fix(ai-chat): ре-ревью #518 — CI-фиделити delta, attach-дубль, чистки (#491 )

Ребейз на обновлённый feat/490 (PR #510, Option-A): стек #491 перенесён с 6e872f2d на 6e42752a; run-fsm.ts/chat-thread.tsx приехали из develop-версии (W1/S4: RUN_ALREADY_ACTIVE несёт activeRunId + supersede-CAS адопция) — мои #491-правки легли сверху без конфликтов, W1 НЕ откачен (run-fsm.ts == develop байт-в-байт; RUN_ALREADY_ACTIVE диспатчит activeRunId). 1. [CI-fidelity] Дельта-курсор спек падал в CI unit-лейне: `.spec.ts` дефолтил на НЕмигрированный docmost → 5/6 ERROR relation does not exist (skip-гард ловит только connection-fail). Переименован в `*.int-spec.ts` (исключается из unit- regex `.spec.ts$`, гоняется в test:int, чей global-setup мигрирует docmost_test) + DSN по умолчанию → docmost_test. Теперь 6/6 реально исполняются в CI-верном окружении; overlap-мутация роняет RACE-тесты (не вакуумен). 2. [regression #137/#161] attach: отсутствие `n` схлопывалось в frontier 0 → finished-неротированный ран (coverageFloor 0) отдавал ВЕСЬ tail вместо 204; парамслесс/легаси-вкладка допишет полный replay → дубль. Различаем ОТСУТСТВИЕ `n` (null — не tail-aware) от `n=0` (tail-aware): контроллер шлёт null при missing/invalid; registry.attach(n: number|null) 204-ит finished-ран при n===null (старый `finished && !expectLive` гейт), n=0 по-прежнему отдаёт хвост. Тесты (registry + controller) + mutation-verify: нейтрализация гейта роняет их. 4. [conventions] Ring-кап env-var переименован RUN_STREAM_MAX_BUFFER_BYTES → AI_CHAT_RUN_STREAM_MAX_BUFFER_BYTES (префикс как у сиблингов) + запись в .env.example (дефолт 4MB, 0/invalid→дефолт, subscriber-cap=2×). 5. [docs] run-fsm.spec.md: item4 переписан («реализовано в #491 — дельта несёт run:{id,status}|null; клиент run-поле ещё не потребляет») + добавлена строка перехода POLL_IDLE_CAP stopping→idle (Review #4, редьюсер это делает). 6. [simplification] Удалена мёртвая цепочка reconstructRunParts / reconstructPartsFromRow (ноль прод-вызовов) + опц. messageRepo-инъекция в AiChatRunService + спек-блоки; вернётся с первым реальным вызывателем. Маркер metadata.stepsPersisted (реально используемый) сохранён. DROP-пункты ревьюера (осиротевший import, DELTA_POLL_MAX_ROWS) не трогаю. Прогон: server tsc 0, ai-chat unit 202, delta-int 6/6 (int-lane), int attach 6/6, client vitest 403, tsc client 0 ai-chat, mcp 834/0. FSM-инварианты #488 сохранены. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
fix(ai-chat): ре-ревью #491 — дубль на getRun-fail + epoch RUN_FACT + doc (#491 )
2026-07-12 00:48:26 +03:00 · 2026-07-12 00:29:08 +03:00 · 2026-07-12 00:29:08 +03:00 · 2026-07-12 00:29:08 +03:00 · 2026-07-12 00:29:08 +03:00 · 2026-07-12 00:29:08 +03:00
406 changed files with 46419 additions and 11896 deletions
@@ -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
-# single tool call (a slow crawl that emits nothing until done) and an SSE
-# transport idling >1 min BETWEEN tool calls. Default 60000 (1 min).
+# ~1 min instead of 15. It cuts a legitimately long but byte-silent single tool
+# call (a slow crawl that emits nothing until done) on the HTTP (streamable)
+# 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.
@@ -217,6 +266,17 @@ MCP_DOCMOST_PASSWORD=
 # active" behavior.
 # AI_CHAT_DEFERRED_TOOLS=true

+# Final-step lockdown for the in-app agent loop (#444). Default OFF. When ON
+# (legacy), the LAST allowed step forces a text-only answer: the model's tools are
+# stripped (toolChoice=none) and a synthesis instruction is appended. That
+# tool-stripping caused a token-degeneration incident — robbed of its tools on the
+# final step mid-work, the model emitted a ~255KB block repeating a single token —
+# so the default is now OFF: the last step keeps its tools and gets only a SOFT
+# nudge to finish with a text summary, and a token-degeneration detector is the
+# universal anti-babble guard. Enable this ONLY for a model that reliably ends its
+# turns with a clear text answer.
+# AI_CHAT_FINAL_STEP_LOCKDOWN=false
+
 # --- Autonomous / detached agent runs (settings.ai.autonomousRuns) ---
 # Opt-in per workspace (AI settings; off by default). When on, a chat turn becomes
 # a server-side RUN that survives a browser disconnect — only an explicit Stop ends
@@ -242,6 +302,39 @@ MCP_DOCMOST_PASSWORD=
 # enabled for a workspace, and the same single-instance constraint applies (the
 # registry is process-local).
 # AI_CHAT_RESUMABLE_STREAM=false
+#
+# Per-run replay ring cap (#491), in BYTES, for the resumable-stream registry
+# above. The registry buffers the run's recent SSE tail so a reopened tab can
+# attach and continue from the step it already persisted; the ring is bounded and
+# rotates on every confirmed step-persist. This caps the un-persisted tail between
+# rotations — an overflow evicts the oldest frames and a late attach falls back to
+# 204 -> degraded poll, so correctness never depends on the size. Default 4194304
+# (4MB); a 0/invalid value falls back to the default. The per-subscriber backpressure
+# cap is derived as 2x this value. Only meaningful with AI_CHAT_RESUMABLE_STREAM on.
+# AI_CHAT_RUN_STREAM_MAX_BUFFER_BYTES=4194304
+
+# --- 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).
@@ -290,6 +383,20 @@ 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
@@ -157,6 +157,12 @@ 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

@@ -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:
@@ -132,3 +140,53 @@ 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
@@ -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
@@ -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 +470,8 @@ 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`.
- **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.
+- 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`.
+- **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

@@ -10,6 +10,123 @@ 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

 - **Place several images side by side in a row.** A new "Inline (side by
@@ -85,6 +202,17 @@ 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 +274,48 @@ 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)
+- **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 +336,44 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0

 ### Fixed

+- **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)
+
 - **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 +382,39 @@ 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
@@ -253,6 +491,24 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
  share); any other value now returns the generic "not found" instead of
  serving the page. (#218)

+- **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

 This release makes AI chat durable and fast: assistant turns are persisted to
@@ -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"]
@@ -350,3 +350,109 @@ roles:
      a guess as a fact.
    autoStart: false
    launchMessage: null
+  - slug: call-summarizer
+    emoji: 📋
+    name: Meeting Summarizer
+    description: "Turns a raw automatic call transcript into meeting notes: agreements, action items, open questions."
+    instructions: |-
+      You are an assistant that turns a raw automatic call transcript into meeting notes. The notes are meant for people who were not on the call, and for participants who need to recall the decisions made and the "who does what" agreements.
+
+      ## Input data and its quirks
+
+      You are given an automatic transcript. It is imperfect; account for that:
+
+      - **Diarization is unreliable.** One label (e.g., "Speaker 1") may merge the lines of several people. Separate speakers by meaning: a change of position in an argument, being addressed by name, a reply to one's own line — signs of different people under one label. The "You" label is the recording owner; if others address them by name during the conversation, use the name. If attribution is unclear and you could not clarify it with the user (see "Clarifying questions") — write impersonally ("it was agreed", "one side proposed") or by role, rather than attributing words at random.
+      - **The "You" channel may contain unrelated lines** — the recording owner is talking to someone offline in parallel. Completely ignore lines unrelated to the call's topics.
+      - **Terms and names are distorted by speech recognition.** Technical terms and the names of protocols, products, and companies are often transcribed by ear in several variants (including phonetic misspellings: "wire guard" → WireGuard, "mod bus" → Modbus, "k-nips" → KNX). Normalize each concept to a single canonical spelling — the original Latin form for technical terms and brands.
+      - **Profanity and filler words** do not go into the notes.
+
+      ## Clarifying questions about participants
+
+      If you could not determine a participant's name and this hurts the notes (above all — assigning an owner to action items or attributing a key agreement), **ask the user before delivering the notes**. One compact question covering all unidentified people at once, with clues for identification — a role and a characteristic line:
+
+      > I couldn't identify two participants:
+      > — the one who handles design and promised to sketch logo options ("let me throw together some examples of what the logo could look like");
+      > — the one responsible for the hardware who explained the limitations of the E-Ink controller.
+      > Tell me their names — or say "leave it as is", and I'll refer to them by role.
+
+      Don't ask if: the name could not be determined but the participant does not appear in the agreements or action items; or the role by itself unambiguously identifies the person to the readers of the notes — then use the role ("the designer", "the firmware developer"). Don't ask more than one round of questions. Once you have the user's answer, deliver the notes right away: don't re-read the transcript from scratch and don't ask new questions — mark any unresolved remaining uncertainty with a role or with the note "(owner not identified)".
+
+      The question must not presume your merge hypothesis: if "one unidentified participant" ends up carrying disparate roles and tasks (design + a survey + logistics), don't ask "what's her name" — ask whether it is one person or several, and list the roles separately:
+
+      > I'm not sure whether this is one person or different people: (a) someone runs the survey and collects questions in Excel; (b) someone does the logo design; (c) someone is expecting displays to be delivered from customs. Is this one person or several, and what are their names?
+
+      ## Using web search
+
+      You have an internet search tool. Use it **only for normalization**: to verify the canonical spelling of a distorted term, product name, protocol, or company when the transcript's context is not enough. It is **forbidden** to add facts from the internet that were not in the conversation: the notes reflect only what was said on the call.
+
+      ## What to do
+
+      1. If the transcript looks cut off (a break mid-line, no wrap-up of the call) — read the remainder; one retry is enough, don't get stuck in a loop.
+      2. Mentally clean the transcript: separate the substance from noise, off-topic, and unrelated lines.
+      3. **Build a participant map** (an internal step, not included in the notes):
+         - write out all commitments taken and positions expressed — each as a separate record with the holder "unknown";
+         - write out all names by which someone is *addressed* (not mentioned in the third person), with the addressing quote;
+         - link a record to a name only when there is evidence: the address stands next to that holder's line, the holder replies to the address, or they are explicitly named as the owner ("Masha, why don't you sketch it"). **The absence of evidence is not a license for the most plausible guess: the record keeps its unknown holder.**
+         - two commitments belong to one person only if there is evidence linking them (one uninterrupted line, a self-reference "I'll also do…"). By default, the holders of different commitments are different people, even if both are "the woman leading the discussion".
+      4. For the remaining unknown holders, ask a clarifying question (see above) if they appear in the agreements or action items.
+      5. Extract the topics, agreements, commitments, and open questions.
+      6. Compose the notes strictly in the format below.
+
+      ## Notes format
+
+      ### Essence of the call
+      2–4 sentences: what the call was about and its main outcome. Below, on a single line — the participants: names and roles if determinable ("Masha — designer, Andrey, Vita — facilitator"); refer to unidentified ones by role.
+
+      ### Agreements
+      Substantive agreements by topic — what was decided and how things will work. Format of each item:
+
+      **Topic (2–4 words):** the essence of the agreement in one or two sentences; if a rationale was voiced — add it briefly ("…— to avoid drift between the converters"). If a status rather than an action was recorded for the topic ("already works", "accepted for work, a matter of priority", "fallback option") — state it.
+
+      This is for what both sides agreed to, including architectural and technical decisions, the division of responsibility ("X takes it on their side"), and chosen and rejected options. Proposals left without agreement don't belong here — their place is in "Open questions".
+
+      ### Action items
+      Concrete commitments taken. If most tasks share a common deadline — pull it into the subheading ("by the end of the week") and don't repeat it on every line. Line format:
+
+      - **Who:** what to do — deadline (if it differs from the common one or was named separately).
+
+      The owner is a name; if none was named, write "unassigned". Only explicit commitments go here ("let me look into it and send it over", "we'll draw it and show you"), not hypothetical "we could".
+
+      ### Open questions
+      Questions that were discussed but left unresolved and will clearly need a follow-up. For each — the essence and, if voiced, the sides' positions in one or two lines. Also here — proposals to which the other side did not agree.
+
+      ### Course of the discussion (by topic)
+      A section for those who were not on the call: the context the agreements grew out of. Group the substantive discussions by topic (not by chronology). For each topic: which options and arguments were voiced, who objected to whom and about what, what it came to. Preserve:
+
+      - the arguments **for and against**, including counterarguments to the decisions taken;
+      - **rejected options with the reasons** ("voice over 2.4 GHz rejected: short range, a second modem needed");
+      - **vivid phrasings and metaphors**, if they carry the meaning of a position ("to play the guitar more often — put it closer to the couch"), — one line each, without retelling the whole remark.
+
+      The section's length depends on the type of call: for a decision-making call (discussed — decided — dispersed) it is short or absent, the whole substance is already in "Agreements". For a discussion-heavy sync this is the largest section by volume. Don't duplicate the wording of the agreements — this section holds the *why* and the *alternatives considered* on the way to them.
+
+      ### Deferred / off-agenda
+      Topics deliberately left untouched for now, and ideas "for the future".
+
+      ## Rules
+
+      - **Don't invent anything.** Every agreement and action item must rest on a specific place in the transcript. If a fact is ambiguous due to transcript quality, mark it: "(uncertain per the transcript)".
+      - **Verify names before delivering.** For every name you use as an owner or the author of a position, find grounds in the transcript: this person is addressed by name, and the address links to their lines. A name merely mentioned in passing in the third person (including in unrelated off-topic) is not grounds to consider them a participant. Subjective confidence is not grounds either: no address — no name; ask the user or use a role. Red flag: one name owns nearly all action items across different roles (design, a survey, specifications) — double-check whether you merged several people into one.
+      - **An agreement ≠ a proposal.** "What if we do X?" is an idea. "Yes, let's", "agreed", "we already discussed this and agreed", "accepted, a matter of priority" — an agreement. Tell them apart.
+      - **Preserve the rationales.** If a decision was explained ("an MQTT broker is more reliable under VPN blocking"), that is one of the most valuable parts of the notes — include the rationale as a single phrase.
+      - **Don't bloat.** The notes should read in 2–3 minutes. Omit empty sections entirely.
+      - **The language of the notes = the main language of the call.** Technical terms — in their canonical spelling (usually Latin).
+      - **Don't evaluate the participants** and don't comment on the quality of the discussion.
+      - The output is the notes only, with no preambles or meta-comments, apart from targeted uncertainty marks.
+
+      ## Style example (excerpt)
+
+      **Agreements**
+
+      - **MicroSerial as the single conversion point:** reuse MicroSerial (the ESP Modbus→MQTT converter) for MQTT and, down the line, KNX — to avoid drift between different converters.
+      - **Remote access:** the primary option is an external MQTT broker (more reliable under VPN blocking, encryption support is needed); WireGuard — as a fallback.
+
+      **Action items (by the end of the week)**
+
+      - **Vladislav:** test MicroSerial with the HES3 template on the MGE, send over the firmware — today or tomorrow.
+      - **Zhenya:** reply about the hardware timeline.
+    autoStart: true
+    launchMessage: Take the current page into work — it contains the call transcript. If there is none, ask the user where the transcript is.
@@ -349,3 +349,109 @@ roles:
      a guess as a fact.
    autoStart: false
    launchMessage: null
+  - slug: call-summarizer
+    emoji: 📋
+    name: Конспектор созвонов
+    description: "Превращает сырую автоматическую расшифровку созвона в конспект: договорённости, action items, открытые вопросы."
+    instructions: |-
+      Ты — ассистент, который превращает сырую автоматическую расшифровку созвона в конспект. Конспект предназначен для тех, кто не был на созвоне, и для участников, которым нужно вспомнить принятые решения и договорённости «кто что делает».
+
+      ## Входные данные и их особенности
+
+      Тебе даётся автоматическая расшифровка. Она несовершенна, учитывай это:
+
+      - **Диаризация ненадёжна.** Под одной меткой (например, «Speaker 1») могут быть слиты реплики нескольких людей. Разделяй говорящих по смыслу: смена позиции в споре, обращение по имени, ответ на собственную реплику — признаки разных людей под одной меткой. Метка «You» — владелец записи; если в разговоре к нему обращаются по имени, используй имя. Если атрибуция неясна и её не удалось уточнить у пользователя (см. «Уточняющие вопросы») — пиши обезличенно («договорились», «одна из сторон предложила») или по роли, а не приписывай слова наугад.
+      - **Канал «You» может содержать посторонние реплики** — владелец записи параллельно разговаривает с кем-то офлайн. Реплики, не связанные с темами созвона, полностью игнорируй.
+      - **Термины и названия искажены распознаванием речи.** Технические термины, названия протоколов, продуктов и компаний часто записаны на слух в нескольких вариантах (в т.ч. англицизмы кириллицей: «вайргард» → WireGuard, «мадбас» → Modbus, «кныипс» → KNX). Приводи каждое понятие к одному каноническому написанию — в оригинальной латинице для технических терминов и брендов.
+      - **Мат и слова-паразиты** в конспект не переносятся.
+
+      ## Уточняющие вопросы об участниках
+
+      Если не удалось определить имя участника, а это мешает конспекту (в первую очередь — назначить исполнителя в action items или атрибутировать ключевую договорённость), **спроси пользователя перед выдачей конспекта**. Один компактный вопрос на всех неопознанных сразу, с зацепками для опознания — ролью и характерной репликой:
+
+      > Не смог определить двух участников:
+      > — тот, кто занимается дизайном и обещал накидать варианты лого («давай накидаю примеры, как может выглядеть лого»);
+      > — тот, кто отвечает за железо и объяснял ограничения E-Ink контроллера.
+      > Подскажи имена — или скажи «оставь как есть», и я обозначу их по ролям.
+
+      Не спрашивай, если: имя не удалось определить, но участник не фигурирует в договорённостях и action items; или роль сама по себе однозначно идентифицирует человека для читателей конспекта — тогда используй роль («дизайнер», «разработчик прошивки»). Не задавай больше одного раунда вопросов. Получив ответ пользователя, сразу выдавай конспект: не перечитывай расшифровку заново и не задавай новых вопросов — неразрешённые остатки неопределённости обозначай ролью или пометкой «(исполнитель не установлен)».
+
+      Вопрос не должен презюмировать твою гипотезу о слиянии: если «один неопознанный участник» получается носителем разнородных ролей и задач (дизайн + опрос + логистика), не спрашивай «как её зовут» — спроси, один это человек или несколько, и перечисли роли по отдельности:
+
+      > Не уверен, один это человек или разные: (а) кто-то ведёт опрос и собирает вопросы в Excel; (б) кто-то делает дизайн лого; (в) кому-то должны привезти дисплеи с таможни. Это один человек или несколько, и как их зовут?
+
+      ## Использование веб-поиска
+
+      У тебя есть инструмент поиска в интернете. Используй его **только для нормализации**: проверить каноническое написание искажённого термина, названия продукта, протокола или компании, когда контекста расшифровки недостаточно. **Запрещено** добавлять в конспект факты из интернета, которых не было в разговоре: конспект отражает только то, что прозвучало на созвоне.
+
+      ## Что нужно сделать
+
+      1. Если расшифровка выглядит оборванной (обрыв на середине реплики, нет завершения созвона) — дочитай остаток; одной повторной попытки достаточно, не зацикливайся.
+      2. Мысленно очисти расшифровку: отдели содержательную часть от шума, оффтопа и посторонних реплик.
+      3. **Построй карту участников** (внутренний шаг, в конспект не выводится):
+         - выпиши все взятые обязательства и выраженные позиции — каждую как отдельную запись с носителем «неизвестно»;
+         - выпиши все имена, по которым к кому-то *обращаются* (не упоминают в третьем лице), с цитатой-обращением;
+         - связывай запись с именем только при наличии улики: обращение стоит рядом с репликой этого носителя, носитель отвечает на обращение, или его прямо называют исполнителем («давай ты, Маша, накидаешь»). **Отсутствие улики — не повод для наиболее правдоподобной догадки: запись остаётся с неизвестным носителем.**
+         - два обязательства принадлежат одному человеку только если есть улика связи между ними (одна непрерывная реплика, самоссылка «я ещё сделаю…»). По умолчанию носители разных обязательств — разные люди, даже если оба «женщина, ведущая обсуждение».
+      4. По оставшимся неизвестным носителям задай уточняющий вопрос (см. ниже), если они фигурируют в договорённостях или action items.
+      5. Выдели темы, договорённости, обязательства и открытые вопросы.
+      6. Составь конспект строго по формату ниже.
+
+      ## Формат конспекта
+
+      ### Суть созвона
+      2–4 предложения: о чём созванивались и главный итог. Ниже одной строкой — участники: имена и роли, если определимы («Маша — дизайнер, Андрей, Вита — ведущая»); неопознанных обозначь по роли.
+
+      ### Договорённости
+      Содержательные соглашения по темам — что решили и как будет устроено. Формат каждого пункта:
+
+      **Тема (2–4 слова):** суть договорённости одним-двумя предложениями; если прозвучало обоснование — добавь его коротко («…— чтобы избежать дрейфа между конвертерами»). Если по теме зафиксирован статус, а не действие («уже работает», «принято в работу, вопрос приоритета», «резервный вариант») — укажи его.
+
+      Сюда попадает то, с чем согласились обе стороны, включая архитектурные и технические решения, распределение зон ответственности («X берёт на свою сторону»), выбранные и отвергнутые варианты. Предложения, оставшиеся без согласия, сюда не входят — им место в «Открытых вопросах».
+
+      ### Action items
+      Конкретные взятые обязательства. Если у большинства задач общий срок — вынеси его в подзаголовок («к концу недели») и не повторяй в каждой строке. Формат строки:
+
+      - **Кто:** что сделать — срок (если отличается от общего или назван отдельно).
+
+      Исполнитель — имя; если не назван, пиши «не назначен». Сюда попадают только явные обязательства («давайте я посмотрю и скину», «мы нарисуем и покажем»), а не гипотетические «можно было бы».
+
+      ### Открытые вопросы
+      Вопросы, которые обсуждались, но остались без решения, и явно потребуют возврата. Для каждого — суть и, если были, позиции сторон в одну-две строки. Сюда же — предложения, на которые вторая сторона не дала согласия.
+
+      ### Ход обсуждения (по темам)
+      Раздел для тех, кто не был на созвоне: контекст, из которого выросли договорённости. Сгруппируй содержательные обсуждения по темам (не по хронологии). По каждой теме: какие варианты и аргументы прозвучали, что кому возразили, к чему пришли. Сохраняй:
+
+      - аргументы **за и против**, включая контраргументы к принятым решениям;
+      - **отвергнутые варианты с причинами** («голос на 2.4 GHz отвергнут: малая дальность, нужен второй модем»);
+      - **яркие формулировки и метафоры**, если они несут смысл позиции («чтобы чаще играть на гитаре — поставь её ближе к дивану»), — одной строкой, без пересказа всей реплики.
+
+      Объём раздела зависит от типа созвона: для решенческого созвона (обсудили — решили — разошлись) он короткий или отсутствует, вся суть уже в «Договорённостях». Для дискуссионного синка это основной по объёму раздел. Не дублируй формулировки договорённостей — здесь живёт то, *почему* и *через какие альтернативы* к ним пришли.
+
+      ### Отложено / вне повестки
+      Темы, которые сознательно решили не трогать сейчас, и идеи «на будущее».
+
+      ## Правила
+
+      - **Ничего не выдумывай.** Каждая договорённость и action item должны опираться на конкретное место в расшифровке. Если факт неоднозначен из-за качества расшифровки, помечай: «(неточно по расшифровке)».
+      - **Проверка имён перед выдачей.** Для каждого имени, которое ты используешь как исполнителя или автора позиции, найди в расшифровке основание: к этому человеку обращаются по имени, и обращение связывается с его репликами. Имя, лишь мельком упомянутое в третьем лице (в т.ч. в постороннем оффтопе), — не основание считать его участником. Субъективная уверенность основанием не является: нет обращения — нет имени, спрашивай пользователя или используй роль. Красный флаг: одно имя владеет почти всеми action items разных ролей (дизайн, опрос, спецификации) — перепроверь, не слил ли ты нескольких людей в одного.
+      - **Договорённость ≠ предложение.** «А может, сделаем X?» — идея. «Да, давайте», «согласен», «мы это уже обсудили и согласились», «принято, вопрос приоритета» — договорённость. Различай.
+      - **Сохраняй обоснования.** Если решение объяснили («MQTT-брокер надёжнее при блокировках VPN»), это одна из самых ценных частей конспекта — включай обоснование одной фразой.
+      - **Не раздувай.** Конспект должен читаться за 2–3 минуты. Пустые разделы опускай целиком.
+      - **Язык конспекта = основной язык созвона.** Технические термины — в каноническом написании (обычно латиницей).
+      - **Не оценивай участников** и не комментируй качество обсуждения.
+      - На выходе — только конспект, без преамбул и мета-комментариев, кроме точечных пометок неуверенности.
+
+      ## Пример стиля (фрагмент)
+
+      **Договорённости**
+
+      - **MicroSerial как единая точка конвертации:** переиспользовать микросериал (ESP-конвертер Modbus→MQTT) для MQTT и в перспективе KNX — чтобы избежать дрейфа между разными конвертерами.
+      - **Удалённый доступ:** основной вариант — внешний MQTT-брокер (надёжнее при блокировках VPN, нужна поддержка шифрования); WireGuard — как резерв.
+
+      **Action items (к концу недели)**
+
+      - **Владислав:** проверить MicroSerial с шаблоном HES3 на MGE, скинуть прошивку — сегодня-завтра.
+      - **Женя:** ответить по срокам железа.
+    autoStart: true
+    launchMessage: Возьми в работу текущую страницу — на ней расшифровка созвона. Если её нет, спроси у пользователя, где расшифровка.
@@ -21,16 +21,18 @@ bundles:
        version: 8
      - slug: narrator
        version: 2
-  - id: research
+  - id: assistants
    name:
-      ru: Исследование
-      en: Research
+      ru: Ассистенты
+      en: Assistants
    description:
-      ru: Глубокое исследование темы с подготовкой отчёта.
-      en: Deep research on a topic with a prepared report.
+      ru: Ассистенты общего назначения
+      en: General-purpose assistants
    languages:
      - ru
      - en
    roles:
      - slug: researcher
-        version: 8
+        version: 9
+      - slug: call-summarizer
+        version: 1
@@ -1,4 +1,8 @@
 {
+  "call-summarizer": {
+    "version": 1,
+    "hash": "edba0c5ac5e27460f73efd361ee4e7cb743a085ae141f3b649e9d306e5929553"
+  },
  "fact-checker": {
    "version": 6,
    "hash": "6bb22a9e5a5079b5cb287b5b26addbd36b9afeb7c9508287dcad9343fc53d685"
@@ -16,8 +20,8 @@
    "hash": "cef39fed321779631ddd1077fcba53399adf0e48b301df281c71eb042610900d"
  },
  "researcher": {
-    "version": 8,
-    "hash": "0e76efa180c3e443c8856b8787e9643923d10486b373ce078c12dc16eb04611b"
+    "version": 9,
+    "hash": "880047f6a8612d420c77c03d9cc6308a25b2cd6f84647da9df9bae0e22bd5e4d"
  },
  "structural-editor": {
    "version": 4,
@@ -13,6 +13,7 @@
  },
  "dependencies": {
    "@ai-sdk/react": "^3.0.208",
+    "@braintree/sanitize-url": "7.1.2",
    "@atlaskit/pragmatic-drag-and-drop": "1.8.1",
    "@atlaskit/pragmatic-drag-and-drop-auto-scroll": "2.1.5",
    "@atlaskit/pragmatic-drag-and-drop-flourish": "2.0.15",
@@ -20,6 +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",
@@ -98,6 +101,7 @@
    "typescript": "5.9.3",
    "typescript-eslint": "8.57.1",
    "vite": "8.0.5",
+    "vite-plugin-compression2": "2.5.3",
    "vitest": "4.1.6"
  }
 }
@@ -1,38 +1,72 @@
+import { lazy, Suspense } from "react";
 import { Navigate, Route, Routes } from "react-router-dom";
+import { Center, Loader } from "@mantine/core";
+import { Error404 } from "@/components/ui/error-404.tsx";
+import Layout from "@/components/layouts/global/layout.tsx";
+import { useTrackOrigin } from "@/hooks/use-track-origin";
+
+// ShareLayout is route-split: its ShareShell chrome pulls in the table of
+// contents (and thus TipTap), so keeping it out of the eager graph removes the
+// editor engine from startup for authenticated users too.
+const ShareLayout = lazy(
+  () => import("@/features/share/components/share-layout.tsx"),
+);
+
+// Auth / entry pages stay eager: they are the first paint for an unauthenticated
+// visitor (e.g. /login) and are already small, so code-splitting them would only
+// add a cold-chunk round trip to the most common cold-start path.
 import SetupWorkspace from "@/pages/auth/setup-workspace.tsx";
 import LoginPage from "@/pages/auth/login";
-import Home from "@/pages/dashboard/home";
-import Page from "@/pages/page/page";
-import AccountSettings from "@/pages/settings/account/account-settings";
-import WorkspaceMembers from "@/pages/settings/workspace/workspace-members";
-import WorkspaceSettings from "@/pages/settings/workspace/workspace-settings";
-import AiSettings from "@/pages/settings/workspace/ai-settings";
-import Groups from "@/pages/settings/group/groups";
-import GroupInfo from "./pages/settings/group/group-info";
-import Spaces from "@/pages/settings/space/spaces.tsx";
-import { Error404 } from "@/components/ui/error-404.tsx";
-import AccountPreferences from "@/pages/settings/account/account-preferences.tsx";
-import SpaceHome from "@/pages/space/space-home.tsx";
-import PageRedirect from "@/pages/page/page-redirect.tsx";
-import Layout from "@/components/layouts/global/layout.tsx";
 import InviteSignup from "@/pages/auth/invite-signup.tsx";
 import ForgotPassword from "@/pages/auth/forgot-password.tsx";
 import PasswordReset from "./pages/auth/password-reset";
-import SharedPage from "@/pages/share/shared-page.tsx";
-import Shares from "@/pages/settings/shares/shares.tsx";
-import ShareLayout from "@/features/share/components/share-layout.tsx";
+import PageRedirect from "@/pages/page/page-redirect.tsx";
 import ShareRedirect from "@/pages/share/share-redirect.tsx";
-import { useTrackOrigin } from "@/hooks/use-track-origin";
-import SpacesPage from "@/pages/spaces/spaces.tsx";
-import SpaceTrash from "@/pages/space/space-trash.tsx";
-import FavoritesPage from "@/pages/favorites/favorites-page";
-import LabelPage from "@/pages/label/label-page";
+
+// Heavy / leaf pages are route-split with React.lazy so their code (most
+// importantly the whole TipTap editor + KaTeX + lowlight grammars + drawio that
+// the page editor and the readonly share editor pull in) is fetched only when
+// the matching route is actually visited. The <Suspense> boundaries live inside
+// each Layout (around its <Outlet/>), so the app shell stays mounted while a
+// route chunk loads.
+const Home = lazy(() => import("@/pages/dashboard/home"));
+const Page = lazy(() => import("@/pages/page/page"));
+const SpaceHome = lazy(() => import("@/pages/space/space-home.tsx"));
+const SpaceTrash = lazy(() => import("@/pages/space/space-trash.tsx"));
+const SpacesPage = lazy(() => import("@/pages/spaces/spaces.tsx"));
+const FavoritesPage = lazy(() => import("@/pages/favorites/favorites-page"));
+const LabelPage = lazy(() => import("@/pages/label/label-page"));
+const SharedPage = lazy(() => import("@/pages/share/shared-page.tsx"));
+
+const AccountSettings = lazy(
+  () => import("@/pages/settings/account/account-settings"),
+);
+const AccountPreferences = lazy(
+  () => import("@/pages/settings/account/account-preferences.tsx"),
+);
+const WorkspaceSettings = lazy(
+  () => import("@/pages/settings/workspace/workspace-settings"),
+);
+const AiSettings = lazy(() => import("@/pages/settings/workspace/ai-settings"));
+const WorkspaceMembers = lazy(
+  () => import("@/pages/settings/workspace/workspace-members"),
+);
+const Groups = lazy(() => import("@/pages/settings/group/groups"));
+const GroupInfo = lazy(() => import("./pages/settings/group/group-info"));
+const Spaces = lazy(() => import("@/pages/settings/space/spaces.tsx"));
+const Shares = lazy(() => import("@/pages/settings/shares/shares.tsx"));

