from the environment, each
+ * defaulting to the compiled constant above. Read fresh per call (not cached at
+ * import) so a test — or a runtime env change — takes effect deterministically.
+ */
+export function degenerationThresholds(): {
+  repeatedLines: number;
+  maxPeriodLen: number;
+  minPeriodRepeats: number;
+  checkStep: number;
+} {
+  return {
+    repeatedLines: envThreshold(
+      'AI_CHAT_DEGENERATION_REPEATED_LINES',
+      REPEATED_LINES_THRESHOLD,
+    ),
+    maxPeriodLen: envThreshold(
+      'AI_CHAT_DEGENERATION_PERIOD_MAX_LEN',
+      MAX_PERIOD_LEN,
+    ),
+    minPeriodRepeats: envThreshold(
+      'AI_CHAT_DEGENERATION_PERIOD_MIN_REPEATS',
+      MIN_PERIOD_REPEATS,
+    ),
+    checkStep: envThreshold(
+      'AI_CHAT_DEGENERATION_CHECK_STEP',
+      DEGENERATION_CHECK_STEP,
+    ),
+  };
+}
+
 /**
  * Rule 1 — ≥`REPEATED_LINES_THRESHOLD` consecutive IDENTICAL non-empty lines at
  * the tail. Catches the classic newline-delimited loop ("loadTools.\n" ×N).
@@ -128,7 +176,37 @@ export function hasPeriodicTail(
  * Pure — the caller owns the abort side effect.
  */
 export function isDegenerateOutput(text: string): boolean {
-  return hasRepeatedLineRun(text) || hasPeriodicTail(text);
+  const cfg = degenerationThresholds();
+  return (
+    hasRepeatedLineRun(text, cfg.repeatedLines) ||
+    hasPeriodicTail(text, cfg.maxPeriodLen, cfg.minPeriodRepeats)
+  );
+}
+
+/**
+ * How many bytes the in-progress text must grow before the (amortized) tail
+ * heuristics are re-run. Shared with ai-chat.service so the throttle the stream
+ * applies is the SAME one the unit test drives.
+ */
+export const DEGENERATION_CHECK_STEP = 2000;
+
+/**
+ * Throttle decision for the degeneration guard (#444/#486). Returns true when
+ * the accumulated text has grown at least DEGENERATION_CHECK_STEP bytes past the
+ * last-checked offset, so the pure rules only fire every ~2KB. Pure; the caller
+ * updates its watermark to `textLen` when this returns true.
+ *
+ * The watermark is an offset INTO the accumulator, so when the accumulator is
+ * reset to '' on a step boundary the caller MUST reset the watermark to 0 too
+ * (#486). Otherwise `textLen - lastCheckLen` goes negative after the reset and
+ * this returns false until a later step re-grows past the stale offset — a whole
+ * degenerate step could stream unchecked.
+ */
+export function shouldCheckDegeneration(
+  textLen: number,
+  lastCheckLen: number,
+): boolean {
+  return textLen - lastCheckLen >= degenerationThresholds().checkStep;
 }
 
 /**

apps/server/src/core/ai-chat/public-share-chat.error-leak.spec.ts

@@ -0,0 +1,241 @@
+// Break the editor-ext import chain (share.service -> collaboration.util ->
+// @docmost/editor-ext -> @tiptap/core) that is unresolvable in this jest env and
+// pre-existingly breaks these specs. jsonToMarkdown is never reached in these
+// tests (the tools fail before rendering markdown).
+jest.mock('../../collaboration/collaboration.util', () => ({
+  jsonToMarkdown: () => '',
+}));
+
+import { Logger } from '@nestjs/common';
+import { MockLanguageModelV3, simulateReadableStream } from 'ai/test';
+import { PublicShareChatService } from './public-share-chat.service';
+import { PublicShareChatToolsService } from './tools/public-share-chat-tools.service';
+
+/**
+ * SECURITY integration guard for #394 (commit 5): a tool's or the provider's raw
+ * error text must NOT leak to an anonymous public-share reader.
