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

Reviewed-on: #532
docs(page-tree): correct isUnloadedBranch comment — no DnD-guard consumer (#525 review)
2026-07-12 05:08:42 +03:00 · 2026-07-12 04:13:49 +03:00 · 2026-07-12 01:15:02 +03:00 · 2026-07-12 01:06:42 +03:00
59 changed files with 1136 additions and 4056 deletions
@@ -302,16 +302,6 @@ 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,
@@ -135,13 +135,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
  new resync path re-reads the live anchor so the suggestion applies against the
  current text, and orphaned anchors (whose marked run was deleted) are
  reconciled rather than left blocking. (#496)
- **Save intentional page versions.** Press `Cmd/Ctrl+S` (or use the page menu)
-  to save a named version of a page. The history panel now distinguishes
-  intentional versions (a "Saved" / "Agent version" badge) from automatic
-  snapshots, dims autosaves, and offers an "Only versions" filter. Automatic
-  snapshots switched from a fixed interval to a trailing idle-flush with a
-  max-wait ceiling, and a boundary snapshot is pinned whenever the editing source
-  changes (e.g. a person's edits followed by the AI agent). (#370)

 - **Place several images side by side in a row.** A new "Inline (side by
  side)" alignment mode in the image bubble menu renders consecutive inline
@@ -206,137 +206,6 @@ start the new migrations apply on top of your existing schema (`CREATE EXTENSION
  existing pages are indexed on their next edit. pgvector is still required for the migration to
  apply at all.

-## Local embeddings server
-
-The AI agent's semantic (RAG) search needs an **embeddings model**. Instead of paying a cloud
-provider (e.g. OpenAI `text-embedding-3-*`) to embed every page, you can run a small open-weights
-model yourself with Hugging Face
-[Text Embeddings Inference](https://github.com/huggingface/text-embeddings-inference) (TEI), which
-serves an OpenAI-compatible `/v1/embeddings` endpoint. `intfloat/multilingual-e5-small` is a good
-default: multilingual, 384-dim, and comfortable on CPU (~1–2 GB RAM, 1–2 vCPU). Point Gitmost at it
-under **Workspace settings → AI → Embeddings**.
-
-### Option A — local (same Docker network as Gitmost)
-
-Run TEI as a container on the network Gitmost is already on. The port is never published, so the
-endpoint stays internal and needs no authentication.
-
-```yaml
-services:
-  embeddings:
-    image: ghcr.io/huggingface/text-embeddings-inference:cpu-1.9   # pin version; use a cuda-* tag for GPU
-    container_name: embeddings
-    restart: unless-stopped
-    networks:
-      - gitmost_net          # same network Gitmost is on
-    command:
-      - "--model-id"
-      - "intfloat/multilingual-e5-small"
-      - "--auto-truncate"    # clamp over-long inputs instead of returning 413
-    volumes:
-      - tei-models:/data     # weights are downloaded once and cached here
-
-networks:
-  gitmost_net:
-    external: true           # the network Gitmost already uses
-
-volumes:
-  tei-models:
-```
-
-Gitmost settings (**Workspace settings → AI → Embeddings**):
-
-| Field             | Value                             |
-|-------------------|-----------------------------------|
-| Model             | `intfloat/multilingual-e5-small`  |
-| Base URL          | `http://embeddings:80/v1/`        |
-| Embedding API key | — (leave empty)                   |
-
-> `embeddings` is the container name — Gitmost resolves it over DNS inside the Docker network.
-> The port is not published, so the endpoint is reachable only by containers on that network and
-> no authorization is required.
-
-### Option B — separate host (public via Traefik + Let's Encrypt)
-
-This assumes the host already runs Traefik with an ACME resolver (the example below uses
-`letsEncrypt`, the `websecure` entrypoint and a shared `docker_main_net` network). Replace the
-domain / network / resolver with your own.
-
-**DNS:** add an A record `embeddings.example.com` → the IP of your Traefik host (same
-challenge / port 80 as the rest of your sites).
-
-```yaml
-services:
-  embeddings:
-    image: ghcr.io/huggingface/text-embeddings-inference:cpu-1.9   # pin version; cuda-* tag for GPU
-    container_name: embeddings
-    restart: unless-stopped
-    networks:
-      - docker_main_net      # the network Traefik is attached to
-    command:
-      - "--model-id"
-      - "intfloat/multilingual-e5-small"
-      - "--auto-truncate"
-      - "--api-key"
-      - "sk-emb-REPLACE_WITH_YOUR_KEY"
-    volumes:
-      - tei-models:/data
-    labels:
-      traefik.enable: "true"
-      traefik.http.routers.embeddings.rule: "Host(`embeddings.example.com`)"
-      traefik.http.routers.embeddings.entrypoints: "websecure"
-      traefik.http.routers.embeddings.tls: "true"
-      traefik.http.routers.embeddings.tls.certresolver: "letsEncrypt"
-      traefik.http.routers.embeddings.service: "embeddings"
-      traefik.http.services.embeddings.loadbalancer.server.port: "80"
-      # TEI enforces the Bearer key itself; Traefik only rate-limits to protect the CPU
-      traefik.http.routers.embeddings.middlewares: "embeddings-rl"
-      traefik.http.middlewares.embeddings-rl.ratelimit.average: "20"
-      traefik.http.middlewares.embeddings-rl.ratelimit.burst: "40"
-      traefik.http.middlewares.embeddings-rl.ratelimit.period: "1s"
-
-networks:
-  docker_main_net:
-    external: true
-
-volumes:
-  tei-models:
-```
-
-Gitmost settings (**Workspace settings → AI → Embeddings**):
-
-| Field             | Value                                 |
-|-------------------|---------------------------------------|
-| Model             | `intfloat/multilingual-e5-small`      |
-| Base URL          | `https://embeddings.example.com/v1/`  |
-| Embedding API key | your `sk-emb-…`                       |
-
-Check it from outside:
-
-```bash
-curl -s https://embeddings.example.com/v1/embeddings \
-  -H "Authorization: Bearer sk-emb-REPLACE_WITH_YOUR_KEY" \
-  -H "Content-Type: application/json" \
-  -d '{"model":"intfloat/multilingual-e5-small","input":"query: hello"}' \
-  | python3 -c 'import sys,json;print("dims:",len(json.load(sys.stdin)["data"][0]["embedding"]))'
-# -> dims: 384
-```
-
-### Embeddings server notes
-
- **Vector dimension is 384.** If this Gitmost was previously embedded with a different model
-  (e.g. `text-embedding-3-large` = 3072-dim), the old pgvector rows won't match the new dimension —
-  clear the existing embeddings / re-index before switching. Gitmost only compares vectors of the
-  same dimension, so mixed-dimension rows are silently ignored rather than searched.
- **First start downloads the weights** (hundreds of MB) from `huggingface.co` into the
-  `tei-models` volume; every start after that reads from the volume.
- **Pin the version.** Pin the image, and optionally the model: add `--revision <commit-sha>` to
-  `command` (the sha is on the model's page on Hugging Face).
- **Air-gapped / no egress:** seed the `tei-models` volume ahead of time and add
-  `environment: [HF_HUB_OFFLINE=1]`.
- **GPU:** use the cuda tag of the same release (e.g.
-  `ghcr.io/huggingface/text-embeddings-inference:cuda-1.9`) and start the container with `gpus: all`.
-
 ## Features

 - Real-time collaboration
@@ -193,137 +193,6 @@ dump/restore, существующий каталог данных переис
 > неизменным и бэкапьте вместе с базой данных.


-## Локальный сервер эмбеддингов
-
-Семантическому (RAG) поиску AI-агента нужна **модель эмбеддингов**. Вместо оплаты облачного
-провайдера (например, OpenAI `text-embedding-3-*`) за эмбеддинг каждой страницы можно запустить
-небольшую open-weights модель у себя через Hugging Face
-[Text Embeddings Inference](https://github.com/huggingface/text-embeddings-inference) (TEI) — он
-отдаёт OpenAI-совместимый эндпоинт `/v1/embeddings`. Хороший дефолт — `intfloat/multilingual-e5-small`:
-многоязычная, 384-мерная, комфортно работает на CPU (~1–2 ГБ RAM, 1–2 vCPU). Пропишите её в
-**Настройки воркспейса → AI → Эмбеддинги**.
-
-### Вариант A — локально (та же Docker-сеть, что и Gitmost)
-
-Запустите TEI контейнером в той же сети, где уже работает Gitmost. Порт наружу не публикуется,
-поэтому эндпоинт остаётся внутренним и не требует авторизации.
-
-```yaml
-services:
-  embeddings:
-    image: ghcr.io/huggingface/text-embeddings-inference:cpu-1.9   # pin version; use a cuda-* tag for GPU
-    container_name: embeddings
-    restart: unless-stopped
-    networks:
-      - gitmost_net          # same network Gitmost is on
-    command:
-      - "--model-id"
-      - "intfloat/multilingual-e5-small"
-      - "--auto-truncate"    # clamp over-long inputs instead of returning 413
-    volumes:
-      - tei-models:/data     # weights are downloaded once and cached here
-
-networks:
-  gitmost_net:
-    external: true           # the network Gitmost already uses
-
-volumes:
-  tei-models:
-```
-
-Настройки Gitmost (**Настройки воркспейса → AI → Эмбеддинги**):
-
-| Поле              | Значение                          |
-|-------------------|-----------------------------------|
-| Model             | `intfloat/multilingual-e5-small`  |
-| Base URL          | `http://embeddings:80/v1/`        |
-| Embedding API key | — (оставить пустым)               |
-
-> `embeddings` — имя контейнера, Gitmost резолвит его по DNS внутри Docker-сети.
-> Наружу порт не публикуется, эндпоинт доступен только контейнерам этой сети, поэтому
-> авторизация не нужна.
-
-### Вариант B — на отдельном хосте (наружу через Traefik + Let's Encrypt)
-
-Предполагается, что на хосте уже есть Traefik с ACME-резолвером (в примере ниже — `letsEncrypt`,
-entrypoint `websecure`, общая сеть `docker_main_net`). Замените домен / сеть / резолвер на свои.
-
-**DNS:** заведите A-запись `embeddings.example.com` → IP хоста с Traefik (тот же challenge / порт 80,
-что и у остальных сайтов).
-
-```yaml
-services:
-  embeddings:
-    image: ghcr.io/huggingface/text-embeddings-inference:cpu-1.9   # pin version; cuda-* tag for GPU
-    container_name: embeddings
-    restart: unless-stopped
-    networks:
-      - docker_main_net      # the network Traefik is attached to
-    command:
-      - "--model-id"
-      - "intfloat/multilingual-e5-small"
-      - "--auto-truncate"
-      - "--api-key"
-      - "sk-emb-REPLACE_WITH_YOUR_KEY"
-    volumes:
-      - tei-models:/data
-    labels:
-      traefik.enable: "true"
-      traefik.http.routers.embeddings.rule: "Host(`embeddings.example.com`)"
-      traefik.http.routers.embeddings.entrypoints: "websecure"
-      traefik.http.routers.embeddings.tls: "true"
-      traefik.http.routers.embeddings.tls.certresolver: "letsEncrypt"
-      traefik.http.routers.embeddings.service: "embeddings"
-      traefik.http.services.embeddings.loadbalancer.server.port: "80"
-      # TEI enforces the Bearer key itself; Traefik only rate-limits to protect the CPU
-      traefik.http.routers.embeddings.middlewares: "embeddings-rl"
-      traefik.http.middlewares.embeddings-rl.ratelimit.average: "20"
-      traefik.http.middlewares.embeddings-rl.ratelimit.burst: "40"
-      traefik.http.middlewares.embeddings-rl.ratelimit.period: "1s"
-
-networks:
-  docker_main_net:
-    external: true
-
-volumes:
-  tei-models:
-```
-
-Настройки Gitmost (**Настройки воркспейса → AI → Эмбеддинги**):
-
-| Поле              | Значение                              |
-|-------------------|---------------------------------------|
-| Model             | `intfloat/multilingual-e5-small`      |
-| Base URL          | `https://embeddings.example.com/v1/`  |
-| Embedding API key | ваш `sk-emb-…`                        |
-
-Проверка снаружи:
-
-```bash
-curl -s https://embeddings.example.com/v1/embeddings \
-  -H "Authorization: Bearer sk-emb-REPLACE_WITH_YOUR_KEY" \
-  -H "Content-Type: application/json" \
-  -d '{"model":"intfloat/multilingual-e5-small","input":"query: hello"}' \
-  | python3 -c 'import sys,json;print("dims:",len(json.load(sys.stdin)["data"][0]["embedding"]))'
-# -> dims: 384
-```
-
-### Заметки про сервер эмбеддингов
-
- **Размерность вектора — 384.** Если раньше этот Gitmost эмбеддился другой моделью
-  (например, `text-embedding-3-large` = 3072-dim), старые строки в pgvector не совпадут по
-  размерности — очистите существующие эмбеддинги / переиндексируйте перед переключением. Gitmost
-  сравнивает только вектора одной размерности, поэтому строки другой размерности не участвуют в
-  поиске, а не ломают его.
- **Первый старт тянет веса** (сотни МБ) с `huggingface.co` в том `tei-models`; дальше — из тома.
- **Пин версии.** Пиньте образ, а при желании и модель: добавьте в `command` `--revision <commit-sha>`
-  (sha берётся со страницы модели на Hugging Face).
- **Без egress (air-gapped):** засейте том `tei-models` заранее и добавьте
-  `environment: [HF_HUB_OFFLINE=1]`.
- **GPU:** возьмите cuda-тег того же релиза (например,
-  `ghcr.io/huggingface/text-embeddings-inference:cuda-1.9`) и запустите контейнер с `gpus: all`.
-
-
 ## Возможности

 - Совместная работа в реальном времени
@@ -1418,14 +1418,5 @@
  "The commented text changed since this suggestion was made; it was not applied.": "The commented text changed since this suggestion was made; it was not applied.",
  "Dismiss": "Dismiss",
  "Suggestion dismissed": "Suggestion dismissed",
-  "Failed to dismiss suggestion": "Failed to dismiss suggestion",
-  "Save version": "Save version",
-  "Ctrl+S": "Ctrl+S",
-  "Version saved": "Version saved",
-  "Already saved as the latest version": "Already saved as the latest version",
-  "Agent version": "Agent version",
-  "Boundary": "Boundary",
-  "Autosave": "Autosave",
-  "Only versions": "Only versions",
-  "No saved versions yet.": "No saved versions yet."
+  "Failed to dismiss suggestion": "Failed to dismiss suggestion"
 }
@@ -1433,14 +1433,5 @@
  "The commented text changed since this suggestion was made; it was not applied.": "Прокомментированный текст изменился после создания предложения; оно не было применено.",
  "Dismiss": "Не применять",
  "Suggestion dismissed": "Предложение отклонено",
-  "Failed to dismiss suggestion": "Не удалось отклонить предложение",
-  "Save version": "Сохранить версию",
-  "Ctrl+S": "Ctrl+S",
-  "Version saved": "Версия сохранена",
-  "Already saved as the latest version": "Уже сохранено как последняя версия",
-  "Agent version": "Версия агента",
-  "Boundary": "Граница",
-  "Autosave": "Автосейв",
-  "Only versions": "Только версии",
-  "No saved versions yet.": "Пока нет сохранённых версий."
+  "Failed to dismiss suggestion": "Не удалось отклонить предложение"
 }
@@ -58,11 +58,8 @@ 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,
@@ -272,64 +269,17 @@ export default function AiChatWindow() {
  const { data: messageRows, isLoading: messagesLoading } =
    useAiChatMessagesQuery(
      activeChatId ?? undefined,
-      // #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.
+      // DELIBERATELY DUMB: poll every 2.5s WHILE ARMED, otherwise off. NO error
+      // checks (TanStack resets fetchFailureCount each fetch; the poll must survive
+      // a server restart), NO tail checks, NO cap here — the settled/stalled/idle-cap
+      // semantics all live in ChatThread's FSM, which disarms via onResumeFallback.
+      () => (degradedPoll === true ? 2500 : false),
+      // #344: gate on windowOpen too — no message history is fetched (and no
+      // degraded poll runs) while the window is closed; it loads when the window
+      // opens with an active chat.
      windowOpen,
    );

-  // #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
@@ -172,18 +172,9 @@ function resetState() {
  h.state.getRun.mockResolvedValue({ run: null, message: null });
 }

-// #491: the streaming tail carries a persisted step frontier (metadata.stepsPersisted),
-// which the tail-only attach reads as `n` in `?anchor=<id>&n=<n>`. Seeded WHOLE now.
 const streamingTail = () => [
  row("u1", "user", undefined, "hi"),
-  {
-    id: "a1",
-    role: "assistant",
-    content: "partial",
-    status: "streaming",
-    createdAt: "2026-01-01T00:00:00Z",
-    metadata: { stepsPersisted: 2 },
-  } as IAiChatMessageRow,
+  row("a1", "assistant", "streaming", "partial"),
 ];
 const settledTail = () => [
  row("u1", "user", undefined, "hi"),
@@ -344,24 +335,20 @@ describe("ChatThread — send now", () => {
    expect(screen.getAllByLabelText("Remove queued message")).toHaveLength(1);
  });

-  it("Stop then a REAL network-drop finish exits to idle (honor-in-stopping), NOT a false reconnect", async () => {
+  it("Stop then a REAL network-drop finish exits to idle (honor-in-stopping), NOT a false reconnect", () => {
    // Regression for the disconnect-first reorder: on the STOP path, even a drop-
    // form finish { isError:true, isDisconnect:true } arriving in `stopping` must be
    // HONORED (reducer) and exit to idle — it must NOT enter the reconnect ladder.
    startLocalStreamWithRun(); // live local stream, autonomous
    fireEvent.click(screen.getByLabelText("Stop")); // STOP_REQUESTED -> stopping
    h.state.error = { message: "Failed to fetch" };
-    // #491: the disconnect re-seeds from persist (async getRun) before dispatching
-    // FINISH_DISCONNECT, which the reducer HONORS in `stopping` -> idle. Flush it.
-    await act(async () => {
+    act(() => {
      h.state.onFinish?.({
        message: { id: "a1", role: "assistant", parts: [] },
        isAbort: false,
        isDisconnect: true,
        isError: true,
      });
-      await Promise.resolve();
-      await Promise.resolve();
    });
    expect(screen.queryByText(/reconnecting/i)).toBeNull();
  });
@@ -816,24 +803,19 @@ describe("ChatThread — resume (attach) machinery", () => {
    expect(h.state.resumeStream).not.toHaveBeenCalled();
  });

-  it("#491 tail-only: seeds the streaming tail WHOLE (no strip), keeps a user tail whole", () => {
+  it("strips the streaming tail from the seed, keeps a user tail whole", () => {
    renderThread({ autonomousRunsEnabled: true, initialRows: streamingTail() });
-    // MUTATION-VERIFY: re-introduce the seed-strip and this goes red — the streaming
-    // tail (steps 0..N-1) MUST be seeded so the SDK continuation appends the tail to
-    // the RIGHT message. Both rows (user + assistant) are seeded.
-    expect(h.state.seededMessages).toHaveLength(2);
+    expect(h.state.seededMessages).toHaveLength(1);
    cleanup();
    resetState();
    renderThread({ autonomousRunsEnabled: true, initialRows: userTail() });
    expect(h.state.seededMessages).toHaveLength(1);
  });

-  it("#491 tail-only: builds the attach URL with ?anchor=&n= from the persisted step frontier", () => {
+  it("builds the attach URL with expect=live&anchor only for a stripped streaming tail", () => {
    renderThread({ autonomousRunsEnabled: true, initialRows: streamingTail() });
-    // n=2 comes from a1's metadata.stepsPersisted (MUTATION-VERIFY: hardcode n=0 and
-    // this fails). No `expect=live` param anymore.
    expect(h.state.transport!.prepareReconnectToStreamRequest!().api).toBe(
-      "/api/ai-chat/runs/c1/stream?anchor=a1&n=2",
+      "/api/ai-chat/runs/c1/stream?expect=live&anchor=a1",
    );
    cleanup();
    resetState();
@@ -857,41 +839,39 @@ describe("ChatThread — resume (attach) machinery", () => {
    });
  }

-  it("204 on a streaming tail: NO restore (row kept) + invalidate + onResumeFallback(true)", async () => {
+  it("204 on a streaming tail: restore + invalidate + onResumeFallback(true)", async () => {
    const { onResumeFallback, invalidateSpy } = renderThread({
      autonomousRunsEnabled: true,
      initialRows: streamingTail(),
    });
    await attachFetch({ status: 204, ok: false });
-    // #491 tail-only: the anchor row was never stripped, so there is NOTHING to
-    // restore. MUTATION-VERIFY: re-add a restore setMessages here and it goes red.
-    expect(h.state.setMessages).not.toHaveBeenCalled();
+    expect(h.state.setMessages).toHaveBeenCalledTimes(1); // restore
    expect(invalidateSpy).toHaveBeenCalledWith({
      queryKey: ["ai-chat-messages", "c1"],
    });
    expect(onResumeFallback).toHaveBeenCalledWith(true);
  });

-  it("F7 restart-survival: a 500 attach failure arms the poll WITHOUT a restore", async () => {
+  it("F7 restart-survival: a 500 attach failure restores the row AND arms the poll", async () => {
    const { onResumeFallback, invalidateSpy } = renderThread({
      autonomousRunsEnabled: true,
      initialRows: streamingTail(),
    });
    await attachFetch({ status: 500, ok: false });
-    expect(h.state.setMessages).not.toHaveBeenCalled();
+    expect(h.state.setMessages).toHaveBeenCalledTimes(1);
    expect(invalidateSpy).toHaveBeenCalledWith({
      queryKey: ["ai-chat-messages", "c1"],
    });
    expect(onResumeFallback).toHaveBeenCalledWith(true);
  });

-  it("F7 restart-survival: a network throw arms the poll WITHOUT a restore", async () => {
+  it("F7 restart-survival: a network throw restores the row AND arms the poll", async () => {
    const { onResumeFallback, invalidateSpy } = renderThread({
      autonomousRunsEnabled: true,
      initialRows: streamingTail(),
    });
    await attachFetch(new Error("network down"), true);
-    expect(h.state.setMessages).not.toHaveBeenCalled();
+    expect(h.state.setMessages).toHaveBeenCalledTimes(1);
    expect(invalidateSpy).toHaveBeenCalledWith({
      queryKey: ["ai-chat-messages", "c1"],
    });
@@ -951,7 +931,7 @@ describe("ChatThread — resume (attach) machinery", () => {
    expect(h.state.sendMessage).not.toHaveBeenCalled();
  });

-  it("an empty resumed message (starved replay) arms the poll WITHOUT a restore", () => {
+  it("an empty resumed message (starved replay) restores the row AND arms the poll", () => {
    h.state.status = "ready";
    const { onResumeFallback } = renderThread({
      autonomousRunsEnabled: true,
@@ -967,9 +947,7 @@ describe("ChatThread — resume (attach) machinery", () => {
        isError: false,
      });
    });
-    // #491 tail-only: the seeded steps 0..N-1 are still on screen (the SDK
-    // continuation never wiped them), so there is nothing to restore — just poll.
-    expect(h.state.setMessages).not.toHaveBeenCalled();
+    expect(h.state.setMessages).toHaveBeenCalledTimes(1); // restore
    expect(onResumeFallback).toHaveBeenCalledWith(true); // arm
  });