 export default function App() {
  useTrackOrigin();

  return (
-    <>
+    <Suspense
+      fallback={
+        <Center h="100vh">
+          <Loader size="sm" />
+        </Center>
+      }
+    >
      <Routes>
        <Route index element={<Navigate to="/home" />} />
        <Route path={"/login"} element={<LoginPage />} />
@@ -83,6 +117,6 @@ export default function App() {

        <Route path="*" element={<Error404 />} />
      </Routes>
-    </>
+    </Suspense>
  );
 }
@@ -0,0 +1,37 @@
+import { describe, it, expect } from "vitest";
+import { isChunkLoadError } 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
+// recovery UI, no reload). A false negative on a real chunk failure re-blanks the
+// app; a false positive would auto-reload on an ordinary error. Pin both sides.
+describe("isChunkLoadError", () => {
+  it("detects the ChunkLoadError name", () => {
+    expect(isChunkLoadError({ name: "ChunkLoadError", message: "x" })).toBe(true);
+  });
+
+  it.each([
+    "Failed to fetch dynamically imported module: https://x/assets/index-abc.js",
+    "error loading dynamically imported module",
+    "Importing a module script failed.",
+  ])("detects the dynamic-import failure message %#", (message) => {
+    expect(isChunkLoadError({ name: "TypeError", message })).toBe(true);
+  });
+
+  it("is case-insensitive on the message", () => {
+    expect(
+      isChunkLoadError({ message: "FAILED TO FETCH DYNAMICALLY IMPORTED MODULE" }),
+    ).toBe(true);
+  });
+
+  it.each([
+    null,
+    undefined,
+    {},
+    { name: "TypeError", message: "Cannot read properties of undefined" },
+    { message: "Network request failed" },
+    new Error("some ordinary render error"),
+  ])("returns false for a non-chunk error %#", (err) => {
+    expect(isChunkLoadError(err)).toBe(false);
+  });
+});
@@ -0,0 +1,71 @@
+import { ReactNode } from "react";
+import { ErrorBoundary } from "react-error-boundary";
+import { Button, Center, Stack, Text } from "@mantine/core";
+
+const RELOAD_FLAG = "chunk-reload-attempted";
+
+// Heuristic detection of a failed dynamic import. Since the code-splitting work,
+// every route (plus Aside / AiChatWindow) is React.lazy: when a new deploy
+// replaces the hashed chunks, a tab left open on the old index.html requests a
+// chunk URL that now 404s, and React.lazy rejects. Browsers / Vite surface these
+// with a ChunkLoadError name or one of these messages.
+export function isChunkLoadError(error: unknown): boolean {
+  if (!error) return false;
+  const name = (error as { name?: string }).name ?? "";
+  const message = (error as { message?: string }).message ?? "";
+  return (
+    name === "ChunkLoadError" ||
+    /Failed to fetch dynamically imported module/i.test(message) ||
+    /error loading dynamically imported module/i.test(message) ||
+    /Importing a module script failed/i.test(message)
+  );
+}
+
+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
+  // (e.g. a genuinely missing chunk) with a one-shot sessionStorage flag. If the
+  // flag is already set we fall through to the manual recovery UI below.
+  try {
+    if (sessionStorage.getItem(RELOAD_FLAG)) return;
+    sessionStorage.setItem(RELOAD_FLAG, "1");
+  } catch {
+    // sessionStorage unavailable (private mode / disabled): skip the automatic
+    // reload rather than risk an unguarded loop; the fallback UI still recovers.
+    return;
+  }
+  window.location.reload();
+}
+
+// Root-level boundary that sits ABOVE every route-level Suspense boundary so a
+// lazy route/component chunk failure is caught here instead of unmounting the
+// whole tree into a blank white screen. Per-feature ErrorBoundaries (page.tsx,
+// transclusion, page-embed) remain in place underneath for their local errors.
+export function ChunkLoadErrorBoundary({ children }: { children: ReactNode }) {
+  return (
+    <ErrorBoundary
+      onError={handleError}
+      fallbackRender={({ error }) => {
+        const chunk = isChunkLoadError(error);
+        return (
+          <Center h="100vh" p="md">
+            <Stack align="center" gap="sm" maw={420}>
+              <Text fw={600}>
+                {chunk ? "A new version is available" : "Something went wrong"}
+              </Text>
+              <Text size="sm" c="dimmed" ta="center">
+                {chunk
+                  ? "Please reload the page to load the latest version."
+                  : "An unexpected error occurred. Reloading the page may help."}
+              </Text>
+              <Button onClick={() => window.location.reload()}>Reload</Button>
+            </Stack>
+          </Center>
+        );
+      }}
+    >
+      {children}
+    </ErrorBoundary>
+  );
+}
@@ -1,9 +1,10 @@
 import { AppShell, Container } from "@mantine/core";
-import React, { useEffect, useRef, useState } from "react";
+import React, { Suspense, useEffect, useRef, useState } from "react";
 import { useLocation } from "react-router-dom";
 import { useTranslation } from "react-i18next";
 import SettingsSidebar from "@/components/settings/settings-sidebar.tsx";
-import { useAtom } from "jotai";
+import { useAtom, useAtomValue } from "jotai";
+import { aiChatWindowOpenAtom } from "@/features/ai-chat/atoms/ai-chat-atom.ts";
 import {
  APP_NAVBAR_ID,
  NAVBAR_COLLAPSE_BREAKPOINT,
@@ -14,8 +15,6 @@ import {
 } from "@/components/layouts/global/hooks/atoms/sidebar-atom.ts";
 import { SpaceSidebar } from "@/features/space/components/sidebar/space-sidebar.tsx";
 import { AppHeader } from "@/components/layouts/global/app-header.tsx";
-import Aside from "@/components/layouts/global/aside.tsx";
-import AiChatWindow from "@/features/ai-chat/components/ai-chat-window.tsx";
 import GitmostGlobalBridge from "@/features/editor/gitmost/gitmost-global-bridge.tsx";
 import classes from "./app-shell.module.css";
 import { useToggleSidebar } from "@/components/layouts/global/hooks/hooks/use-toggle-sidebar.ts";
@@ -23,6 +22,21 @@ import GlobalSidebar from "@/components/layouts/global/global-sidebar.tsx";
 import { ASIDE_PANEL_ID } from "@/hooks/use-toggle-aside.tsx";
 import { MAIN_CONTENT_ID, SkipToMain } from "@/components/ui/skip-to-main.tsx";

+// Lazily load the AI chat window so the AI SDK runtime it pulls in is fetched
+// only after the user first opens the chat, instead of for every authenticated
+// user on load. The window itself renders null while closed, so there is no
+// behavior difference — it simply is not mounted until first opened.
+const AiChatWindow = React.lazy(
+  () => import("@/features/ai-chat/components/ai-chat-window.tsx"),
+);
+
+// The right aside hosts the comment panel and table of contents, both of which
+// pull in TipTap. It only ever renders on page routes, so lazy-loading it keeps
+// the whole editor engine out of the eager global-shell startup graph.
+const Aside = React.lazy(
+  () => import("@/components/layouts/global/aside.tsx"),
+);
+
 export default function GlobalAppShell({
  children,
 }: {
@@ -37,6 +51,15 @@ export default function GlobalAppShell({
  const [isResizing, setIsResizing] = useState(false);
  const sidebarRef = useRef(null);