+ *
+ * The render gate (ToolCallCard showErrors=false) hides the text in the DOM but
+ * NOT on the wire, so this test asserts on the RAW SSE BYTES the server writes —
+ * exactly the channel the render gate masks. We drive the real
+ * PublicShareChatService.stream() with a real share toolset (its underlying
+ * services mocked to fail) and a mock model, then inspect every byte piped to the
+ * fake socket.
+ */
+
+// A minimal ServerResponse stand-in that records every written chunk.
+class FakeSocket {
+  chunks: string[] = [];
+  statusCode = 200;
+  writableEnded = false;
+  destroyed = false;
+  headersSent = false;
+  writeHead(): this {
+    this.headersSent = true;
+    return this;
+  }
+  setHeader(): void {}
+  removeHeader(): void {}
+  getHeader(): undefined {
+    return undefined;
+  }
+  flushHeaders(): void {}
+  write(chunk: unknown): boolean {
+    this.chunks.push(
+      typeof chunk === 'string' ? chunk : Buffer.from(chunk as never).toString('utf8'),
+    );
+    return true;
+  }
+  end(chunk?: unknown): void {
+    if (chunk) this.write(chunk);
+    this.writableEnded = true;
+  }
+  on(): this {
+    return this;
+  }
+  once(): this {
+    return this;
+  }
+  get body(): string {
+    return this.chunks.join('');
+  }
+}
+
+/** Mock model that issues one getSharePage tool call, then finishes with text. */
+function toolCallingModel(): MockLanguageModelV3 {
+  let call = 0;
+  return new MockLanguageModelV3({
+    doStream: async () => {
+      call++;
+      if (call === 1) {
+        return {
+          stream: simulateReadableStream({
+            chunks: [
+              { type: 'stream-start' as const, warnings: [] },
+              { type: 'tool-input-start' as const, id: 't1', toolName: 'getSharePage' },
+              { type: 'tool-input-end' as const, id: 't1' },
+              {
+                type: 'tool-call' as const,
+                toolCallId: 't1',
+                toolName: 'getSharePage',
+                input: '{"pageId":"secret-page"}',
+              },
+              {
+                type: 'finish' as const,
+                finishReason: { unified: 'tool-calls' as const, raw: 'tool_calls' },
+                usage: {
+                  inputTokens: { total: 1, noCache: undefined, cacheRead: undefined, cacheWrite: undefined },
+                  outputTokens: { total: 1, text: 1, reasoning: undefined },
+                },
+              },
+            ],
+          }),
+        };
+      }
+      return {
+        stream: simulateReadableStream({
+          chunks: [
+            { type: 'stream-start' as const, warnings: [] },
+            { type: 'text-start' as const, id: '1' },
+            { type: 'text-delta' as const, id: '1', delta: 'Sorry.' },
+            { type: 'text-end' as const, id: '1' },
+            {
+              type: 'finish' as const,
+              finishReason: { unified: 'stop' as const, raw: 'stop' },
+              usage: {
+                inputTokens: { total: 1, noCache: undefined, cacheRead: undefined, cacheWrite: undefined },
+                outputTokens: { total: 1, text: 1, reasoning: undefined },
+              },
+            },
+          ],
+        }),
+      };
+    },
+  });
+}
+
+/** Mock model whose stream emits a provider error carrying an internal secret. */
+function providerErrorModel(secret: string): MockLanguageModelV3 {
+  return new MockLanguageModelV3({
+    doStream: async () => ({
+      stream: simulateReadableStream({
+        chunks: [
+          { type: 'stream-start' as const, warnings: [] },
+          {
+            type: 'error' as const,
+            error: {
+              statusCode: 503,
+              message: 'Service Unavailable',
+              responseBody: `upstream ${secret} model=internal-gpt`,
+            },
+          },
+        ],
+      }),
+    }),
+  });
+}
+
+function makeService(toolsService: PublicShareChatToolsService): {
+  svc: PublicShareChatService;
+  logSpy: jest.SpyInstance;
+} {
+  const svc = Object.create(PublicShareChatService.prototype);
+  const logger = new Logger('test');
+  const logSpy = jest.spyOn(logger, 'error').mockImplementation(() => undefined);
+  jest.spyOn(logger, 'warn').mockImplementation(() => undefined);
+  svc.tools = toolsService;
+  svc.logger = logger;
+  svc.tokenBudget = { record: jest.fn().mockResolvedValue(undefined) };
+  return { svc, logSpy };
+}
+
+async function runStream(
+  svc: PublicShareChatService,
+  model: MockLanguageModelV3,
+): Promise<FakeSocket> {
+  const socket = new FakeSocket();
+  await svc.stream({
+    workspaceId: 'ws1',
+    shareId: 'share1',
+    share: { id: 'share1', pageId: 'p1', sharedPage: { id: 'p1', title: 'Docs' } },
+    openedPage: null,
+    messages: [
+      { id: 'm1', role: 'user', parts: [{ type: 'text', text: 'read the page' }] } as never,
+    ],
+    res: { raw: socket } as never,
+    signal: new AbortController().signal,
+    model: model as never,
+    role: null,
+  });
+  // Let the piped stream drain fully.