@@ -1017,41 +995,24 @@ describe("ChatThread — live reconnect + stalled", () => {
    cleanup();
  });

-  // #491: the authoritative PERSISTED assistant row `getRun` projects on a local
-  // disconnect — the re-seed source. Its metadata.stepsPersisted becomes `n`.
-  const persistedAnchor = (steps = 3) => ({
-    run: { id: "run-1", status: "running" },
-    message: {
-      id: "a2",
-      role: "assistant",
-      content: "persisted 0..N-1",
-      status: "streaming",
-      createdAt: "2026-01-01T00:00:00Z",
-      metadata: { stepsPersisted: steps },
-    },
-  });
-
  // A REAL live SSE drop. ai@6.0.207 emits BOTH { isError:true, isDisconnect:true }
-  // for a network TypeError AND sets useChat `error`. #491: an autonomous local drop
-  // now RE-SEEDS from persist (async getRun) BEFORE entering the reconnect ladder, so
-  // this helper is async and flushes the getRun microtask before returning.
-  async function disconnect(message: unknown = liveMsg) {
+  // for a network TypeError AND sets useChat `error` — NOT the { isError:false,
+  // error:null } form the old tests fed. This is the form browser QA hit; with the
+  // buggy isError-first routing OR without the errorView render-gate these tests go
+  // red (a real drop surfaces the terminal error banner, masking the reconnect
+  // ladder). MUTATION-VERIFY of disconnect-first + the errorView phase-gate.
+  function disconnect(message: unknown = liveMsg) {
    h.state.error = { message: "Failed to fetch" }; // the SDK sets error on the drop
-    await act(async () => {
+    act(() => {
      h.state.onFinish?.({
        message,
        isAbort: false,
        isDisconnect: true,
        isError: true,
      });
-      // Flush the getRun().then re-seed + the deferred FINISH_DISCONNECT dispatch.
-      await Promise.resolve();
-      await Promise.resolve();
    });
  }
  function renderLive() {
-    // The persisted-anchor read the local disconnect performs to re-seed from persist.
-    h.state.getRun.mockResolvedValue(persistedAnchor());
    const view = renderThread({
      autonomousRunsEnabled: true,
      initialRows: settledTail(),
@@ -1071,80 +1032,35 @@ describe("ChatThread — live reconnect + stalled", () => {
    });
  }

-  it("#491: a live disconnect RE-SEEDS from persist, then backs off to reconnect with ?anchor=&n=", async () => {
+  it("a live disconnect starts a backoff reconnect (banner + resumeStream after backoff)", () => {
    renderLive();
-    await disconnect();
-    // The re-seed read the authoritative persisted row and replaced the live partial.
-    // MUTATION-VERIFY: skip the getRun re-seed (send `n` off the live message) and the
-    // n below no longer matches the PERSISTED stepsPersisted.
-    expect(h.state.getRun).toHaveBeenCalledWith("c1");
-    expect(h.state.setMessages).toHaveBeenCalled(); // re-seeded the store from persist
+    disconnect();
    expect(screen.getByText(/reconnecting/i)).toBeTruthy();
    expect(h.state.resumeStream).not.toHaveBeenCalled();
    advanceToAttempt(1);
    expect(h.state.resumeStream).toHaveBeenCalledTimes(1);
-    // n=3 is the PERSISTED row's stepsPersisted (from getRun), NOT the live store.
    expect(h.state.transport!.prepareReconnectToStreamRequest!().api).toBe(
-      "/api/ai-chat/runs/c1/stream?anchor=a2&n=3",
+      "/api/ai-chat/runs/c1/stream?expect=live&anchor=a2",
    );
  });

-  it("#491 regression (#137/#161 dup): getRun REJECT on a live disconnect drops the live partial + nulls the anchor", async () => {
-    // The re-seed source (getRun) FAILS — a flaky-network blip (SSE + getRun both
-    // fail, network recovers in ~1s). The OLD .catch just re-entered the ladder with
-    // NO re-seed and NO filter, so the reconnect could tail-apply the registry's
-    // frames onto the live partial that ALREADY has those steps -> duplicated text.
-    renderLive();
-    h.state.getRun.mockReset();
-    h.state.getRun.mockRejectedValue(new Error("network"));
-    await disconnect(); // live partial = liveMsg (id "a2")
-    expect(h.state.getRun).toHaveBeenCalledWith("c1");
-    // THE GUARANTEE: on the getRun failure the live partial (a2) is FILTERED from the
-    // store, so the reconnect can never tail-apply already-present steps onto it.
-    // MUTATION-VERIFY: revert the .catch fix (enterReconnect only, no filter) and no
-    // setMessages call removes a2 -> this reddens.
-    const removedLivePartial = (
-      h.state.setMessages as unknown as {
-        mock: { calls: [unknown][] };
-      }
-    ).mock.calls.some(([updater]) => {
-      if (typeof updater !== "function") return false;
-      const out = (updater as (p: { id: string }[]) => { id: string }[])([
-        { id: "a2" },
-        { id: "u1" },
-      ]);
-      return !out.some((m) => m.id === "a2");
-    });
-    expect(removedLivePartial).toBe(true);
-    expect(screen.getByText(/reconnecting/i)).toBeTruthy();
-    advanceToAttempt(1);
-    expect(h.state.resumeStream).toHaveBeenCalledTimes(1);
-    // Anchor was nulled -> replay-from-start (no params) / 204 -> poll; never a stale
-    // ?anchor=&n= over the live partial.
-    expect(h.state.transport!.prepareReconnectToStreamRequest!().api).toBe(
-      "/api/ai-chat/runs/c1/stream",
-    );
-  });
-
-  it("#488 (browser QA): the reconnect banner is SHOWN, not masked by the residual useChat error", async () => {
+  it("#488 (browser QA): the reconnect banner is SHOWN, not masked by the residual useChat error", () => {
    // The drop sets useChat `error` (real SDK), and the terminal errorView describes
    // it ("Lost connection to the server"). The FSM phase-gate must let the
    // `reconnecting` banner WIN over that residual error. MUTATION-VERIFY: revert the
    // errorView phase-gate (show errorView whenever error is set) and the terminal
    // banner masks "reconnecting…" -> red.
    renderLive();
-    await disconnect();
+    disconnect();
    expect(h.state.error).not.toBeNull(); // the SDK error IS set during recovery
    expect(screen.getByText(/reconnecting/i)).toBeTruthy();
    // The terminal "Lost connection… reload" banner must NOT be showing.
    expect(screen.queryByText(/reload and try again/i)).toBeNull();
  });

-  it("#488 commit 2: a disconnect BEFORE the first assistant frame reconnects with NO anchor", async () => {
+  it("#488 commit 2: a disconnect BEFORE the first assistant frame reconnects with NO anchor", () => {
    renderLive();
-    // No persisted assistant row for a pre-first-frame break -> no anchor.
-    h.state.getRun.mockResolvedValue({ run: null, message: null });
-    await disconnect(null); // no assistant message yet (pre-first-frame break)
+    disconnect(null); // no assistant message yet (pre-first-frame break)
    expect(screen.getByText(/reconnecting/i)).toBeTruthy();
    expect(
      screen.queryByText("Connection lost — the answer was interrupted."),
@@ -1158,7 +1074,7 @@ describe("ChatThread — live reconnect + stalled", () => {

  it("a live re-attach (2xx) clears the reconnect banner", async () => {
    renderLive();
-    await disconnect();
+    disconnect();
    advanceToAttempt(1);
    await reconnect({ status: 200, ok: true });
    expect(screen.queryByText(/reconnecting/i)).toBeNull();
@@ -1166,7 +1082,7 @@ describe("ChatThread — live reconnect + stalled", () => {

  it("a 204 arms the degraded poll and backs off to the next attempt", async () => {
    const { onResumeFallback } = renderLive();
-    await disconnect();
+    disconnect();
    advanceToAttempt(1);
    expect(h.state.resumeStream).toHaveBeenCalledTimes(1);
    await reconnect({ status: 204, ok: false });
@@ -1178,7 +1094,7 @@ describe("ChatThread — live reconnect + stalled", () => {

  it("exhausts the attempt limit into a manual Retry, which restarts the sequence", async () => {
    renderLive();
-    await disconnect();
+    disconnect();
    for (let n = 1; n <= 5; n++) {
      advanceToAttempt(n);
      expect(h.state.resumeStream).toHaveBeenCalledTimes(n);
@@ -1196,23 +1112,22 @@ describe("ChatThread — live reconnect + stalled", () => {
  it("#488 commit 3: two breaks in a row produce two reconnect cycles", async () => {
    renderLive();
    // First break -> reconnect -> re-attach live.
-    await disconnect();
+    disconnect();
    advanceToAttempt(1);
    expect(h.state.resumeStream).toHaveBeenCalledTimes(1);
    await reconnect({ status: 200, ok: true });
    expect(screen.queryByText(/reconnecting/i)).toBeNull();
-    // The re-attached observer (live-follow) stream drops AGAIN -> a SECOND reconnect
-    // cycle. #491: this too re-seeds from persist before re-attaching (never tail-
-    // applies over the live-follow partial).
-    await disconnect();
+    // The re-attached observer stream drops AGAIN -> a SECOND reconnect cycle
+    // (the old one-shot !wasResumed gate sent this to silent poll).
+    disconnect();
    expect(screen.getByText(/reconnecting/i)).toBeTruthy();
    advanceToAttempt(1);
    expect(h.state.resumeStream).toHaveBeenCalledTimes(2);
  });

-  it("does NOT reconnect when autonomous runs are disabled", async () => {
+  it("does NOT reconnect when autonomous runs are disabled", () => {
    renderThread({ autonomousRunsEnabled: false, initialRows: settledTail() });
-    await disconnect();
+    disconnect();
    expect(screen.queryByText(/reconnecting/i)).toBeNull();
    expect(
      screen.getByText("Connection lost — the answer was interrupted."),
@@ -1223,7 +1138,7 @@ describe("ChatThread — live reconnect + stalled", () => {

  it("#488 commit 4a: the poll idle cap surfaces a stalled banner + Retry (not silent)", async () => {
    renderLive();
-    await disconnect();
+    disconnect();
    advanceToAttempt(1);
    await reconnect({ status: 204, ok: false }); // arms the poll (reconnecting)
    // No activity for the whole idle cap -> stalled.
@@ -1254,88 +1169,4 @@ describe("ChatThread — live reconnect + stalled", () => {
    });
    expect(onResumeFallback).toHaveBeenCalledWith(false); // POLL_IDLE_CAP -> idle -> disarm
  });
-
-  it("#541: getRun HANGS on a live disconnect — the timeout race still enters reconnect (no silent freeze in `streaming`)", async () => {
-    // MUTATION-VERIFY: revert the race to a bare `getRun(cid).then/.catch` and this
-    // reddens — a HUNG (never-settling, NOT rejected) getRun leaves the FSM stuck in
-    // `streaming` with no reconnect banner and no poll (the axios client sets no
-    // request timeout, and the stalled-idle cap only arms AFTER reconnecting/polling).
-    renderLive();
-    h.state.getRun.mockReset();
-    h.state.getRun.mockReturnValue(new Promise(() => {})); // getRun HANGS forever
-    await disconnect(); // live partial = liveMsg (id "a2")
-    expect(h.state.getRun).toHaveBeenCalledWith("c1");
-    // BEFORE the bound fires the FSM is still in the live turn — the very freeze bug.
-    expect(screen.queryByText(/reconnecting/i)).toBeNull();
-    // The recovery-start bound fires -> the SAME fallback as the reject path.
-    act(() => {
-      vi.advanceTimersByTime(4_000);
-    });
-    expect(screen.getByText(/reconnecting/i)).toBeTruthy();
-    // The live partial (a2) was DROPPED from the store (replay-from-start, no stale
-    // tail-apply base). Mirrors the getRun-REJECT test's inspection.
-    const removedLivePartial = (
-      h.state.setMessages as unknown as {
-        mock: { calls: [unknown][] };
-      }
-    ).mock.calls.some(([updater]) => {
-      if (typeof updater !== "function") return false;
-      const out = (updater as (p: { id: string }[]) => { id: string }[])([
-        { id: "a2" },
-        { id: "u1" },
-      ]);
-      return !out.some((m) => m.id === "a2");
-    });
-    expect(removedLivePartial).toBe(true);
-    // ...and the anchor was NULLED -> replay-from-start (no ?anchor=&n= over the partial).
-    advanceToAttempt(1);
-    expect(h.state.resumeStream).toHaveBeenCalledTimes(1);
-    expect(h.state.transport!.prepareReconnectToStreamRequest!().api).toBe(
-      "/api/ai-chat/runs/c1/stream",
-    );
-  });
-
-  it("#541: a getRun resolve AFTER the timeout already fired is IGNORED (no double reconnect, no stale re-seed)", async () => {
-    // The timeout wins first and enters the ladder via replay-from-start. When the
-    // hung getRun FINALLY answers, its late `.then` must be a full no-op: it must not
-    // re-seed the store from the (now stale) persisted row, must not re-set the
-    // anchor, and must not re-enter reconnect. The local `settled` flag makes the
-    // resolve/reject/timeout branches mutually exclusive.
-    // MUTATION-VERIFY: drop the `settled` guard (let the late `.then` run) and the
-    // late re-seed re-sets the anchor (URL regains ?anchor=a2&n=3) + calls setMessages.
-    renderLive();
-    let resolveGetRun!: (v: unknown) => void;
-    h.state.getRun.mockReset();
-    h.state.getRun.mockReturnValue(
-      new Promise((r) => {
-        resolveGetRun = r;
-      }),
-    );
-    await disconnect();
-    act(() => {
-      vi.advanceTimersByTime(4_000); // bound fires -> replay-from-start, reconnecting
-    });
-    expect(screen.getByText(/reconnecting/i)).toBeTruthy();
-    advanceToAttempt(1);
-    expect(h.state.resumeStream).toHaveBeenCalledTimes(1);
-    // Anchor is null -> replay-from-start URL (the pre-condition the late resolve must
-    // not undo).
-    expect(h.state.transport!.prepareReconnectToStreamRequest!().api).toBe(
-      "/api/ai-chat/runs/c1/stream",
-    );
-    const setMessagesCallsBefore = h.state.setMessages.mock.calls.length;
-    // NOW the hung getRun finally resolves with a persisted anchor (id a2, steps 3).
-    await act(async () => {
-      resolveGetRun(persistedAnchor());
-      await Promise.resolve();
-    });
-    // The late resolve did NOT re-seed the store...
-    expect(h.state.setMessages.mock.calls.length).toBe(setMessagesCallsBefore);
-    // ...did NOT re-set the anchor (URL stays replay-from-start, no ?anchor=&n=)...
-    expect(h.state.transport!.prepareReconnectToStreamRequest!().api).toBe(
-      "/api/ai-chat/runs/c1/stream",
-    );
-    // ...and did NOT trigger a fresh reconnect attach.
-    expect(h.state.resumeStream).toHaveBeenCalledTimes(1);
-  });
 });
@@ -42,7 +42,7 @@ import { assistantMessageHasVisibleContent } from "@/features/ai-chat/utils/mess
 import {
  isStreamingTail,
  isSettledAssistantTail,
-  stepsPersistedOf,
+  seedRows,
  mergeById,
 } from "@/features/ai-chat/utils/resume-helpers.ts";
 import { getRun } from "@/features/ai-chat/services/ai-chat-service.ts";
@@ -81,17 +81,6 @@ const STREAM_THROTTLE_MS = 50;
 // THREAD now (the FSM owns polling->stalled); the window just polls while armed.
 const DEGRADED_POLL_IDLE_MAX_MS = 10 * 60_000;

-// #541: the bound on the persist re-seed (getRun) wait when ENTERING the reconnect
-// ladder after a live SSE drop. The axios client (lib/api-client.ts) sets NO request
-// timeout, and the stalled-idle cap only arms AFTER the FSM enters reconnecting/
-// polling — which never happens if getRun HANGS (connection established, no response).
-// Without this bound a live drop + a hung getRun sticks the FSM in `streaming` with
-// no banner and no poll until the browser socket timeout (minutes) — the silent-freeze
-// class #497 eliminates. This is a deliberate RECOVERY-START bound (drop the live
-// partial + enter the ladder so the poll/idle-cap arms), intentionally much shorter
-// than any network socket timeout — not a network read timeout.
-const RECONNECT_RESEED_TIMEOUT_MS = 4_000;
-
 /** The #487 active (non-terminal) run statuses — mirrors the server's
 *  ACTIVE_RUN_STATUSES. A run-fact is "active" only for these. */
 function isActiveRunStatus(status: string | null | undefined): boolean {
@@ -277,36 +266,25 @@ export default function ChatThread({
  // is NOT one of the lifecycle flags the FSM replaced.
  const mountedRef = useRef(true);

-  // attachStrategy DATA (behind the resumeStream effect; #491 tail-only, WITHOUT
-  // touching the FSM). The controller is effect-owned (aborted in cleanup, I5).
-  // `anchorRef` is the PERSISTED assistant row that pins the run (server invariant
-  // 6) and its persisted step frontier N: it feeds `?anchor=<id>&n=<stepsPersisted>`
-  // so the tail-only attach returns frames for steps >= N (the seed carries 0..N-1).
-  // It is NOT a "stripped" row — the seed keeps every row (tail-only replaces the
-  // old full-replay+strip). Null when there is no streaming/active tail to resume.
+  // attachStrategy DATA (behind the resumeStream effect; #491 swaps it to tail-only
+  // WITHOUT touching the FSM). The controller is effect-owned (aborted in cleanup,
+  // I5). `stripRef`/`strippedRowRef` are the current full-replay+strip anchor.
  const attachAbortRef = useRef<AbortController | null>(null);
-  const anchorRef = useRef<{ id: string; stepsPersisted: number } | null>(
-    (() => {
-      if (chatId === null || !isStreamingTail(initialRows ?? [])) return null;
-      const rows = initialRows ?? [];
-      const tail = rows[rows.length - 1];
-      return { id: tail.id, stepsPersisted: stepsPersistedOf(tail) };
-    })(),
+  const stripRef = useRef(chatId !== null && isStreamingTail(initialRows ?? []));
+  const strippedRowRef = useRef<IAiChatMessageRow | null>(
+    stripRef.current ? (initialRows ?? [])[initialRows!.length - 1] : null,
  );
  // Effect-owned backoff timers (not lifecycle flags): the reconnect ladder and the
  // stalled inactivity cap. Cleared by the cancelReconnect effect / the cap effect.
  const reconnectTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
  const idleCapTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
-  // #541: the persist re-seed (getRun) timeout race on the disconnect->reconnect
-  // entry. Held in a ref so unmount (DISPOSE cleanup) clears it — no dangling timer.
-  const reseedTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);

-  // #491 tail-only: seed EVERY persisted row unchanged (no strip). The streaming
-  // tail holds steps 0..N-1; the run-stream registry's tail (steps >= N) is APPENDED
-  // to it by the SDK continuation (readUIMessageStream({ message })), so it must be
-  // present in the store for the attach to continue the RIGHT message.
  const initialMessages = useMemo<UIMessage[]>(
-    () => (initialRows ?? []).map(rowToUiMessage),
+    () =>
+      seedRows(
+        initialRows ?? [],
+        stripRef.current && autonomousRunsEnabled === true,
+      ).map(rowToUiMessage),
    [initialRows],
  );

@@ -357,16 +335,21 @@ export default function ChatThread({
    (eff: RunEffect, epoch: number) => {
      switch (eff.type) {
        case "resumeStream": {
-          // The attach GET. Stamp the outcome's generation (I1). #491 tail-only: the
-          // store already holds EXACTLY the persisted steps 0..N-1 (the mount seed IS
-          // persist; a reconnect was re-seeded from persist BEFORE FINISH_DISCONNECT
-          // scheduled it — see the onFinish disconnect handler), so there is nothing
-          // to filter here: the SDK continues that seeded message, appending the tail
-          // (steps >= N) without duplicating the pre-drop partial step.
+          // The attach GET. Stamp the outcome's generation (I1). A reconnect
+          // attempt filters the pinned live row from the store first (the mount
+          // seed already stripped it), so the live replay's text-start rebuilds it
+          // without duplicating parts (#430).
          pendingAttachEpochRef.current = epoch;
          // The resumed stream's onFinish is stamped with THIS attach generation
          // (F1), so a superseded attempt's late finish is dropped.
          turnEpochRef.current = epoch;
+          if (machineRef.current.phase.name === "reconnecting") {
+            const anchor = strippedRowRef.current;
+            if (anchor)
+              setMessagesRef.current?.((prev) =>
+                prev.filter((m) => m.id !== anchor.id),
+              );
+          }
          void resumeStreamRef.current?.();
          break;
        }
@@ -481,23 +464,18 @@ export default function ChatThread({
      new DefaultChatTransport<UIMessage>({
        api: "/api/ai-chat/stream",
        credentials: "include",
-        prepareReconnectToStreamRequest: () => {
-          // #491 tail-only attach URL. When there is an anchor (a streaming/active
-          // tail to resume) build `?anchor=<assistantRowId>&n=<stepsPersisted>`: the
-          // server returns the TAIL — a synthetic `start` frame + frames for steps
-          // >= n, then live — which the SDK continuation appends to the seeded row.
-          // The server 204s (-> restore-noop + poll) when it cannot cover the
-          // frontier (overflow/rotation gap) or the anchor mismatches (a newer run).
-          // No anchor (a user tail / pre-first-frame break) => no params.
-          const anchor = anchorRef.current;
-          return {
-            api: `/api/ai-chat/runs/${chatIdRef.current}/stream${
-              anchor
-                ? `?anchor=${anchor.id}&n=${anchor.stepsPersisted}`
-                : ""
-            }`,
-          };
-        },
+        prepareReconnectToStreamRequest: () => ({
+          // Build the attach URL from the REAL chat id. ?expect=live&anchor=<row id>
+          // only when a streaming tail was stripped: expect=live opts into a
+          // finished-retained replay (safe only because the row is stripped and the
+          // replay rebuilds it), and the anchor pins the replay to OUR run — a
+          // mismatching (newer) run 204s into the restore+poll path instead.
+          api: `/api/ai-chat/runs/${chatIdRef.current}/stream${
+            stripRef.current
+              ? `?expect=live&anchor=${strippedRowRef.current!.id}`
+              : ""
+          }`,
+        }),
        fetch: async (input: RequestInfo | URL, init: RequestInit = {}) => {
          if ((init.method ?? "GET") !== "GET") {
            // Send path (POST). #488 commit 5: NO client 409 retry ladder anymore
@@ -584,9 +562,8 @@ export default function ChatThread({