+  // Latch: once the AI chat window has been opened, keep it mounted so an
+  // in-flight stream is never torn down. Before the first open the AI chat chunk
+  // is never fetched.
+  const aiChatOpen = useAtomValue(aiChatWindowOpenAtom);
+  const [aiChatEverOpened, setAiChatEverOpened] = useState(false);
+  useEffect(() => {
+    if (aiChatOpen) setAiChatEverOpened(true);
+  }, [aiChatOpen]);
+
  const startResizing = React.useCallback((mouseDownEvent) => {
    mouseDownEvent.preventDefault();
    setIsResizing(true);
@@ -67,14 +90,20 @@ export default function GlobalAppShell({
  );

  useEffect(() => {
-    //https://codesandbox.io/p/sandbox/kz9de
+    // Attach the global mousemove/mouseup only WHILE resizing (started on the
+    // handle's mousedown via startResizing → isResizing=true) and detach on
+    // mouseup (stopResizing → isResizing=false). Previously these listeners were
+    // attached for the whole app lifetime, so every mouse move over the app ran
+    // the resize handler.
+    // https://codesandbox.io/p/sandbox/kz9de
+    if (!isResizing) return;
    window.addEventListener("mousemove", resize);
    window.addEventListener("mouseup", stopResizing);
    return () => {
      window.removeEventListener("mousemove", resize);
      window.removeEventListener("mouseup", stopResizing);
    };
-  }, [resize, stopResizing]);
+  }, [isResizing, resize, stopResizing]);

  const location = useLocation();
  const isSettingsRoute = location.pathname.startsWith("/settings");
@@ -160,13 +189,21 @@ export default function GlobalAppShell({
                  : undefined
          }
        >
-          <Aside />
+          <Suspense fallback={null}>
+            <Aside />
+          </Suspense>
        </AppShell.Aside>
      )}
    </AppShell>
-    {/* Floating AI chat window. Mounted once globally; it is position: fixed
-        and self-hides when closed, so its place in the tree is not critical. */}
-    <AiChatWindow />
+    {/* Floating AI chat window. Mounted once globally on first open; it is
+        position: fixed and self-hides when closed, so its place in the tree is
+        not critical. Kept mounted after the first open so a live stream is not
+        aborted. */}
+    {aiChatEverOpened && (
+      <Suspense fallback={null}>
+        <AiChatWindow />
+      </Suspense>
+    )}
      {/* Global gitmost native bridge: registers listSpaces / listPages /
          createPageWithRecording on window.gitmost so the native host can
          create a page with a recording even when no page editor is open. */}
@@ -1,5 +1,7 @@
+import { Suspense, useEffect } from "react";
 import { UserProvider } from "@/features/user/user-provider.tsx";
 import { Outlet, useParams } from "react-router-dom";
+import { Center, Loader } from "@mantine/core";
 import GlobalAppShell from "@/components/layouts/global/global-app-shell.tsx";
 import { SearchSpotlight } from "@/features/search/components/search-spotlight.tsx";
 import { useGetSpaceBySlugQuery } from "@/features/space/queries/space-query.ts";
@@ -8,10 +10,39 @@ export default function Layout() {
  const { spaceSlug } = useParams();
  const { data: space } = useGetSpaceBySlugQuery(spaceSlug);

+  // Warm the (now route-split) editor chunk during idle time on authenticated
+  // routes, so the first navigation to a page renders from cache instead of a
+  // cold chunk fetch. Best-effort: gated on requestIdleCallback and never blocks
+  // startup — the dynamic import mirrors the App.tsx route lazy loader so both
+  // resolve to the same chunk.
+  useEffect(() => {
+    const ric =
+      typeof window !== "undefined" && (window as any).requestIdleCallback;
+    const warm = () => {
+      // Best-effort prefetch: a failed warm-up (offline, stale 404) is harmless
+      // and must not surface as an unhandledrejection.
+      void import("@/pages/page/page").catch(() => {});
+    };
+    if (ric) {
+      const id = ric(warm);
+      return () => (window as any).cancelIdleCallback?.(id);
+    }
+    const timer = setTimeout(warm, 2000);
+    return () => clearTimeout(timer);
+  }, []);
+
  return (
    <UserProvider>
      <GlobalAppShell>
-        <Outlet />
+        <Suspense
+          fallback={
+            <Center h="60vh">
+              <Loader size="sm" />
+            </Center>
+          }
+        >
+          <Outlet />
+        </Suspense>
      </GlobalAppShell>
      <SearchSpotlight spaceId={space?.id} />
    </UserProvider>
@@ -5,7 +5,7 @@ import {
  Button,
  useMantineColorScheme,
 } from "@mantine/core";
-import { useClickOutside, useDisclosure, useWindowEvent } from "@mantine/hooks";
+import { useClickOutside, useDisclosure } from "@mantine/hooks";
 import { Suspense } from "react";
 import { useTranslation } from "react-i18next";

@@ -57,14 +57,22 @@ function EmojiPicker({
    [dropdown, target],
  );

-  // We need this because the default Mantine popover closeOnEscape does not work
-  useWindowEvent("keydown", (event) => {
-    if (opened && event.key === "Escape") {
-      event.stopPropagation();
-      event.preventDefault();
-      handlers.close();
-    }
-  });
+  // We need this because the default Mantine popover closeOnEscape does not work.
+  // Attach the global keydown ONLY while the picker is open (every tree row
+  // renders an EmojiPicker, so an always-on window listener meant ~20-30 idle
+  // keydown handlers firing on each keystroke).
+  useEffect(() => {
+    if (!opened) return;
+    const handleKeydown = (event: KeyboardEvent) => {
+      if (event.key === "Escape") {
+        event.stopPropagation();
+        event.preventDefault();
+        handlers.close();
+      }
+    };
+    window.addEventListener("keydown", handleKeydown);
+    return () => window.removeEventListener("keydown", handleKeydown);
+  }, [opened, handlers]);

  // emoji-mart's built-in autoFocus calls .focus() without preventScroll, which
  // makes the browser scroll every scrollable ancestor of the search input to
@@ -36,7 +36,7 @@ import {
  desktopSidebarAtom,
  mobileSidebarAtom,
 } from "@/components/layouts/global/hooks/atoms/sidebar-atom.ts";
-import { usePageQuery } from "@/features/page/queries/page-query.ts";
+import { usePageMetaQuery } from "@/features/page/queries/page-query.ts";
 import {
  pageEditorAtom,
  readOnlyEditorAtom,
@@ -58,8 +58,11 @@ import ConversationList from "@/features/ai-chat/components/conversation-list.ts
 import ChatThread from "@/features/ai-chat/components/chat-thread.tsx";
 import {
  exportAiChat,
+  getAiChatMessagesDelta,
  stopRun,
 } from "@/features/ai-chat/services/ai-chat-service.ts";
+import { mergeDeltaRowsIntoPages } from "@/features/ai-chat/utils/resume-helpers.ts";
+import type { IAiChatMessageRow } from "@/features/ai-chat/types/ai-chat.types.ts";
 import { useChatSession } from "@/features/ai-chat/hooks/use-chat-session.ts";
 import {
  shouldCollapseOnOutsidePointer,
@@ -86,11 +89,11 @@ const MIN_HEIGHT = 400;
 // Margin kept between the window and the viewport edges while dragging.
 const EDGE_MARGIN = 8;

-// #184 phase 1.5: hard cap on the degraded-poll fallback. The poll is armed when
-// a resume attempt could not attach to the live run and disarmed by the thread on
-// settle / local stream; this cap is the ONLY backstop against an endless tick
-// (a stuck 'streaming' row before the boot-sweep, or a user-tail 204 with no run).
-const DEGRADED_POLL_MAX_MS = 10 * 60_000;
+// #184 phase 1.5 / #430 / #488: the degraded-poll fallback. The window owns only
+// a DUMB 2.5s timer, gated by an armed flag; the THREAD's run-lifecycle FSM owns
+// arm/disarm AND the inactivity cap that turns a stuck run into a `stalled` banner
+// (#488 commit 4a — the cap moved into the thread so polling->stalled is a single
+// FSM transition; the window no longer silently stops polling at the cap).

 /** Compact token formatter: 1.2M / 3.4k / 950. */
 function formatTokens(n: number): string {
@@ -237,7 +240,9 @@ export default function AiChatWindow() {
  // left partly off-screen).
  const [geom, setGeom] = useAtom(aiChatWindowGeomAtom);

-  const { data: chats } = useAiChatsQuery();
+  // Gated on windowOpen: the chat list is only needed once the window is open,
+  // so a closed window issues no chat-list request/refetch on navigation.
+  const { data: chats } = useAiChatsQuery(windowOpen);
  // Roles for the new-chat picker (any member may list them). Only fetched while
  // the window is open.
  const { data: roles } = useAiRolesQuery(windowOpen);
@@ -249,14 +254,13 @@ export default function AiChatWindow() {
    [roles],
  );

-  // #184 phase 1.5: degraded-poll fallback (replaces the F4/F5/F7 latches). When
-  // ChatThread could not attach to a still-running run it arms this via
-  // onResumeFallback(true); the thread disarms it on settle / local stream. The
-  // window only OWNS the timer (armedAtRef stamps when it was armed for the cap).
+  // #184 phase 1.5 / #488: degraded-poll fallback. ChatThread's FSM arms this via
+  // onResumeFallback(true) when it enters a poll-bearing recovery (attach 204 /
+  // starved finish / stop) and disarms it on settle / local stream / stalled. The
+  // 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);
-  const armedAtRef = useRef(0);
  const onResumeFallback = useCallback((active: boolean): void => {
-    if (active) armedAtRef.current = Date.now();
    setDegradedPoll(active);
  }, []);
  // Reset the degraded poll whenever the open chat changes: it is scoped to the
@@ -268,19 +272,64 @@ 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
-      // and under the 10-min cap; otherwise off. NO error checks (TanStack v5
-      // resets fetchFailureCount each fetch, so consecutive errors are not
-      // expressible — and the poll must survive a server restart) and NO tail
-      // checks (the settled/local-stream semantics live in ChatThread, which
-      // disarms via onResumeFallback(false)). The time cap is the only backstop.
-      () =>
-        degradedPoll === true &&
-        Date.now() - armedAtRef.current < DEGRADED_POLL_MAX_MS
-          ? 2500
-          : false,
+      // #491: the full infinite-query no longer POLLS. It seeds the thread ONCE; the
+      // degraded fallback now runs a DELTA poller (below) that augments THIS cache
+      // idempotently, instead of refetching every page (with full parts) every 2.5s.
+      false,
+      // #344: gate on windowOpen too — no message history is fetched while the window
+      // is closed; it loads when the window opens with an active chat.
+      windowOpen,
    );

+  // #491 degraded DELTA poll. While armed (degradedPoll) and the window is open on a
+  // chat, poll POST /ai-chat/messages/delta every 2.5s: it returns only the rows
+  // CHANGED since the previous cursor (+ the run fact) in ONE round-trip. We merge
+  // those rows into the SAME infinite-query cache the thread reads (idempotently by
+  // id — the delta's overlap window re-delivers rows), so the thread's reconcile
+  // effect follows the detached run to its terminal row from a fraction of the wire
+  // cost. The run-fact settle stays the thread FSM's job (row-status reconcile), so
+  // we do NOT double-poll /run here. Cursor resets when the chat changes / disarms.
+  const deltaCursorRef = useRef<string | undefined>(undefined);
+  useEffect(() => {
+    deltaCursorRef.current = undefined;
+  }, [activeChatId, degradedPoll]);
+  useEffect(() => {
+    if (!degradedPoll || !windowOpen || !activeChatId) return;
+    const chatId = activeChatId;
+    let cancelled = false;
+    const tick = async (): Promise<void> => {
+      try {
+        const res = await getAiChatMessagesDelta(chatId, deltaCursorRef.current);
+        if (cancelled) return;
+        deltaCursorRef.current = res.cursor;
+        if (res.rows.length > 0) {
+          queryClient.setQueryData(
+            AI_CHAT_MESSAGES_RQ_KEY(chatId),
+            (
+              old:
+                | {
+                    pages: { items: IAiChatMessageRow[]; meta: unknown }[];
+                    pageParams: unknown[];
+                  }
+                | undefined,
+            ) =>
+              old
+                ? { ...old, pages: mergeDeltaRowsIntoPages(old.pages, res.rows) }
+                : old,
+          );
+        }
+      } catch {
+        // Transient failure (e.g. a server restart mid-run): swallow and retry on
+        // the next tick — the poll must survive a bounce, like the old dumb refetch.
+      }
+    };
+    const id = setInterval(() => void tick(), 2500);
+    return () => {
+      cancelled = true;
+      clearInterval(id);
+    };
+  }, [degradedPoll, windowOpen, activeChatId, queryClient]);
+
  // #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
@@ -315,7 +364,7 @@ export default function AiChatWindow() {
  // reads/writes via its CASL-enforced page tools using the id.
  const pageRouteMatch = useMatch("/s/:spaceSlug/p/:pageSlug");
  const pageSlug = pageRouteMatch?.params?.pageSlug;
-  const { data: openPageData } = usePageQuery({
+  const { data: openPageData } = usePageMetaQuery({
    pageId: extractPageSlugId(pageSlug),
  });
  const openPage = openPageData
@@ -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);
@@ -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) —
@@ -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
@@ -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>
@@ -53,8 +53,12 @@ export const AI_CHAT_MESSAGES_RQ_KEY = (chatId: string) => [
  chatId,
 ];

-/** Paginated list of the current user's chats (auto-loads further pages). */
-export function useAiChatsQuery() {
+/**
+ * Paginated list of the current user's chats (auto-loads further pages).
+ * `enabled` (default true) lets the AI chat window skip fetching while it is
+ * closed — the list is only needed once the window is open.
+ */
+export function useAiChatsQuery(enabled: boolean = true) {
  const query = useInfiniteQuery({
    queryKey: AI_CHATS_RQ_KEY,
    queryFn: ({ pageParam }) => getAiChats({ cursor: pageParam, limit: 50 }),
@@ -63,6 +67,7 @@ export function useAiChatsQuery() {
      lastPage.meta.hasNextPage
        ? (lastPage.meta.nextCursor ?? undefined)
        : undefined,
+    enabled,
  });

  const data = useMemo<IPagination<IAiChat> | undefined>(() => {
@@ -93,6 +98,9 @@ export function useAiChatMessagesQuery(
  // follow the detached run to settle. The callback form lives in AiChatWindow;
  // threaded here verbatim so this query owns the polling. Undefined => no poll.
  refetchInterval?: number | false | (() => number | false),
+  // #344: gate the query so a backgrounded/hidden window stops issuing refetches
+  // and duplicating work. Defaults to enabled to preserve existing call-sites.
+  enabled: boolean = true,
 ) {
  const query = useInfiniteQuery({
    queryKey: AI_CHAT_MESSAGES_RQ_KEY(chatId ?? ""),
@@ -103,7 +111,7 @@ export function useAiChatMessagesQuery(
      lastPage.meta.hasNextPage
        ? (lastPage.meta.nextCursor ?? undefined)
        : undefined,
-    enabled: !!chatId,
+    enabled: !!chatId && enabled,
    refetchInterval,
  });

@@ -57,6 +57,50 @@ export async function stopRun(
  return req.data;
 }

+/**
+ * Delta poll (#491): the chat's message rows changed since `cursor` (a DB-clock
+ * timestamp echoed from the previous poll) plus the current run fact, in ONE
+ * round-trip — the degraded-poll fallback's payload, replacing the old "refetch
+ * ALL infinite-query pages every 2.5s with full parts" poll. Omit `cursor` on the
+ * first poll (returns just a fresh cursor, no rows, to start the chain). The
+ * overlap window guarantees occasional REPEATS, so the caller MUST merge rows
+ * idempotently by id (mergeById). Owner-gated server-side.
+ */
+export async function getAiChatMessagesDelta(
+  chatId: string,
+  cursor?: string,
+): Promise<{
+  rows: IAiChatMessageRow[];
+  cursor: string;
+  run: { id: string; status: string } | null;
+}> {
+  const req = await api.post<{
+    rows: IAiChatMessageRow[];
+    cursor: string;
+    run: { id: string; status: string } | null;
+  }>("/ai-chat/messages/delta", { chatId, cursor });
+  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.
@@ -0,0 +1,190 @@
+# 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) |
+| `POLL_IDLE_CAP` (inactivity cap) | stopping | idle | `[disarmPoll, cancelReconnect]`, runFact←null (Review #4: a Stop-armed poll with no SDK/terminal backstop gets a bounded exit — NOT `stalled`, Stop was already pressed so nothing to retry) |
+| `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) |
+| 14–15 | `anchorRef {id, stepsPersisted}` | **data** (attachStrategy) | #491 tail-only: replaced `stripRef`/`strippedRowRef`. The PERSISTED assistant row that pins the run (server invariant 6) + its step frontier N; feeds `?anchor=<id>&n=<stepsPersisted>`. No strip — the seed keeps every row; entering reconnecting re-seeds from persist |
+| 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 (#491, implemented):** the degraded poll now hits the delta endpoint
+   (`POST /ai-chat/messages/delta`), which ALREADY carries the run fact
+   (`run: {id, status} | null`) alongside the changed rows. The client does NOT yet
+   consume that run field — it still drives to a terminal ROW (merged by id),
+   dispatched as `POLL_TERMINAL` — so the run field rides the wire for a future
+   client that settles straight off it.
+
+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** is behind the `resumeStream` effect; #491 swapped it to
+  tail-only (`?anchor=&n=`, `anchorRef` data) WITHOUT touching the FSM. Entering
+  reconnecting always re-seeds from persist; on a getRun failure the live partial
+  is dropped + replay-from-start so it is never the tail-apply base (no #137/#161
+  duplication).
+- **Queue** stays a data structure; flush/interrupt decisions are transitions.
@@ -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"]),
+    );
+  });
+});
@@ -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);
+    }
+  }
+}
@@ -181,6 +181,12 @@ export interface IAiChatMessageRow {
  toolCalls?: unknown;
  metadata?: {
    parts?: UIMessage["parts"];
+    // #491 step-alignment anchor: the count of FINISHED steps whose parts are in
+    // THIS row, written atomically with `parts` server-side (flushAssistant). The
+    // resume client reads it as its persisted step frontier N — the tail-only
+    // attach asks the run-stream registry for the frames of step N onward (the
+    // seed already carries steps 0..N-1). Absent on pre-#491 rows -> read as 0.
+    stepsPersisted?: number;
    // AI SDK v6 `totalUsage` persisted on assistant rows. Legacy cumulative
    // figure (sum of every step's usage for the turn); kept for back-compat and
    // as the fallback for older rows that have no `contextTokens`.
@@ -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();
+  });
+});
@@ -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
@@ -33,29 +33,44 @@ describe("collapseBlankLines", () => {
  });
 });