+  await new Promise((r) => setTimeout(r, 300));
+  return socket;
+}
+
+describe('public share chat error leak (#394)', () => {
+  afterEach(() => jest.restoreAllMocks());
+
+  it('does NOT leak a tool\'s raw internal error to the SSE bytes (generic classified string instead)', async () => {
+    const SECRET = 'INTERNAL_baseUrl_http://provider.internal:8080/v1';
+    const shareService = {
+      // The canonical boundary throws a RAW internal error (with a secret).
+      resolveReadableSharePage: jest
+        .fn()
+        .mockRejectedValue(new Error(`db failed at ${SECRET} stack@line42`)),
+    };
+    const tools = new PublicShareChatToolsService(
+      shareService as never,
+      {} as never,
+      {} as never,
+    );
+    const { svc } = makeService(tools);
+
+    const socket = await runStream(svc, toolCallingModel());
+
+    // The tool-output-error frame is present on the wire...
+    expect(socket.body).toContain('tool-output-error');
+    // ...but it carries ONLY the generic classified string — never the secret,
+    // the raw driver message, or a stack fragment.
+    expect(socket.body).toContain('The tool could not complete the request.');
+    expect(socket.body).not.toContain(SECRET);
+    expect(socket.body).not.toContain('stack@line42');
+    expect(socket.body).not.toContain('db failed');
+  });
+
+  it('passes a SAFE ShareToolError message (page not available) through to the bytes', async () => {
+    const shareService = {
+      // Not found in this share -> the tool throws the classified SAFE message.
+      resolveReadableSharePage: jest.fn().mockResolvedValue(null),
+    };
+    const tools = new PublicShareChatToolsService(
+      shareService as never,
+      {} as never,
+      {} as never,
+    );
+    const { svc } = makeService(tools);
+
+    const socket = await runStream(svc, toolCallingModel());
+    expect(socket.body).toContain('tool-output-error');
+    expect(socket.body).toContain('not available in this share');
+  });
+
+  it('does NOT leak a provider error (statusCode + response body) to the SSE bytes', async () => {
+    const SECRET = 'http://provider.internal:8080';
+    const tools = new PublicShareChatToolsService(
+      {} as never,
+      {} as never,
+      {} as never,
+    );
+    const { svc, logSpy } = makeService(tools);
+
+    const socket = await runStream(svc, providerErrorModel(SECRET));
+
+    // The anon sees a fixed classified string, not the provider body/baseUrl/model.
+    expect(socket.body).toContain('temporarily unavailable');
+    expect(socket.body).not.toContain(SECRET);
+    expect(socket.body).not.toContain('internal-gpt');
+    // The FULL provider detail is logged server-side only.