  // Attach GET outcome -> FSM event. The epoch guard replaces BOTH the one-shot
  // 204 guard (noStreamHandledRef) and the unmount gate: a stale/superseded or
-  // post-DISPOSE outcome is dropped (I1). #491 tail-only: on a NONE outcome there is
-  // NOTHING to restore — the anchor row was never stripped from the view (the seed
-  // keeps it) — so we only invalidate for a fresh poll + dispatch the FSM event.
+  // post-DISPOSE outcome is dropped (I1). For a NONE outcome the attachStrategy
+  // recovery (restore the stripped row + invalidate for a fresh poll) runs first.
  const handleAttachOutcome = useCallback(
    (ep: number, wasReconnecting: boolean, live: boolean) => {
      if (ep !== epochRef.current) return; // stale generation — drop
@@ -598,6 +575,10 @@ export default function ChatThread({
        );
        return;
      }
+      if (strippedRowRef.current)
+        setMessagesRef.current?.((prev) =>
+          mergeById(prev, rowToUiMessage(strippedRowRef.current!)),
+        );
      queryClient.invalidateQueries({
        queryKey: AI_CHAT_MESSAGES_RQ_KEY(chatIdRef.current),
      });
@@ -680,155 +661,71 @@ export default function ChatThread({
      // keeps executing server-side — must win; only a NON-disconnect error (a
      // provider 500, `{ isError:true, isDisconnect:false }`) is terminal.
      if (isDisconnect) {
-        if (!mountedRef.current) {
+        if (wasObserver) {
+          // A resumed/attached OBSERVER stream dropped. Recover via the degraded
+          // poll (restore the stripped row only when there is no visible content;
+          // never clobber a fuller on-screen tail, invariant 9). The FSM decides
+          // reconnect-vs-poll from liveFollow (a live-follow drop reconnects again,
+          // #488 commit 3; a mount-resume drop polls).
+          if (mountedRef.current) {
+            const hasVisible = msgHasVisible;
+            if (!hasVisible && strippedRowRef.current)
+              setMessages((prev) =>
+                mergeById(prev, rowToUiMessage(strippedRowRef.current!)),
+              );
+            queryClient.invalidateQueries({
+              queryKey: AI_CHAT_MESSAGES_RQ_KEY(chatIdRef.current),
+            });
+            dispatch({
+              type: "FINISH_DISCONNECT",
+              hasVisibleContent: hasVisible,
+              epoch: stampEpoch,
+            });
+          }
          setStopNotice(null);
          return;
        }
-        // No detached run to recover (legacy, non-autonomous): a plain disconnect —
-        // terminal notice, no reconnect. (An observer only exists in autonomous mode,
-        // so this is always a local turn.)
-        if (autonomousRunsEnabled !== true) {
+        // A LOCAL live turn dropped. #488 commit 2: recover by the RUN-FACT, not by
+        // the presence of an assistant message — a setup-phase break (before the
+        // first frame) still leaves a detached run writing to pages. In autonomous
+        // mode a run is active for the whole turn, so seed the run-fact from the
+        // start-metadata runId when known, else a sentinel (the attach GET goes by
+        // chatId, not runId). Pin the assistant row as the strip/anchor when present.
+        if (autonomousRunsEnabled === true && mountedRef.current) {
+          const hasAnchor =
+            message?.role === "assistant" && typeof message.id === "string";
+          if (hasAnchor) {
+            strippedRowRef.current = {
+              id: message.id,
+              role: "assistant",
+              content: "",
+              status: "streaming",
+              createdAt: new Date().toISOString(),
+              metadata: { parts: message.parts },
+            };
+            stripRef.current = true;
+          } else {
+            strippedRowRef.current = null;
+            stripRef.current = false;
+          }
+          dispatch({
+            type: "RUN_FACT",
+            runFact: { runId: extractRunId(message) ?? "pending" },
+          });
+          dispatch({
+            type: "FINISH_DISCONNECT",
+            hasVisibleContent: msgHasVisible,
+            epoch: stampEpoch,
+          });
+          setStopNotice(null);
+        } else {
          dispatch({
            type: "FINISH_DISCONNECT",
            hasVisibleContent: false,
            epoch: stampEpoch,
          });
          setStopNotice("disconnect");
-          return;
        }
-        // A mount-resume OBSERVER (one-shot resume, NOT live-follow) drop falls to
-        // the degraded POLL, which merges by id — it does NOT attach, so there is
-        // nothing to re-seed. #491 tail-only: the anchor row was never removed from
-        // the view (the seed keeps it; the continuation only APPENDED), so nothing to
-        // restore either. The FSM routes this to `polling` (ownership observer,
-        // !liveFollow).
-        if (wasObserver && !machineRef.current.ctx.liveFollow) {
-          queryClient.invalidateQueries({
-            queryKey: AI_CHAT_MESSAGES_RQ_KEY(chatIdRef.current),
-          });
-          dispatch({
-            type: "FINISH_DISCONNECT",
-            hasVisibleContent: msgHasVisible,
-            epoch: stampEpoch,
-          });
-          setStopNotice(null);
-          return;
-        }
-        // We will (re-)ENTER THE RECONNECT LADDER (an attach): a LOCAL live turn's
-        // first drop, OR a live-follow observer's SUBSEQUENT drop (#488 commit 3).
-        // #488 commit 2: recover by the RUN-FACT, not by the presence of an assistant
-        // message — a setup-phase break still leaves a detached run writing to pages.
-        //
-        // #491 tail-only (THE crux): the live store holds a PARTIAL step that is AHEAD
-        // of the persisted boundary; tail-applying the reconnect's step frames over it
-        // would DUPLICATE that partial step. So entering reconnecting is ALWAYS via a
-        // RE-SEED FROM PERSIST — never the live store. Fetch the authoritative
-        // persisted assistant row (`getRun` returns the projected `message`), replace
-        // the live partial by id (mergeById -> the store now holds EXACTLY steps
-        // 0..N-1), and set the anchor to `{ id, n = stepsPersisted }`. Only AFTER the
-        // re-seed is applied do we enter the ladder (FINISH_DISCONNECT schedules the
-        // backoff) — so the attach can never tail-apply over the live partial.
-        const cid = chatIdRef.current;
-        // The live-message runId is the run-fact source (the attach GET keys on
-        // chatId, so a sentinel still recovers a setup-phase break).
-        const runId = extractRunId(message ?? undefined) ?? "pending";
-        const enterReconnect = (fact: string): void => {
-          if (!mountedRef.current) return;
-          // Epoch-stamp the run-fact too (I1): the getRun rtt widens the
-          // onFinish->dispatch window, so a concurrent SEND_LOCAL during it must be
-          // able to drop this stale RUN_FACT (else it clobbers the new turn's
-          // runFact.runId). Consistent with the postRun RUN_FACT stamp.
-          dispatch({ type: "RUN_FACT", runFact: { runId: fact }, epoch: stampEpoch });
-          dispatch({
-            type: "FINISH_DISCONNECT",
-            hasVisibleContent: msgHasVisible,
-            epoch: stampEpoch,
-          });
-        };
-        // Restore the STRUCTURAL guarantee that the live partial is never the
-        // tail-apply base: drop the live partial from the store by id and null the
-        // anchor, so the reconnect replays from step 0 into a CLEAN store (a full
-        // rebuild) or, past any rotation, 204s -> degraded poll. Used on BOTH the
-        // no-persisted-row and getRun-FAILURE paths — after this there is no path
-        // where the attach tail-applies frames onto a row that already has them
-        // (the #137/#161 duplication class).
-        const dropLivePartialAndReplayFromStart = (): void => {
-          if (message?.role === "assistant" && typeof message.id === "string") {
-            const liveId = message.id;
-            setMessagesRef.current?.((prev) =>
-              prev.filter((m) => m.id !== liveId),
-            );
-          }
-          anchorRef.current = null;
-        };
-        if (cid) {
-          // #541: bound the persist re-seed wait with a timeout race. getRun goes
-          // through the axios client, which has NO request timeout; a HUNG getRun
-          // (connection open, no response) — distinct from a REJECT, which the
-          // `.catch` already handles — would otherwise never let us enter the ladder,
-          // leaving the FSM stuck in `streaming` with no banner and no poll until the
-          // browser socket timeout. `settled` makes the three branches (resolve /
-          // reject / timeout) mutually exclusive: whichever fires FIRST wins and the
-          // others become no-ops. So a LATE getRun resolve AFTER the timeout is fully
-          // ignored — it cannot (i) re-enter reconnect a second time, (ii) overwrite
-          // the timeout's replay-from-start with a stale re-seed, or (iii) re-arm any
-          // timer. On timeout we take the SAME fallback as the reject path (drop the
-          // live partial + enter the ladder, so the poll and the stalled-idle cap arm).
-          let settled = false;
-          const finishReseed = (apply: () => void): void => {
-            if (settled) return;
-            settled = true;
-            if (reseedTimerRef.current) {
-              clearTimeout(reseedTimerRef.current);
-              reseedTimerRef.current = null;
-            }
-            if (!mountedRef.current) return;
-            apply();
-          };
-          reseedTimerRef.current = setTimeout(() => {
-            finishReseed(() => {
-              dropLivePartialAndReplayFromStart();
-              enterReconnect(runId);
-            });
-          }, RECONNECT_RESEED_TIMEOUT_MS);
-          void getRun(cid)
-            .then((res) => {
-              finishReseed(() => {
-                const persisted = res.message;
-                if (persisted && persisted.role === "assistant") {
-                  anchorRef.current = {
-                    id: persisted.id,
-                    stepsPersisted: stepsPersistedOf(persisted),
-                  };
-                  // Replace the live partial with the persisted row IN PLACE by id —
-                  // the re-seed from persist. The attach's tail (steps >= N) then
-                  // appends to a store holding EXACTLY steps 0..N-1: no duplication.
-                  setMessages((prev) => mergeById(prev, rowToUiMessage(persisted)));
-                } else {
-                  // No persisted assistant row (pre-first-frame break): drop the live
-                  // partial + replay from start (no anchor/n) so nothing is duplicated.
-                  dropLivePartialAndReplayFromStart();
-                }
-                enterReconnect(res.run?.id ?? runId);
-              });
-            })
-            .catch(() => {
-              finishReseed(() => {
-                // Persist read FAILED: we cannot re-seed from fresh persist, and a
-                // stale mount-time anchor over the live partial would tail-apply
-                // already-present steps -> duplication (a flaky-network blip:
-                // SSE + getRun both fail, network recovers in ~1s, the registry still
-                // covers from the mount frontier). Restore the removed-filter guarantee
-                // instead: drop the live partial + replay from start / 204 -> poll.
-                dropLivePartialAndReplayFromStart();
-                enterReconnect(runId);
-              });
-            });
-        } else {
-          dropLivePartialAndReplayFromStart();
-          enterReconnect(runId);
-        }
-        setStopNotice(null);
        return;
      }
      // A NON-disconnect stream error (a provider 500 etc.) -> terminal error banner.
@@ -849,10 +746,11 @@ export default function ChatThread({
        if (mountedRef.current) {
          const hasVisible = msgHasVisible;
          if (!hasVisible) {
-            // Starved replay (the tail carried no new steps). #491 tail-only: the
-            // seeded steps 0..N-1 are still on screen (the SDK continuation never
-            // wiped them — `start` does not reset parts), so there is nothing to
-            // restore; just poll to the real terminal.
+            // Starved replay: restore the stripped row + poll to the real terminal.
+            if (strippedRowRef.current)
+              setMessages((prev) =>
+                mergeById(prev, rowToUiMessage(strippedRowRef.current!)),
+              );
            queryClient.invalidateQueries({
              queryKey: AI_CHAT_MESSAGES_RQ_KEY(chatIdRef.current),
            });
@@ -948,12 +846,6 @@ export default function ChatThread({
    }
    return () => {
      mountedRef.current = false;
-      // #541: clear the in-flight persist re-seed timeout (not an FSM effect timer,
-      // so DISPOSE does not touch it) — no dangling setTimeout after unmount.
-      if (reseedTimerRef.current) {
-        clearTimeout(reseedTimerRef.current);
-        reseedTimerRef.current = null;
-      }
      dispatch({ type: "DISPOSE" }); // aborts attach + timers, bumps epoch (I5)
    };
    // Mount-only by design; the parent remounts per chat via `key`.
@@ -971,12 +863,12 @@ export default function ChatThread({
    const tail = rows[rows.length - 1];
    if (!tail || tail.role !== "assistant") return;
    setMessages((prev) => mergeById(prev, rowToUiMessage(tail)));
-    // Anchor-mismatch coherence: if a DIFFERENT run's row B has replaced our anchor
-    // row A as the tail, A would linger as an orphan — reconcile A by id from FRESH
-    // PERSISTED history (not the pinned live row) so no phantom row survives.
-    const anchor = anchorRef.current;
-    if (anchor && anchor.id !== tail.id) {
-      const historical = rows.find((r) => r.id === anchor.id);
+    // Anchor-mismatch coherence: a restored stripped row A that a DIFFERENT run's
+    // row B has replaced as the tail would linger as an orphan — settle A from
+    // fresh history so no phantom row survives.
+    const stripped = strippedRowRef.current;
+    if (stripped && stripped.id !== tail.id) {
+      const historical = rows.find((r) => r.id === stripped.id);
      if (historical)
        setMessages((prev) => mergeById(prev, rowToUiMessage(historical)));
    }
@@ -57,31 +57,6 @@ 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
@@ -48,7 +48,6 @@ Legend: **†** = command-transition (bumps `epoch`, I1). Effects in `[…]`.
 | `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) |
@@ -122,7 +121,8 @@ holds. **Pending column: empty.**
 | 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 |
+| 14 | `stripRef` | **data** (attachStrategy) | strip+replay detail; the `resumeStream` effect reads it |
+| 15 | `strippedRowRef` | **data** (attachStrategy) | the anchor row |
 | 16 | `attachAbortRef` | **effect-owned controller** | aborted by the `abortAttach` effect in cleanup (I5) |
 | 17–25 | `chatIdRef`, `openPageRef`, `getEditorSelectionRef`, `roleIdRef`, `stableIdRef`, `queuedRef`, `sendMessageRef`, `statusRef`, `lastForwardedChatIdRef` | **data** (identity/send mirrors) | unchanged — not lifecycle flags |
 | NEW | `pendingSupersedeRef` | **data** (send-plumbing) | the runId injected into the next `POST /stream {supersede}`; the single replacement for the 3 DELETED one-shots (#8/#9/#10) — net −2 refs |
@@ -151,12 +151,8 @@ message. Sources, in the order they update `ctx.runFact`:
 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.
+4. **Poll (future resume-stack iteration #491):** the delta will carry the run field;
+   until then the poll drives to a terminal ROW, dispatched as `POLL_TERMINAL`.

 Pessimism rule: a stale-but-positive fact PERMITS entering recovery (attach); the
 204 then cuts it. A fresh negative fact gates recovery OUT immediately.
@@ -182,9 +178,6 @@ Pessimism rule: a stale-but-positive fact PERMITS entering recovery (attach); th
  /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).
+- **attachStrategy** (strip+replay today) is behind the `resumeStream` effect; the
+  resume-stack iteration (#491) swaps it to tail-only WITHOUT touching the FSM.
 - **Queue** stays a data structure; flush/interrupt decisions are transitions.
@@ -181,12 +181,6 @@ 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`.
@@ -4,8 +4,7 @@ import type { IAiChatMessageRow } from "@/features/ai-chat/types/ai-chat.types.t
 import {
  isStreamingTail,
  isSettledAssistantTail,
-  stepsPersistedOf,
-  mergeDeltaRowsIntoPages,
+  seedRows,
  mergeById,
 } from "./resume-helpers.ts";

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

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

-describe("stepsPersistedOf", () => {
-  it("reads metadata.stepsPersisted", () => {
-    expect(stepsPersistedOf(row("a1", "assistant", "streaming", 3))).toBe(3);
-    expect(stepsPersistedOf(row("a1", "assistant", "streaming", 0))).toBe(0);
+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);
  });

-  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("drops the last row when stripping", () => {
+    const seeded = seedRows(rows, true);
+    expect(seeded).toHaveLength(1);
+    expect(seeded[0].id).toBe("u1");
  });

-  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"]);
+  it("returns an empty list when stripping a single-row list", () => {
+    expect(seedRows([row("a1", "assistant", "streaming")], true)).toHaveLength(
+      0,
+    );
  });
 });

@@ -189,37 +109,4 @@ 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);
-  });
 });
@@ -11,10 +11,9 @@ 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'`. #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.
+ * `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.
 */
 export function isStreamingTail(rows: IAiChatMessageRow[]): boolean {
  const tail = rows[rows.length - 1];
@@ -33,61 +32,15 @@ export function isSettledAssistantTail(rows: IAiChatMessageRow[]): boolean {
 }

 /**
- * #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.
+ * 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).
 */
-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[],
+export function seedRows(
  rows: IAiChatMessageRow[],
-): 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;
+  strip: boolean,
+): IAiChatMessageRow[] {
+  return strip ? rows.slice(0, -1) : rows;
 }

 /**
@@ -1,83 +0,0 @@
-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" });
-  });
-});
@@ -3,20 +3,11 @@ import { atom } from "jotai";
 // 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 type { HocuspocusProvider } from "@hocuspocus/provider";
 import { PageEditMode } from "@/features/user/types/user.types.ts";
 import type { DictationUnavailableReason } from "@/features/dictation/dictation-status";

 export const pageEditorAtom = atom<Editor | null>(null);

-// #370 — the active page's collab provider, published by the page editor so the
-// header menu can emit the "save-version" stateless signal (Cmd+S / button).
-// Null when the page is read-only / collab isn't connected. A typed initial
-// value (rather than an explicit generic) keeps jotai's overload resolution on
-// the writable PrimitiveAtom branch.
-const initialCollabProvider: HocuspocusProvider | null = null;
-export const collabProviderAtom = atom(initialCollabProvider);
-
 export const titleEditorAtom = atom<Editor | null>(null);

 export const readOnlyEditorAtom = atom<Editor | null>(null);
@@ -31,18 +31,11 @@ import { useAtom, useAtomValue, useSetAtom } from "jotai";
 import useCollaborationUrl from "@/features/editor/hooks/use-collaboration-url";
 import { currentUserAtom } from "@/features/user/atoms/current-user-atom";
 import {
-  collabProviderAtom,
  currentPageEditModeAtom,
  dictationAvailabilityAtom,
  pageEditorAtom,
  yjsConnectionStatusAtom,
 } from "@/features/editor/atoms/editor-atoms";
-import { notifications } from "@mantine/notifications";
-import {
-  VERSION_SAVED_MESSAGE_TYPE,
-  type VersionSavedMessage,
-  saveVersionPending,
-} from "@/features/page-history/version-messages";
 import { asideStateAtom } from "@/components/layouts/global/hooks/atoms/sidebar-atom";
 import {
  activeCommentIdAtom,
@@ -131,7 +124,6 @@ export default function PageEditor({

  const [currentUser] = useAtom(currentUserAtom);
  const [, setEditor] = useAtom(pageEditorAtom);
-  const setCollabProvider = useSetAtom(collabProviderAtom);
  const [, setAsideState] = useAtom(asideStateAtom);
  const [, setActiveCommentId] = useAtom(activeCommentIdAtom);
  const [showCommentPopup, setShowCommentPopup] = useAtom(showCommentPopupAtom);
@@ -189,24 +181,6 @@ export default function PageEditor({
      const onStatelessHandler = ({ payload }: onStatelessParameters) => {
        try {
          const message = JSON.parse(payload);
-          // #370 — a version was saved somewhere; live-refresh the history panel
-          // on every client. Only the client that pressed Save (tracked by the
-          // module-level flag) shows the confirmation toast.
-          if (message?.type === VERSION_SAVED_MESSAGE_TYPE) {
-            const versionMsg = message as VersionSavedMessage;
-            queryClient.invalidateQueries({
-              queryKey: ["page-history-list"],
-            });
-            if (saveVersionPending.current) {
-              saveVersionPending.current = false;
-              notifications.show({
-                message: versionMsg.alreadySaved
-                  ? t("Already saved as the latest version")
-                  : t("Version saved"),
-              });
-            }
-            return;
-          }
          if (message?.type !== "page.updated" || !message.updatedAt) return;
          const pageData = queryClient.getQueryData<IPage>(["pages", slugId]);
          if (pageData) {
@@ -264,16 +238,12 @@ export default function PageEditor({

      local.on("synced", onLocalSyncedHandler);
      providersRef.current = { socket, local, remote };
-      // #370 — publish the provider so the header menu can emit save-version.
-      setCollabProvider(remote);
      setProvidersReady(true);
    } else {
-      setCollabProvider(providersRef.current.remote);
      setProvidersReady(true);
    }
    // Only destroy on final unmount
    return () => {
-      setCollabProvider(null);
      providersRef.current?.socket.destroy();
      providersRef.current?.remote.destroy();
      providersRef.current?.local.destroy();
@@ -1,11 +1,4 @@
-import {
-  Text,
-  Group,
-  UnstyledButton,
-  Avatar,
-  Tooltip,
-  Badge,
-} from "@mantine/core";
+import { Text, Group, UnstyledButton, Avatar, Tooltip } from "@mantine/core";
 import { CustomAvatar } from "@/components/ui/custom-avatar.tsx";
 import { AgentAvatarStack } from "@/components/ui/agent-avatar-stack.tsx";
 import { formattedDate } from "@/lib/time";
@@ -14,59 +7,36 @@ import clsx from "clsx";
 import { IPageHistory } from "@/features/page-history/types/page.types";
 import { memo, useCallback } from "react";
 import { useSetAtom } from "jotai";
-import { useTranslation } from "react-i18next";
 import { historyAtoms } from "@/features/page-history/atoms/history-atoms.ts";

 const MAX_VISIBLE_AVATARS = 5;

-/**
- * #370 — map a snapshot's intentionality tier to its badge. `version: true`
- * marks the intentional points (manual / agent); autosaves (boundary / idle /
- * legacy null) are non-versions and get dimmed in the list.
- */
-type HistoryKindMeta = { labelKey: string; color: string; version: boolean };
-export function historyKindMeta(kind?: string | null): HistoryKindMeta {
-  switch (kind) {
-    case "manual":
-      return { labelKey: "Saved", color: "blue", version: true };
-    case "agent":
-      return { labelKey: "Agent version", color: "violet", version: true };
-    case "boundary":
-      return { labelKey: "Boundary", color: "gray", version: false };
-    default: // "idle" | null | undefined (legacy autosave)
-      return { labelKey: "Autosave", color: "gray", version: false };
-  }
-}
-
 interface HistoryItemProps {
  historyItem: IPageHistory;
-  // The previous snapshot for diff/restore is resolved by id from the FULL list
-  // in the parent (resolvePrevSnapshotId), so the item only needs to report its
-  // own id — never a list index (which would be the filtered-view index).
-  onSelect: (id: string) => void;
-  onHover?: (id: string) => void;
+  index: number;
+  onSelect: (id: string, index: number) => void;
+  onHover?: (id: string, index: number) => void;
  onHoverEnd?: () => void;
  isActive: boolean;
 }

 const HistoryItem = memo(function HistoryItem({
  historyItem,
+  index,
  onSelect,
  onHover,
  onHoverEnd,
  isActive,
 }: HistoryItemProps) {
  const setHistoryModalOpen = useSetAtom(historyAtoms);
-  const { t } = useTranslation();
-  const kindMeta = historyKindMeta(historyItem.kind);

  const handleClick = useCallback(() => {
-    onSelect(historyItem.id);
-  }, [onSelect, historyItem.id]);
+    onSelect(historyItem.id, index);
+  }, [onSelect, historyItem.id, index]);

  const handleMouseEnter = useCallback(() => {
-    onHover?.(historyItem.id);
-  }, [onHover, historyItem.id]);
+    onHover?.(historyItem.id, index);
+  }, [onHover, historyItem.id, index]);

  const contributors = historyItem.contributors;
  const hasContributors = contributors && contributors.length > 0;
@@ -79,20 +49,8 @@ const HistoryItem = memo(function HistoryItem({
      onMouseEnter={handleMouseEnter}
      onMouseLeave={onHoverEnd}
      className={clsx(classes.history, { [classes.active]: isActive })}
-      // #370 — dim autosnapshots so intentional versions stand out.
-      style={{ opacity: kindMeta.version ? 1 : 0.55 }}
    >
-      <Group gap={6} wrap="nowrap" justify="space-between">
-        <Text size="sm">{formattedDate(new Date(historyItem.createdAt))}</Text>
-        <Badge
-          size="xs"
-          radius="sm"
-          variant={kindMeta.version ? "filled" : "light"}
-          color={kindMeta.color}
-        >
-          {t(kindMeta.labelKey)}
-        </Badge>
-      </Group>
+      <Text size="sm">{formattedDate(new Date(historyItem.createdAt))}</Text>