-describe("collapseBlankLines + renderChatMarkdown (tight reasoning rendering)", () => {
-  it("renders a blank-line-separated list as a TIGHT list (no <li><p>)", () => {
+describe("collapseBlankLines + renderChatMarkdown (canonical converter)", () => {
+  // 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>.
-    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>).
+    // Clean, un-namespaced HTML (DOMSerializer, not XMLSerializer) — no xmlns.
    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.toContain("<li><p>");
+    expect(html).not.toMatch(/<ol[^>]*xmlns/);
+    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>",
+    );
  });
 });
@@ -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("abcde")).toBe(2);
-    expect(estimateTokens("12345678")).toBe(2);
+    expect(estimateTokens("ab")).toBe(1);
+    expect(estimateTokens("abcde")).toBe(2); // 5 / 2.5 = 2
+    expect(estimateTokens("x".repeat(10))).toBe(4); // 10 / 2.5 = 4
  });
 });
@@ -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
- * a real BPE tokenizer (that would be O(n²) on the hot path, bloat the bundle,
- * and be wrong for Gemini/Ollama anyway). Used by the in-body reasoning counter
- * ("Thinking · N tokens").
+ * is a CLIENT ESTIMATE. This re-exports the SHARED estimator from
+ * `@docmost/token-estimate` (chars/2.5) so the in-body counter and the server's
+ * replay budgeter use the SAME heuristic — two divergent estimators would mean
+ * "the badge shows 60%" while "the budgeter already trimmed" (#490). Used by the
+ * in-body reasoning counter ("Thinking · N tokens").
 */
-
-/**
- * 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);
-}
+export { estimateTokens } from "@docmost/token-estimate";
@@ -23,6 +23,72 @@ 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 dropped connection (ECONNRESET) as a lost-connection error", () => {
    expect(
      describeChatError("Cannot connect to API: read ECONNRESET", t).title,
@@ -24,6 +24,59 @@ 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.",
+      ),
+    };
+  }
+
  if (/"statusCode"\s*:\s*403\b/.test(msg)) {
    return {
      title: t("AI chat is disabled"),
@@ -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
- * chat output matches the editor's markdown flavor, then sanitize with
- * DOMPurify — LLM output is untrusted, so it must never reach the DOM unsanitized.
+ * canonical converter (issue #347): markdown -> ProseMirror JSON (the SAME
+ * `markdownToProseMirrorSync` the editor paste/import path uses, so chat output
+ * 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
- * extensions registered). In practice plain chat markdown resolves
- * synchronously, but we guard the Promise case by returning a safe empty string
- * for that branch (the caller renders the raw text fallback instead).
+ * Stays SYNCHRONOUS: both callers render inside React (a memo and a useMemo),
+ * so the whole pipeline must resolve without awaiting. The converter's sync
+ * entry makes that possible; on any conversion error we return "" so the caller
+ * 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);
-  if (typeof html !== "string") return "";
+  let html: string;
+  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.
@@ -4,7 +4,8 @@ import type { IAiChatMessageRow } from "@/features/ai-chat/types/ai-chat.types.t
 import {
  isStreamingTail,
  isSettledAssistantTail,
-  seedRows,
+  stepsPersistedOf,
+  mergeDeltaRowsIntoPages,
  mergeById,
 } from "./resume-helpers.ts";

@@ -12,8 +13,18 @@ function row(
  id: string,
  role: string,
  status?: string,
+  stepsPersisted?: number,
 ): IAiChatMessageRow {
-  return { id, role, content: "", status, createdAt: "2026-01-01T00:00:00Z" };
+  return {
+    id,
+    role,
+    content: "",
+    status,
+    createdAt: "2026-01-01T00:00:00Z",
+    ...(stepsPersisted !== undefined
+      ? { metadata: { stepsPersisted } }
+      : {}),
+  };
 }

 function makeMsg(id: string, text: string): UIMessage {
@@ -65,23 +76,92 @@ describe("isSettledAssistantTail", () => {
  });
 });

-describe("seedRows", () => {
-  const rows = [row("u1", "user"), row("a1", "assistant", "streaming")];
-
-  it("returns the rows unchanged when not stripping", () => {
-    expect(seedRows(rows, false)).toBe(rows);
+describe("stepsPersistedOf", () => {
+  it("reads metadata.stepsPersisted", () => {
+    expect(stepsPersistedOf(row("a1", "assistant", "streaming", 3))).toBe(3);
+    expect(stepsPersistedOf(row("a1", "assistant", "streaming", 0))).toBe(0);
  });

-  it("drops the last row when stripping", () => {
-    const seeded = seedRows(rows, true);
-    expect(seeded).toHaveLength(1);
-    expect(seeded[0].id).toBe("u1");
+  it("defaults to 0 for a pre-#491 row (absent), null/undefined, or a bad value", () => {
+    expect(stepsPersistedOf(row("a1", "assistant", "streaming"))).toBe(0);
+    expect(stepsPersistedOf(null)).toBe(0);
+    expect(stepsPersistedOf(undefined)).toBe(0);
+    expect(
+      stepsPersistedOf({
+        id: "a1",
+        role: "assistant",
+        content: "",
+        createdAt: "x",
+        metadata: { stepsPersisted: -2 },
+      }),
+    ).toBe(0);
  });

-  it("returns an empty list when stripping a single-row list", () => {
-    expect(seedRows([row("a1", "assistant", "streaming")], true)).toHaveLength(
-      0,
-    );
+  it("floors a non-integer count", () => {
+    expect(
+      stepsPersistedOf({
+        id: "a1",
+        role: "assistant",
+        content: "",
+        createdAt: "x",
+        metadata: { stepsPersisted: 2.9 },
+      }),
+    ).toBe(2);
+  });
+});
+
+describe("mergeDeltaRowsIntoPages", () => {
+  const pages = () => [
+    { items: [row("u1", "user"), row("a1", "assistant", "streaming", 1)], meta: {} },
+  ];
+
+  it("returns the pages unchanged for an empty delta", () => {
+    const p = pages();
+    expect(mergeDeltaRowsIntoPages(p, [])).toBe(p);
+  });
+
+  it("appends a genuinely new row to the last page in chronological order", () => {
+    const merged = mergeDeltaRowsIntoPages(pages(), [row("a2", "assistant", "streaming", 0)]);
+    expect(merged[0].items.map((i) => i.id)).toEqual(["u1", "a1", "a2"]);
+  });
+
+  it("replaces a grown row in place (per-step growth), never appends a duplicate", () => {
+    const merged = mergeDeltaRowsIntoPages(pages(), [
+      row("a1", "assistant", "streaming", 2),
+    ]);
+    expect(merged[0].items.map((i) => i.id)).toEqual(["u1", "a1"]);
+    // the in-place replacement carries the grown step frontier.
+    expect(stepsPersistedOf(merged[0].items[1])).toBe(2);
+  });
+
+  it("does not mutate the input pages", () => {
+    const input = pages();
+    const before = input[0].items.slice();
+    mergeDeltaRowsIntoPages(input, [row("a2", "assistant", "streaming", 0)]);
+    expect(input[0].items).toEqual(before); // untouched
+  });
+
+  // #491 CONTRACT: the delta overlap window re-delivers the same rows, so merging
+  // MUST be idempotent — applying a delta twice equals applying it once (no growth,
+  // no reorder). A regression re-introduces duplicate assistant bubbles per poll.
+  it("is idempotent: applying the same delta twice equals once", () => {
+    const delta = [
+      row("a1", "assistant", "streaming", 2), // grown existing row
+      row("a2", "assistant", "streaming", 0), // new row
+    ];
+    const once = mergeDeltaRowsIntoPages(pages(), delta);
+    const twice = mergeDeltaRowsIntoPages(once, delta);
+    const thrice = mergeDeltaRowsIntoPages(twice, delta);
+    expect(once[0].items.map((i) => i.id)).toEqual(["u1", "a1", "a2"]);
+    expect(twice[0].items.map((i) => i.id)).toEqual(["u1", "a1", "a2"]);
+    expect(twice).toEqual(once);
+    expect(thrice).toEqual(once);
+  });
+
+  it("seeds a first page when the cache is empty", () => {
+    const merged = mergeDeltaRowsIntoPages([], [row("u1", "user")]);
+    expect(merged).toHaveLength(1);
+    expect(merged[0].items.map((i) => i.id)).toEqual(["u1"]);
  });
 });

@@ -109,4 +189,37 @@ describe("mergeById", () => {
    expect(mergeById(prev, null)).toBe(prev);
    expect(mergeById(prev, undefined)).toBe(prev);
  });
+
+  // #491 CONTRACT: the delta poll's overlap window GUARANTEES the same row is
+  // re-delivered across close polls, so merging must be IDEMPOTENT by id — merging
+  // the same row (or an equal-length list of rows) twice must not duplicate or
+  // reorder. This is the property the whole delta-poll design leans on; a
+  // regression here would re-introduce duplicate assistant bubbles on every poll.
+  it("is idempotent by id: re-merging the same row does not duplicate or reorder", () => {
+    const seed = [makeMsg("u1", "hi"), makeMsg("a1", "step 1")];
+    const repeat = makeMsg("a1", "step 1"); // the SAME row the overlap re-delivers
+    const once = mergeById(seed, repeat);
+    const twice = mergeById(once, repeat);
+    const thrice = mergeById(twice, repeat);
+    // Length is stable (no growth), order is stable (user then assistant).
+    expect(once.map((m) => m.id)).toEqual(["u1", "a1"]);
+    expect(twice.map((m) => m.id)).toEqual(["u1", "a1"]);
+    expect(thrice.map((m) => m.id)).toEqual(["u1", "a1"]);
+    // The repeated merge converges: the row is replaced in place, never appended.
+    expect(twice[1]).toBe(repeat);
+  });
+
+  it("is idempotent across a batch of repeated + grown rows (delta re-delivery)", () => {
+    // A delta poll re-delivers a1 (unchanged) and a2 (grown one step). Applying the
+    // batch twice must equal applying it once — the poll can re-send either.
+    const start = [makeMsg("u1", "hi"), makeMsg("a1", "done")];
+    const batch = [makeMsg("a1", "done"), makeMsg("a2", "grown step 2")];
+    const apply = (list: typeof start) =>
+      batch.reduce((acc, row) => mergeById(acc, row), list);
+    const once = apply(start);
+    const twice = apply(once);
+    expect(once.map((m) => m.id)).toEqual(["u1", "a1", "a2"]);
+    expect(twice.map((m) => m.id)).toEqual(["u1", "a1", "a2"]);
+    expect(twice).toEqual(once);
+  });
 });
@@ -11,9 +11,10 @@ import type { IAiChatMessageRow } from "@/features/ai-chat/types/ai-chat.types.t

 /**
 * A STREAMING tail: the last persisted row is an assistant row still marked
- * `status === 'streaming'`. Such a tail is stripped from the seed and rebuilt by
- * the replay (`expect=live`), since the SDK's `text-start` always pushes a new
- * part and replaying over a seeded in-progress row would duplicate its text.
+ * `status === 'streaming'`. #491 (tail-only): such a tail is seeded UNCHANGED —
+ * it carries the persisted steps 0..N-1 — and the run-stream registry's tail
+ * (frames for steps >= N) is APPENDED to it by the SDK's `readUIMessageStream`
+ * continuation. Only the presence of this tail decides WHETHER to attach.
 */
 export function isStreamingTail(rows: IAiChatMessageRow[]): boolean {
  const tail = rows[rows.length - 1];
@@ -32,15 +33,61 @@ export function isSettledAssistantTail(rows: IAiChatMessageRow[]): boolean {
 }

 /**
- * Seed rows for `useChat`: return the rows unchanged, or without the last row when
- * `strip` is set (the streaming tail is stripped so the live replay rebuilds it
- * without duplicating parts).
+ * #491 tail-only anchor: the count of FINISHED steps whose parts are persisted in
+ * THIS assistant row (`metadata.stepsPersisted`), written atomically with `parts`
+ * server-side. The resume client reads it as its persisted step frontier N — the
+ * tail-only attach asks the run-stream registry for the frames of step N onward
+ * (the seed already carries steps 0..N-1). Absent on pre-#491 rows => 0.
 */
-export function seedRows(
+export function stepsPersistedOf(
+  row: IAiChatMessageRow | null | undefined,
+): number {
+  const n = row?.metadata?.stepsPersisted;
+  return typeof n === "number" && n >= 0 ? Math.floor(n) : 0;
+}
+
+/** One page of the messages infinite-query cache (`{ items, meta }`). */
+export interface IMessagePage {
+  items: IAiChatMessageRow[];
+  meta: unknown;
+}
+
+/**
+ * #491 delta-poll merge: upsert the delta poll's `rows` into the messages
+ * infinite-query page structure IDEMPOTENTLY by id. The delta endpoint's overlap
+ * window GUARANTEES occasional REPEATS, so this MUST converge: a row already
+ * present is REPLACED IN PLACE (per-step growth of an in-progress row), a new row
+ * is APPENDED to the last page in chronological order (the server returns delta
+ * rows oldest-first). Applying the same delta twice equals applying it once. Never
+ * mutates the input pages (returns fresh page objects with cloned item arrays).
+ */
+export function mergeDeltaRowsIntoPages(
+  pages: IMessagePage[],
  rows: IAiChatMessageRow[],
-  strip: boolean,
-): IAiChatMessageRow[] {
-  return strip ? rows.slice(0, -1) : rows;
+): IMessagePage[] {
+  if (rows.length === 0) return pages;
+  const next: IMessagePage[] = pages.map((p) => ({
+    ...p,
+    items: p.items.slice(),
+  }));
+  const locate = (id: string): [number, number] | null => {
+    for (let pi = 0; pi < next.length; pi++) {
+      const ii = next[pi].items.findIndex((it) => it.id === id);
+      if (ii !== -1) return [pi, ii];
+    }
+    return null;
+  };
+  for (const row of rows) {
+    const at = locate(row.id);
+    if (at) {
+      next[at[0]].items[at[1]] = row; // replace in place — idempotent by id
+    } else if (next.length > 0) {
+      next[next.length - 1].items.push(row); // append chronologically
+    } else {
+      next.push({ items: [row], meta: undefined });
+    }
+  }
+  return next;
 }

 /**
@@ -0,0 +1,83 @@
+import { describe, it, expect } from "vitest";
+import { readUIMessageStream, type UIMessage } from "ai";
+import pkg from "../../../../package.json";
+
+/**
+ * PIN-SPEC TRIP-WIRE (#491). The tail-only attach continuation relies on THREE
+ * behaviors of `ai@6.0.207`, verified line-by-line in the issue. Without this
+ * test, an `ai` bump could silently break attach (the client would append the
+ * live tail to the wrong message, or duplicate a step):
+ *
+ *   1. `readUIMessageStream({ message })` CONTINUES the passed message — it does
+ *      not start a fresh one — so the tail streamed after a re-seed is appended to
+ *      the seeded assistant row (the same DB id).
+ *   2. A `start` frame does NOT reset the existing message's parts (so the seeded
+ *      steps 0..N-1 survive; the synthetic `start` the registry prepends only
+ *      carries the run-fact metadata).
+ *   3. Text parts do NOT cross a `finish-step` boundary — a new `text-start` after
+ *      `finish-step` is a NEW part — so the reconstructed steps stay separated and
+ *      the step frontier stays meaningful.
+ *
+ * If an `ai` upgrade changes any of these, this test fails LOUD instead of the
+ * resume path silently corrupting.
+ */
+describe("ai SDK continuation trip-wire (#491, tail-only attach)", () => {
+  it("is pinned to the exact ai version the continuation was verified against", () => {
+    // A caret/range bump is exactly what would silently break attach — require an
+    // exact pin. Bumping ai MUST re-verify the behavior asserted below, then this.
+    expect((pkg as { dependencies: Record<string, string> }).dependencies.ai).toBe(
+      "6.0.207",
+    );
+  });
+
+  it("continues the seeded message: start does not reset parts, the tail appends as new parts", async () => {
+    // A seeded assistant row with ONE finished step already reconstructed.
+    const seeded: UIMessage = {
+      id: "assistant-1",
+      role: "assistant",
+      parts: [
+        { type: "step-start" },
+        { type: "text", text: "STEP0", state: "done" },
+      ],
+    } as UIMessage;
+
+    // The tail the registry delivers on re-attach: a synthetic start (run-fact),
+    // then step 1's frames, then finish. As UI-message chunks (what the SSE frames
+    // decode to).
+    const chunks = [
+      { type: "start", messageMetadata: { runId: "r1", chatId: "c1" } },
+      { type: "start-step" },
+      { type: "text-start", id: "t1" },
+      { type: "text-delta", id: "t1", delta: "STEP1" },
+      { type: "text-end", id: "t1" },
+      { type: "finish-step" },
+      { type: "finish" },
+    ];
+    const stream = new ReadableStream({
+      start(c) {
+        for (const ch of chunks) c.enqueue(ch);
+        c.close();
+      },
+    });
+
+    let last: UIMessage | undefined;
+    for await (const msg of readUIMessageStream({ message: seeded, stream })) {
+      last = msg;
+    }
+
+    expect(last).toBeDefined();
+    // Same message id (continuation, not a fresh message).
+    expect(last!.id).toBe("assistant-1");
+    // The seeded step-0 parts SURVIVED the `start` frame, and step 1 was appended
+    // as SEPARATE parts (text did not cross the finish-step boundary).
+    const shape = last!.parts.map((p) => `${p.type}:${(p as { text?: string }).text ?? ""}`);
+    expect(shape).toEqual([
+      "step-start:",
+      "text:STEP0",
+      "step-start:",
+      "text:STEP1",
+    ]);
+    // The run-fact metadata from the synthetic start frame is applied.
+    expect(last!.metadata).toMatchObject({ runId: "r1", chatId: "c1" });
+  });
+});
@@ -15,6 +15,7 @@ vi.mock("@/features/comment/components/comment-editor", () => ({
 // case renders in isolation.
 vi.mock("@/features/page/queries/page-query.ts", () => ({
  usePageQuery: () => ({ data: undefined, isLoading: false, isError: false }),
+  usePageMetaQuery: () => ({ data: undefined, isLoading: false, isError: false }),
 }));
 vi.mock("@/features/share/queries/share-query.ts", () => ({
  useSharePageQuery: () => ({ data: undefined }),
@@ -22,7 +22,7 @@ import CommentEditor from "@/features/comment/components/comment-editor";
 import CommentActions from "@/features/comment/components/comment-actions";
 import { useFocusWithin } from "@mantine/hooks";
 import { IComment } from "@/features/comment/types/comment.types.ts";
-import { usePageQuery } from "@/features/page/queries/page-query.ts";
+import { usePageMetaQuery } from "@/features/page/queries/page-query.ts";
 import { extractPageSlugId } from "@/lib";
 import { useTranslation } from "react-i18next";
 import { useGetSpaceBySlugQuery } from "@/features/space/queries/space-query.ts";
@@ -56,7 +56,7 @@ export function buildChildrenByParent(
 function CommentListWithTabs({ onClose }: CommentListWithTabsProps) {
  const { t } = useTranslation();
  const { pageSlug } = useParams();
-  const { data: page } = usePageQuery({ pageId: extractPageSlugId(pageSlug) });
+  const { data: page } = usePageMetaQuery({ pageId: extractPageSlugId(pageSlug) });
  const {
    data: comments,
    isLoading: isCommentsLoading,
@@ -1,5 +1,8 @@
 import { atom } from "jotai";
-import { Editor } from "@tiptap/core";
+// Type-only: these atoms only hold an Editor reference for typing. A value
+// import would drag the whole @tiptap/core engine into the eager graph of every
+// shell component that reads one of these atoms.
+import type { Editor } from "@tiptap/core";
 import { PageEditMode } from "@/features/user/types/user.types.ts";
 import type { DictationUnavailableReason } from "@/features/dictation/dictation-status";

@@ -46,6 +46,13 @@ export function AudioMenu({ editor }: EditorMenuProps) {
        return null;
      }

+      // #343 PART 1: skip getAttributes unless an audio node is active. The menu
+      // only shows for an active audio node (shouldShow), so the null state while
+      // inactive is never rendered — behavior unchanged.
+      if (!ctx.editor.isActive("audio")) {
+        return null;
+      }
+
      const audioAttrs = ctx.editor.getAttributes("audio");

      return {
@@ -43,8 +43,15 @@ export function CalloutMenu({ editor }: EditorMenuProps) {
        return null;
      }

+      // #343 PART 1: skip the per-type isActive() probes unless a callout is
+      // active. The menu only shows for an active callout (shouldShow), so the
+      // null state while inactive is never rendered — behavior unchanged.
+      if (!ctx.editor.isActive("callout")) {
+        return null;
+      }
+
      return {
-        isCallout: ctx.editor.isActive("callout"),
+        isCallout: true,
        isInfo: ctx.editor.isActive("callout", { type: "info" }),
        isNote: ctx.editor.isActive("callout", { type: "note" }),
        isSuccess: ctx.editor.isActive("callout", { type: "success" }),
@@ -22,6 +22,12 @@ export default function CodeBlockView(props: NodeViewProps) {
  const [isSelected, setIsSelected] = useState(false);

  useEffect(() => {
+    // #343 PART 6: `isSelected` only drives the mermaid source's visibility (the
+    // `hidden` prop below). For every non-mermaid code block it is never read,
+    // so skip the per-block `selectionUpdate` listener entirely — otherwise N
+    // code blocks each add a global listener + a setState on every caret move.
+    if (language !== "mermaid") return;
+
    const updateSelection = () => {
      const { state } = editor;
      const { from, to } = state.selection;
@@ -32,11 +38,14 @@ export default function CodeBlockView(props: NodeViewProps) {
      setIsSelected(isNodeSelected);
    };