+    const logged = logSpy.mock.calls.map((c) => String(c[0])).join('\n');
+    expect(logged).toContain(SECRET);
+  });
+});

apps/server/src/core/ai-chat/public-share-chat.service.ts

@@ -12,7 +12,10 @@ import { AiAgentRoleRepo } from '@docmost/db/repos/ai-agent-roles/ai-agent-roles
 import { AiAgentRole } from '@docmost/db/types/entity.types';
 import { AiService } from '../../integrations/ai/ai.service';
 import { AiSettingsService } from '../../integrations/ai/ai-settings.service';
-import { PublicShareChatToolsService } from './tools/public-share-chat-tools.service';
+import {
+  PublicShareChatToolsService,
+  ShareToolError,
+} from './tools/public-share-chat-tools.service';
 import { buildShareSystemPrompt } from './public-share-chat.prompt';
 import { roleModelOverride } from './roles/role-model-config';
 import {
@@ -102,6 +105,30 @@ export function filterShareTranscript(messages: UIMessage[]): UIMessage[] {
   );
 }
 
+/**
+ * Fixed, classified strings an ANONYMOUS share reader may see when the assistant
+ * stream fails (#394). These reveal NOTHING about the internal provider, its
+ * baseUrl, the model name, or the raw response body — unlike describeProviderError
+ * (which is for the server log / the authenticated operator only). We classify by
+ * HTTP status where available so the reader still gets a useful hint (retry vs.
+ * give up) without any internal detail.
+ */
+export function classifyAnonStreamError(error: unknown): string {
+  const status =
+    typeof error === 'object' && error !== null
+      ? (error as { statusCode?: number }).statusCode
+      : undefined;
+  if (status === 429) {
+    return 'The assistant is receiving too many requests right now. Please try again shortly.';
+  }
+  if (typeof status === 'number' && status >= 500) {
+    return 'The assistant is temporarily unavailable. Please try again.';
+  }
+  // Any other failure (including a bare connection error with no status): a
+  // single neutral line. No provider identity, no config, no response body.
+  return 'The assistant could not complete your request. Please try again.';
+}
+
 /**
  * Anonymous, read-only AI assistant for a single PUBLIC share tree.
  *
@@ -280,6 +307,10 @@ export class PublicShareChatService {
         system,
         messages: modelMessages,
         tools,
+        // Pin the AI SDK per-request retry budget explicitly (matches the SDK
+        // default of 2). Connection arithmetic: (1 + maxRetries) × (1 +
+        // AI_STREAM_PRE_RESPONSE_RETRIES) worst-case connects per turn.
+        maxRetries: 2,
         // Bound the agent loop for anonymous callers.
         stopWhen: stepCountIs(5),
         // Cap per-request output so one anonymous call cannot run up the provider
@@ -318,11 +349,28 @@ export class PublicShareChatService {
       result.pipeUIMessageStreamToResponse(res.raw, {
         headers: { 'X-Accel-Buffering': 'no' },
         onError: (error: unknown) => {
-          // Reuse the shared formatter so provider error formatting stays
+          // SECURITY (#394): the string this returns is written verbatim into the
-          // unified between the log line and the streamed error message — a
+          // SSE error frame delivered to an ANONYMOUS reader (for a tool failure
-          // share reader sees 402/429/503 causes consistently with the
+          // it becomes the atomic `tool-output-error` frame's errorText; for a
-          // authenticated path.
+          // stream/provider failure, the terminal error frame).
-          return describeProviderError(error, 'AI stream error');
+          //
+          // A ShareToolError is already a classified, safe tool message (see
+          // PublicShareChatToolsService.wrapToolErrors) — pass it through so the
+          // reader still gets the useful "page not available in this share" hint.
+          if (error instanceof ShareToolError) {
+            return error.message;
+          }
+          // Anything else is a provider/stream error. describeProviderError
+          // bundles the provider statusCode AND response body, which can carry the
+          // internal baseUrl or model name — NEVER expose that to the public. Log
+          // the full detail server-side only and return a fixed classified string.
+          this.logger.error(
+            `Public share chat pipe error: ${describeProviderError(
+              error,
+              'AI stream error',
+            )}`,
+          );
+          return classifyAnonStreamError(error);
         },
       });