      <Group gap={6} wrap="nowrap" mt={4}>
        {hasContributors ? (
@@ -2,16 +2,14 @@ import {
  usePageHistoryListQuery,
  prefetchPageHistory,
 } from "@/features/page-history/queries/page-history-query";
-import HistoryItem, {
-  historyKindMeta,
-} from "@/features/page-history/components/history-item";
+import HistoryItem from "@/features/page-history/components/history-item";
 import {
  activeHistoryIdAtom,
  activeHistoryPrevIdAtom,
  historyAtoms,
 } from "@/features/page-history/atoms/history-atoms";
 import { useAtom, useSetAtom } from "jotai";
-import { useCallback, useEffect, useMemo, useRef, useState } from "react";
+import { useCallback, useEffect, useMemo, useRef } from "react";
 import {
  Button,
  ScrollArea,
@@ -19,12 +17,9 @@ import {
  Divider,
  Loader,
  Center,
-  Switch,
-  Text,
 } from "@mantine/core";
 import { useTranslation } from "react-i18next";
 import { useHistoryRestore } from "@/features/page-history/hooks";
-import { resolvePrevSnapshotId } from "@/features/page-history/utils/resolve-prev-snapshot";

 const PREFETCH_DELAY_MS = 150;

@@ -52,22 +47,6 @@ function HistoryList({ pageId }: Props) {
    [pageHistoryData],
  );

-  // #370 — "only versions" filter: hide autosnapshots (idle/boundary/legacy
-  // null), keep only intentional points (manual/agent). Filtering is over the
-  // already-loaded pages; the diff/restore still targets the true previous
-  // snapshot, so items carry their index within the FULL list.
-  const [onlyVersions, setOnlyVersions] = useState(false);
-  // Reuse historyKindMeta().version — the SAME predicate the badge (HistoryItem)
-  // uses to mark intentional points — so the "Only versions" filter and the badge
-  // can never drift apart when a future intentional kind is added.
-  const visibleItems = useMemo(
-    () =>
-      onlyVersions
-        ? historyItems.filter((item) => historyKindMeta(item.kind).version)
-        : historyItems,
-    [historyItems, onlyVersions],
-  );
-
  const loadMoreRef = useRef<HTMLDivElement>(null);
  const prefetchTimeoutRef = useRef<ReturnType<typeof setTimeout> | null>(null);

@@ -81,13 +60,11 @@ function HistoryList({ pageId }: Props) {
  }, []);

  const handleHover = useCallback(
-    (historyId: string) => {
+    (historyId: string, index: number) => {
      clearPrefetchTimeout();
      prefetchTimeoutRef.current = setTimeout(() => {
        prefetchPageHistory(historyId);
-        // The true previous snapshot in the FULL list (not the previous visible
-        // one under the "only versions" filter).
-        const prevId = resolvePrevSnapshotId(historyItems, historyId);
+        const prevId = historyItems[index + 1]?.id;
        if (prevId) {
          prefetchPageHistory(prevId);
        }
@@ -101,11 +78,9 @@ function HistoryList({ pageId }: Props) {
  }, [clearPrefetchTimeout]);

  const handleSelect = useCallback(
-    (id: string) => {
+    (id: string, index: number) => {
      setActiveHistoryId(id);
-      // Baseline = true previous snapshot in the FULL list, so the "only
-      // versions" filter never diffs/restores against the wrong item.
-      setActiveHistoryPrevId(resolvePrevSnapshotId(historyItems, id));
+      setActiveHistoryPrevId(historyItems[index + 1]?.id ?? "");
    },
    [historyItems, setActiveHistoryId, setActiveHistoryPrevId],
  );
@@ -153,27 +128,12 @@ function HistoryList({ pageId }: Props) {

  return (
    <div>
-      <Group px="xs" py={6} justify="flex-end">
-        <Switch
-          size="xs"
-          checked={onlyVersions}
-          onChange={(e) => setOnlyVersions(e.currentTarget.checked)}
-          label={t("Only versions")}
-        />
-      </Group>
-
      <ScrollArea h={620} w="100%" type="scroll" scrollbarSize={5}>
-        {onlyVersions && visibleItems.length === 0 && (
-          <Center py="md">
-            <Text size="sm" c="dimmed">
-              {t("No saved versions yet.")}
-            </Text>
-          </Center>
-        )}
-        {visibleItems.map((historyItem) => (
+        {historyItems.map((historyItem, index) => (
          <HistoryItem
            key={historyItem.id}
            historyItem={historyItem}
+            index={index}
            onSelect={handleSelect}
            onHover={handleHover}
            onHoverEnd={clearPrefetchTimeout}
@@ -24,10 +24,6 @@ export interface IPageHistory {
  updatedAt: string;
  lastUpdatedBy: IPageHistoryUser;
  contributors?: IPageHistoryUser[];
-  // #370 — intentionality tier: 'manual'/'agent' are versions (intentional
-  // points), 'idle'/'boundary' are autosnapshots; null/undefined = legacy
-  // autosave. Derived server-side, drives the history badge + "versions" filter.
-  kind?: "manual" | "agent" | "idle" | "boundary" | null;
  // Provenance markers copied off the page row when the snapshot was saved.
  // `'agent'` marks a version written by the AI agent; `lastUpdatedAiChatId`
  // (when present) deep-links to the chat that produced the edit.
@@ -1,42 +0,0 @@
-import { describe, it, expect } from "vitest";
-import { resolvePrevSnapshotId } from "./resolve-prev-snapshot";
-
-// #370 F4 — the risky client path: with the "only versions" filter active, diff
-// and restore must still baseline against the TRUE previous snapshot in the FULL
-// list, never the previous VISIBLE version (which would skip the autosnapshots
-// between two versions). These pin that the resolution is by FULL-list order.
-describe("resolvePrevSnapshotId", () => {
-  // Newest-first, as the history list stores it: a version, then two autosaves,
-  // then an older version.
-  const full = [
-    { id: "v2", kind: "manual" },
-    { id: "a2", kind: "idle" },
-    { id: "a1", kind: "boundary" },
-    { id: "v1", kind: "manual" },
-    { id: "a0", kind: null },
-  ];
-
-  it("returns the immediate FULL-list successor, not the previous visible version", () => {
-    // Selecting v2 while filtered to versions-only must baseline against a2 (the
-    // real chronological predecessor), NOT v1 (the previous visible version).
-    expect(resolvePrevSnapshotId(full, "v2")).toBe("a2");
-  });
-
-  it("resolves an autosnapshot's predecessor by full-list order", () => {
-    expect(resolvePrevSnapshotId(full, "a1")).toBe("v1");
-  });
-
-  it("returns '' for the oldest item (no predecessor)", () => {
-    expect(resolvePrevSnapshotId(full, "a0")).toBe("");
-  });
-
-  it("returns '' for an id not in the list", () => {
-    expect(resolvePrevSnapshotId(full, "missing")).toBe("");
-  });
-
-  it("does not depend on a filtered subset — same result whatever is visible", () => {
-    // The helper only ever sees the full list; a filtered view cannot change the
-    // baseline it computes.
-    expect(resolvePrevSnapshotId(full, "v1")).toBe("a0");
-  });
-});
@@ -1,22 +0,0 @@
-/**
- * #370 — resolve the TRUE previous snapshot for a history item.
- *
- * The history panel can be filtered to "only versions" (manual/agent), but diff
- * and restore must always compare against the immediately-preceding snapshot in
- * the FULL, unfiltered list — NOT the previous VISIBLE item. Comparing against
- * the previous visible version would silently skip the autosnapshots between two
- * versions and diff/restore the wrong baseline.
- *
- * Given the full (newest-first) list and an item id, this returns the id of the
- * item right after it in the full list (its chronological predecessor), or "" if
- * it is the oldest / not found. Pure and list-order-preserving so it can be unit
- * tested without mounting the component.
- */
-export function resolvePrevSnapshotId(
-  fullItems: ReadonlyArray<{ id: string }>,
-  id: string,
-): string {
-  const index = fullItems.findIndex((item) => item.id === id);
-  if (index === -1) return "";
-  return fullItems[index + 1]?.id ?? "";
-}
@@ -1,28 +0,0 @@
-/**
- * #370 — page-version stateless wire formats. Kept in one place so the client
- * emitter (Save hotkey / button) and the client listener (page-editor) agree
- * with the server (PersistenceExtension) on the message shapes.
- */
-
-/** Client → server: "save a version now". The server derives the tier
- * (manual/agent) from the signed connection actor, never from this payload. */
-export const SAVE_VERSION_MESSAGE_TYPE = "save-version";
-
-/** Server → all clients: a version was saved (or promoted / already existed). */
-export const VERSION_SAVED_MESSAGE_TYPE = "version.saved";
-
-export interface VersionSavedMessage {
-  type: typeof VERSION_SAVED_MESSAGE_TYPE;
-  historyId: string;
-  kind: "manual" | "agent";
-  /** True when the latest snapshot was already a manual version (a no-op save). */
-  alreadySaved: boolean;
-}
-
-/**
- * Cross-component coordination flag so only the client that pressed Save shows
- * the confirmation toast, while every other client silently refreshes its
- * history panel on the broadcast. A module-level ref avoids stale-closure
- * pitfalls in the editor's long-lived stateless handler.
- */
-export const saveVersionPending = { current: false };
@@ -3,7 +3,6 @@ import {
  IconArrowRight,
  IconArrowsHorizontal,
  IconClockHour4,
-  IconDeviceFloppy,
  IconDots,
  IconEye,
  IconEyeOff,
@@ -18,7 +17,7 @@ import {
  IconTrash,
  IconWifiOff,
 } from "@tabler/icons-react";
-import React, { useCallback, useEffect, useRef, useState } from "react";
+import React, { useEffect, useRef, useState } from "react";
 import { useAsideTriggerProps } from "@/hooks/use-toggle-aside.tsx";
 import { useAtom, useAtomValue } from "jotai";
 import { historyAtoms } from "@/features/page-history/atoms/history-atoms.ts";
@@ -40,14 +39,9 @@ import { Trans, useTranslation } from "react-i18next";
 import ExportModal from "@/components/common/export-modal";
 import { convertProseMirrorToMarkdown } from "@docmost/prosemirror-markdown/browser";
 import {
-  collabProviderAtom,
  pageEditorAtom,
  yjsConnectionStatusAtom,
 } from "@/features/editor/atoms/editor-atoms.ts";
-import {
-  SAVE_VERSION_MESSAGE_TYPE,
-  saveVersionPending,
-} from "@/features/page-history/version-messages.ts";
 import { formattedDate } from "@/lib/time.ts";
 import { PageEditModeToggle } from "@/features/user/components/page-state-pref.tsx";
 import MovePageModal from "@/features/page/components/move-page-modal.tsx";
@@ -78,34 +72,9 @@ export default function PageHeaderMenu({ readOnly }: PageHeaderMenuProps) {
  });
  const isDeleted = !!page?.deletedAt;
  const [workspace] = useAtom(workspaceAtom);
-  const collabProvider = useAtomValue(collabProviderAtom);
  // Community public-sharing entry point (replaces the removed EE PageShareModal)
  const workspaceSharingDisabled = workspace?.settings?.sharing?.disabled === true;

-  // #370 — explicit "save a version" (Cmd+S / Save button). One path for the
-  // human; the server derives the tier from the signed actor. Readers can't save
-  // (the button is hidden and the collab connection is read-only server-side).
-  const handleSaveVersion = useCallback(() => {
-    if (readOnly || !collabProvider) return;
-    // Flag this client as the initiator so only it shows the confirmation toast;
-    // a safety timeout clears it if no broadcast comes back (e.g. offline).
-    saveVersionPending.current = true;
-    window.setTimeout(() => {
-      saveVersionPending.current = false;
-    }, 5000);
-    collabProvider.sendStateless(
-      JSON.stringify({ type: SAVE_VERSION_MESSAGE_TYPE }),
-    );
-  }, [readOnly, collabProvider]);
-
-  // mod+S must also block the browser's "Save page" dialog. `triggerOnContent-
-  // Editable` + empty ignore-list so it fires while typing in the editor/title.
-  useHotkeys(
-    [["mod+S", handleSaveVersion, { preventDefault: true }]],
-    [],
-    true,
-  );
-
  useHotkeys(
    [
      [
@@ -164,16 +133,15 @@ export default function PageHeaderMenu({ readOnly }: PageHeaderMenuProps) {
        </ActionIcon>
      </Tooltip>

-      <PageActionMenu readOnly={readOnly} onSaveVersion={handleSaveVersion} />
+      <PageActionMenu readOnly={readOnly} />
    </>
  );
 }

 interface PageActionMenuProps {
  readOnly?: boolean;
-  onSaveVersion?: () => void;
 }
-function PageActionMenu({ readOnly, onSaveVersion }: PageActionMenuProps) {
+function PageActionMenu({ readOnly }: PageActionMenuProps) {
  const { t } = useTranslation();
  const [, setHistoryModalOpen] = useAtom(historyAtoms);
  const clipboard = useClipboard({ timeout: 500 });
@@ -335,20 +303,6 @@ function PageActionMenu({ readOnly, onSaveVersion }: PageActionMenuProps) {
            </Group>
          </Menu.Item>

-          {!readOnly && (
-            <Menu.Item
-              leftSection={<IconDeviceFloppy size={16} />}
-              onClick={onSaveVersion}
-              rightSection={
-                <Text size="xs" c="dimmed">
-                  {t("Ctrl+S")}
-                </Text>
-              }
-            >
-              {t("Save version")}
-            </Menu.Item>
-          )}
-
          <Menu.Item
            leftSection={<IconHistory size={16} />}
            onClick={openHistoryModal}
@@ -665,6 +665,13 @@ export function updateCacheOnMovePage(
  pageData: Partial<IPage>,
 ) {
  invalidatePageTree();
+  // Invalidate the moved page's breadcrumbs (#523). The tree-side child-loss
+  // guard removes the moved node from the local tree when its new parent is an
+  // unloaded branch, so `findBreadcrumbPath` misses it and the breadcrumb bar
+  // falls back to the server `["breadcrumbs", pageId]` query — which this move
+  // must invalidate, otherwise the crumbs keep showing the OLD parent until a
+  // refocus/navigation.
+  queryClient.invalidateQueries({ queryKey: ["breadcrumbs", pageId] });
  // Remove page from old parent's cache
  const oldQueryKey =
    oldParentId === null
@@ -0,0 +1,40 @@
+import { describe, it, expect, beforeEach, vi } from "vitest";
+import type { IPage } from "@/features/page/types/page.types";
+
+// A fresh QueryClient stands in for the app singleton (importing the real
+// @/main.tsx would run ReactDOM.createRoot, which has no DOM root in jsdom).
+vi.mock("@/main.tsx", async () => {
+  const { QueryClient } = await import("@tanstack/react-query");
+  return { queryClient: new QueryClient() };
+});
+
+import { queryClient } from "@/main.tsx";
+import { updateCacheOnMovePage } from "./page-query";
+
+// #523: the tree-side child-loss guard removes the moved node from the local
+// tree when its new parent is an unloaded branch, so `findBreadcrumbPath` misses
+// it and the breadcrumb bar falls back to the server `["breadcrumbs", pageId]`
+// query. That query MUST be invalidated by a move, or the crumbs keep showing
+// the OLD parent until a refocus/navigation.
+describe("updateCacheOnMovePage — breadcrumbs invalidation (#523)", () => {
+  beforeEach(() => {
+    queryClient.clear();
+    vi.restoreAllMocks();
+  });
+
+  it("invalidates the moved page's ['breadcrumbs', pageId] query", () => {
+    const spy = vi.spyOn(queryClient, "invalidateQueries");
+
+    updateCacheOnMovePage("s1", "moved-page", "old-parent", "new-parent", {
+      id: "moved-page",
+    } as Partial<IPage>);
+
+    const invalidatedBreadcrumbs = spy.mock.calls.some(
+      ([arg]) =>
+        Array.isArray((arg as { queryKey?: unknown[] })?.queryKey) &&
+        (arg as { queryKey: unknown[] }).queryKey[0] === "breadcrumbs" &&
+        (arg as { queryKey: unknown[] }).queryKey[1] === "moved-page",
+    );
+    expect(invalidatedBreadcrumbs).toBe(true);
+  });
+});
@@ -55,7 +55,14 @@ type Props<T extends object> = {
 };

 const DRAG_TYPE = 'doc-tree-item';
-const AUTO_EXPAND_MS = 500;
+// Hover-hold before a collapsed row auto-expands during a drag. 2s (not ~0.5s)
+// so merely dragging the cursor THROUGH the tree never expands rows — only a
+// deliberate hold does (#523).
+const AUTO_EXPAND_MS = 2000;
+// How long the "a page just moved in here" cue stays on a collapsed target after
+// a make-child drop. Long enough to notice at a glance during frequent
+// collapsed-drops, short enough not to linger. Code-only UX constant (#523).
+const DROP_LANDED_HIGHLIGHT_MS = 1800;

 function DocTreeRowInner<T extends object>(props: Props<T>) {
  const {
@@ -93,7 +100,11 @@ function DocTreeRowInner<T extends object>(props: Props<T>) {
  const rowRef = useRef<HTMLElement>(null);
  const [isDragging, setIsDragging] = useState(false);
  const [instruction, setInstruction] = useState<Instruction | null>(null);
+  // Transient "just received a child" cue: a make-child drop no longer expands
+  // the (collapsed) target, so flash the row instead so the move isn't invisible.
+  const [landedChild, setLandedChild] = useState(false);
  const autoExpandTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
+  const landedChildTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);

  const cancelAutoExpand = useCallback(() => {
    if (autoExpandTimerRef.current) {
@@ -249,11 +260,24 @@ function DocTreeRowInner<T extends object>(props: Props<T>) {
              ? getDragLabel(sourceNode)
              : 'item';
            liveRegion.announce(`Moved ${sourceLabel} under ${parentName}.`);
-            // After a make-child drop, expand this row so the user sees the
-            // just-dropped child — especially important when the row had no
-            // children before (chevron just appeared) so the drop would
-            // otherwise be invisible.
-            if (op.kind === 'make-child') onToggle(node.id, true);
+            // Do NOT auto-expand the target on drop: a drop must leave the node
+            // collapsed. Intentional expansion is handled solely by the
+            // hover-hold timer (AUTO_EXPAND_MS). Feedback that the drop landed is
+            // given by the post-move flash + landed-cue highlight + live-region
+            // announce above. When the make-child target is collapsed, flash a
+            // distinct "child moved in here" cue on the row (it stays collapsed).
+            if (op.kind === 'make-child' && !isOpen) {
+              if (landedChildTimerRef.current) {
+                clearTimeout(landedChildTimerRef.current);
+              }
+              setLandedChild(true);
+              landedChildTimerRef.current = setTimeout(() => {
+                setLandedChild(false);
+                landedChildTimerRef.current = null;
+              }, DROP_LANDED_HIGHLIGHT_MS);
+            }
+            // Restore the openness of the MOVED page itself (source) — untouched
+            // by the above; the target is never expanded here.
            if (source.data.isOpenOnDragStart) onToggle(sourceId, true);
          },
        }),
@@ -281,6 +305,17 @@ function DocTreeRowInner<T extends object>(props: Props<T>) {

  useEffect(() => () => cancelAutoExpand(), [cancelAutoExpand]);