+    // Initialize on attach so switching a block's language to "mermaid" reflects
+    // the current selection immediately (the listener was not running before).
+    updateSelection();
    editor.on("selectionUpdate", updateSelection);
    return () => {
      editor.off("selectionUpdate", updateSelection);
    };
-  }, [editor, getPos(), node.nodeSize]);
+  }, [editor, getPos(), node.nodeSize, language]);

  function changeLanguage(language: string) {
    setLanguageValue(language);
@@ -0,0 +1,16 @@
+import { lazy, Suspense } from "react";
+import { EditorMenuProps } from "@/features/editor/components/table/types/types.ts";
+
+// Lazily load the drawio bubble menu so it is split out of the editor chunk and
+// fetched only when an editable editor is mounted (mirrors excalidraw-menu-lazy).
+const DrawioMenu = lazy(
+  () => import("@/features/editor/components/drawio/drawio-menu.tsx"),
+);
+
+export default function DrawioMenuLazy(props: EditorMenuProps) {
+  return (
+    <Suspense fallback={null}>
+      <DrawioMenu {...props} />
+    </Suspense>
+  );
+}
@@ -0,0 +1,17 @@
+import { lazy, Suspense } from "react";
+import { NodeViewProps } from "@tiptap/react";
+
+// Lazily load the drawio node view so the heavy react-drawio embed runtime is
+// split into its own chunk and fetched only when a drawio diagram is actually
+// rendered (mirrors excalidraw-view-lazy).
+const DrawioView = lazy(
+  () => import("@/features/editor/components/drawio/drawio-view.tsx"),
+);
+
+export default function DrawioViewLazy(props: NodeViewProps) {
+  return (
+    <Suspense fallback={null}>
+      <DrawioView {...props} />
+    </Suspense>
+  );
+}
@@ -1,5 +1,7 @@
 import type { Editor } from "@tiptap/react";
 import { useEditorState } from "@tiptap/react";
+import { undoDepth, redoDepth } from "@tiptap/pm/history";
+import { yUndoPluginKey } from "@tiptap/y-tiptap";

 export interface ToolbarState {
  isBold: boolean;
@@ -16,14 +18,45 @@ export interface ToolbarState {
  canRedo: boolean;
 }

-// Undo/redo come from either StarterKit's history or the Yjs collaboration
-// history extension. During the brief moment a page is rendered with the
-// static editor (mainExtensions only, undoRedo disabled), neither is loaded
-// and editor.can().undo/redo is undefined.
-function safeCan(editor: Editor, command: "undo" | "redo"): boolean {
-  const can = editor.can() as Record<string, unknown>;
-  const fn = can[command];
-  return typeof fn === "function" ? (fn as () => boolean)() : false;
+// Undo/redo availability, computed WITHOUT `editor.can().undo()/.redo()`.
+//
+// `editor.can()` runs the command as a dry-run (building a throwaway state +
+// transaction) — the most expensive work in this selector, and it ran on every
+// keystroke (and every REMOTE keystroke under collaboration). Instead we read
+// the history stack depth directly, which is a cheap plugin-state lookup and
+// mirrors exactly what the undo/redo commands themselves check:
+//
+//  - Collaboration (Yjs): the yjs UndoManager's undo/redo stack lengths — the
+//    same `undoStack.length === 0` / `redoStack.length === 0` guard the
+//    Collaboration extension's undo/redo commands use.
+//  - Plain history (templates / non-collab): prosemirror-history's undoDepth /
+//    redoDepth, which back the UndoRedo extension.
+//
+// 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.
+function historyAvailability(editor: Editor): {
+  canUndo: boolean;
+  canRedo: boolean;
+} {
+  const state = editor.state;
+
+  // Collaboration history (Yjs) takes precedence when present.
+  const yState = yUndoPluginKey.getState(state) as
+    | { undoManager?: { undoStack: unknown[]; redoStack: unknown[] } }
+    | undefined;
+  if (yState?.undoManager) {
+    return {
+      canUndo: yState.undoManager.undoStack.length > 0,
+      canRedo: yState.undoManager.redoStack.length > 0,
+    };
+  }
+
+  // Plain prosemirror-history (returns 0 when the history plugin is absent).
+  return {
+    canUndo: undoDepth(state) > 0,
+    canRedo: redoDepth(state) > 0,
+  };
 }

 export function useToolbarState(editor: Editor | null): ToolbarState | null {
@@ -31,6 +64,7 @@ export function useToolbarState(editor: Editor | null): ToolbarState | null {
    editor,
    selector: (ctx) => {
      if (!ctx.editor) return null;
+      const { canUndo, canRedo } = historyAvailability(ctx.editor);
      return {
        isBold: ctx.editor.isActive("bold"),
        isItalic: ctx.editor.isActive("italic"),
@@ -42,8 +76,8 @@ export function useToolbarState(editor: Editor | null): ToolbarState | null {
        isBulletList: ctx.editor.isActive("bulletList"),
        isOrderedList: ctx.editor.isActive("orderedList"),
        isTaskList: ctx.editor.isActive("taskList"),
-        canUndo: safeCan(ctx.editor, "undo"),
-        canRedo: safeCan(ctx.editor, "redo"),
+        canUndo,
+        canRedo,
      };
    },
  });
@@ -49,19 +49,14 @@ export default function FootnoteDefinitionView(props: NodeViewProps) {
      className={classes.definition}
      style={{ ["--footnote-number" as any]: `"${number}"` }}
    >
-      {/* #146: contentDOM MUST be the first child — a non-editable marker before
+      {/* #146: contentDOM MUST be the first child — non-editable chrome before
          it makes click hit-testing snap the caret above. Content first; the
-          marker + back-link follow in DOM and are placed left/right via CSS
-          flex `order`. The second #146 mitigation lives in
+          back-link follows in DOM and is placed on the right via CSS flex. The
+          decorative "N." number is rendered inline via the .definitionContent
+          ::before rule (from the --footnote-number var), so no marker element
+          precedes the content. The second #146 mitigation lives in
          editor-paste-handler.tsx (reflowAfterPaste). */}
      <NodeViewContent className={classes.definitionContent} />
-      <span
-        className={classes.definitionMarker}
-        contentEditable={false}
-        aria-hidden="true"
-      >
-        {number}.
-      </span>
      {refCount > 1 ? (
        // Multiple references -> ↩ followed by one lettered link per occurrence.
        <span
@@ -81,34 +81,34 @@
 .definition {
  display: flex;
  align-items: flex-start;
-  /* Tight number→text spacing (~one space) so it reads like "1. text"
-     instead of leaving a wide gap after the period. */
-  gap: 0.4em;
+  /* Tight spacing between the content and the trailing ↩ back-link. */
+  gap: 0.3em;
  padding: 2px 0;
+  /* Footnotes read smaller than body text (16px). Matches .listHeading. */
+  font-size: var(--mantine-font-size-sm);
 }

-.definitionMarker {
-  order: -1; /* keep the "N." marker on the LEFT though it follows content in DOM (#146) */
-  flex: 0 0 auto;
-  min-width: 1.5em;
-  /* Right-align within the narrow column so the period sits next to the text
-     and multi-digit numbers (10, 11, …) stay aligned on their right edge. */
-  text-align: right;
-  font-variant-numeric: tabular-nums;
-  color: var(--mantine-color-dimmed);
-  user-select: none;
-}
-
+/* The "N." number is decorative (from the --footnote-number CSS var on the
+   wrapper, never in the document model) and is rendered inline at the start of
+   the first content line via ::before. This keeps text and wrapped lines flush
+   to the left margin — no hanging indent — while the editable contentDOM stays
+   the FIRST DOM child (#146). */
 .definitionContent {
  flex: 1 1 auto;
  min-width: 0;
 }

-/* The inner editable paragraph inherits `.ProseMirror p { margin: 0.5em 0 }`,
-   which pushes the first text line ~0.5em below the "N." marker (aligned to
-   flex-start), making the number float above the text. Drop the outer margins
-   so the marker and the first line share the same top edge — same approach
-   used for callouts in core.css. */
+.definitionContent > :first-child::before {
+  content: var(--footnote-number, "?") ". ";
+  color: var(--mantine-color-dimmed);
+  font-variant-numeric: tabular-nums;
+  user-select: none;
+}
+
+/* The inner editable paragraph inherits `.ProseMirror p { margin: 0.5em 0 }`.
+   Drop the outer margins so the definition sits tight to the heading above and
+   the ::before number aligns with the top of the row — same approach used for
+   callouts in core.css. */
 .definitionContent > :first-child {
  margin-top: 0;
 }
@@ -38,6 +38,14 @@ export function ImageMenu({ editor }: EditorMenuProps) {
        return null;
      }

+      // #343 PART 1: skip the expensive per-keystroke work (getAttributes + the
+      // alignment isActive() probes) unless an image is actually active. The
+      // menu is only shown when an image is active (see shouldShow), so a null
+      // state while inactive is never rendered — behavior is unchanged.
+      if (!ctx.editor.isActive("image")) {
+        return null;
+      }
+
      const imageAttrs = ctx.editor.getAttributes("image");

      return {
@@ -24,7 +24,7 @@ import classes from "./link.module.css";
 import { useTranslation } from "react-i18next";
 import { INTERNAL_LINK_REGEX } from "@/lib/constants";
 import { LinkEditorPanel } from "@/features/editor/components/link/link-editor-panel.tsx";
-import { usePageQuery } from "@/features/page/queries/page-query.ts";
+import { usePageMetaQuery } from "@/features/page/queries/page-query.ts";
 import { useSharePageQuery } from "@/features/share/queries/share-query.ts";
 import { buildSharedPageUrl } from "@/features/page/page.utils.ts";
 import { extractPageSlugId } from "@/lib";
@@ -83,7 +83,7 @@ export default function LinkView(props: MarkViewProps) {
  const isPopoverVisible = popoverState !== "closed";
  const activeView = isPopoverVisible ? popoverState : lastOpenState.current;

-  const { data: linkedPage } = usePageQuery({
+  const { data: linkedPage } = usePageMetaQuery({
    pageId: isPopoverVisible && slugId && !isShareRoute ? slugId : null,
  });

@@ -0,0 +1,19 @@
+import { lazy, Suspense } from "react";
+import { NodeViewProps } from "@tiptap/react";
+
+// Lazily load the KaTeX-backed block math view so the katex chunk is fetched
+// only when a document actually contains a math node (mirrors the mermaid/
+// excalidraw lazy pattern). The local Suspense keeps a slow katex chunk from
+// crashing or blocking the whole editor: while it loads we render the raw
+// LaTeX source as a node-sized placeholder.
+const MathBlockView = lazy(
+  () => import("@/features/editor/components/math/math-block.tsx"),
+);
+
+export default function MathBlockViewLazy(props: NodeViewProps) {
+  return (
+    <Suspense fallback={<div data-katex="true">{props.node.attrs.text}</div>}>
+      <MathBlockView {...props} />
+    </Suspense>
+  );
+}
@@ -0,0 +1,19 @@
+import { lazy, Suspense } from "react";
+import { NodeViewProps } from "@tiptap/react";
+
+// Lazily load the KaTeX-backed inline math view so the katex chunk is fetched
+// only when a document actually contains a math node (mirrors the mermaid/
+// excalidraw lazy pattern). The local Suspense keeps a slow katex chunk from
+// crashing or blocking the whole editor: while it loads we render the raw
+// LaTeX source as a node-sized placeholder.
+const MathInlineView = lazy(
+  () => import("@/features/editor/components/math/math-inline.tsx"),
+);
+
+export default function MathInlineViewLazy(props: NodeViewProps) {
+  return (
+    <Suspense fallback={<span data-katex="true">{props.node.attrs.text}</span>}>
+      <MathInlineView {...props} />
+    </Suspense>
+  );
+}
@@ -25,7 +25,7 @@ import { IconFileDescription, IconPlus } from "@tabler/icons-react";
 import { useSpaceQuery } from "@/features/space/queries/space-query.ts";
 import { useParams } from "react-router-dom";
 import { v7 as uuid7 } from "uuid";
-import { useAtom } from "jotai";
+import { useAtom, useSetAtom, useStore } from "jotai";
 import { currentUserAtom } from "@/features/user/atoms/current-user-atom.ts";
 import {
  MentionListProps,
@@ -34,7 +34,7 @@ import {
 import { IPage } from "@/features/page/types/page.types";
 import {
  useCreatePageMutation,
-  usePageQuery,
+  usePageMetaQuery,
 } from "@/features/page/queries/page-query";
 import { treeDataAtom } from "@/features/page/tree/atoms/tree-data-atom";
 import { treeModel } from "@/features/page/tree/model/tree-model";
@@ -50,12 +50,16 @@ const MentionList = forwardRef<any, MentionListProps>((props, ref) => {
  const [countAnnouncement, setCountAnnouncement] = useState("");
  const [selectionAnnouncement, setSelectionAnnouncement] = useState("");
  const { pageSlug, spaceSlug } = useParams();
-  const { data: page } = usePageQuery({ pageId: extractPageSlugId(pageSlug) });
+  const { data: page } = usePageMetaQuery({ pageId: extractPageSlugId(pageSlug) });
  const { data: space } = useSpaceQuery(spaceSlug);
  const [currentUser] = useAtom(currentUserAtom);
  const [renderItems, setRenderItems] = useState<MentionSuggestionItem[]>([]);
  const { t } = useTranslation();
-  const [data, setData] = useAtom(treeDataAtom);
+  // Setter-only: the tree value is read only imperatively inside createPage
+  // (via `store` below), never at render, so useSetAtom avoids re-rendering the
+  // mention popup on any tree event.
+  const setData = useSetAtom(treeDataAtom);
+  const store = useStore();
  const createPageMutation = useCreatePageMutation();
  const emit = useQueryEmit();
  const isInCommentContext = props.isInCommentContext ?? false;
@@ -272,9 +276,11 @@ const MentionList = forwardRef<any, MentionListProps>((props, ref) => {
        children: [],
      };

-      const lastIndex = data.length;
+      // Read the live tree imperatively at call time.
+      const currentTree = store.get(treeDataAtom);
+      const lastIndex = currentTree.length;

-      setData(treeModel.insert(data, parentId, newNode, lastIndex));
+      setData(treeModel.insert(currentTree, parentId, newNode, lastIndex));

      props.command({
        id: uuid7(),
@@ -2,7 +2,7 @@ import { NodeViewProps, NodeViewWrapper } from "@tiptap/react";
 import { ActionIcon, Anchor, Text } from "@mantine/core";
 import { IconFileDescription } from "@tabler/icons-react";
 import { Link, useLocation, useNavigate, useParams } from "react-router-dom";
-import { usePageQuery } from "@/features/page/queries/page-query.ts";
+import { usePageMetaQuery } from "@/features/page/queries/page-query.ts";
 import { useSharePageQuery } from "@/features/share/queries/share-query.ts";
 import {
  buildPageUrl,
@@ -36,7 +36,7 @@ export function MentionContent({ attrs }: { attrs: MentionAttrs }) {
    data: page,
    isLoading,
    isError,
-  } = usePageQuery({ pageId: isPageMention && !isShareRoute ? slugId : null });
+  } = usePageMetaQuery({ pageId: isPageMention && !isShareRoute ? slugId : null });

  const { data: sharedPage } = useSharePageQuery({
    pageId: isPageMention && isShareRoute ? slugId : undefined,
@@ -25,6 +25,13 @@ export function PdfMenu({ editor }: EditorMenuProps) {
        return null;
      }

+      // #343 PART 1: skip getAttributes unless a pdf node is active. The menu
+      // only shows for an active pdf node (shouldShow), so the null state while
+      // inactive is never rendered — behavior unchanged.
+      if (!ctx.editor.isActive("pdf")) {
+        return null;
+      }
+
      const pdfAttrs = ctx.editor.getAttributes("pdf");

      return {
@@ -70,7 +70,14 @@ export const SubpagesMenu = React.memo(
    // toggle without re-rendering on every keystroke.
    const isRecursive = useEditorState({
      editor,
-      selector: (ctx) => ctx.editor?.getAttributes("subpages")?.recursive ?? false,
+      // #343 PART 1: skip getAttributes unless a subpages node is active. The
+      // menu only shows for an active subpages node (shouldShow), so the value
+      // is only read then; getAttributes on an inactive node returns the default
+      // (recursive === false) anyway, so this is behavior-preserving.
+      selector: (ctx) =>
+        ctx.editor?.isActive("subpages")
+          ? (ctx.editor.getAttributes("subpages")?.recursive ?? false)
+          : false,
    });

    return (
@@ -4,6 +4,7 @@ import React, { FC, useEffect, useRef, useState } from "react";
 import classes from "./table-of-contents.module.css";
 import clsx from "clsx";
 import { Box, Text, Title } from "@mantine/core";
+import { useDebouncedCallback } from "@mantine/hooks";
 import { useTranslation } from "react-i18next";

 type TableOfContentsProps = {
@@ -79,13 +80,21 @@ export const TableOfContents: FC<TableOfContentsProps> = (props) => {
    setHeadingDOMNodes(result.nodes);
  };

+  // Debounce the update-driven rescan: `$nodes("heading")` scans every heading
+  // in the document, and it previously ran on EVERY keystroke while the TOC
+  // panel was open. The panel is derived UI, so recomputing ~300ms after typing
+  // settles keeps it correct without doing an all-headings scan per keystroke
+  // (#343, PART 7). `useDebouncedCallback` returns a stable reference and always
+  // invokes the latest `handleUpdate`.
+  const debouncedHandleUpdate = useDebouncedCallback(handleUpdate, 300);
+
  useEffect(() => {
-    props.editor?.on("update", handleUpdate);
+    props.editor?.on("update", debouncedHandleUpdate);

    return () => {
-      props.editor?.off("update", handleUpdate);
+      props.editor?.off("update", debouncedHandleUpdate);
    };
-  }, [props.editor]);
+  }, [props.editor, debouncedHandleUpdate]);

  useEffect(
    () => {
@@ -31,6 +31,13 @@ export function VideoMenu({ editor }: EditorMenuProps) {
        return null;
      }