+  // Clear the landed-child cue timer on unmount (mirrors autoExpandTimerRef).
+  useEffect(
+    () => () => {
+      if (landedChildTimerRef.current) {
+        clearTimeout(landedChildTimerRef.current);
+        landedChildTimerRef.current = null;
+      }
+    },
+    [],
+  );
+
  const effectiveInst =
    instruction?.type === 'instruction-blocked'
      ? instruction.desired
@@ -317,6 +352,7 @@ function DocTreeRowInner<T extends object>(props: Props<T>) {
        className={styles.node}
        data-dragging={isDragging || undefined}
        data-selected={isSelected || undefined}
+        data-landed-child={landedChild || undefined}
        data-receiving-drop={
          receivingDrop === 'make-child'
            ? blocked
@@ -281,10 +281,12 @@ const SpaceTree = forwardRef<SpaceTreeApi, SpaceTreeProps>(function SpaceTree(
      setOpenTreeNodes((prev) => ({ ...prev, [id]: isOpen }));
      if (isOpen) {
        const node = treeModel.find(data, id) as SpaceTreeNode | null;
-        if (
-          node?.hasChildren &&
-          (!node.children || node.children.length === 0)
-        ) {
+        // Same "unloaded branch" predicate the realtime insert paths use
+        // (`isUnloadedBranch`) so the lazy-load gate and the realtime inserts
+        // (`insertByPosition` / `placeByPosition`) can never disagree about what
+        // counts as unloaded (#525). Note: local raw `insert` (DnD/create-page)
+        // does not yet route through it — see #525 follow-up.
+        if (treeModel.isUnloadedBranch(node)) {
          const fetched = await fetchAllAncestorChildren({
            pageId: id,
            spaceId: node.spaceId,
@@ -0,0 +1,149 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { renderHook, act } from "@testing-library/react";
+import { Provider, createStore } from "jotai";
+import type { ReactNode } from "react";
+
+import { treeDataAtom } from "@/features/page/tree/atoms/tree-data-atom.ts";
+import { treeModel } from "@/features/page/tree/model/tree-model";
+import type { SpaceTreeNode } from "@/features/page/tree/types";
+
+// --- Boundary mocks: only the network/query + router/i18n surfaces the hook
+// touches. The tree math (treeModel, dropOpToMovePayload) runs for real so the
+// child-loss guard is exercised end-to-end.
+const moveMutate = vi.fn().mockResolvedValue({});
+const updateCacheOnMovePageMock = vi.fn();
+vi.mock("@/features/page/queries/page-query.ts", () => ({
+  useCreatePageMutation: () => ({ mutateAsync: vi.fn() }),
+  useUpdatePageMutation: () => ({ mutateAsync: vi.fn() }),
+  useRemovePageMutation: () => ({ mutateAsync: vi.fn() }),
+  useMovePageMutation: () => ({ mutateAsync: moveMutate }),
+  updateCacheOnMovePage: (...args: unknown[]) =>
+    updateCacheOnMovePageMock(...args),
+}));
+vi.mock("react-router-dom", () => ({
+  useNavigate: () => vi.fn(),
+  useParams: () => ({ spaceSlug: "space", pageSlug: undefined }),
+}));
+vi.mock("react-i18next", () => ({
+  useTranslation: () => ({ t: (s: string) => s }),
+}));
+vi.mock("@mantine/notifications", () => ({
+  notifications: { show: vi.fn() },
+}));
+
+// Import AFTER mocks so the hook binds to them.
+import { useTreeMutation } from "./use-tree-mutation";
+
+function node(
+  id: string,
+  over: Partial<SpaceTreeNode> = {},
+): SpaceTreeNode {
+  return {
+    id,
+    slugId: `slug-${id}`,
+    name: id.toUpperCase(),
+    position: "a0",
+    spaceId: "space-1",
+    parentPageId: null as unknown as string,
+    hasChildren: false,
+    children: [],
+    ...over,
+  };
+}
+
+function setup(before: SpaceTreeNode[]) {
+  const store = createStore();
+  store.set(treeDataAtom, before);
+  const wrapper = ({ children }: { children: ReactNode }) => (
+    <Provider store={store}>{children}</Provider>
+  );
+  const { result } = renderHook(() => useTreeMutation("space-1"), { wrapper });
+  return { store, result };
+}
+
+describe("useTreeMutation.handleMove — child-loss guard (#523)", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    moveMutate.mockResolvedValue({});
+  });
+
+  it("make-child into an UNLOADED folder does NOT materialize [source] — keeps it lazy-loadable", async () => {
+    // F has children on the server but none are loaded here (canonical unloaded
+    // form: hasChildren + children:[]). X sits at root.
+    const before = [
+      node("F", { position: "a0", hasChildren: true, children: [] }),
+      node("X", { position: "a5" }),
+    ];
+    const { store, result } = setup(before);
+
+    await act(async () => {
+      await result.current.handleMove("X", {
+        kind: "make-child",
+        targetId: "F",
+      });
+    });
+
+    const tree = store.get(treeDataAtom);
+    const f = treeModel.find(tree, "F");
+    // The guard leaves F unloaded (children stay []), so a later expand fetches
+    // the FULL server set (incl. X) instead of showing a misleading partial [X].
+    // MUTATION: dropping the guard (using the `move` result) would put children
+    // === [X] here and redden this.
+    expect(f?.children).toEqual([]);
+    expect(f?.hasChildren).toBe(true);
+    // X is removed from its old (root) slot; it reappears on expand/load of F.
+    expect(treeModel.find(tree, "X")).toBeNull();
+    // The server move is still persisted.
+    expect(moveMutate).toHaveBeenCalledTimes(1);
+  });
+
+  it("make-child into a LOADED folder appends source and KEEPS the existing children", async () => {
+    // F is loaded with one child c1; moving X in must preserve c1 (no loss) and
+    // append X — this path does NOT hit the guard.
+    const before = [
+      node("F", {
+        position: "a0",
+        hasChildren: true,
+        children: [node("c1", { position: "a1", parentPageId: "F" })],
+      }),
+      node("X", { position: "a5" }),
+    ];
+    const { store, result } = setup(before);
+
+    await act(async () => {
+      await result.current.handleMove("X", {
+        kind: "make-child",
+        targetId: "F",
+      });
+    });
+
+    const tree = store.get(treeDataAtom);
+    const f = treeModel.find(tree, "F");
+    expect(f?.children?.map((n) => n.id)).toEqual(["c1", "X"]);
+    expect(f?.hasChildren).toBe(true);
+    // X now lives under F.
+    expect(treeModel.find(tree, "X")?.parentPageId).toBe("F");
+  });
+
+  it("make-child into a genuinely-empty leaf materializes the child (nothing to lose)", async () => {
+    // Leaf L has no server children (hasChildren:false). Dropping X in should
+    // show X immediately — the guard must NOT fire here.
+    const before = [
+      node("L", { position: "a0", hasChildren: false, children: [] }),
+      node("X", { position: "a5" }),
+    ];
+    const { store, result } = setup(before);
+
+    await act(async () => {
+      await result.current.handleMove("X", {
+        kind: "make-child",
+        targetId: "L",
+      });
+    });
+
+    const tree = store.get(treeDataAtom);
+    const l = treeModel.find(tree, "L");
+    expect(l?.children?.map((n) => n.id)).toEqual(["X"]);
+    expect(l?.hasChildren).toBe(true);
+  });
+});
@@ -61,11 +61,48 @@ export function useTreeMutation(spaceId: string): UseTreeMutation {
      if (!source) return;
      const oldParentId = source.parentPageId ?? null;

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

      // If the old parent has no children left, mark hasChildren: false so the
      // chevron disappears. Without this, the empty parent keeps rendering an
@@ -79,14 +116,6 @@ export function useTreeMutation(spaceId: string): UseTreeMutation {
        }
      }

-      // For make-child onto a previously-childless target: flip hasChildren on
-      // so the new parent shows its chevron.
-      if (op.kind === "make-child") {
-        optimistic = treeModel.update(optimistic, op.targetId, {
-          hasChildren: true,
-        } as Partial<SpaceTreeNode>);
-      }
-
      setData(optimistic);

      try {
@@ -74,6 +74,48 @@ describe("treeModel.isDescendant", () => {
  });
 });

+// #525: the single "is this branch unloaded?" predicate shared by the lazy-load
+// gate and the insert paths. Unloaded == server says hasChildren but none are
+// present locally (canonical form `children: []`, also `undefined`). A parent
+// without hasChildren is genuinely empty, not unloaded.
+describe("treeModel.isUnloadedBranch", () => {
+  type PH = TreeNode<{ name: string; hasChildren?: boolean }>;
+  it("true for hasChildren + empty array (canonical unloaded form)", () => {
+    const n: PH = { id: "p", name: "P", hasChildren: true, children: [] };
+    expect(treeModel.isUnloadedBranch(n)).toBe(true);
+  });
+  it("true for hasChildren + undefined children", () => {
+    const n: PH = { id: "p", name: "P", hasChildren: true };
+    expect(treeModel.isUnloadedBranch(n)).toBe(true);
+  });
+  it("false for hasChildren + already-loaded children", () => {
+    const n: PH = {
+      id: "p",
+      name: "P",
+      hasChildren: true,
+      children: [{ id: "c", name: "C" }],
+    };
+    expect(treeModel.isUnloadedBranch(n)).toBe(false);
+  });
+  it("false for a genuinely-empty parent (no hasChildren)", () => {
+    expect(
+      treeModel.isUnloadedBranch({
+        id: "p",
+        name: "P",
+        hasChildren: false,
+        children: [],
+      } as PH),
+    ).toBe(false);
+    expect(
+      treeModel.isUnloadedBranch({ id: "p", name: "P" } as PH),
+    ).toBe(false);
+  });
+  it("false for null/undefined", () => {
+    expect(treeModel.isUnloadedBranch(null)).toBe(false);
+    expect(treeModel.isUnloadedBranch(undefined)).toBe(false);
+  });
+});
+
 describe("treeModel.visible", () => {
  it("returns only root nodes when no openIds", () => {
    const v = treeModel.visible(fixture, new Set());
@@ -197,43 +239,64 @@ describe("treeModel.insertByPosition", () => {
    ]);
  });

-  // #159 #1: inserting/moving a node under a parent whose children are NOT
-  // loaded (`children === undefined`, e.g. a collapsed page) must NOT materialize
-  // a partial `[node]` list — that would defeat the lazy-load gate and hide the
-  // parent's other real children. The node is left to be lazy-loaded; only
-  // `hasChildren` is flagged so the chevron appears.
-  it("does NOT materialize a child under an UNLOADED parent (children undefined)", () => {
-    type PH = TreeNode<{
-      name: string;
-      position?: string;
-      hasChildren?: boolean;
-    }>;
+  type PH = TreeNode<{
+    name: string;
+    position?: string;
+    hasChildren?: boolean;
+  }>;
+
+  // #159 #1 / #525: inserting/moving a node under an UNLOADED parent must NOT
+  // materialize a partial `[node]` list — that would defeat the lazy-load gate and
+  // hide the parent's other real children. The canonical unloaded form here is
+  // `children: []` + `hasChildren: true` (from `pageToTreeNode` /
+  // `pruneCollapsedChildren`), which the pre-#525 `=== undefined` guard MISSED.
+  // The node is left to be lazy-loaded; the chevron stays enabled.
+  it("does NOT materialize a child under an UNLOADED parent (children: [], hasChildren: true)", () => {
    const tree: PH[] = [
-      { id: "p", name: "P", position: "a0", hasChildren: false }, // children: undefined
+      { id: "p", name: "P", position: "a0", hasChildren: true, children: [] },
    ];
    const node: PH = { id: "x", name: "X", position: "a1" };
    const t = treeModel.insertByPosition(tree, "p", node);
    const parent = treeModel.find(t, "p");
    // The node was NOT inserted (children stay unloaded -> lazy-load fetches the
-    // full set, including this node, on expand).
-    expect(parent?.children).toBeUndefined();
+    // full set, including this node, on expand). MUTATION: the pre-#525 predicate
+    // `children === undefined` does not fire for `[]`, so it would insert `[x]`
+    // here and reredden this expectation.
+    expect(parent?.children).toEqual([]);
    expect(treeModel.find(t, "x")).toBeNull();
-    // ...but the chevron is enabled so the user can expand to load it.
+    // ...and the chevron stays enabled so the user can expand to load it.
    expect((parent as PH).hasChildren).toBe(true);
  });

-  it("DOES insert under a LOADED-but-empty parent (children: [])", () => {
-    type PH = TreeNode<{
-      name: string;
-      position?: string;
-      hasChildren?: boolean;
-    }>;
+  it("does NOT materialize a child under an UNLOADED parent (children undefined, hasChildren: true)", () => {
+    const tree: PH[] = [
+      { id: "p", name: "P", position: "a0", hasChildren: true }, // children: undefined
+    ];
+    const node: PH = { id: "x", name: "X", position: "a1" };
+    const t = treeModel.insertByPosition(tree, "p", node);
+    const parent = treeModel.find(t, "p");
+    expect(parent?.children).toBeUndefined();
+    expect(treeModel.find(t, "x")).toBeNull();
+    expect((parent as PH).hasChildren).toBe(true);
+  });
+
+  it("DOES insert under a genuinely-empty parent (children: [], hasChildren: false)", () => {
    const tree: PH[] = [
      { id: "p", name: "P", position: "a0", hasChildren: false, children: [] },
    ];
    const node: PH = { id: "x", name: "X", position: "a1" };
    const t = treeModel.insertByPosition(tree, "p", node);
-    // A loaded (empty) child list is complete, so the node IS inserted.
+    // No server children (`hasChildren: false`), so materializing the first child
+    // is correct — nothing is hidden.
+    expect(treeModel.find(t, "p")?.children?.map((n) => n.id)).toEqual(["x"]);
+  });
+
+  it("DOES insert under a genuinely-empty parent (children undefined, hasChildren: false)", () => {
+    const tree: PH[] = [
+      { id: "p", name: "P", position: "a0", hasChildren: false }, // children: undefined
+    ];
+    const node: PH = { id: "x", name: "X", position: "a1" };
+    const t = treeModel.insertByPosition(tree, "p", node);
    expect(treeModel.find(t, "p")?.children?.map((n) => n.id)).toEqual(["x"]);
  });

@@ -43,6 +43,26 @@ export const treeModel = {
    };
  },

+  // A branch is "unloaded" when the server says it HAS children (`hasChildren`)
+  // but none are present locally. The canonical unloaded form in this codebase
+  // is `children: []` (produced by `pageToTreeNode` and by `pruneCollapsedChildren`
+  // resetting collapsed branches), NOT `children: undefined` — so a predicate that
+  // only checks `=== undefined` misses the real case and materializes a misleading
+  // partial list (#525). This is the SINGLE source of truth for "should a
+  // fetch/materialize be deferred?", shared by the lazy-load gate (`handleToggle`)
+  // and the realtime insert paths (`insertByPosition` / `placeByPosition`), so they
+  // can never drift apart again. (The local raw `insert` primitive and its DnD/
+  // create-page callers do NOT yet route through this predicate — see #525
+  // follow-up.) A parent WITHOUT `hasChildren` is genuinely empty
+  // (no server children) — inserting its first child is correct, not deferred.
+  isUnloadedBranch<T extends object>(
+    node: TreeNode<T> | null | undefined,
+  ): boolean {
+    if (!node) return false;
+    const hasChildren = (node as { hasChildren?: boolean }).hasChildren === true;
+    return hasChildren && (node.children == null || node.children.length === 0);
+  },
+
  isDescendant<T extends object>(
    tree: TreeNode<T>[],
    ancestorId: string,
@@ -127,14 +147,15 @@ export const treeModel = {
    }
    const parent = treeModel.find(tree, parentId);
    // The parent is in the tree but its children have NOT been lazy-loaded yet
-    // (`children === undefined`, distinct from a loaded-but-empty `[]`). Inserting
+    // (`hasChildren` set + children absent/empty — see `isUnloadedBranch`; the
+    // canonical unloaded form is `children: []`, NOT just `undefined`). Inserting
    // here would MATERIALIZE a misleading partial child list (`[node]`) that
    // defeats the lazy-load gate — which fetches only when children are
    // absent/empty — so the parent's OTHER real children would never load and the
    // moved/added node would be the only one shown (a silent data loss, #159 #1).
    // Instead, leave the children unloaded and just flag `hasChildren` so the
    // chevron appears; expanding fetches the FULL set (including this node).
-    if (parent && parent.children === undefined) {
+    if (parent && treeModel.isUnloadedBranch(parent)) {
      return treeModel.update(
        tree,
        parentId,
@@ -150,6 +150,45 @@
    );
 }

+/* "A page just moved in here" cue (#523). A make-child drop no longer expands
+   the collapsed target, so the moved page is momentarily invisible; pulse the
+   target row in a distinct teal (NOT the blue make-child highlight, NOT the
+   neutral post-move flash) so the landing is noticeable while the node stays
+   collapsed. Two short pulses fit inside DROP_LANDED_HIGHLIGHT_MS (1.8s), after
+   which the row clears the attribute and the animation stops. */
+@keyframes landedChildPulse {
+    0% {
+        background-color: light-dark(
+            var(--mantine-color-teal-2),
+            rgba(45, 212, 191, 0.30)
+        );
+        outline-color: light-dark(
+            var(--mantine-color-teal-6),
+            var(--mantine-color-teal-5)
+        );
+    }
+    100% {
+        background-color: transparent;
+        outline-color: transparent;
+    }
+}
+
+.node[data-landed-child="true"] {
+    outline: 2px solid transparent;
+    outline-offset: -1px;
+    animation: landedChildPulse 0.9s ease-out 2;
+}
+
+@media (prefers-reduced-motion: reduce) {
+    .node[data-landed-child="true"] {
+        animation: none;
+        background-color: light-dark(
+            var(--mantine-color-teal-1),
+            rgba(45, 212, 191, 0.18)
+        );
+    }
+}
+
 .dropLine {
    position: absolute;
    left: var(--drop-line-indent, 0);
@@ -82,17 +82,19 @@ describe("applyMoveTreeNode", () => {
    ]);
  });

-  it("does NOT create a partial child list when the destination is loaded-but-collapsed (children unloaded) — keeps it lazy-loadable (#159)", () => {
-    // `dstCollapsed` is in the tree but its children were never lazy-loaded
-    // (children === undefined). The OLD behavior inserted `src` as the ONLY
-    // child ([src]), which defeated the lazy-load gate and HID the parent's
-    // other real children. Now the move leaves children unloaded (so expanding
-    // fetches the FULL set, including src) and just flags hasChildren.
+  it("does NOT create a partial child list when the destination is loaded-but-collapsed (children unloaded) — keeps it lazy-loadable (#159 #525)", () => {
+    // `dstCollapsed` is in the tree but its children were never lazy-loaded. The
+    // CANONICAL unloaded form here is `hasChildren: true` + `children: []` (from
+    // `pageToTreeNode` / `pruneCollapsedChildren`), NOT `children: undefined`.
+    // The pre-#525 predicate (`children === undefined`) missed this form and
+    // inserted `src` as the ONLY child ([src]), defeating the lazy-load gate and
+    // HIDING the parent's other real children. Now the move leaves children
+    // unloaded (so expanding fetches the FULL set, including src).
    const tree: SpaceTreeNode[] = [
      node("dstCollapsed", {
        position: "a0",
-        hasChildren: false,
-        children: undefined as unknown as SpaceTreeNode[],
+        hasChildren: true,
+        children: [],
      }),
      node("src", { position: "a9" }),
    ];
@@ -105,9 +107,10 @@ describe("applyMoveTreeNode", () => {
      pageData: {},
    });
    const dst = treeModel.find(next, "dstCollapsed");
-    // Children stay unloaded -> the lazy-load gate fetches the FULL set (incl.
-    // src) on expand, rather than showing a misleading partial [src] list.
-    expect(dst?.children).toBeUndefined();
+    // Children stay unloaded ([] not materialized to [src]) -> the lazy-load gate
+    // fetches the FULL set (incl. src) on expand. MUTATION: the pre-#525
+    // `=== undefined` predicate would insert [src] here and redden this.
+    expect(dst?.children).toEqual([]);
    expect(dst?.hasChildren).toBe(true);
    // src moved away from its old root slot (it lives under dstCollapsed
    // server-side and reappears when the parent is expanded/loaded).
@@ -1,36 +1,10 @@
+export const HISTORY_INTERVAL = 5 * 60 * 1000;
+export const HISTORY_FAST_INTERVAL = 60 * 1000;
+export const HISTORY_FAST_THRESHOLD = 5 * 60 * 1000;
+
 // #348 — debounce window for the per-page RAG re-embed job. Repeated saves
 // within this window collapse to a single delayed job (coalesced by a stable
 // jobId), so active editing does not pile up expensive re-embeds (external API
 // + page_embeddings rewrite, concurrency 1). The worker reads the CURRENT page
 // state at run time, so the last content within the window wins.
 export const EMBED_DEBOUNCE_MS = 30 * 1000;
-
-/**
- * #370 — page-history intentionality tiers. Domain of `page_history.kind`.
- *   - 'manual' / 'agent'  → Tier 1 versions (intentional points)
- *   - 'idle' / 'boundary' → Tier 0 autosnapshots (safety net)
- * A legacy `null` kind is treated as an autosave.
- */
-export type PageHistoryKind = 'manual' | 'agent' | 'idle' | 'boundary';
-
-/**
- * #370 — trailing idle-flush windows. A page's pending idle snapshot is
- * re-armed on every store and fires this long after edits go quiet, so a burst
- * of edits collapses into a single autosnapshot instead of one-per-store. Human
- * sessions are noisier and less risky, so they flush less often than the agent.
- */
-export const IDLE_INTERVAL_USER = 60 * 60 * 1000; // 60m
-export const IDLE_INTERVAL_AGENT = 15 * 60 * 1000; // 15m
-
-/**
- * #370 — max-wait ceiling for the idle flush. Pure trailing debounce starves the
- * safety net: hocuspocus stores at least every ~45s, so a CONTINUOUS editing
- * session would re-arm the trailing timer forever and never take an idle
- * snapshot until edits finally go quiet (up to IDLE_INTERVAL_USER = 60m). This
- * ceiling bounds the actual wait from the FIRST edit of a burst, so an idle
- * snapshot fires at least this often during a long unbroken session — restoring
- * a recovery point cadence closer to the old heuristic without one-per-store
- * noise. Mirrors hocuspocus's own maxDebounce idea.
- */
-export const IDLE_MAX_WAIT_USER = 10 * 60 * 1000; // 10m
-export const IDLE_MAX_WAIT_AGENT = 5 * 60 * 1000; // 5m
@@ -1,93 +1,84 @@
-import { computeHistoryJob, resolveSource } from './persistence.extension';
 import {
-  IDLE_INTERVAL_AGENT,
-  IDLE_INTERVAL_USER,
-  IDLE_MAX_WAIT_AGENT,
-  IDLE_MAX_WAIT_USER,
+  computeHistoryJob,
+  resolveSource,
+} from './persistence.extension';
+import {
+  HISTORY_FAST_INTERVAL,
+  HISTORY_FAST_THRESHOLD,
+  HISTORY_INTERVAL,
 } from '../constants';

+// A fixed clock + fixed createdAt make pageAge deterministic.
+const NOW = 1_700_000_000_000;
 const PAGE_ID = '550e8400-e29b-41d4-a716-446655440000';

-const page = { id: PAGE_ID };
+// Build a minimal page whose age (NOW - createdAt) is exactly `ageMs`.
+const pageAged = (ageMs: number) => ({
+  id: PAGE_ID,
+  createdAt: new Date(NOW - ageMs),
+});

-describe('computeHistoryJob (#370 — shared trailing idle pipeline)', () => {
-  it('human edit → user idle window, bare page.id job', () => {
-    // Humans and the agent now share ONE idle job per page (jobId = page.id).
-    // The agent's old delay=0 fast path is GONE — intentional agent points now
-    // arrive via the explicit save-version signal, not a zero-delay snapshot.
-    const { jobId, delay } = computeHistoryJob(page, 'user');
-    expect(delay).toBe(IDLE_INTERVAL_USER);
+describe('computeHistoryJob', () => {
+  it('agent edit → delay MUST be 0 and job id is source-keyed', () => {
+    // INVARIANT (§15 H2 / persistence.extension): the agent delay MUST stay 0.
+    // The worker re-reads the page row at run time, so any non-zero delay risks
+    // snapshotting content a later human edit has already overwritten. This is
+    // the load-bearing assertion of this spec — do not relax it.
+    const { jobId, delay } = computeHistoryJob(pageAged(0), 'agent', NOW);
+    expect(delay).toBe(0);
+    expect(jobId).toBe(`${PAGE_ID}-agent`);
+  });
+
+  it('agent edit on an OLD page is still delay 0 (age never applies to agents)', () => {
+    // Even when the page is far older than the fast threshold, the agent path
+    // must short-circuit to 0 — age-based debounce is a human-only concern.
+    const { jobId, delay } = computeHistoryJob(
+      pageAged(HISTORY_FAST_THRESHOLD + 60_000),
+      'agent',
+      NOW,
+    );
+    expect(delay).toBe(0);
+    expect(jobId).toBe(`${PAGE_ID}-agent`);
+  });
+
+  it('human edit on a YOUNG page (age < threshold) → fast interval, bare job id', () => {
+    const { jobId, delay } = computeHistoryJob(
+      pageAged(HISTORY_FAST_THRESHOLD - 1),
+      'user',
+      NOW,
+    );
+    expect(delay).toBe(HISTORY_FAST_INTERVAL);
    expect(jobId).toBe(PAGE_ID);
  });

-  it('agent edit → agent idle window (shorter), still the bare page.id job', () => {
-    const { jobId, delay } = computeHistoryJob(page, 'agent');
-    expect(delay).toBe(IDLE_INTERVAL_AGENT);
-    // No `-agent` suffix anymore: the agent joins the common idle pipeline.
+  it('human edit on an OLD page (age > threshold) → standard interval', () => {
+    const { jobId, delay } = computeHistoryJob(
+      pageAged(HISTORY_FAST_THRESHOLD + 1),
+      'user',
+      NOW,
+    );
+    expect(delay).toBe(HISTORY_INTERVAL);
    expect(jobId).toBe(PAGE_ID);
  });

-  it('agent flushes sooner than a human', () => {
-    expect(IDLE_INTERVAL_AGENT).toBeLessThan(IDLE_INTERVAL_USER);
+  it('boundary: pageAge EXACTLY === threshold takes the slow branch (the `<` is strict)', () => {
+    // Off-by-one guard: the condition is `pageAge < HISTORY_FAST_THRESHOLD`, so
+    // an age of exactly the threshold is NOT "fast" — it must use HISTORY_INTERVAL.
+    const { delay } = computeHistoryJob(
+      pageAged(HISTORY_FAST_THRESHOLD),
+      'user',
+      NOW,
+    );
+    expect(delay).toBe(HISTORY_INTERVAL);
  });