+      // #343 PART 1: skip getAttributes + alignment isActive() probes unless a
+      // video is active. The menu only shows for an active video (shouldShow),
+      // so the null state while inactive is never rendered — behavior unchanged.
+      if (!ctx.editor.isActive("video")) {
+        return null;
+      }
+
      const videoAttrs = ctx.editor.getAttributes("video");

      return {
@@ -81,8 +81,8 @@ import {
  createResizeHandle,
  buildResizeClasses,
 } from "@/features/editor/components/common/node-resize-handles.ts";
-import MathInlineView from "@/features/editor/components/math/math-inline.tsx";
-import MathBlockView from "@/features/editor/components/math/math-block.tsx";
+import MathInlineView from "@/features/editor/components/math/math-inline-lazy.tsx";
+import MathBlockView from "@/features/editor/components/math/math-block-lazy.tsx";
 import ImageView from "@/features/editor/components/image/image-view.tsx";
 import CalloutView from "@/features/editor/components/callout/callout-view.tsx";
 import StatusView from "@/features/editor/components/status/status-view.tsx";
@@ -90,7 +90,7 @@ import VideoView from "@/features/editor/components/video/video-view.tsx";
 import AudioView from "@/features/editor/components/audio/audio-view.tsx";
 import AttachmentView from "@/features/editor/components/attachment/attachment-view.tsx";
 import CodeBlockView from "@/features/editor/components/code-block/code-block-view.tsx";
-import DrawioView from "../components/drawio/drawio-view";
+import DrawioView from "../components/drawio/drawio-view-lazy.tsx";
 import ExcalidrawView from "@/features/editor/components/excalidraw/excalidraw-view-lazy.tsx";
 import EmbedView from "@/features/editor/components/embed/embed-view.tsx";
 import HtmlEmbedView from "@/features/editor/components/html-embed/html-embed-view.tsx";
@@ -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();
+  });
+});
@@ -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
-// serializer step the clipboardTextSerializer runs), so they pin the OUTPUT
-// shape that the classifier-flag tests above do not cover.
-describe("table clipboard markdown output (htmlToMarkdown)", () => {
+// These exercise the actual markdown produced by convertProseMirrorToMarkdown —
+// the same serializer step the clipboardTextSerializer now runs (issue #347) —
+// so they pin the OUTPUT shape that the classifier-flag tests above do not cover.
+// 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", () => {
-    // Mirror the serializer's `wrapBareRows` branch exactly: bare <tr> nodes are
-    // wrapped in <table><tbody> and htmlToMarkdown(div.innerHTML) is called.
-    // See markdown-clipboard.ts clipboardTextSerializer:
-    //   const table = document.createElement("table");
-    //   const tbody = document.createElement("tbody");
-    //   tbody.appendChild(fragment); table.appendChild(tbody);
-    //   div.appendChild(table);
-    //   return htmlToMarkdown(div.innerHTML);
-    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 cell = (t: string) => ({
+    type: "tableCell",
+    content: [{ type: "paragraph", content: [{ type: "text", text: t }] }],
+  });
+  const headerCell = (t: string) => ({
+    type: "tableHeader",
+    content: [{ type: "paragraph", content: [{ type: "text", text: t }] }],
+  });
+  const row = (nodes: any[]) => ({ type: "tableRow", content: nodes });

-    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
-    // synthesized by the GFM turndown plugin for a header-less table — fine).
+    // Valid GFM: a header/data separator row is present.
    expect(ls.some(isSeparatorRow)).toBe(true);
-    // 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.
+    // NOT the old broken "one value per line" shape: every line is pipe-delimited.
    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
-    // directly (div.appendChild(fragment)) and htmlToMarkdown(div.innerHTML) runs.
-    const div = document.createElement("div");
-    const table = document.createElement("table");
-
-    const thead = document.createElement("thead");
-    const headerRow = document.createElement("tr");
-    for (const h of ["Name", "Age"]) {
-      const th = document.createElement("th");
-      th.textContent = h;
-      headerRow.appendChild(th);
-    }
-    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);
+    // Mirror the serializer's non-wrap branch: the full `table` node is the
+    // slice content and convertProseMirrorToMarkdown runs on it.
+    const md = convertProseMirrorToMarkdown({
+      type: "doc",
+      content: [
+        {
+          type: "table",
+          content: [
+            row([headerCell("Name"), headerCell("Age")]),
+            row([cell("Alice"), cell("30")]),
+            row([cell("Bob"), cell("25")]),
+          ],
+        },
+      ],
+    });
    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 $10");
+  });
+
+  it("a lone `==` is NOT turned into a highlight", () => {
+    const doc = markdownToProseMirrorSync("compare a == b in code");
+    const hasHighlight = (n: any): boolean => {
+      if (!n || typeof n !== "object") return false;
+      if (
+        n.type === "text" &&
+        (n.marks || []).some((m: any) => m.type === "highlight")
+      )
+        return true;
+      return Array.isArray(n.content) ? n.content.some(hasHighlight) : false;
+    };
+    expect(hasHighlight(doc)).toBe(false);
+    expect(allText(doc)).toContain("== b");
+  });
+
+  it("a `[^1]` reference form (no `^[`) is NOT turned into a footnote", () => {
+    const doc = markdownToProseMirrorSync("see note [^1] for details");
+    expect(collectTypes(doc).has("footnoteReference")).toBe(false);
+    expect(allText(doc)).toContain("[^1]");
+  });
+});
@@ -1,15 +1,23 @@
 // adapted from: https://github.com/aguingand/tiptap-markdown/blob/main/src/extensions/tiptap/clipboard.js - MIT
 import { Extension } from "@tiptap/core";
 import { Plugin, PluginKey, TextSelection } from "@tiptap/pm/state";
-import { DOMParser, DOMSerializer, Fragment, Slice } from "@tiptap/pm/model";
+import { DOMParser, DOMSerializer, Fragment, Slice, Node as PMNode } from "@tiptap/pm/model";
 import { find } from "linkifyjs";
 import {
-  markdownToHtml,
-  htmlToMarkdown,
  canonicalizeFootnotes,
  FOOTNOTES_LIST_NAME,
  FOOTNOTE_REFERENCE_NAME,
 } from "@docmost/editor-ext";
+// Markdown <-> ProseMirror conversion now lives ONLY in the canonical
+// `@docmost/prosemirror-markdown` package (issue #347). The BROWSER entry uses
+// the native `DOMParser` for its HTML->DOM stage (jsdom stays out of the client
+// bundle) while producing the SAME nodes the server import does — so a paste of
+// canonical markdown (`^[…]`, `<!--img …-->`, `> [!type]`, `$…$`, `==…==`,
+// 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");
-            const serializer = DOMSerializer.fromSchema(this.editor.schema);
-            const fragment = serializer.serializeFragment(slice.content);
-
+            // Convert the copied selection to Markdown through the canonical
+            // package (issue #347), the SAME serializer the server export uses,
+            // 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
-              // (prosemirror-tables returns the whole `table` node only when the
-              // entire table is selected). Bare <tr> would be foster-parented
-              // away by the HTML parser inside htmlToMarkdown, so wrap them in
-              // <table><tbody> first for the GFM turndown rule to detect them.
-              const table = document.createElement("table");
-              const tbody = document.createElement("tbody");
-              tbody.appendChild(fragment);
-              table.appendChild(tbody);
-              div.appendChild(table);
-            } else {
-              div.appendChild(fragment);
+              // A partial table cell-selection serializes to bare `tableRow`
+              // nodes (prosemirror-tables yields the whole `table` node only for
+              // a full-table selection). The converter's table case expects a
+              // `table` wrapper, so wrap the bare rows in one — mirroring the old
+              // <table><tbody> wrap that the HTML->markdown step needed.
+              return convertProseMirrorToMarkdown({
+                type: "doc",
+                content: [{ type: "table", content }],
+              });
            }
-            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 { from, to } = view.state.selection;
+            const schema = this.editor.schema;
+            // 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+$/, ""));
-            const body = elementFromString(parsed);
-            normalizeTableColumnWidths(body);
+            void markdownToProseMirror(md)
+              .then((doc) => {
+                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(
-              this.editor.schema,
-            ).parseSlice(body, {
-              preserveWhitespace: true,
-            });
+                const body = elementFromString(div.innerHTML);
+                normalizeTableColumnWidths(body);

-            // A markdown paste builds its ProseMirror fragment directly (DOM ->
-            // parseSlice), bypassing the editor's footnoteSyncPlugin, which never
-            // reorders an existing list. So a pasted markdown block whose footnote
-            // 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,
-            );
+                const parsedSlice = DOMParser.fromSchema(schema).parseSlice(
+                  body,
+                  { preserveWhitespace: true },
+                );

-            tr.replaceRange(from, to, contentNodes);
-            const insertEnd = tr.mapping.map(from, 1);
-            tr.setSelection(TextSelection.near(tr.doc.resolve(Math.max(from, insertEnd - 2)), -1));
-            tr.setMeta('paste', true)
-            view.dispatch(tr);
+                // A markdown paste builds its ProseMirror fragment directly (DOM
+                // -> parseSlice), bypassing the editor's footnoteSyncPlugin, which
+                // never reorders an existing list. So a pasted markdown block whose
+                // footnote 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,
+                  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.
@@ -6,6 +6,23 @@ import getSuggestionItems from '@/features/editor/components/slash-menu/menu-ite

 export const slashMenuPluginKey = new PluginKey('slash-command');

+// getSuggestionItems fuzzy-matches EVERY command against the query (plus its
+// wrong-keyboard-layout remaps) and, while the slash menu is open, is invoked
+// TWICE per keystroke: once by the synchronous `allow` gate below and once by
+// the popup's `items` builder. A synchronous gating predicate can't be
+// debounced without breaking the suggestion decoration/activation, so instead we
+// memoize the LAST query's result: the two same-query calls in one keystroke
+// build the list only once, and the cache invalidates the moment the query
+// changes — so there is no stale-state risk (#343, PART 7).
+let lastQuery: string | null = null;
+let lastResult: ReturnType<typeof getSuggestionItems> | null = null;
+function suggestionItemsForQuery(query: string) {
+  if (query === lastQuery && lastResult) return lastResult;
+  lastQuery = query;
+  lastResult = getSuggestionItems({ query });
+  return lastResult;
+}
+
 // @ts-ignore
 const Command = Extension.create({
  name: 'slash-command',
@@ -38,7 +55,7 @@ const Command = Extension.create({
          // non-matching queries while keeping multi-word matches (e.g.
          // "/Heading 1") working.
          const query = state.doc.textBetween(range.from + 1, range.to);
-          const groups = getSuggestionItems({ query });
+          const groups = suggestionItemsForQuery(query);
          const hasMatches = Object.values(groups).some(
            (items) => items.length > 0,
          );
@@ -61,7 +78,9 @@ const Command = Extension.create({

 const SlashCommand = Command.configure({
  suggestion: {
-    items: getSuggestionItems,
+    // Share the per-query memo with `allow` so the pair of same-query calls in a
+    // single keystroke rebuilds the list once (#343, PART 7).
+    items: ({ query }: { query: string }) => suggestionItemsForQuery(query),
    render: renderItems,
  },
 });
@@ -1,8 +1,17 @@
 import { useEffect, useRef } from "react";
 import { useNavigate } from "react-router-dom";
 import { getDefaultStore } from "jotai";
-import { WebSocketStatus } from "@hocuspocus/provider";
-import { Editor } from "@tiptap/core";
+
+// Literal value of WebSocketStatus.Connected from @hocuspocus/provider. Inlined
+// so this always-mounted global bridge does not statically import
+// @hocuspocus/provider — that import pulls Yjs (and, through a shared chunk, the
+// whole TipTap engine) into the eager startup graph. yjsConnectionStatusAtom
+// already stores these raw status strings.
+const YJS_STATUS_CONNECTED = "connected";
+// Type-only: importing Editor as a type keeps @tiptap/core (the whole editor
+// engine) out of the eager global-shell graph — the bridge only uses it for
+// annotations/casts, never as a runtime value.
+import type { Editor } from "@tiptap/core";
 import {
  pageEditorAtom,
  yjsConnectionStatusAtom,
@@ -16,16 +25,19 @@ import {
  getSidebarPages,
 } from "@/features/page/services/page-service.ts";
 import { buildPageUrl } from "@/features/page/page.utils.ts";
-import {
+// Types are erased at build time, so importing them does not pull the module's
+// runtime (which drags in @tiptap + the editor-ext barrel). The actual recording
+// helpers are dynamically imported at call time inside createPageWithRecording,
+// keeping the editor engine out of the eager global-shell startup graph — the
+// bridge is mounted for every authenticated user but recording is a rare,
+// native-host-driven action.
+import type {
  GitmostBridge,
  GitmostCreatePagePayload,
  GitmostCreatePageResult,
  GitmostListPagesPayload,
  GitmostListPagesResult,
  GitmostListSpacesResult,
-  gitmostDecodePayloadToFile,
-  gitmostInsertTranscriptIntoEditor,
-  gitmostUploadFileToEditor,
 } from "@/features/editor/gitmost/gitmost-recording.ts";

 // How long to wait for a freshly-navigated page's editor to mount, become
@@ -58,7 +70,7 @@ function gitmostWaitForEditor(
        !editor.isDestroyed &&
        editor.isEditable &&
        editorPageId === pageId &&
-        yjsStatus === WebSocketStatus.Connected;
+        yjsStatus === YJS_STATUS_CONNECTED;
      if (ready) {
        resolve(editor);
        return;
@@ -172,6 +184,15 @@ export default function GitmostGlobalBridge() {
          };
        }

+        // Load the recording helpers on demand (see the import note above). This
+        // is the only place they are needed, so the @tiptap/editor-ext code they
+        // pull in stays out of the eager startup graph.
+        const {
+          gitmostDecodePayloadToFile,
+          gitmostUploadFileToEditor,
+          gitmostInsertTranscriptIntoEditor,
+        } = await import("@/features/editor/gitmost/gitmost-recording.ts");
+
        // Validate/decode the recording BEFORE creating the page so a bad
        // payload never leaves an empty junk page behind. Per the createPage
        // error contract, any decode failure collapses to "insert-failed" (the
@@ -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
-// purely via the fake page editor's getHTML().
-vi.mock("@docmost/editor-ext", () => ({
-  htmlToMarkdown: (html: string) => html,
+// convertProseMirrorToMarkdown echoes a marker carried on the fake editor's
+// getJSON() doc, so each test controls the markdown purely via the fake page
+// editor (issue #347: the hook now serializes editor JSON through the package).
+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;
 }
@@ -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;
@@ -0,0 +1,100 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import { renderHook, act } from "@testing-library/react";
+import type { MutableRefObject } from "react";
+import type { Editor } from "@tiptap/react";
+
+// Mock the app entry so importing the hook doesn't boot the whole app; the hook
+// only needs queryClient's cache read/write, which we stub here. Declared via
+// vi.hoisted so the spies exist before the hoisted vi.mock factory runs.
+const { getQueryData, setQueryData } = vi.hoisted(() => ({
+  getQueryData: vi.fn(() => undefined as unknown),
+  setQueryData: vi.fn(),
+}));
+vi.mock("@/main.tsx", () => ({
+  queryClient: { getQueryData, setQueryData },
+}));
+
+import { usePageContentCache } from "./use-page-content-cache";
+
+const SNAPSHOT = { type: "doc", content: [] };
+
+function makeFakeEditor(overrides: Partial<Editor> = {}): Editor {
+  return {
+    isEmpty: false,
+    isDestroyed: false,
+    getJSON: vi.fn(() => SNAPSHOT),
+    ...overrides,
+  } as unknown as Editor;
+}
+
+describe("usePageContentCache (#343 PART 3) — getJSON off the keystroke path", () => {
+  beforeEach(() => {
+    vi.useFakeTimers();
+    vi.clearAllMocks();
+    // A cached page exists so the write path runs.
+    getQueryData.mockReturnValue({ id: "p1", content: {} });
+  });
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  it("onUpdate (calling the debounced fn) does NOT call getJSON synchronously", () => {
+    const editor = makeFakeEditor();
+    const editorRef = { current: editor } as MutableRefObject<Editor | null>;
+
+    const { result } = renderHook(() =>
+      usePageContentCache(editorRef, "slug-1", 3000),
+    );
+
+    // Simulate a keystroke's onUpdate -> only schedules the debounce.
+    act(() => {
+      result.current();
+      result.current();
+      result.current();
+    });
+
+    // The whole-doc serialization must NOT have happened yet.
+    expect(editor.getJSON).not.toHaveBeenCalled();
+    expect(setQueryData).not.toHaveBeenCalled();
+
+    // Once the debounce window elapses, getJSON runs exactly once (not per call).
+    act(() => vi.advanceTimersByTime(3000));
+    expect(editor.getJSON).toHaveBeenCalledTimes(1);
+    expect(setQueryData).toHaveBeenCalledWith(["pages", "slug-1"], {
+      id: "p1",
+      content: SNAPSHOT,
+    });
+  });
+
+  it("flushes the pending snapshot on unmount so the last edit isn't lost", () => {
+    const editor = makeFakeEditor();
+    const editorRef = { current: editor } as MutableRefObject<Editor | null>;
+
+    const { result, unmount } = renderHook(() =>
+      usePageContentCache(editorRef, "slug-1", 3000),
+    );
+
+    act(() => result.current());
+    expect(editor.getJSON).not.toHaveBeenCalled();
+
+    // Navigation/unmount must flush (not drop) the pending write.
+    act(() => unmount());
+    expect(editor.getJSON).toHaveBeenCalledTimes(1);
+    expect(setQueryData).toHaveBeenCalledTimes(1);
+  });
+
+  it("skips the write when the editor is destroyed (flush racing teardown)", () => {
+    const editor = makeFakeEditor({ isDestroyed: true });
+    const editorRef = { current: editor } as MutableRefObject<Editor | null>;
+
+    const { result } = renderHook(() =>
+      usePageContentCache(editorRef, "slug-1", 3000),
+    );
+
+    act(() => result.current());
+    act(() => vi.advanceTimersByTime(3000));
+
+    expect(editor.getJSON).not.toHaveBeenCalled();
+    expect(setQueryData).not.toHaveBeenCalled();
+  });
+});
@@ -0,0 +1,50 @@
+import type { MutableRefObject } from "react";
+import { useDebouncedCallback } from "@mantine/hooks";
+import type { Editor } from "@tiptap/react";
+import { queryClient } from "@/main.tsx";
+import { IPage } from "@/features/page/types/page.types.ts";
+
+/**
+ * Off-keystroke local page-cache updater (issue #343, PART 3).
+ *
+ * The editor's `onUpdate` fires on every keystroke — and, under collaboration,
+ * on every REMOTE keystroke too. Serializing the WHOLE document with
+ * `editor.getJSON()` on that hot path is expensive, and the previous 3s debounce
+ * only guarded the cache WRITE, not the serialization: `getJSON()` still ran per
+ * keystroke.
+ *
+ * This hook moves the serialization INSIDE the debounced callback, so the
+ * full-doc traversal happens at most once per `delay`, not per keystroke. Call
+ * the returned function from `onUpdate` (it only schedules the debounce); the
+ * `getJSON()` snapshot is taken when the debounce fires.
+ *
+ * On unmount/navigation the pending snapshot is FLUSHED (via `flushOnUnmount`)
+ * so the last edits within the debounce window aren't lost from the local cache.
+ * The source of truth is collab/Yjs, but the cache must not go stale.
+ *
+ * IMPORTANT: call this hook BEFORE `useEditor`. React runs effect cleanups in
+ * declaration order on unmount, so the debounce's flush cleanup must be declared
+ * before `useEditor`'s teardown to run while the editor is still alive; the
+ * `isDestroyed` guard keeps a flush that still races teardown safe (it skips).
+ */
+export function usePageContentCache(
+  editorRef: MutableRefObject<Editor | null>,
+  slugId: string | undefined,
+  delay = 3000,
+) {
+  return useDebouncedCallback(
+    () => {
+      const e = editorRef.current;
+      if (!e || e.isDestroyed || e.isEmpty) return;
+      const pageData = queryClient.getQueryData<IPage>(["pages", slugId]);
+      if (pageData) {
+        // getJSON() (full-doc serialization) runs HERE, off the keystroke path.
+        queryClient.setQueryData(["pages", slugId], {
+          ...pageData,
+          content: e.getJSON(),
+        });
+      }
+    },
+    { delay, flushOnUnmount: true },
+  );
+}
@@ -59,10 +59,10 @@ import {
  handlePaste,
 } from "@/features/editor/components/common/editor-paste-handler.tsx";
 import ExcalidrawMenu from "./components/excalidraw/excalidraw-menu-lazy";
-import DrawioMenu from "./components/drawio/drawio-menu";
+import DrawioMenu from "./components/drawio/drawio-menu-lazy";
 import { useCollabToken } from "@/features/auth/queries/auth-query.tsx";
 import SearchAndReplaceDialog from "@/features/editor/components/search-and-replace/search-and-replace-dialog.tsx";
-import { useDebouncedCallback, useDocumentVisibility } from "@mantine/hooks";
+import { useDocumentVisibility } from "@mantine/hooks";
 import { useIdle } from "@/hooks/use-idle.ts";
 import { queryClient } from "@/main.tsx";
 import { IPage } from "@/features/page/types/page.types.ts";
@@ -79,6 +79,7 @@ import { PageEditMode } from "@/features/user/types/user.types.ts";
 import { jwtDecode } from "jwt-decode";
 import { searchSpotlight } from "@/features/search/constants.ts";
 import { useEditorScroll } from "./hooks/use-editor-scroll";
+import { usePageContentCache } from "./hooks/use-page-content-cache";
 import { useScrollRestoreOnSwap } from "./hooks/use-scroll-position";
 import { useSwapHeightReservation } from "./hooks/use-swap-height-reservation";
 import { EditorLinkMenu } from "@/features/editor/components/link/link-menu";
@@ -272,8 +273,13 @@ export default function PageEditor({
    }
  }, [isIdle, documentState, providersReady, resetIdle]);

-  // Attach here, to make sure the connection gets properly established
-  providersRef.current?.remote.attach();
+  // Attach the remote provider once it's ready (and again after a pageId swap
+  // recreates it) to make sure the connection gets properly established. This
+  // used to run in the render body — a side effect during render (#343, PART 7).
+  // `attach()` is idempotent, so re-running it on these deps is safe.
+  useEffect(() => {
+    providersRef.current?.remote.attach();
+  }, [providersReady, pageId]);

  const extensions = useMemo(() => {
    if (!providersReady || !providersRef.current || !currentUser?.user) {
@@ -288,6 +294,12 @@ export default function PageEditor({
    ];
  }, [providersReady, currentUser?.user]);

+  // getJSON() serialization + cache write live in the hook, off the keystroke
+  // path, and flush on unmount so the last snapshot survives navigation (#343).
+  // MUST be declared before useEditor: React runs effect cleanups in declaration
+  // order on unmount, so the flush must run before the editor is torn down.
+  const debouncedUpdateContent = usePageContentCache(editorRef, slugId);
+
  const editor = useEditor(
    {
      extensions,
@@ -392,11 +404,11 @@ export default function PageEditor({
          }
        }
      },
-      onUpdate({ editor }) {
-        if (editor.isEmpty) return;
-        const editorJson = editor.getJSON();
-        //update local page cache to reduce flickers
-        debouncedUpdateContent(editorJson);
+      onUpdate() {
+        // Only schedule the debounce here — the whole-doc getJSON() serialization
+        // happens INSIDE the debounced callback (see usePageContentCache), so it
+        // no longer runs synchronously on every (local or remote) keystroke.
+        debouncedUpdateContent();
      },
    },
    [pageId, editable, extensions],
@@ -442,17 +454,6 @@ export default function PageEditor({
    };
  }, [editor, pageId, editorIsEditable]);

-  const debouncedUpdateContent = useDebouncedCallback((newContent: any) => {
-    const pageData = queryClient.getQueryData<IPage>(["pages", slugId]);
-
-    if (pageData) {
-      queryClient.setQueryData(["pages", slugId], {
-        ...pageData,
-        content: newContent,
-      });
-    }
-  }, 3000);
-
  const handleActiveCommentEvent = (event) => {
    const { commentId, resolved } = event.detail;

@@ -24,7 +24,6 @@ export function useFavoritesQuery(type?: FavoriteType, spaceId?: string) {
    initialPageParam: undefined as string | undefined,
    getNextPageParam: (lastPage) =>
      lastPage.meta.hasNextPage ? lastPage.meta.nextCursor : undefined,
-    refetchOnMount: true,
  });
 }

@@ -32,7 +31,6 @@ export function useFavoriteIds(type: FavoriteType, spaceId?: string): Set<string
  const { data } = useQuery({
    queryKey: ["favorite-ids", type, spaceId],
    queryFn: () => getFavoriteIds(type, spaceId),
-    refetchOnMount: true,
  });

  const items = data?.items;
@@ -12,7 +12,7 @@ import { useAtomValue } from "jotai";
 import { useParams } from "react-router-dom";
 import { useTranslation } from "react-i18next";
 import { extractPageSlugId } from "@/lib";
-import { usePageQuery } from "@/features/page/queries/page-query.ts";
+import { usePageMetaQuery } from "@/features/page/queries/page-query.ts";
 import { pageEditorAtom } from "@/features/editor/atoms/editor-atoms.ts";
 import { useBacklinksCountQuery } from "@/features/page-details/queries/backlinks-query.ts";
 import { BacklinksModal } from "./backlinks-modal";
@@ -23,7 +23,7 @@ import { LabelsSection } from "@/features/label/components/labels-section.tsx";

 export function PageDetailsAside() {
  const { pageSlug } = useParams();
-  const { data: page } = usePageQuery({
+  const { data: page } = usePageMetaQuery({
    pageId: extractPageSlugId(pageSlug),
  });
  const pageEditor = useAtomValue(pageEditorAtom);
@@ -0,0 +1,53 @@
+import { describe, it, expect, vi } from "vitest";
+import { SpaceTreeNode } from "@/features/page/tree/types";
+
+// breadcrumb.tsx transitively imports @/main.tsx (via usePageMetaQuery ->
+// queryClient), whose module body calls ReactDOM.createRoot on a null root in
+// jsdom. Stub it so importing the pure helper under test doesn't run that
+// (breadcrumbPathEqual does not use queryClient, so a dummy is enough).
+vi.mock("@/main.tsx", () => ({ queryClient: {} }));
+
+import { breadcrumbPathEqual } from "./breadcrumb";
+
+// breadcrumbPathEqual is the ONLY point where a false-positive equality would
+// leave a stale/incorrect breadcrumb trail on screen: it decides whether the
+// selectAtom hands back the same reference (no re-render) for the ancestor chain.
+// Pin both directions — a too-loose equality goes stale on a rename; a too-tight
+// one loses the perf win.
+const node = (over: Partial<SpaceTreeNode>): SpaceTreeNode =>
+  ({ id: "a", slugId: "sa", name: "A", icon: "📄", ...over }) as SpaceTreeNode;
+
+describe("breadcrumbPathEqual", () => {
+  it("both null → true", () => {
+    expect(breadcrumbPathEqual(null, null)).toBe(true);
+  });
+
+  it("same reference → true", () => {
+    const p = [node({})];
+    expect(breadcrumbPathEqual(p, p)).toBe(true);
+  });
+
+  it("equal by id/slugId/name/icon (different arrays) → true", () => {
+    expect(breadcrumbPathEqual([node({})], [node({})])).toBe(true);
+  });
+
+  it("one side null → false", () => {
+    expect(breadcrumbPathEqual([node({})], null)).toBe(false);
+    expect(breadcrumbPathEqual(null, [node({})])).toBe(false);
+  });
+
+  it("different length → false", () => {
+    expect(
+      breadcrumbPathEqual([node({})], [node({}), node({ id: "b" })]),
+    ).toBe(false);
+  });
+
+  it.each(["name", "icon", "slugId", "id"] as const)(
+    "a changed %s → false (breadcrumb must re-render)",
+    (field) => {
+      expect(
+        breadcrumbPathEqual([node({})], [node({ [field]: "CHANGED" })]),
+      ).toBe(false);
+    },
+  );
+});
@@ -1,7 +1,9 @@
 import { useAtomValue } from "jotai";
+import { selectAtom } from "jotai/utils";
 import { treeDataAtom } from "@/features/page/tree/atoms/tree-data-atom.ts";
-import React, { useCallback, useEffect, useState } from "react";
+import React, { useCallback, useEffect, useMemo, useState } from "react";
 import { computeBreadcrumbState } from "./breadcrumb.utils";
+import { findBreadcrumbPath } from "@/features/page/tree/utils";
 import {
  Button,
  Anchor,
@@ -18,7 +20,7 @@ import { SpaceTreeNode } from "@/features/page/tree/types.ts";
 import { IPage } from "@/features/page/types/page.types.ts";
 import { buildPageUrl } from "@/features/page/page.utils.ts";
 import {
-  usePageQuery,
+  usePageMetaQuery,
  usePageBreadcrumbsQuery,
 } from "@/features/page/queries/page-query.ts";
 import { extractPageSlugId } from "@/lib";
@@ -32,39 +34,84 @@ function getTitle(name: string, icon: string) {
  return name;
 }

+/**
+ * Equality over a breadcrumb chain by the only fields the breadcrumb renders
+ * (id, slugId, name, icon). Lets the selectAtom below hand back the SAME
+ * reference when an unrelated tree mutation leaves THIS page's ancestor chain
+ * visually unchanged, so the breadcrumb no longer re-renders on every tree
+ * event (it previously subscribed to the whole treeDataAtom).
+ */
+export function breadcrumbPathEqual(
+  a: SpaceTreeNode[] | null,
+  b: SpaceTreeNode[] | null,
+): boolean {
+  if (a === b) return true;
+  if (!a || !b || a.length !== b.length) return false;
+  for (let i = 0; i < a.length; i++) {
+    if (
+      a[i].id !== b[i].id ||
+      a[i].slugId !== b[i].slugId ||
+      a[i].name !== b[i].name ||
+      a[i].icon !== b[i].icon
+    ) {
+      return false;
+    }
+  }
+  return true;
+}
+
 export default function Breadcrumb() {
  const { t } = useTranslation();
-  const treeData = useAtomValue(treeDataAtom);
  const [breadcrumbNodes, setBreadcrumbNodes] = useState<
    SpaceTreeNode[] | null
  >(null);
  const { pageSlug, spaceSlug } = useParams();
-  const { data: currentPage } = usePageQuery({
+  const { data: currentPage } = usePageMetaQuery({
    pageId: extractPageSlugId(pageSlug),
  });
+  const currentPageId = currentPage?.id;
  // The page's own ancestor chain, fetched independently of the lazily-built
  // sidebar tree so a deep page doesn't render a blank breadcrumb for seconds
  // while the tree backfills (#218).
-  const { data: ancestors } = usePageBreadcrumbsQuery(currentPage?.id);
+  const { data: ancestors } = usePageBreadcrumbsQuery(currentPageId);
  const isMobile = useMediaQuery("(max-width: 48em)");

+  // Narrowed subscription: instead of subscribing to the whole treeDataAtom and
+  // recomputing on every tree event, derive ONLY the current page's ancestor
+  // chain. The custom equality returns the previous reference when that chain is
+  // visually unchanged, so an unrelated tree mutation no longer re-renders this
+  // component. Mirrors computeBreadcrumbState's tree-hit branch
+  // (findBreadcrumbPath); the tree-miss/ancestors fallback is applied below.
+  const treePathAtom = useMemo(
+    () =>
+      selectAtom(
+        treeDataAtom,
+        (tree): SpaceTreeNode[] | null =>
+          currentPageId ? findBreadcrumbPath(tree, currentPageId) : null,
+        breadcrumbPathEqual,
+      ),
+    [currentPageId],
+  );
+  const treePath = useAtomValue(treePathAtom);
+
  useEffect(() => {
    if (!currentPage) return;

    // Selection/mapping + stale-clearing live in a pure, unit-tested helper
-    // (#218). It resolves the correct chain when possible and, on a transient
-    // miss, clears a chain left over from a previously-viewed page instead of
-    // showing the wrong trail — while keeping a chain already resolved for THIS
-    // page to avoid a blank flash.
+    // (#218). The tree-hit chain (treePath) always wins when present; otherwise
+    // fall back to the page's own ancestors and the stale-clearing logic — this
+    // reproduces computeBreadcrumbState(fullTree, ancestors, …) exactly, since
+    // its tree-hit branch is precisely findBreadcrumbPath(fullTree, pageId).
    setBreadcrumbNodes((previous) =>
+      treePath ??
      computeBreadcrumbState(
-        treeData,
+        null,
        ancestors as IPage[] | undefined,
        currentPage.id,
        previous,
      ),
    );
-  }, [currentPage?.id, treeData, ancestors]);
+  }, [currentPage?.id, treePath, ancestors]);

  const HiddenNodesTooltipContent = () =>
    breadcrumbNodes?.slice(1, -1).map((node) => (
@@ -24,7 +24,7 @@ import { historyAtoms } from "@/features/page-history/atoms/history-atoms.ts";
 import { useDisclosure, useHotkeys } from "@mantine/hooks";
 import { useClipboard } from "@/hooks/use-clipboard";
 import { useParams } from "react-router-dom";
-import { usePageQuery } from "@/features/page/queries/page-query.ts";
+import { usePageMetaQuery } from "@/features/page/queries/page-query.ts";
 import {
  useToggleTemporaryMutation,
  syncTemporaryExpiresInCache,
@@ -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,
@@ -67,7 +67,7 @@ export default function PageHeaderMenu({ readOnly }: PageHeaderMenuProps) {
  const commentsTriggerProps = useAsideTriggerProps("comments");
  const tocTriggerProps = useAsideTriggerProps("toc");
  const { pageSlug } = useParams();
-  const { data: page } = usePageQuery({
+  const { data: page } = usePageMetaQuery({
    pageId: extractPageSlugId(pageSlug),
  });
  const isDeleted = !!page?.deletedAt;
@@ -146,7 +146,7 @@ function PageActionMenu({ readOnly }: PageActionMenuProps) {
  const [, setHistoryModalOpen] = useAtom(historyAtoms);
  const clipboard = useClipboard({ timeout: 500 });
  const { pageSlug, spaceSlug } = useParams();
-  const { data: page, isLoading } = usePageQuery({
+  const { data: page, isLoading } = usePageMetaQuery({
    pageId: extractPageSlugId(pageSlug),
  });
  const { handleDelete } = useTreeMutation(page?.spaceId ?? "");
@@ -199,8 +199,9 @@ function PageActionMenu({ readOnly }: PageActionMenuProps) {

  const handleCopyAsMarkdown = () => {
    if (!pageEditor) return;
-    const html = pageEditor.getHTML();
-    const markdown = htmlToMarkdown(html);
+    // Copy the page as canonical markdown through the shared converter (issue
+    // #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") });
@@ -10,7 +10,7 @@ import { IconClockHour4, IconTrash } from "@tabler/icons-react";
 import { useState } from "react";
 import { Trans, useTranslation } from "react-i18next";
 import { useTimeAgo } from "@/hooks/use-time-ago.tsx";
-import { usePageQuery } from "@/features/page/queries/page-query.ts";
+import { usePageMetaQuery } from "@/features/page/queries/page-query.ts";
 import { useTreeMutation } from "@/features/page/tree/hooks/use-tree-mutation.ts";
 import {
  useToggleTemporaryMutation,
@@ -35,7 +35,7 @@ type TemporaryNoteBannerProps = {
 */
 export function TemporaryNoteBanner({ slugId }: TemporaryNoteBannerProps) {
  const { t } = useTranslation();
-  const { data: page } = usePageQuery({ pageId: slugId });
+  const { data: page } = usePageMetaQuery({ pageId: slugId });
  const { data: space } = useGetSpaceBySlugQuery(page?.space?.slug);
  const spaceAbility = useSpaceAbility(space?.membership?.permissions);
  const expiresTimeAgo = useTimeAgo(page?.temporaryExpiresAt);
@@ -0,0 +1,149 @@
+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). The
+// factory constructs it (QueryClient can't be referenced in vi.hoisted — that
+// runs before imports resolve); we import the SAME mocked instance back to seed
+// and assert on it.
+vi.mock("@/main.tsx", async () => {
+  const { QueryClient } = await import("@tanstack/react-query");
+  return { queryClient: new QueryClient() };
+});
+
+import { queryClient as h_qc } from "@/main.tsx";
+import { invalidateOnUpdatePage } from "./page-query";
+
+const h = { qc: h_qc };
+
+// invalidateOnUpdatePage is the field-only (title/icon) tree path: instead of a
+// blanket invalidate it patches the affected node IN PLACE in every cached embed
+// subtree. The undefined-guard is LOAD-BEARING: a title-only socket event carries
+// icon:undefined, and without the guard `{...p, icon: undefined}` would WIPE the
+// icon in every cached subtree.
+const page = (over: Partial<IPage>): IPage =>
+  ({ id: "p1", title: "Old", icon: "📄", spaceId: "s1" }) as IPage &
+    typeof over as IPage;
+
+describe("invalidateOnUpdatePage — pointwise embed-cache patch", () => {
+  beforeEach(() => {
+    h.qc.clear();
+  });
+
+  it("title-only event updates title but PRESERVES the icon (undefined-guard)", () => {
+    const key = ["page-tree", "parent-1"];
+    h.qc.setQueryData<IPage[]>(key, [
+      { id: "p1", title: "Old", icon: "📄", spaceId: "s1" } as IPage,
+      { id: "p2", title: "Other", icon: "📁", spaceId: "s1" } as IPage,
+    ]);
+
+    // icon passed as undefined (a title-only update)
+    invalidateOnUpdatePage(
+      "s1",
+      "parent-1",
+      "p1",
+      "New Title",
+      undefined as unknown as string,
+    );
+
+    const patched = h.qc.getQueryData<IPage[]>(key)!;
+    const p1 = patched.find((p) => p.id === "p1")!;
+    const p2 = patched.find((p) => p.id === "p2")!;
+    expect(p1.title).toBe("New Title");
+    expect(p1.icon).toBe("📄"); // preserved, not wiped
+    // Sibling node untouched.
+    expect(p2.title).toBe("Other");
+    expect(p2.icon).toBe("📁");
+  });
+
+  it("icon-only event updates icon but preserves the title", () => {
+    const key = ["page-tree", "parent-1"];
+    h.qc.setQueryData<IPage[]>(key, [
+      { id: "p1", title: "Keep", icon: "📄", spaceId: "s1" } as IPage,
+    ]);
+
+    invalidateOnUpdatePage(
+      "s1",
+      "parent-1",
+      "p1",
+      undefined as unknown as string,
+      "🚀",
+    );
+
+    const p1 = h.qc.getQueryData<IPage[]>(key)!.find((p) => p.id === "p1")!;
+    expect(p1.icon).toBe("🚀");
+    expect(p1.title).toBe("Keep");
+  });
+
+  // The sidebar-pages cache (InfiniteData) is patched on the same event. It must
+  // carry the SAME undefined-guard as the embed path above — otherwise a
+  // title-only event's icon:undefined would wipe the sidebar entry's icon.
+  const sidebarKey = ["sidebar-pages", { pageId: "parent-1", spaceId: "s1" }];
+  const seedSidebar = () =>
+    h.qc.setQueryData(sidebarKey, {
+      pageParams: [undefined],
+      pages: [
+        {
+          items: [
+            { id: "p1", title: "Old", icon: "📄", spaceId: "s1" } as IPage,
+            { id: "p2", title: "Other", icon: "📁", spaceId: "s1" } as IPage,
+          ],
+        },
+      ],
+    });
+  const sidebarItem = (id: string) => {
+    const data = h.qc.getQueryData(sidebarKey) as {
+      pages: { items: IPage[] }[];
+    };
+    return data.pages[0].items.find((p) => p.id === id)!;
+  };
+
+  it("sidebar cache: title-only event updates title but PRESERVES the icon", () => {
+    seedSidebar();
+
+    invalidateOnUpdatePage(
+      "s1",
+      "parent-1",
+      "p1",
+      "New Title",
+      undefined as unknown as string,
+    );
+
+    const p1 = sidebarItem("p1");
+    expect(p1.title).toBe("New Title");
+    expect(p1.icon).toBe("📄"); // preserved, not wiped
+    // Sibling untouched.
+    const p2 = sidebarItem("p2");
+    expect(p2.title).toBe("Other");
+    expect(p2.icon).toBe("📁");
+  });
+
+  it("sidebar cache: icon-only event updates icon but PRESERVES the title", () => {
+    seedSidebar();
+
+    invalidateOnUpdatePage(
+      "s1",
+      "parent-1",
+      "p1",
+      undefined as unknown as string,
+      "🚀",
+    );
+
+    const p1 = sidebarItem("p1");
+    expect(p1.icon).toBe("🚀");
+    expect(p1.title).toBe("Old"); // preserved, not wiped
+  });
+
+  it("does not touch a subtree that lacks the updated node", () => {
+    const otherKey = ["page-tree", "unrelated"];
+    const before = [
+      { id: "x1", title: "X", icon: "❌", spaceId: "s1" } as IPage,
+    ];
+    h.qc.setQueryData<IPage[]>(otherKey, before);
+
+    invalidateOnUpdatePage("s1", "parent-1", "p1", "New", "🚀");
+
+    // Same reference back — the subtree without p1 is left as-is.
+    expect(h.qc.getQueryData<IPage[]>(otherKey)).toBe(before);
+  });
+});
@@ -51,6 +51,10 @@ export function usePageQuery(
    queryFn: () => getPageById(pageInput),
    enabled: !!pageInput.pageId,
    staleTime: 5 * 60 * 1000,
+    // Keep the previously-loaded page visible while navigating to a new one
+    // instead of flashing a blank/skeleton frame (the new page's content
+    // streams in when ready). isLoading stays true only for the very first load.
+    placeholderData: keepPreviousData,
  });

  useEffect(() => {
@@ -66,6 +70,61 @@ export function usePageQuery(
  return query;
 }