-  it('treats any non-"agent" source string as human (keys strictly on === agent)', () => {
-    const { jobId, delay } = computeHistoryJob(page, 'user');
-    expect(delay).toBe(IDLE_INTERVAL_USER);
+  it('treats any non-"agent" source string as human', () => {
+    // resolveSource only ever yields 'agent' | 'user', but guard the contract:
+    // the agent branch keys strictly on === 'agent'.
+    const { jobId, delay } = computeHistoryJob(pageAged(0), 'user', NOW);
+    expect(delay).toBe(HISTORY_FAST_INTERVAL);
    expect(jobId).toBe(PAGE_ID);
  });
-
-  // #370 review round-1 WARNING: the max-wait ceiling prevents autosnapshot
-  // starvation during a continuous editing session (the trailing timer would
-  // otherwise re-arm forever and never fire).
-  describe('max-wait ceiling', () => {
-    const T0 = 1_000_000; // arbitrary fixed epoch for deterministic tests
-
-    it('once a burst is armed, delay clamps to the remaining max-wait budget', () => {
-      // 1 minute into the burst the USER interval (60m) far exceeds the remaining
-      // max-wait budget (10m - 1m = 9m), so the delay is clamped DOWN to that
-      // remaining budget — the full interval is NOT used once a ceiling applies.
-      const { delay } = computeHistoryJob(page, 'user', T0, T0 + 60_000);
-      expect(delay).toBe(IDLE_MAX_WAIT_USER - 60_000);
-    });
-
-    it('never waits longer than the max-wait budget from the burst start', () => {
-      // A store arriving right at the ceiling → delay 0 (fire promptly).
-      const { delay } = computeHistoryJob(
-        page,
-        'user',
-        T0,
-        T0 + IDLE_MAX_WAIT_USER,
-      );
-      expect(delay).toBe(0);
-    });
-
-    it('past the ceiling never returns a negative delay', () => {
-      const { delay } = computeHistoryJob(
-        page,
-        'user',
-        T0,
-        T0 + IDLE_MAX_WAIT_USER + 5 * 60_000,
-      );
-      expect(delay).toBe(0);
-    });
-
-    it('the agent ceiling is shorter than the user ceiling', () => {
-      expect(IDLE_MAX_WAIT_AGENT).toBeLessThan(IDLE_MAX_WAIT_USER);
-      const { delay } = computeHistoryJob(
-        page,
-        'agent',
-        T0,
-        T0 + IDLE_MAX_WAIT_AGENT,
-      );
-      expect(delay).toBe(0);
-    });
-
-    it('without a burstStart there is no ceiling (backward-compatible)', () => {
-      expect(computeHistoryJob(page, 'user').delay).toBe(IDLE_INTERVAL_USER);
-      expect(computeHistoryJob(page, 'agent').delay).toBe(IDLE_INTERVAL_AGENT);
-    });
-  });
 });

 describe('resolveSource (truth table)', () => {
@@ -40,12 +40,11 @@ describe('PersistenceExtension.onStoreDocument — Approach-A boundary snapshot'
  let pageHistoryRepo: {
    saveHistory: jest.Mock;
    findPageLastHistory: jest.Mock;
-    updateHistoryKind: jest.Mock;
  };
  let aiQueue: { add: jest.Mock };
-  let historyQueue: { add: jest.Mock; remove: jest.Mock };
+  let historyQueue: { add: jest.Mock };
  let notificationQueue: { add: jest.Mock };
-  let collabHistory: { addContributors: jest.Mock; popContributors: jest.Mock };
+  let collabHistory: { addContributors: jest.Mock };
  let transclusionService: {
    syncPageTransclusions: jest.Mock;
    syncPageReferences: jest.Mock;
@@ -94,22 +93,13 @@ describe('PersistenceExtension.onStoreDocument — Approach-A boundary snapshot'
    pageHistoryRepo = {
      saveHistory: jest.fn().mockImplementation(async () => {
        callOrder.push('saveHistory');
-        return { id: 'history-1' };
      }),
      findPageLastHistory: jest.fn().mockResolvedValue(null),
-      updateHistoryKind: jest.fn().mockResolvedValue(undefined),
    };
    aiQueue = { add: jest.fn().mockResolvedValue(undefined) };
-    historyQueue = {
-      add: jest.fn().mockResolvedValue(undefined),
-      // #370 — enqueuePageHistory now removes any pending idle job before re-adding.
-      remove: jest.fn().mockResolvedValue(undefined),
-    };
+    historyQueue = { add: jest.fn().mockResolvedValue(undefined) };
    notificationQueue = { add: jest.fn().mockResolvedValue(undefined) };
-    collabHistory = {
-      addContributors: jest.fn().mockResolvedValue(undefined),
-      popContributors: jest.fn().mockResolvedValue([]),
-    };
+    collabHistory = { addContributors: jest.fn().mockResolvedValue(undefined) };
    transclusionService = {
      syncPageTransclusions: jest.fn().mockResolvedValue(undefined),
      syncPageReferences: jest.fn().mockResolvedValue(undefined),
@@ -175,50 +165,6 @@ describe('PersistenceExtension.onStoreDocument — Approach-A boundary snapshot'
    expect(pageRepo.updatePage.mock.calls[0][0].lastUpdatedSource).toBe('user');
  });

-  // #370 review round-1 SUGGESTION: the boundary was GENERALIZED from a
-  // user→agent special-case to ANY lastUpdatedSource transition. These pin the
-  // generalized behaviour it was rebuilt for.
-  describe('generalized boundary — any source transition', () => {
-    // Same persisted page but with an explicit prior source.
-    const pageWithPriorSource = (prior: string | null) => ({
-      ...persistedHumanPage('NEW CONTENT'),
-      lastUpdatedSource: prior,
-    });
-
-    it('agent→user transition fires the boundary (pins the prior agent revision)', async () => {
-      const document = ydocFor(doc('NEW CONTENT'));
-      pageRepo.findById.mockResolvedValue(pageWithPriorSource('agent'));
-      pageHistoryRepo.findPageLastHistory.mockResolvedValue(null);
-
-      await ext.onStoreDocument(buildData(document, 'user') as any);
-
-      expect(pageHistoryRepo.saveHistory).toHaveBeenCalledTimes(1);
-      expect(callOrder).toEqual(['saveHistory', 'updatePage']);
-      expect(pageRepo.updatePage.mock.calls[0][0].lastUpdatedSource).toBe('user');
-    });
-
-    it('git→user transition fires the boundary (git-sync overwrite is a source change)', async () => {
-      const document = ydocFor(doc('NEW CONTENT'));
-      pageRepo.findById.mockResolvedValue(pageWithPriorSource('git'));
-      pageHistoryRepo.findPageLastHistory.mockResolvedValue(null);
-
-      await ext.onStoreDocument(buildData(document, 'user') as any);
-
-      expect(pageHistoryRepo.saveHistory).toHaveBeenCalledTimes(1);
-      expect(callOrder).toEqual(['saveHistory', 'updatePage']);
-    });
-
-    it('a null prior source (first-ever edit) does NOT fire the boundary', async () => {
-      const document = ydocFor(doc('NEW CONTENT'));
-      pageRepo.findById.mockResolvedValue(pageWithPriorSource(null));
-
-      await ext.onStoreDocument(buildData(document, 'agent') as any);
-
-      expect(pageHistoryRepo.saveHistory).not.toHaveBeenCalled();
-      expect(pageRepo.updatePage).toHaveBeenCalledTimes(1);
-    });
-  });
-
  it('idempotency: unchanged content → no updatePage, no history, no queues', async () => {
    // The Y.Doc content equals the persisted content deeply → early skip.
    // A Y.Doc round-trip normalizes attrs (e.g. paragraph indent), so derive
@@ -533,231 +479,4 @@ describe('PersistenceExtension.onStoreDocument — Approach-A boundary snapshot'
    // Contributors keyed by the UUID so they match the PAGE_HISTORY job (page.id).
    expect(collabHistory.addContributors.mock.calls[0][0]).toBe(PAGE_ID);
  });
-
-  // #370 — explicit save-version (Cmd+S / agent save tool) over the stateless
-  // seam. The tier is derived from the SIGNED connection actor, the store path
-  // is reused, and promote-not-dup avoids duplicating heavy content rows.
-  describe('save-version (#370)', () => {
-    const emitSave = (document: any, actor: 'user' | 'agent') =>
-      ext.onStateless({
-        connection: {
-          readOnly: false,
-          context: { user: { id: USER_ID, name: 'Alice' }, actor },
-        } as any,
-        documentName: `page.${PAGE_ID}`,
-        document: document as any,
-        payload: JSON.stringify({ type: 'save-version' }),
-      } as any);
-
-    // findById returns a page whose content already equals the live doc, so the
-    // store path is a no-op and we isolate the versioning decision.
-    const pageMatchingDoc = (document: any) => ({
-      ...persistedHumanPage('IGNORED'),
-      content: TiptapTransformer.fromYdoc(document, 'default'),
-    });
-
-    it('human save with no prior snapshot → writes a manual version + broadcasts', async () => {
-      const document = ydocFor(doc('VERSION ME'));
-      pageRepo.findById.mockResolvedValue(pageMatchingDoc(document));
-      pageHistoryRepo.findPageLastHistory.mockResolvedValue(null);
-
-      await emitSave(document, 'user');
-
-      expect(pageHistoryRepo.saveHistory).toHaveBeenCalledTimes(1);
-      expect(pageHistoryRepo.saveHistory.mock.calls[0][1]).toEqual(
-        expect.objectContaining({ kind: 'manual' }),
-      );
-      // The pending idle autosnapshot is cancelled by the explicit version.
-      expect(historyQueue.remove).toHaveBeenCalledWith(PAGE_ID);
-      const msg = JSON.parse(
-        (document as any).broadcastStateless.mock.calls[(document as any).broadcastStateless.mock.calls.length - 1][0],
-      );
-      expect(msg).toMatchObject({
-        type: 'version.saved',
-        kind: 'manual',
-        alreadySaved: false,
-      });
-    });
-
-    it('agent save derives kind=agent from the signed actor', async () => {
-      const document = ydocFor(doc('AGENT VERSION'));
-      pageRepo.findById.mockResolvedValue(pageMatchingDoc(document));
-      pageHistoryRepo.findPageLastHistory.mockResolvedValue(null);
-
-      await emitSave(document, 'agent');
-
-      expect(pageHistoryRepo.saveHistory.mock.calls[pageHistoryRepo.saveHistory.mock.calls.length - 1][1]).toEqual(
-        expect.objectContaining({ kind: 'agent' }),
-      );
-    });
-
-    it('promote-not-dup: latest snapshot is an autosave with identical content → upgrades in place', async () => {
-      const document = ydocFor(doc('SAME'));
-      const page = pageMatchingDoc(document);
-      pageRepo.findById.mockResolvedValue(page);
-      pageHistoryRepo.findPageLastHistory.mockResolvedValue({
-        id: 'auto-1',
-        content: page.content,
-        kind: 'idle',
-      });
-
-      await emitSave(document, 'user');
-
-      // No heavy new content row — the existing autosave is promoted to manual.
-      expect(pageHistoryRepo.updateHistoryKind).toHaveBeenCalledWith(
-        'auto-1',
-        'manual',
-        expect.anything(),
-      );
-      expect(pageHistoryRepo.saveHistory).not.toHaveBeenCalled();
-      const msg = JSON.parse(
-        (document as any).broadcastStateless.mock.calls[(document as any).broadcastStateless.mock.calls.length - 1][0],
-      );
-      expect(msg).toMatchObject({ historyId: 'auto-1', alreadySaved: false });
-    });
-
-    it('no-op when the latest snapshot is already a manual version of this content', async () => {
-      const document = ydocFor(doc('ALREADY SAVED'));
-      const page = pageMatchingDoc(document);
-      pageRepo.findById.mockResolvedValue(page);
-      pageHistoryRepo.findPageLastHistory.mockResolvedValue({
-        id: 'ver-1',
-        content: page.content,
-        kind: 'manual',
-      });
-
-      await emitSave(document, 'user');
-
-      expect(pageHistoryRepo.updateHistoryKind).not.toHaveBeenCalled();
-      expect(pageHistoryRepo.saveHistory).not.toHaveBeenCalled();
-      const msg = JSON.parse(
-        (document as any).broadcastStateless.mock.calls[(document as any).broadcastStateless.mock.calls.length - 1][0],
-      );
-      expect(msg).toMatchObject({ alreadySaved: true, kind: 'manual' });
-    });
-
-    it('a read-only connection cannot save a version', async () => {
-      const document = ydocFor(doc('READER'));
-      pageRepo.findById.mockResolvedValue(pageMatchingDoc(document));
-
-      await ext.onStateless({
-        connection: {
-          readOnly: true,
-          context: { user: { id: USER_ID }, actor: 'user' },
-        } as any,
-        documentName: `page.${PAGE_ID}`,
-        document: document as any,
-        payload: JSON.stringify({ type: 'save-version' }),
-      } as any);
-
-      expect(pageHistoryRepo.saveHistory).not.toHaveBeenCalled();
-      expect(pageHistoryRepo.updateHistoryKind).not.toHaveBeenCalled();
-    });
-
-    // #370 F8-twin — a COMMIT abort (serialization/deadlock/conn-drop) rejects
-    // OUTSIDE the tx callback, AFTER the destructive popContributors (SPOP) and
-    // saveHistory ran but the INSERT rolled back. onStateless has no retry, so
-    // the outer catch MUST re-add (SADD) the popped set or attribution is lost
-    // irrecoverably. MUTATION: drop the outer catch → addContributors is never
-    // called → this reddens.
-    it('restores popped contributors when the commit aborts after the callback', async () => {
-      const document = ydocFor(doc('VERSION ME'));
-      pageRepo.findById.mockResolvedValue(pageMatchingDoc(document));
-      // No matching snapshot → fresh version branch → pops contributors.
-      pageHistoryRepo.findPageLastHistory.mockResolvedValue(null);
-      collabHistory.popContributors.mockResolvedValue(['u1', 'u2']);
-
-      // A db whose commit REJECTS after the callback body resolved: the SPOP and
-      // saveHistory already ran, then the tx aborts. onStoreDocument's flush uses
-      // the same db but its content matches (no-op branch) and its own retry loop
-      // swallows the throw, so only the versioning tx exercises the restore.
-      const commitFailingDb = {
-        transaction: () => ({
-          execute: async (fn: (trx: any) => Promise<any>) => {
-            await fn(trxStub);
-            throw new Error('commit aborted (serialization_failure)');
-          },
-        }),
-      };
-      const ext2 = new PersistenceExtension(
-        pageRepo as any,
-        pageHistoryRepo as any,
-        commitFailingDb as any,
-        aiQueue as any,
-        historyQueue as any,
-        notificationQueue as any,
-        collabHistory as any,
-        transclusionService as any,
-      );
-      jest.spyOn(ext2['logger'], 'debug').mockImplementation(() => undefined);
-      jest.spyOn(ext2['logger'], 'warn').mockImplementation(() => undefined);
-      jest.spyOn(ext2['logger'], 'error').mockImplementation(() => undefined);
-
-      await expect(
-        ext2.onStateless({
-          connection: {
-            readOnly: false,
-            context: { user: { id: USER_ID, name: 'Alice' }, actor: 'user' },
-          } as any,
-          documentName: `page.${PAGE_ID}`,
-          document: document as any,
-          payload: JSON.stringify({ type: 'save-version' }),
-        } as any),
-      ).rejects.toThrow();
-
-      // Attribution preserved: the popped set is SADD-restored, keyed by the page
-      // UUID it was popped under.
-      expect(collabHistory.addContributors).toHaveBeenCalledWith(PAGE_ID, [
-        'u1',
-        'u2',
-      ]);
-    });
-
-    // #370 #260 — for a `page.<slugId>` document the idle job is armed under the
-    // page UUID (computeHistoryJob's jobId = page.id), so the supersede-remove
-    // must target page.id, not the raw slugId doc-name id, or it silently misses.
-    it('cancels the superseded idle job by the page UUID for a slugId doc', async () => {
-      const SLUG = 'slug-1'; // persistedHumanPage.slugId
-      const document = ydocFor(doc('VERSION ME'));
-      pageRepo.findById.mockResolvedValue(pageMatchingDoc(document));
-      pageHistoryRepo.findPageLastHistory.mockResolvedValue(null);
-
-      await ext.onStateless({
-        connection: {
-          readOnly: false,
-          context: { user: { id: USER_ID, name: 'Alice' }, actor: 'user' },
-        } as any,
-        documentName: `page.${SLUG}`,
-        document: document as any,
-        payload: JSON.stringify({ type: 'save-version' }),
-      } as any);
-
-      // remove() keyed by the UUID (the real jobId), never the slugId.
-      expect(historyQueue.remove).toHaveBeenCalledWith(PAGE_ID);
-      expect(historyQueue.remove).not.toHaveBeenCalledWith(SLUG);
-    });
-  });
-
-  // #370 — the in-memory idle-burst marker must be dropped on doc unload (like
-  // its sibling per-document maps) or it grows unbounded for every page that was
-  // edited but never manually saved. MUTATION: drop the afterUnloadDocument
-  // delete → the entry survives → this reddens.
-  describe('idleBurstStart housekeeping', () => {
-    it('afterUnloadDocument clears the idle-burst marker armed by a store', async () => {
-      const document = ydocFor(doc('EDIT'));
-      pageRepo.findById.mockResolvedValue(persistedHumanPage('EDIT'));
-
-      await ext.onStoreDocument(buildData(document, 'user') as any);
-
-      const map = ext['idleBurstStart'] as Map<string, number>;
-      // Keyed by documentName (buildData uses `page.${PAGE_ID}`).
-      expect(map.has(`page.${PAGE_ID}`)).toBe(true);
-
-      await ext.afterUnloadDocument({
-        documentName: `page.${PAGE_ID}`,
-      } as any);
-
-      expect(map.has(`page.${PAGE_ID}`)).toBe(false);
-    });
-  });
 });
@@ -37,11 +37,9 @@ import { Page } from '@docmost/db/types/entity.types';
 import { CollabHistoryService } from '../services/collab-history.service';
 import {
  EMBED_DEBOUNCE_MS,
-  IDLE_INTERVAL_AGENT,
-  IDLE_INTERVAL_USER,
-  IDLE_MAX_WAIT_AGENT,
-  IDLE_MAX_WAIT_USER,
-  PageHistoryKind,
+  HISTORY_FAST_INTERVAL,
+  HISTORY_FAST_THRESHOLD,
+  HISTORY_INTERVAL,
 } from '../constants';
 import { TransclusionService } from '../../core/page/transclusion/transclusion.service';
 import {
@@ -58,16 +56,6 @@ import { hasTransclusionFamilyNodes } from '../../core/page/transclusion/utils/t
 */
 export const INTENTIONAL_CLEAR_MESSAGE_TYPE = 'intentional-clear';

-/**
- * #370 — wire format of the client→server "save a version" signal. Sent by the
- * human (Cmd+S / Save button) and by the agent's explicit save tool over the
- * SAME stateless channel. The intentionality tier ('manual' vs 'agent') is
- * derived SERVER-SIDE from the signed connection actor, never from this
- * payload, so a version's type is unforgeable. The document is taken from the
- * connection (not the payload), so the signal cannot be aimed at another page.
- */
-export const SAVE_VERSION_MESSAGE_TYPE = 'save-version';
-
 /**
 * #251 — how long an intentional-clear signal stays "pending" before it is
 * ignored. The signal is set on the clearing keystroke but consumed by the
@@ -104,39 +92,35 @@ export function resolveSource(
 }

 /**
- * #370 — compute the BullMQ job id + delay for a page's trailing idle-flush
- * autosnapshot. Pure so the timing is unit-testable.
+ * Compute the BullMQ job id + delay for a page-history snapshot job. Pure so
+ * the data-loss-sensitive timing arithmetic is unit-testable; `now` is injected
+ * (caller passes `Date.now()`) for determinism.
 *
- * Both humans and the agent now share ONE idle pipeline (the agent's old
- * `delay=0` fast path is gone — intentional agent points arrive via the
- * explicit save-version signal instead). The job id is the bare `page.id`, so a
- * page has at most one pending idle job; the caller removes-and-re-adds it on
- * every store to keep it debounced to the trailing edge of an edit burst. The
- * window differs by source only: the agent flushes sooner than a human.
+ * - Agent edits: delay 0 and a source-keyed job id `${page.id}-agent`. The
+ *   delay MUST stay 0 — the worker re-reads the page row at run time, so any
+ *   delay risks reading content a later human edit has already overwritten
+ *   (mis-tagged snapshot). 0 minimizes that window. The `-agent` suffix keeps
+ *   the job from coalescing with the bare-page.id human job.
+ * - Human edits: age-based debounce so rapid human edits coalesce into one
+ *   snapshot; job id is the bare `page.id`.
+ *
+ * BullMQ forbids ':' in custom job ids (Redis key separator), so '-' is used;
+ * page.id is a UUID, so `${page.id}-agent` cannot collide with a human job.
 */
 export function computeHistoryJob(
-  page: Pick<Page, 'id'>,
+  page: Pick<Page, 'id' | 'createdAt'>,
  source: string,
-  // Epoch ms of the FIRST edit in the current burst (when the pending idle job
-  // was first armed). Used to enforce the max-wait ceiling so a continuous
-  // editing session cannot re-arm the trailing timer forever. `now` is injectable
-  // for tests; both default to a live clock / no ceiling when omitted.
-  burstStart?: number,
-  now: number = Date.now(),
+  now: number,
 ): { jobId: string; delay: number } {
  const isAgent = source === 'agent';
-  const interval = isAgent ? IDLE_INTERVAL_AGENT : IDLE_INTERVAL_USER;
-  const maxWait = isAgent ? IDLE_MAX_WAIT_AGENT : IDLE_MAX_WAIT_USER;
-
-  let delay = interval;
-  if (burstStart !== undefined) {
-    // Time already elapsed since the burst's first edit; the snapshot must fire
-    // no later than `maxWait` after that, so shrink the trailing delay to the
-    // remaining budget (never negative, so BullMQ fires it promptly).
-    const remaining = burstStart + maxWait - now;
-    delay = Math.max(0, Math.min(interval, remaining));
-  }
-  return { jobId: page.id, delay };
+  const pageAge = now - new Date(page.createdAt).getTime();
+  const delay = isAgent
+    ? 0
+    : pageAge < HISTORY_FAST_THRESHOLD
+      ? HISTORY_FAST_INTERVAL
+      : HISTORY_INTERVAL;
+  const jobId = isAgent ? `${page.id}-agent` : page.id;
+  return { jobId, delay };
 }