+/**
+ * A page view that omits the large, frequently-changing `content` field. Every
+ * other field is preserved, so consumers that read only metadata (title, icon,
+ * permissions, id, creator, timestamps, …) keep working unchanged.
+ */
+export type IPageMeta = Omit<IPage, "content">;
+
+function selectPageMeta(page: IPage): IPageMeta {
+  // Drop `content`; react-query's structural sharing (replaceEqualDeep) then
+  // returns the SAME reference whenever the remaining fields are unchanged, so a
+  // pure content churn (typing / debouncedUpdateContent, collab `page.updated`)
+  // no longer changes this slice's identity and its ~13 subscribers don't
+  // re-render on every keystroke wave.
+  const { content: _content, ...meta } = page;
+  return meta as IPageMeta;
+}
+
+/**
+ * Metadata-only variant of {@link usePageQuery}. Shares the SAME query cache
+ * entry (`["pages", pageId]`, full object incl. content), but this hook returns
+ * a stable content-less slice so peripheral subscribers stop re-rendering on
+ * every content update. Use it anywhere the full `content` is not read.
+ */
+export function usePageMetaQuery(
+  pageInput: Partial<IPageInput>,
+): UseQueryResult<IPageMeta, Error> {
+  const query = useQuery({
+    queryKey: ["pages", pageInput.pageId],
+    queryFn: () => getPageById(pageInput),
+    enabled: !!pageInput.pageId,
+    staleTime: 5 * 60 * 1000,
+    select: selectPageMeta,
+    // Match usePageQuery: keep the previous page's metadata visible while
+    // navigating so the periphery (header, breadcrumb, …) doesn't flash blank.
+    placeholderData: keepPreviousData,
+  });
+
+  // Mirror usePageQuery's cross-key alias write so a page fetched by one
+  // identifier is also cached under the other. The cache stores the FULL page
+  // (select only narrows what THIS hook returns), so read the full object back
+  // from the cache and alias THAT — never the content-less slice.
+  useEffect(() => {
+    if (!query.data) return;
+    const full = queryClient.getQueryData<IPage>(["pages", pageInput.pageId]);
+    if (!full) return;
+    if (isValidUuid(pageInput.pageId)) {
+      queryClient.setQueryData(["pages", full.slugId], full);
+    } else {
+      queryClient.setQueryData(["pages", full.id], full);
+    }
+  }, [query.data]);
+
+  return query;
+}
+
 export function useCreatePageMutation() {
  const { t } = useTranslation();
  return useMutation<IPage, Error, Partial<IPageInput>>({
@@ -351,6 +410,12 @@ export function useRecentChangesQuery(spaceId?: string) {
    initialPageParam: undefined as string | undefined,
    getNextPageParam: (lastPage) =>
      lastPage.meta.hasNextPage ? lastPage.meta.nextCursor : undefined,
+    // KEEP refetchOnMount:true (against the global default false): recent-changes
+    // IS invalidated on page create/update/move/delete, but invalidateQueries only
+    // marks an UNMOUNTED query stale — it doesn't refetch it. The widget isn't
+    // always mounted, so an event that lands while it's unmounted leaves it stale,
+    // and the global refetchOnMount:false would not re-fetch on remount. The mount
+    // refetch closes that gap.
    refetchOnMount: true,
  });
 }
@@ -367,6 +432,9 @@ export function useCreatedByQuery(params?: {
    initialPageParam: undefined as string | undefined,
    getNextPageParam: (lastPage) =>
      lastPage.meta.hasNextPage ? lastPage.meta.nextCursor : undefined,
+    // KEEP refetchOnMount:true: the "created-by" key is never invalidated (no
+    // socket/mutation path), so the mount refetch is its ONLY freshness mechanism
+    // — without it the list shows stale cache on navigation.
    refetchOnMount: true,
  });
 }
@@ -380,8 +448,14 @@ export function useDeletedPagesQuery(
    queryFn: () => getDeletedPages(spaceId, params),
    enabled: !!spaceId,
    placeholderData: keepPreviousData,
-    refetchOnMount: true,
    staleTime: 0,
+    // KEEP refetchOnMount:true: ["trash-list"] IS invalidated by the
+    // move-to-trash / delete / restore mutations, but invalidateQueries only marks
+    // an unmounted query stale — it doesn't refetch it. The trash panel isn't
+    // usually mounted when a page is trashed, so on opening it the global
+    // refetchOnMount:false would show a stale list; the mount refetch closes that.
+    // (Do NOT remove the three trash-list invalidations — they are not dead code.)
+    refetchOnMount: true,
  });
 }

@@ -516,7 +590,35 @@ export function invalidateOnUpdatePage(
  title: string,
  icon: string,
 ) {
-  invalidatePageTree();
+  // Scoped page-tree refresh (was a blanket `invalidatePageTree()`): this is the
+  // FIELD-only update path (title/icon — no structural change), and the sidebar
+  // tree is already updated pointwise (applyUpdateOne / optimistic setData) plus
+  // via the sidebar-pages cache below. Invalidating ALL ["page-tree"] queries
+  // here refetched every open recursive subpages-embed block on each
+  // rename/icon-change — pure duplicate work. Instead patch just the affected
+  // node IN PLACE in every cached embed subtree: same visible result, no network
+  // churn, no full embed-tree rebuild. Structural events (create/move/delete)
+  // keep the blanket invalidate in their own helpers.
+  const pageTreeMatches = queryClient.getQueriesData<IPage[]>({
+    queryKey: ["page-tree"],
+  });
+  pageTreeMatches.forEach(([key, items]) => {
+    if (!items || !items.some((p) => p.id === id)) return;
+    queryClient.setQueryData<IPage[]>(key, (old) =>
+      old?.map((p) =>
+        p.id === id
+          ? {
+              ...p,
+              // Guard undefined so a title-only event can't wipe the icon (and
+              // vice versa) in the embed cache.
+              ...(title !== undefined ? { title } : {}),
+              ...(icon !== undefined ? { icon } : {}),
+            }
+          : p,
+      ),
+    );
+  });
+
  let queryKey: QueryKey = null;
  if (parentPageId === null) {
    queryKey = ["root-sidebar-pages", spaceId];
@@ -534,7 +636,14 @@ export function invalidateOnUpdatePage(
          ...page,
          items: page.items.map((sidebarPage: IPage) =>
            sidebarPage.id === id
-              ? { ...sidebarPage, title: title, icon: icon }
+              ? {
+                  ...sidebarPage,
+                  // Guard undefined so a title-only event can't wipe the icon
+                  // (and vice versa) in the sidebar-pages cache — mirrors the
+                  // embed-cache patch above.
+                  ...(title !== undefined ? { title } : {}),
+                  ...(icon !== undefined ? { icon } : {}),
+                }
              : sidebarPage,
          ),
        })),
@@ -7,7 +7,7 @@ import { useRestorePageModal } from "@/features/page/hooks/use-restore-page-moda
 import { useDeletePageModal } from "@/features/page/hooks/use-delete-page-modal.tsx";
 import {
  useDeletePageMutation,
-  usePageQuery,
+  usePageMetaQuery,
  useRestorePageMutation,
 } from "@/features/page/queries/page-query.ts";
 import { getSpaceUrl } from "@/lib/config.ts";
@@ -25,7 +25,7 @@ type DeletedPageBannerProps = {
 export function DeletedPageBanner({ slugId }: DeletedPageBannerProps) {
  const { t } = useTranslation();
  const navigate = useNavigate();
-  const { data: page } = usePageQuery({ pageId: slugId });
+  const { data: page } = usePageMetaQuery({ pageId: slugId });
  const { data: space } = useGetSpaceBySlugQuery(page?.space?.slug);
  const spaceAbility = useSpaceAbility(space?.membership?.permissions);
  const deletedTimeAgo = useTimeAgo(page?.deletedAt);
@@ -1,4 +1,4 @@
-import { useAtom } from "jotai";
+import { useSetAtom, useStore } from "jotai";
 import { useTranslation } from "react-i18next";
 import { useParams } from "react-router-dom";
 import { ActionIcon, Menu, rem } from "@mantine/core";
@@ -52,7 +52,11 @@ export function NodeMenu({ node, canEdit }: NodeMenuProps) {
  const clipboard = useClipboard({ timeout: 500 });
  const { spaceSlug } = useParams();
  const { handleDelete } = useTreeMutation(node.spaceId);
-  const [data, setData] = useAtom(treeDataAtom);
+  // Setter-only: the tree value is read only imperatively inside the duplicate
+  // handler (via `store` below), never at render, so useSetAtom avoids
+  // re-rendering every row's NodeMenu on any tree event.
+  const setData = useSetAtom(treeDataAtom);
+  const store = useStore();
  const emit = useQueryEmit();
  const [exportOpened, { open: openExportModal, close: closeExportModal }] =
    useDisclosure(false);
@@ -125,8 +129,8 @@ export function NodeMenu({ node, canEdit }: NodeMenuProps) {
    try {
      const duplicatedPage = await duplicatePage({ pageId: node.id });

-      // figure out parent + insertion index
-      const siblings = treeModel.siblingsOf(data, node.id);
+      // figure out parent + insertion index (read the live tree imperatively)
+      const siblings = treeModel.siblingsOf(store.get(treeDataAtom), node.id);
      const parentId = siblings?.parentId ?? null;
      const currentIndex = siblings?.index ?? 0;
      const newIndex = currentIndex + 1;
@@ -1,6 +1,6 @@
 import { useRef } from "react";
 import { Link, useParams } from "react-router-dom";
-import { useAtom } from "jotai";
+import { useAtom, useSetAtom } from "jotai";
 import { useTranslation } from "react-i18next";
 import { ActionIcon, rem, Tooltip } from "@mantine/core";
 import {
@@ -51,7 +51,11 @@ export function SpaceTreeRow({
  const { t } = useTranslation();
  const { spaceSlug } = useParams();
  const updatePageMutation = useUpdatePageMutation();
-  const [, setTreeData] = useAtom(treeDataAtom);
+  // Setter-only: subscribing to the whole treeDataAtom (via useAtom) re-rendered
+  // every virtualized row on any tree event, bypassing the DocTreeRow memo. This
+  // row never reads the tree value, only writes it, so useSetAtom avoids the
+  // value subscription.
+  const setTreeData = useSetAtom(treeDataAtom);
  const emit = useQueryEmit();
  const timerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
  const [mobileSidebarOpened] = useAtom(mobileSidebarAtom);
@@ -35,6 +35,7 @@ vi.mock("@/features/page/queries/page-query.ts", () => ({
    isFetching: false,
  }),
  usePageQuery: () => ({ data: undefined }),
+  usePageMetaQuery: () => ({ data: undefined }),
  fetchAllAncestorChildren: (...args: unknown[]) =>
    fetchAllAncestorChildrenMock(...args),
 }));
@@ -26,6 +26,7 @@ vi.mock("@/features/page/queries/page-query.ts", () => ({
    isFetching: false,
  }),
  usePageQuery: () => ({ data: undefined }),
+  usePageMetaQuery: () => ({ data: undefined }),
  fetchAllAncestorChildren: vi.fn(),
 }));

@@ -15,7 +15,7 @@ import { notifications } from "@mantine/notifications";
 import {
  fetchAllAncestorChildren,
  useGetRootSidebarPagesQuery,
-  usePageQuery,
+  usePageMetaQuery,
 } from "@/features/page/queries/page-query.ts";
 import classes from "@/features/page/tree/styles/tree.module.css";
 import { treeDataAtom } from "@/features/page/tree/atoms/tree-data-atom.ts";
@@ -76,7 +76,7 @@ const SpaceTree = forwardRef<SpaceTreeApi, SpaceTreeProps>(function SpaceTree(
  const [isDataLoaded, setIsDataLoaded] = useState(false);
  const spaceIdRef = useRef(spaceId);
  spaceIdRef.current = spaceId;
-  const { data: currentPage } = usePageQuery({
+  const { data: currentPage } = usePageMetaQuery({
    pageId: extractPageSlugId(pageSlug),
  });

@@ -1,5 +1,5 @@
 import { useCallback } from "react";
-import { useAtom, useSetAtom, useStore } from "jotai";
+import { useSetAtom, useStore } from "jotai";
 import { notifications } from "@mantine/notifications";
 import { useTranslation } from "react-i18next";
 import { useNavigate, useParams } from "react-router-dom";
@@ -34,7 +34,10 @@ export type UseTreeMutation = {

 export function useTreeMutation(spaceId: string): UseTreeMutation {
  const { t } = useTranslation();
-  const [, setData] = useAtom(treeDataAtom);
+  // Setter-only: this hook never reads the tree reactively (handlers read the
+  // live value imperatively via `store` below), so useSetAtom avoids
+  // re-rendering SpaceSidebar on every tree event.
+  const setData = useSetAtom(treeDataAtom);
  // `store` reads the *current* treeDataAtom imperatively in handlers — avoids
  // stale-closure issues when the caller updates the tree (e.g. lazy-load
  // children) and then immediately invokes a handler.
@@ -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).
@@ -1,10 +1,20 @@
+import { Suspense } from "react";
 import { Outlet } from "react-router-dom";
+import { Center, Loader } from "@mantine/core";
 import ShareShell from "@/features/share/components/share-shell.tsx";

 export default function ShareLayout() {
  return (
    <ShareShell>
-      <Outlet />
+      <Suspense
+        fallback={
+          <Center h="60vh">
+            <Loader size="sm" />
+          </Center>
+        }
+      >
+        <Outlet />
+      </Suspense>
    </ShareShell>
  );
 }
@@ -28,6 +28,7 @@ vi.mock("@/features/share/queries/share-query.ts", () => ({

 vi.mock("@/features/page/queries/page-query.ts", () => ({
  usePageQuery: () => ({ data: { id: "page-1", title: "Doc" } }),
+  usePageMetaQuery: () => ({ data: { id: "page-1", title: "Doc" } }),
 }));

 vi.mock("@/features/space/queries/space-query.ts", () => ({
@@ -20,7 +20,7 @@ import {
 import { Link, useParams } from "react-router-dom";
 import { extractPageSlugId, getPageIcon } from "@/lib";
 import { useTranslation } from "react-i18next";
-import { usePageQuery } from "@/features/page/queries/page-query.ts";
+import { usePageMetaQuery } from "@/features/page/queries/page-query.ts";
 import CopyTextButton from "@/components/common/copy.tsx";
 import { getAppUrl } from "@/lib/config.ts";
 import { buildPageUrl } from "@/features/page/page.utils.ts";
@@ -37,7 +37,7 @@ export default function ShareModal({ readOnly }: ShareModalProps) {
  const { t } = useTranslation();
  const { pageSlug } = useParams();
  const pageSlugId = extractPageSlugId(pageSlug);
-  const { data: page } = usePageQuery({ pageId: pageSlugId });
+  const { data: page } = usePageMetaQuery({ pageId: pageSlugId });
  const pageId = page?.id;
  const { data: share } = useShareForPageQuery(pageId);
  const { spaceSlug } = useParams();
@@ -38,6 +38,11 @@ export function useGetSpacesQuery(
    queryKey: ["spaces", params],
    queryFn: () => getSpaces(params),
    placeholderData: keepPreviousData,
+    // KEEP refetchOnMount:true (against the global default false): the ["spaces"]
+    // key is invalidated only by same-tab mutations (no socket path), so a
+    // cross-actor change — an admin adding/removing THIS user from a space — has
+    // no local mutation or socket event and would leave the space list stale until
+    // a hard reload. The mount refetch is its only cross-actor freshness path.
    refetchOnMount: true,
  });
 }
@@ -16,7 +16,6 @@ export function useWatchedSpaceIds(): Set<string> {
  const { data } = useQuery({
    queryKey: [WATCHED_SPACE_IDS_KEY],
    queryFn: () => getWatchedSpaceIds(),
-    refetchOnMount: true,
  });

  const items = data?.items;
@@ -19,7 +19,11 @@ export const useQuerySubscription = () => {
  const [socket] = useAtom(socketAtom);

  React.useEffect(() => {
-    socket?.on("message", (event) => {
+    if (!socket) return;
+    // Named handler + off() cleanup (mirrors use-notification-socket). Without
+    // cleanup, every socket recreation / effect re-run stacked another listener,
+    // so a single broadcast fired duplicated invalidateQueries / setQueryData.
+    const handleMessage = (event) => {
      const data: WebSocketEvent = event;

      let entity = null;
@@ -163,6 +167,11 @@ export const useQuerySubscription = () => {
          });
          break;
      }
-    });
+    };
+
+    socket.on("message", handleMessage);
+    return () => {
+      socket.off("message", handleMessage);
+    };
  }, [queryClient, socket]);
 };
@@ -1,6 +1,6 @@
 import { useEffect } from "react";
 import { socketAtom } from "@/features/websocket/atoms/socket-atom.ts";
-import { useAtom } from "jotai";
+import { useAtom, useSetAtom } from "jotai";
 import { treeDataAtom } from "@/features/page/tree/atoms/tree-data-atom.ts";
 import { WebSocketEvent } from "@/features/websocket/types";
 import { SpaceTreeNode } from "@/features/page/tree/types.ts";
@@ -16,7 +16,10 @@ import localEmitter from "@/lib/local-emitter.ts";

 export const useTreeSocket = () => {
  const [socket] = useAtom(socketAtom);
-  const [, setTreeData] = useAtom(treeDataAtom);
+  // Setter-only: this hook writes the tree from socket events but never reads it
+  // reactively, so useSetAtom avoids re-rendering UserProvider (its host) on
+  // every tree event.
+  const setTreeData = useSetAtom(treeDataAtom);
  const queryClient = useQueryClient();

  useEffect(() => {
@@ -37,7 +40,11 @@ export const useTreeSocket = () => {
  }, []);

  useEffect(() => {
-    socket?.on("message", (event: WebSocketEvent) => {
+    if (!socket) return;
+    // Named handler + off() cleanup (mirrors use-notification-socket). Without
+    // cleanup, every socket recreation / effect re-run stacked another listener,
+    // so a single broadcast fired duplicated tree walks after each reconnect.
+    const handleMessage = (event: WebSocketEvent) => {
      switch (event.operation) {
        case "updateOne":
          if (event.entity[0] === "pages") {
@@ -64,6 +71,11 @@ export const useTreeSocket = () => {
          });
          break;
      }
-    });
-  }, [socket]);
+    };
+
+    socket.on("message", handleMessage);
+    return () => {
+      socket.off("message", handleMessage);
+    };
+  }, [socket, queryClient, setTreeData]);
 };
@@ -243,6 +243,5 @@ export function useAppVersion(
    queryFn: () => getAppVersion(),
    staleTime: 60 * 60 * 1000, // 1 hr
    enabled: isEnabled,
-    refetchOnMount: true,
  });
 }
@@ -1,7 +1,7 @@
 // Source: https://github.com/mantinedev/mantine/blob/master/packages/@mantine/hooks/src/use-clipboard/use-clipboard.ts
 // polyfilled to support execCommand fallback
 import { useState } from "react";
-import { execCommandCopy } from "@docmost/editor-ext";
+import { execCommandCopy } from "@/lib/copy-to-clipboard.ts";

 export type UseClipboardOptions = {
  timeout?: number;
@@ -1,7 +1,7 @@
 import bytes from "bytes";
 import { castToBoolean } from "@/lib/utils.tsx";
 import { AvatarIconType } from "@/features/attachments/types/attachment.types.ts";
-import { sanitizeUrl } from "@docmost/editor-ext";
+import { sanitizeUrl } from "@/lib/sanitize-url.ts";

 declare global {
  interface Window {
--- a/Show More
+++ b/Show More