@Injectable()
@@ -148,28 +132,6 @@ export class PersistenceExtension implements Extension {
  // coalescing window" per document and OR it across all edits in the window,
  // so the snapshot is marked 'agent' regardless of who wrote last.
  private agentTouched: Map<string, boolean> = new Map();
-  // #370 — epoch ms of the FIRST edit in the current idle-flush burst. Keyed by
-  // documentName (like its sibling per-document maps above), NOT by page.id, so
-  // it can be cleaned in afterUnloadDocument alongside `contributors` /
-  // `agentTouched` / `intentionalClear` when the doc unloads — otherwise any page
-  // that was edited but never manually saved (the common case) would keep its
-  // entry forever and the Map would grow unbounded in this long-lived process.
-  // Set when the pending idle job is first armed (empty entry), read to enforce
-  // the max-wait ceiling in computeHistoryJob, and cleared on doc unload or when
-  // a manual save cancels the idle job so the next burst starts a fresh window.
-  //
-  // Single-process assumption (like `contributors` / `agentTouched` above): this
-  // lives only in THIS collab process's memory. A restart, or a page's ownership
-  // moving to another node, loses the burst-start marker. Consequence: a burst
-  // that spans the restart looks like a fresh burst to the surviving process, so
-  // its max-wait ceiling is re-anchored to the first post-restart edit — a single
-  // continuous session straddling a restart can therefore wait up to ~2× the cap
-  // for its idle snapshot (once for the lost pre-restart window, once for the new
-  // one). Bounded and benign (it only DELAYS a safety-net autosnapshot; manual
-  // saves are unaffected and the next quiet period always flushes), but the
-  // assumption and its consequence are recorded here so no one mistakes the
-  // in-memory marker for a durable, cross-process guarantee.
-  private idleBurstStart: Map<string, number> = new Map();
  // #251 — per-document "intentional clear pending" flags. Keyed by
  // documentName, value = expiry timestamp (ms). Set by onStateless when the
  // client reports a deliberate clear; consumed once by the next
@@ -401,19 +363,20 @@ export class PersistenceExtension implements Extension {
            //this.logger.debug('Contributors error:' + err?.['message']);
          }

-          // #370 — boundary snapshot on ANY source transition. When the store
-          // flips the page's provenance (user↔agent↔git), pin the OUTGOING
-          // state as its own history version BEFORE the incoming source
-          // overwrites it. `page` still holds the OLD content/provenance here,
-          // so saveHistory(page) captures the pre-transition state tagged with
-          // its own source, kind='boundary'. The incoming content is snapshotted
-          // later by the debounced idle job. Skip if the page is effectively
-          // empty or if the latest existing snapshot already equals this state
-          // (the shared isDeepStrictEqual gate — avoids duplicates). Generalizing
-          // beyond the old user→agent special-case also covers git-sync for free.
+          // Approach A — boundary snapshot before the agent's first edit.
+          // When this store is the agent's and the page's currently persisted
+          // state was authored by a human, pin that human state as its own
+          // history version BEFORE the agent overwrites it. `page` still holds
+          // the OLD content/provenance here, so saveHistory(page) captures the
+          // pre-agent state tagged 'user'. The agent's new content is
+          // snapshotted later by the debounced PAGE_HISTORY job ('agent'). Skip
+          // if the prior state is already agent-authored (boundary already
+          // pinned on the user->agent transition), if the page is effectively
+          // empty, or if the latest existing snapshot already equals this human
+          // state (avoid duplicates).
          if (
-            page.lastUpdatedSource &&
-            page.lastUpdatedSource !== lastUpdatedSource
+            lastUpdatedSource === 'agent' &&
+            page.lastUpdatedSource !== 'agent'
          ) {
            // pageHistory.pageId is uuid-typed; use page.id (never the doc-name
            // slugId) so a `page.<slugId>` doc cannot throw 22P02 here (#260).
@@ -421,13 +384,15 @@ export class PersistenceExtension implements Extension {
              page.id,
              { includeContent: true, trx },
            );
-            const baselineMissing =
+            const humanBaselineMissing =
              !lastHistory ||
              !isDeepStrictEqual(lastHistory.content, page.content);
-            if (!isEmptyParagraphDoc(page.content as any) && baselineMissing) {
+            if (
+              !isEmptyParagraphDoc(page.content as any) &&
+              humanBaselineMissing
+            ) {
              await this.pageHistoryRepo.saveHistory(page, {
                contributorIds: page.contributorIds ?? undefined,
-                kind: 'boundary',
                trx,
              });
            }
@@ -557,7 +522,7 @@ export class PersistenceExtension implements Extension {
        { jobId: `embed-${page.id}`, delay: EMBED_DEBOUNCE_MS },
      );

-      await this.enqueuePageHistory(page, documentName, lastUpdatedSource);
+      await this.enqueuePageHistory(page, lastUpdatedSource);
    }

    // #402 — report the serialized size for the store histogram's size_bucket.
@@ -589,14 +554,6 @@ export class PersistenceExtension implements Extension {
      return; // unrelated / malformed stateless message
    }

-    // #370 — explicit "save a version" (human Cmd+S / agent save tool). Edit
-    // rights are already enforced by the readOnly reject above (a reader can't
-    // create a version), exactly as intentional-clear requires.
-    if (message?.type === SAVE_VERSION_MESSAGE_TYPE) {
-      await this.handleSaveVersion(data);
-      return;
-    }
-
    if (message?.type !== INTENTIONAL_CLEAR_MESSAGE_TYPE) return;

    this.intentionalClear.set(
@@ -605,160 +562,6 @@ export class PersistenceExtension implements Extension {
    );
  }

-  /**
-   * #370 — persist an intentional version from the live in-memory ydoc.
-   *
-   * One stateless path serves BOTH the human and the agent; the tier is derived
-   * SERVER-SIDE from the signed connection actor ('agent' → 'agent', anything
-   * else → 'manual'), so the version type cannot be spoofed by the client. We
-   * take the fresh ydoc from the collab process memory and run it through the
-   * EXISTING store path first (so pages.content/ydoc reflect the exact content
-   * being versioned — a REST endpoint would race the up-to-10s-stale page row),
-   * then snapshot it into page_history with the intentional kind.
-   *
-   * Promote-not-dup: if the latest history row already holds this exact content
-   * and it is an autosave (idle/boundary/legacy-null), upgrade its kind in place
-   * instead of duplicating a heavy content row; if it is already 'manual', it is
-   * a no-op (the client shows an "already saved" toast). Otherwise a fresh
-   * version row is written, popping the aggregated contributors from Redis.
-   */
-  private async handleSaveVersion(data: onStatelessPayload): Promise<void> {
-    const { connection, document, documentName } = data;
-    const context = connection?.context;
-    const pageId = getPageId(documentName);
-    // Unforgeable: 'agent' only for a signed agent connection, else 'manual'.
-    const kind: PageHistoryKind =
-      context?.actor === 'agent' ? 'agent' : 'manual';
-
-    // Flush the live ydoc through the normal store path so the page row + ydoc
-    // hold exactly what we are about to version (also fires the idle enqueue we
-    // supersede below, plus any source-transition boundary). onStoreDocument
-    // only needs document/documentName/context.
-    await this.onStoreDocument({
-      document,
-      documentName,
-      context,
-    } as onStoreDocumentPayload);
-
-    let result:
-      | { historyId: string; kind: PageHistoryKind; alreadySaved: boolean }
-      | undefined;
-
-    // #370 F8-twin — the contributor set popped from Redis (destructive SPOP)
-    // must be restored if the version row does not durably land. The inner
-    // try/catch below only covers a throw INSIDE the callback; but executeTx
-    // COMMITS after the callback, so a commit-abort (serialization/deadlock/
-    // connection drop — the transient class the epic retries in the processor)
-    // rejects OUTSIDE the callback, after saveHistory already ran and the SPOP
-    // already happened, while the INSERT rolls back. onStateless does NOT retry,
-    // so an unrestored pop is a one-shot irrecoverable attribution loss (the
-    // processor got exactly this fix: poppedForRestore + an outer catch). We
-    // track the popped set here (keyed by the page UUID it was popped by — never
-    // the doc-name id, which may be a slugId, #260) and restore it in the outer
-    // catch. addContributors is an idempotent Redis SADD, so a double-restore is
-    // harmless. versionedPageId is also reused below to remove the superseded
-    // idle job by its real jobId (page.id).
-    let poppedForRestore: string[] = [];
-    let versionedPageId: string | undefined;
-
-    try {
-      await executeTx(this.db, async (trx) => {
-        const page = await this.pageRepo.findById(pageId, {
-          withLock: true,
-          includeContent: true,
-          trx,
-        });
-        if (!page) return;
-        versionedPageId = page.id;
-        // Never version an effectively-empty page (mirrors the processor's
-        // first-history guard); there is nothing intentional to pin.
-        if (isEmptyParagraphDoc(page.content as any)) return;
-
-        const lastHistory = await this.pageHistoryRepo.findPageLastHistory(
-          page.id,
-          { includeContent: true, trx },
-        );
-
-        if (
-          lastHistory &&
-          isDeepStrictEqual(lastHistory.content, page.content)
-        ) {
-          // Content is already snapshotted. Promote-not-dup.
-          if (lastHistory.kind === 'manual') {
-            result = {
-              historyId: lastHistory.id,
-              kind: 'manual',
-              alreadySaved: true,
-            };
-            return;
-          }
-          await this.pageHistoryRepo.updateHistoryKind(
-            lastHistory.id,
-            kind,
-            trx,
-          );
-          result = { historyId: lastHistory.id, kind, alreadySaved: false };
-          return;
-        }
-
-        // Fresh version row. Pop the contributors aggregated since the last
-        // snapshot (SPOP); restore them if the write fails so they aren't lost.
-        const contributorIds = await this.collabHistory.popContributors(
-          page.id,
-        );
-        poppedForRestore = contributorIds;
-        try {
-          const saved = await this.pageHistoryRepo.saveHistory(page, {
-            contributorIds,
-            kind,
-            trx,
-          });
-          result = { historyId: saved.id, kind, alreadySaved: false };
-        } catch (err) {
-          await this.collabHistory.addContributors(page.id, contributorIds);
-          poppedForRestore = [];
-          throw err;
-        }
-      });
-    } catch (err) {
-      // A throw here means the tx did NOT commit (callback threw, or the commit
-      // itself failed and rolled back). If we popped contributors and the inner
-      // catch did not already restore them, restore now so attribution is not
-      // lost — onStateless has no retry to recover it. Restore by the page UUID
-      // the pop was keyed under (versionedPageId is always set before the pop).
-      if (poppedForRestore.length && versionedPageId) {
-        await this.collabHistory.addContributors(
-          versionedPageId,
-          poppedForRestore,
-        );
-      }
-      throw err;
-    }
-
-    // Housekeeping: this explicit version supersedes the page's pending idle
-    // autosnapshot, so cancel it and end the current idle burst so the next edit
-    // starts a fresh max-wait window. Remove the idle job by its REAL jobId
-    // (page.id UUID — computeHistoryJob arms it under page.id), not the raw
-    // doc-name id which may be a slugId for a `page.<slugId>` doc (#260), or the
-    // remove silently misses. The burst marker is keyed by documentName (like its
-    // sibling per-document maps), and is also cleaned in afterUnloadDocument.
-    if (versionedPageId) {
-      await this.historyQueue.remove(versionedPageId).catch(() => undefined);
-    }
-    this.idleBurstStart.delete(documentName);
-
-    if (result) {
-      document.broadcastStateless(
-        JSON.stringify({
-          type: 'version.saved',
-          historyId: result.historyId,
-          kind: result.kind,
-          alreadySaved: result.alreadySaved,
-        }),
-      );
-    }
-  }
-
  async onChange(data: onChangePayload) {
    const documentName = data.documentName;
    const userId = data.context?.user?.id;
@@ -783,10 +586,6 @@ export class PersistenceExtension implements Extension {
    this.contributors.delete(documentName);
    this.agentTouched.delete(documentName);
    this.intentionalClear.delete(documentName);
-    // #370 — drop the idle-burst marker with the other per-document maps so it
-    // cannot accumulate across the process lifetime for never-manually-saved
-    // pages. The pending idle job (if any) is a self-expiring BullMQ delayed job.
-    this.idleBurstStart.delete(documentName);
  }

  private consumeContributors(documentName: string): string[] {
@@ -818,80 +617,19 @@ export class PersistenceExtension implements Extension {

  private async enqueuePageHistory(
    page: Page,
-    documentName: string,
    lastUpdatedSource: string,
  ): Promise<void> {
-    // #370 — trailing idle debounce with a max-wait ceiling. One pending idle
-    // job per page (jobId = page.id); on every store we remove the pending
-    // delayed job and re-add it, so the snapshot lands `delay` after edits go
-    // quiet rather than once per store (precedent: workspace.service.ts).
-    // remove() on a delayed job simply deletes it (0 if absent, no throw); if the
-    // job is already ACTIVE and the remove is a no-op, the add still de-dups and
-    // the processor's isDeepStrictEqual gate collapses the duplicate content.
-    //
-    // The FIRST arm of a burst records `burstStart`; computeHistoryJob shrinks
-    // the delay to the remaining max-wait budget from that point, so a continuous
-    // session cannot re-arm the trailing timer forever and starve the snapshot.
-    // A burst marker older than THIS TIER's max-wait means the previous idle job
-    // has already fired — start a fresh window instead of firing immediately on
-    // the next edit. Must use the SAME source-specific max-wait computeHistoryJob
-    // uses (agent 5m / user 10m): a hardcoded USER ceiling would leave an agent
-    // burst's marker stale for 5..10m, forcing delay=0 on every store in that
-    // window and writing one idle row per store — exactly the per-store bloat the
-    // debounce exists to prevent, on the continuous-agent path.
-    const maxWait =
-      lastUpdatedSource === 'agent' ? IDLE_MAX_WAIT_AGENT : IDLE_MAX_WAIT_USER;
-    const now = Date.now();
-    // Keyed by documentName (see the map declaration) so afterUnloadDocument can
-    // clean it; the queue jobId stays page.id (computeHistoryJob) as required.
-    let burstStart = this.idleBurstStart.get(documentName);
-    if (burstStart === undefined || now - burstStart >= maxWait) {
-      burstStart = now;
-      this.idleBurstStart.set(documentName, burstStart);
-    }
-
+    // Job id + delay arithmetic lives in the pure `computeHistoryJob` (see its
+    // doc comment for the agent-delay-0 / age-based-debounce invariants).
    const { jobId, delay } = computeHistoryJob(
      page,
      lastUpdatedSource,
-      burstStart,
-      now,
+      Date.now(),
    );

-    // remove-then-add trailing-debounce idiom, and its ONE race. We delete the
-    // pending delayed job and re-add it under the same jobId so the timer resets
-    // to the trailing edge of the burst. The race is the small window between
-    // these two awaits: if the delayed job's `delay` elapses in that gap it goes
-    // ACTIVE, and then:
-    //   - remove() on an active/locked job is a no-op (BullMQ won't yank a job a
-    //     worker holds), and our `.catch(() => undefined)` swallows that too; and
-    //   - add() with a jobId that already exists (the now-active job's id) is
-    //     DROPPED by BullMQ — a duplicate add is a no-op.
-    // So this store fails to re-arm the trailing job: the just-fired snapshot
-    // captured content up to the moment it went active, and THIS edit is left
-    // without a pending trailing job. It is bounded and self-healing — the NEXT
-    // store re-arms a fresh delayed job (the id is free again once the active job
-    // completes / removeOnComplete frees it), and the processor's
-    // isDeepStrictEqual gate collapses any content-identical duplicate. The only
-    // uncovered case is when the racing store was the LAST in the session: the
-    // tail edits made after the job went active get NO trailing snapshot until
-    // the next edit re-arms one. That is an acceptable safety-net gap (a manual
-    // Save, a source-transition boundary, or simply the next edit all still cover
-    // it), which is why the reviewer accepts documenting it here rather than
-    // adding a post-add "did the add actually arm a job?" re-check.
-    //
-    // NOTE — do NOT "unify" this with the neighbouring embed-debounce idiom
-    // (aiQueue.add of PAGE_CONTENT_UPDATED above): that one uses a STABLE jobId
-    // and NO remove(), relying purely on BullMQ coalescing a repeated add under
-    // the same id, because a re-embed only needs to eventually run once on the
-    // latest content and re-anchoring its delay on every keystroke is undesirable.
-    // THIS idiom deliberately removes-then-adds precisely to PUSH the delay back
-    // to the trailing edge on every store (a true debounce), which coalescing
-    // alone cannot do. Collapsing them would silently change the history cadence.
-    await this.historyQueue.remove(jobId).catch(() => undefined);
-
    await this.historyQueue.add(
      QueueJob.PAGE_HISTORY,
-      { pageId: page.id, kind: 'idle' } as IPageHistoryJob,
+      { pageId: page.id } as IPageHistoryJob,
      { jobId, delay },
    );
  }
@@ -66,15 +66,6 @@ describe('HistoryProcessor.process', () => {
    notificationQueue = { add: jest.fn().mockResolvedValue(undefined) };
    generalQueue = { add: jest.fn().mockResolvedValue(undefined) };

-    // #370 F3 — the processor now serializes its find+save under a page-row lock
-    // via executeTx. A db whose transaction().execute(fn) runs fn with a trx stub
-    // drives the real executeTx() helper without a database.
-    const db = {
-      transaction: () => ({
-        execute: (fn: (trx: any) => Promise<any>) => fn({ __trx: true }),
-      }),
-    };
-
    // WorkerHost's constructor reads `this.worker`; passing repos positionally
    // matches the constructor and avoids the Nest DI container.
    proc = new HistoryProcessor(
@@ -82,7 +73,6 @@ describe('HistoryProcessor.process', () => {
      pageRepo as any,
      collabHistory as any,
      watcherService as any,
-      db as any,
      notificationQueue as any,
      generalQueue as any,
    );
@@ -136,26 +126,15 @@ describe('HistoryProcessor.process', () => {
    await proc.process(buildJob());

    expect(collabHistory.popContributors).toHaveBeenCalledWith(PAGE_ID);
-    // #370 F3/F9 — the snapshot decision runs under a page-row lock. Pin the lock
-    // structurally so a refactor that drops withLock/trx (silently reintroducing
-    // the TOCTOU double-insert) turns this red. The tx stub is { __trx: true }.
-    expect(pageRepo.findById).toHaveBeenCalledWith(
-      PAGE_ID,
-      expect.objectContaining({ withLock: true, trx: { __trx: true } }),
-    );
-    // #370 F7 — addPageWatchers MUST receive the trx, or its FK-check runs on a
-    // separate connection and self-deadlocks against our FOR UPDATE. Asserting
-    // the trx arg here is exactly what would have caught that regression.
    expect(watcherService.addPageWatchers).toHaveBeenCalledWith(
      ['u1', 'u2'],
      PAGE_ID,
      SPACE_ID,
      WORKSPACE_ID,
-      { __trx: true },
    );
    expect(pageHistoryRepo.saveHistory).toHaveBeenCalledWith(
      expect.objectContaining({ id: PAGE_ID }),
-      { contributorIds: ['u1', 'u2'], kind: 'idle', trx: { __trx: true } },
+      { contributorIds: ['u1', 'u2'] },
    );
    expect(generalQueue.add).toHaveBeenCalledWith(
      QueueJob.PAGE_BACKLINKS,
@@ -207,48 +186,6 @@ describe('HistoryProcessor.process', () => {
    ]);
  });

-  it('COMMIT failure (throw outside the tx callback) → contributors RESTORED', async () => {
-    // #370 F8 — a commit-time failure throws OUTSIDE the callback, so the inner
-    // try/catch does not run; the outer catch must restore the popped set (else a
-    // BullMQ retry writes an unattributed version). Use a db whose execute() runs
-    // the callback THEN throws, simulating a commit abort.
-    pageHistoryRepo.findPageLastHistory.mockResolvedValue({
-      content: { type: 'doc', content: [] },
-    });
-    const commitFail = {
-      transaction: () => ({
-        execute: async (fn: (trx: any) => Promise<any>) => {
-          await fn({ __trx: true }); // callback succeeds (saveHistory ok)
-          throw new Error('commit aborted'); // ...but the COMMIT fails
-        },
-      }),
-    };
-    const procCommitFail = new HistoryProcessor(
-      pageHistoryRepo as any,
-      pageRepo as any,
-      collabHistory as any,
-      watcherService as any,
-      commitFail as any,
-      notificationQueue as any,
-      generalQueue as any,
-    );
-    jest
-      .spyOn(procCommitFail['logger'], 'error')
-      .mockImplementation(() => undefined);
-
-    await expect(procCommitFail.process(buildJob())).rejects.toThrow(
-      'commit aborted',
-    );
-    // The inner catch did NOT run (save succeeded), so only the outer catch can
-    // restore — assert it did.
-    expect(collabHistory.addContributors).toHaveBeenCalledWith(PAGE_ID, [
-      'u1',
-      'u2',
-    ]);
-    // And the post-snapshot queue work must NOT have run (we rethrew).
-    expect(generalQueue.add).not.toHaveBeenCalled();
-  });
-
  it('backlinks + notification queue failures are swallowed (history still committed)', async () => {
    pageHistoryRepo.findPageLastHistory.mockResolvedValue({
      content: { type: 'doc', content: [] },
@@ -19,9 +19,6 @@ import { isDeepStrictEqual } from 'node:util';
 import { CollabHistoryService } from '../services/collab-history.service';
 import { WatcherService } from '../../core/watcher/watcher.service';
 import { isEmptyParagraphDoc } from '../collaboration.util';
-import { InjectKysely } from 'nestjs-kysely';
-import { KyselyDB } from '@docmost/db/types/kysely.types';
-import { executeTx } from '@docmost/db/utils';

@Processor(QueueName.HISTORY_QUEUE)
 export class HistoryProcessor extends WorkerHost implements OnModuleDestroy {
@@ -32,7 +29,6 @@ export class HistoryProcessor extends WorkerHost implements OnModuleDestroy {
    private readonly pageRepo: PageRepo,
    private readonly collabHistory: CollabHistoryService,
    private readonly watcherService: WatcherService,
-    @InjectKysely() private readonly db: KyselyDB,
    @InjectQueue(QueueName.NOTIFICATION_QUEUE) private notificationQueue: Queue,
    @InjectQueue(QueueName.GENERAL_QUEUE) private generalQueue: Queue,
  ) {
@@ -45,9 +41,6 @@ export class HistoryProcessor extends WorkerHost implements OnModuleDestroy {
    try {
      const { pageId } = job.data;

-      // Read the page WITHOUT a lock first, only to bail early on the two cheap
-      // no-write cases (page gone / empty first snapshot) without opening a
-      // transaction. The authoritative check-then-write happens locked below.
      const page = await this.pageRepo.findById(pageId, {
        includeContent: true,
      });
@@ -58,109 +51,40 @@ export class HistoryProcessor extends WorkerHost implements OnModuleDestroy {
        return;
      }

-      // #370 F3 — the snapshot decision (findPageLastHistory → saveHistory) must
-      // be serialized against manual-save/boundary writers, which run under a
-      // page-row lock in onStoreDocument. Without it, this processor and a
-      // concurrent manual-save each read the same lastHistory (MVCC), both see
-      // content != lastHistory, and both insert — producing two page_history rows
-      // with IDENTICAL content (one 'idle', one 'manual'), defeating
-      // promote-not-dup and the version-vs-autosave split. Taking the same
-      // page-row lock makes the second writer observe the first's committed row so
-      // the isDeepStrictEqual gate collapses the duplicate. Only the read+write
-      // is transacted; the post-snapshot queue work stays outside.
-      let contributorIds: string[] = [];
-      let snapshotWritten = false;
-      let lastHistoryContent: unknown;
-      // #370 F8 — the contributor set popped from Redis (destructive SPOP) must be
-      // restored if the snapshot does not durably land. The inner try/catch only
-      // covers a throw INSIDE the callback; a COMMIT failure (connection drop,
-      // serialization/deadlock abort on commit — the transient class the epic
-      // already retries) throws OUTSIDE it, rolling the snapshot back while the
-      // pop is already gone. We track the popped set here and restore it in the
-      // outer catch so a BullMQ retry re-attributes the version. addContributors
-      // is an idempotent Redis SADD, so a double-restore is harmless.
-      let poppedForRestore: string[] = [];
+      const lastHistory = await this.pageHistoryRepo.findPageLastHistory(
+        pageId,
+        { includeContent: true },
+      );

-      try {
-        await executeTx(this.db, async (trx) => {
-          const lockedPage = await this.pageRepo.findById(pageId, {
-            includeContent: true,
-            withLock: true,
-            trx,
-          });
-          if (!lockedPage) return;
-
-          const lastHistory = await this.pageHistoryRepo.findPageLastHistory(
-            pageId,
-            { includeContent: true, trx },
-          );
-          lastHistoryContent = lastHistory?.content;
-
-          if (!lastHistory && isEmptyParagraphDoc(lockedPage.content as any)) {
-            this.logger.debug(
-              `Skipping first history for page ${pageId}: empty content`,
-            );
-            return;
-          }
-
-          if (
-            lastHistory &&
-            isDeepStrictEqual(lastHistory.content, lockedPage.content)
-          ) {
-            return; // already snapshotted at this content — nothing to write
-          }
-
-          contributorIds = await this.collabHistory.popContributors(pageId);
-          poppedForRestore = contributorIds;
-          try {
-            // Pass `trx` so the watcher insert's FK check (FOR KEY SHARE on
-            // pages[pageId]) runs on the SAME connection that already holds the
-            // FOR UPDATE lock from findById — otherwise it takes the FK lock on a
-            // separate pool connection and self-deadlocks against our own tx.
-            await this.watcherService.addPageWatchers(
-              contributorIds,
-              pageId,
-              lockedPage.spaceId,
-              lockedPage.workspaceId,
-              trx,
-            );
-
-            // #370 — every job on this queue is a trailing idle-flush autosnapshot.
-            await this.pageHistoryRepo.saveHistory(lockedPage, {
-              contributorIds,
-              kind: job.data.kind ?? 'idle',
-              trx,
-            });
-            snapshotWritten = true;
-            this.logger.debug(`History created for page: ${pageId}`);
-          } catch (err) {
-            await this.collabHistory.addContributors(pageId, contributorIds);
-            poppedForRestore = [];
-            throw err;
-          }
-        });
-      } catch (err) {
-        // A throw here means the tx did NOT commit (callback threw, or the commit
-        // itself failed and rolled back). If we popped contributors and the inner
-        // catch did not already restore them, restore now so the retry keeps
-        // attribution. snapshotWritten is irrelevant: it is set before commit, so
-        // it can be true even when the commit rolled the snapshot back.
-        if (poppedForRestore.length) {
-          await this.collabHistory.addContributors(pageId, poppedForRestore);
-        }
-        throw err;
-      }
-
-      // No snapshot written (page vanished / empty-first / unchanged content) →
-      // clear the contributor set for the skip cases and stop.
-      if (!snapshotWritten) {
-        if (!lastHistoryContent && isEmptyParagraphDoc(page.content as any)) {
-          await this.collabHistory.clearContributors(pageId);
-        }
+      if (!lastHistory && isEmptyParagraphDoc(page.content as any)) {
+        this.logger.debug(
+          `Skipping first history for page ${pageId}: empty content`,
+        );
+        await this.collabHistory.clearContributors(pageId);
        return;
      }

-      {
+      if (
+        !lastHistory ||
+        !isDeepStrictEqual(lastHistory.content, page.content)
+      ) {
+        const contributorIds = await this.collabHistory.popContributors(pageId);
+
+        try {
+          await this.watcherService.addPageWatchers(
+            contributorIds,
+            pageId,
+            page.spaceId,
+            page.workspaceId,
+          );
+
+          await this.pageHistoryRepo.saveHistory(page, { contributorIds });
+          this.logger.debug(`History created for page: ${pageId}`);
+        } catch (err) {
+          await this.collabHistory.addContributors(pageId, contributorIds);
+          throw err;
+        }
+
        const mentions = extractMentions(page.content);
        const pageMentions = extractPageMentions(mentions);
        const internalLinkSlugIds = extractInternalLinkSlugIds(page.content);
@@ -178,7 +102,7 @@ export class HistoryProcessor extends WorkerHost implements OnModuleDestroy {
            );
          });

-        if (contributorIds.length > 0 && lastHistoryContent) {
+        if (contributorIds.length > 0 && lastHistory?.content) {
          await this.notificationQueue
            .add(QueueJob.PAGE_UPDATED, {
              pageId,
@@ -1,122 +1,42 @@
 import { Injectable, Logger, OnModuleDestroy } from '@nestjs/common';

 /**
- * In-memory run-stream registry (#184 phase 1.5, step-aligned retention #491). A
- * durable agent run tees its SSE frames here (via
- * `pipeUIMessageStreamToResponse({ consumeSseStream })`) so a LATE tab — one that
- * reloaded, or opened after the starter dropped — can attach through
- * `GET /ai-chat/runs/:chatId/stream`, be handed the TAIL past the step it already
- * has persisted, and then follow the live tail as a normal streamer.
+ * In-memory run-stream registry (#184 phase 1.5). A durable agent run tees its
+ * SSE frames here (via `pipeUIMessageStreamToResponse({ consumeSseStream })`)
+ * so a LATE tab — one that reloaded, or opened after the starter dropped — can
+ * attach through `GET /ai-chat/runs/:chatId/stream`, replay the frames buffered
+ * so far, and then follow the live tail as a normal streamer.
 *
 * This is deliberately single-process and best-effort: it holds nothing the DB
 * does not (the run + assistant row are the source of truth), so a process
 * restart simply drops in-flight entries and the client falls back to its
 * restore + degraded-poll path. The async `attach` return type is the seam for a
 * future phase-2 cross-process backend (Redis) — the interface does not change.
- *
- * ── #491 step-aligned retention (the OOM fix) ────────────────────────────────
- * The old registry buffered up to 32MB of raw SSE frames PER active run (V8 ~2×
- * in memory) and, on attach, blasted the WHOLE buffer to the socket synchronously
- * with no drain — a handful of marathon runs on a 1GB container OOM'd. #491 caps
- * the ring at a few MB (env-tunable, default 4MB) and keeps it there by ROTATING:
- *
- *  - Every buffered frame is STAMPED with a step number at tee (see ingestFrame).
- *    Convention: the stamp of a frame is the number of `finish-step` parts seen
- *    BEFORE it (starting at 0). The finish-step frame itself carries the current
- *    value, THEN the counter increments. So a frame stamped `s` is the content of
- *    the (s+1)-th step — 0-based step index `s` — and the stamp aligns EXACTLY
- *    with `metadata.stepsPersisted`: a client whose persisted `stepsPersisted` is
- *    N has steps 0..N-1 on disk (and in its seed) and needs the tail `stamp >= N`.
- *
- *  - The ring rotates ONLY on a CONFIRMED persist of step N
- *    (`confirmPersistedStep`), dropping frames with `stamp < N` (those steps are
- *    now on disk and a fresh client seed carries them). A NON-confirmed step is
- *    never rotated away, so a persist FAILURE just makes the ring cover MORE
- *    (auto-safe). This is the anti-inversion rule: a naive "rotate in .then()"
- *    that rotated after an UNwritten step would drop a step nobody has → silent
- *    hole. Rotation is gated on a real, successful persist.
- *
- *  - If the ring still exceeds its byte cap after rotation (a single fat step, or
- *    a lagging persist), the OLDEST frames are evicted to stay bounded. Evicting a
- *    not-yet-persisted frame opens a GAP: an attach whose N falls at or below an
- *    evicted step answers 204 and the client degrades to restore+poll. The gap is
- *    NOT sticky — the coverage floor is recomputed from the ring, so a later
- *    persist that rotates past the holey steps clears it.
- *
- * ── attach numbering / coverage (the wire convention) ────────────────────────
- * The step marker N comes ONLY FROM THE CLIENT (a query param). The server never
- * reads the row to derive N — a server-side N from a stale seed would open a
- * silent one-step hole. N is the client's persisted `stepsPersisted` (a COUNT):
- *   - the tail it needs = frames with `stamp >= N`;
- *   - coverage is OK ⟺ `coverageFloor(entry) <= N`, where coverageFloor is the
- *     smallest step FULLY present in the ring (its smallest retained stamp, bumped
- *     by one when that leading step was only partially evicted by overflow). If
- *     `coverageFloor > N` the ring starts AFTER the client's frontier (a hole, or
- *     the client's seed simply lagged behind a rotation) → 204 → the client
- *     refetches (a larger N) and re-attaches.
- * The N cutoff is applied in ALL branches, INCLUDING the finished-retained replay.
- *
- * ── same-tick invariants (unchanged, still load-bearing) ─────────────────────
- * invariant 1: only the matching run may mutate/observe an entry (runId check).
- * invariant 2: retention deletes ONLY its own entry (a replacement may own the key).
- * invariant 3: open() over a live entry mirrors the done-path (subscribers released).
- * invariant 4: the tail SLICE + subscriber registration happen in ONE synchronous
- *              tick inside attach() — no await between them — so a concurrently
- *              ingested frame is EITHER in the snapshot (buffered before the sync
- *              block, and the just-added subscriber never sees it) OR fanned out to
- *              the paused subscriber's `pending` (ingested after) — never both and
- *              never neither: no loss, no duplication. NOTE (#491): the controller
- *              now AWAITS the drain-respecting tail write BEFORE calling start(), so
- *              frames ingested during that await accumulate in `pending`; this is
- *              bounded by the subscriber cap (an overflow degrades start() to an
- *              end(), a 204-equivalent). It is the SYNCHRONOUS snapshot+registration
- *              — not a same-tick start() — that makes this correct.
- * invariant 5: the controller wires close-cleanup BEFORE any write.
- * invariant 6: no cross-run replay — the `anchor` (the client's assistant row id)
- *              must match this run's assistant id, or a foreign run's transcript
- *              would be appended to the client's message.
 */

 /** How long a finished entry is retained for late attach (replay + immediate end). */
 export const RUN_STREAM_RETAIN_FINISHED_MS = 30_000;

 /**
- * DEFAULT per-run replay ring cap (#491, down from 32MB). SSE frames carry
- * UNcompacted tool outputs + framing overhead (×1.5–2 vs the persisted parts), so
- * a "2–3 large reads + reasoning" step routinely blows past 2MB; 4MB comfortably
- * holds a step or two of TAIL, which is all a resuming client needs (steps below
- * its persisted frontier come from the seed, not the ring). The ring stays bounded
- * because it rotates on every confirmed persist; this cap is only the ceiling for
- * the un-persisted tail between rotations. Env-tunable via
- * AI_CHAT_RUN_STREAM_MAX_BUFFER_BYTES (bytes); a 0/invalid value falls back to this.
+ * Per-run replay buffer cap. Past this the buffer is dropped (attach -> 204, and
+ * the client falls back to its restore + degraded-poll path, #430).
+ *
+ * Raised from 4MB to 32MB (#430): marathon autonomous runs (11-25 min observed)
+ * stream far more than 4MB of SSE frames, so a live disconnect mid-run would find
+ * an already-overflowed buffer and could only degrade-poll instead of re-attaching
+ * to the live tail. 32MB comfortably covers those runs while staying bounded.
+ *
+ * Memory cost: this is the WORST-CASE retained size PER ACTIVE run (the buffer is
+ * freed on finish + retention, or dropped immediately on overflow). With the small
+ * number of concurrent autonomous runs a single workspace realistically has, 32MB
+ * each is an acceptable ceiling; the overflow->204->degraded-poll fallback remains
+ * the backstop for anything larger, so correctness never depends on this bound.
 */
-export const AI_CHAT_RUN_STREAM_MAX_BUFFER_BYTES = 4 * 1024 * 1024;
+export const RUN_STREAM_MAX_BUFFER_BYTES = 32 * 1024 * 1024;

-// 2× the ring cap: a just-written full-tail burst alone can never trip the
-// per-subscriber cap (see controller); only a genuinely stalled socket can. This
-// derivative relationship is preserved even when the ring cap is env-overridden.
-export const SUBSCRIBER_MAX_BUFFERED_BYTES = 2 * AI_CHAT_RUN_STREAM_MAX_BUFFER_BYTES;
-
-/**
- * A finish-step boundary frame is exactly `data: {"type":"finish-step"...}\n\n`
- * (verified empirically against ai@6.0.207 — each UI-message-stream part is a
- * single `data: {json}\n\n` event, never split across `data:` lines, and `type`
- * is always the first key). A prefix match is cheaper than JSON.parse-per-frame
- * and has no false positives: a literal `"type":"finish-step"` inside a text
- * delta is JSON-escaped (`\"type\":...`), and the frame would start with
- * `data: {"type":"text-delta"` anyway.
- */
-const FINISH_STEP_FRAME_PREFIX = 'data: {"type":"finish-step"';
-
-/** Resolve the ring cap from the environment, falling back to the default. */
-function resolveMaxBufferBytes(): number {
-  const raw = process.env.AI_CHAT_RUN_STREAM_MAX_BUFFER_BYTES;
-  if (!raw) return AI_CHAT_RUN_STREAM_MAX_BUFFER_BYTES;
-  const parsed = Number(raw);
-  return Number.isFinite(parsed) && parsed > 0
-    ? Math.floor(parsed)
-    : AI_CHAT_RUN_STREAM_MAX_BUFFER_BYTES;
-}
+// 2x the replay cap: a just-written full-replay burst alone can never trip the
+// per-subscriber cap (see controller); only a genuinely stalled socket can.
+export const SUBSCRIBER_MAX_BUFFERED_BYTES = 2 * RUN_STREAM_MAX_BUFFER_BYTES;

 export interface RunStreamCallbacks {
  onFrame: (frame: string) => void;
@@ -124,9 +44,6 @@ export interface RunStreamCallbacks {
 }

 export interface RunStreamAttachment {
-  // The synthetic `start` frame (carrying { runId, chatId }) followed by the
-  // buffered TAIL filtered to `stamp >= N`. The controller writes these to the
-  // socket in chunks respecting drain, then calls start().
  replay: string[];
  finished: boolean;
  start(): void; // drain pending frames (order preserved) and go live
@@ -136,19 +53,14 @@ export interface RunStreamAttachment {
 interface Subscriber extends RunStreamCallbacks {
  started: boolean;
  pending: string[];
-  // Byte size of `pending`, capped at the subscriber cap. `start()` is called in
-  // the SAME tick as `attach()` today, so `pending` never holds more than one
-  // microtask of frames — but the controller writes the (potentially large) tail
-  // respecting drain BEFORE start(), so a stalled socket can accumulate here; the
-  // cap is the structural backstop (an overflow degrades start() to an end()).
+  // Byte size of `pending`, capped at SUBSCRIBER_MAX_BUFFERED_BYTES. `start()` is
+  // called in the SAME tick as `attach()` today (see attach), so `pending` never
+  // holds more than one microtask of frames — but the async `attach` signature is
+  // a phase-2 seam: an await between attach and start would let a stalled paused
+  // subscriber buffer the WHOLE run here. The cap is the structural backstop.
  pendingBytes: number;
  overflowed: boolean;
  pendingEnd: boolean;
-  // The client's step frontier N: this subscriber only receives frames with
-  // `stamp >= minStamp` (the tail past what it already persisted). Live frames
-  // always satisfy this (their stamp is the current, highest step), so it only
-  // filters the rare out-of-order below-frontier frame.
-  minStamp: number;
 }

 interface Entry {
@@ -156,20 +68,8 @@ interface Entry {
  // The persisted assistant row id of this run (set at bind; undefined if the
  // seed failed). Used by the attach anchor check (invariant 6).
  assistantMessageId?: string;
-  // Parallel arrays: frames[i] is the SSE string, stamps[i] its step number.
  frames: string[];
-  stamps: number[];
  bytes: number;
-  // The running step counter used to stamp the NEXT frame (number of finish-step
-  // frames seen so far).
-  currentStamp: number;
-  // The highest confirmed `stepsPersisted`: frames with stamp < persistedFloor are
-  // on disk (safe to drop, never re-buffered). Monotonic (confirmPersistedStep).
-  persistedFloor: number;
-  // The highest stamp EVICTED by an overflow (unsafe) drop, -1 if none. Used to
-  // detect a partially-evicted leading step when computing the coverage floor.
-  overflowThroughStamp: number;
-  // Sticky-for-logging only: at least one unsafe (overflow) eviction happened.
  overflowed: boolean;
  finished: boolean;
  subscribers: Set<Subscriber>;
@@ -180,10 +80,6 @@ interface Entry {
 export class AiChatStreamRegistryService implements OnModuleDestroy {
  private readonly logger = new Logger(AiChatStreamRegistryService.name);
  private readonly entries = new Map<string, Entry>(); // key: chatId
-  // Env-resolved caps (per instance) so a deployment can tune the ceiling without
-  // a code change. The subscriber cap keeps the documented 2× relationship.
-  readonly maxBufferBytes = resolveMaxBufferBytes();
-  readonly subscriberMaxBufferedBytes = 2 * this.maxBufferBytes;

  /**
   * Register a fresh entry at the START of a run (before any frame), so a tab
@@ -209,11 +105,7 @@ export class AiChatStreamRegistryService implements OnModuleDestroy {
    this.entries.set(chatId, {
      runId,
      frames: [],
-      stamps: [],
      bytes: 0,
-      currentStamp: 0,
-      persistedFloor: 0,
-      overflowThroughStamp: -1,
      overflowed: false,
      finished: false,
      subscribers: new Set<Subscriber>(),
@@ -258,34 +150,6 @@ export class AiChatStreamRegistryService implements OnModuleDestroy {
    void pump();
  }

-  /**
-   * Confirm that step `stepsPersisted` (a COUNT: steps 0..stepsPersisted-1) is on
-   * disk for this run, and ROTATE the ring: drop the buffered frames of those
-   * now-persisted steps (stamp < stepsPersisted). This is the ONLY thing that
-   * rotates the ring, and it is called ONLY after a genuinely SUCCESSFUL per-step
-   * persist (see ai-chat.service updateStreaming). A failed persist never calls
-   * it, so the ring covers more (auto-safe). Identity-checked (invariant 1) and
-   * monotonic (a stale lower count is ignored).
-   */
-  confirmPersistedStep(
-    chatId: string,
-    runId: string,
-    stepsPersisted: number,
-  ): void {
-    const entry = this.entries.get(chatId);
-    if (!entry || entry.runId !== runId) return;
-    if (!Number.isFinite(stepsPersisted) || stepsPersisted <= entry.persistedFloor)
-      return;
-    entry.persistedFloor = stepsPersisted;
-    // Clean rotation: drop the persisted steps from the head. These frames are on
-    // disk + carried by a fresh client seed, so this NEVER opens a gap.
-    while (entry.frames.length > 0 && entry.stamps[0] < stepsPersisted) {
-      entry.bytes -= Buffer.byteLength(entry.frames[0]);
-      entry.frames.shift();
-      entry.stamps.shift();
-    }
-  }
-
  /**
   * Terminate a run's entry from the OUTER catch of the stream method (a failure
   * before/while wiring the pipe, so `done` will never arrive). Identity-checked
@@ -298,77 +162,36 @@ export class AiChatStreamRegistryService implements OnModuleDestroy {
  }

  /**
-   * Attach to a run's stream from the client's step frontier `n` (its persisted
-   * `stepsPersisted`). Async only for the phase-2 Redis seam — the body runs
-   * synchronously so the tail SLICE and the subscriber registration happen in ONE
-   * tick with no await between them (invariant 4).
+   * Attach to a run's stream. Async only for the phase-2 Redis seam — the body
+   * runs synchronously so the replay snapshot and the subscriber registration
+   * happen in ONE tick with no await between them (invariant 4): a frame ingested
+   * concurrently cannot slip into the gap and be lost or duplicated.
   *
   * Returns null (-> the caller answers 204) when:
-   *  - there is no entry;
-   *  - the `anchor` does not match this run's assistant id (invariant 6);
-   *  - the ring does not cover the client's frontier (coverageFloor > n): a hole
-   *    from overflow, or the client's seed simply lagged behind a rotation. The
-   *    client then refetches (a larger n) and re-attaches.
-   *
-   * Otherwise the attachment's `replay` is a synthetic `start` frame (the run-fact
-   * on re-attach) followed by the buffered tail filtered to `stamp >= n`. For a
-   * FINISHED run this is replay-only (no subscriber) and ends after the replay —
-   * with n = N_final that tail is just the run's `finish` frame, so the client
-   * closes the stream. For a LIVE run a paused subscriber is registered; the
-   * caller writes the replay (respecting drain) then calls start() to drain the
-   * pending frames and go live.
+   *  - there is no entry, or it overflowed (replay is gone);
+   *  - expect=live with an anchor that does not match this run's assistant id
+   *    (invariant 6: a stripped tab must never replay a FOREIGN run's transcript);
+   *  - the run finished and the caller did not expect a live tail.
+   * A finished run with expect=live yields a replay-only attachment (no
+   * subscriber registered). Otherwise a paused subscriber is registered and the
+   * caller replays `replay`, then calls start() to drain and go live.
   */
  async attach(
    chatId: string,
+    expectLive: boolean,
    anchor: string | undefined,
-    // The client's persisted step frontier. `null` = a NOT-tail-aware client (no
-    // `n` query param) — a legacy/parameterless tab that expects the old
-    // "finished -> 204 -> poll" contract; distinct from `0` (a tail-aware client
-    // with nothing persisted yet).
-    n: number | null,
    cb: RunStreamCallbacks,
  ): Promise<RunStreamAttachment | null> {
    const entry = this.entries.get(chatId);
-    if (!entry) return null;
+    if (!entry || entry.overflowed) return null;
    // Invariant 6: cross-run replay is forbidden. Before bind, assistantMessageId
    // is undefined and mismatches any anchor -> 204 -> client restore+poll path.
-    if (anchor && entry.assistantMessageId !== anchor) return null;
-    // #491 regression guard (#137/#161 dup): a NOT-tail-aware client (no `n`)
-    // resuming a FINISHED run must 204 and poll — the old `finished && !expectLive`
-    // gate. Without this, a missing `n` collapsing to frontier 0 would serve the
-    // WHOLE tail of a finished, NON-rotated run (coverageFloor 0), and a
-    // parameterless client that never stripped its transcript would APPEND that
-    // full replay onto the steps it already shows -> duplicated text. A tail-aware
-    // client (n present, incl. n=0) still gets the tail past its frontier.
-    if (entry.finished && n === null) return null;
-    // A finished entry with NOTHING in the ring (aborted before the first frame,
-    // or fully overflowed) has no tail to deliver -> 204 -> the client polls.
-    if (entry.finished && entry.frames.length === 0) return null;
-    // A LIVE run with no `n` (legacy parameterless) replays from step 0 (the old
-    // behavior); a tail-aware client resumes from its frontier.
-    const frontier = n ?? 0;
-    const floor = this.coverageFloor(entry);
-    if (floor > frontier) {
-      this.logger.warn(
-        `run-stream attach gap for run=${entry.runId}: coverageFloor=${floor} ` +
-          `> client frontier=${frontier} -> 204 (client refetches + re-attaches)`,
-      );
-      return null;
-    }
-
-    const startFrame = this.buildStartFrame(chatId, entry.runId);
-    const sliceTail = (): string[] => {
-      const out: string[] = [startFrame];
-      for (let i = 0; i < entry.frames.length; i++) {
-        if (entry.stamps[i] >= frontier) out.push(entry.frames[i]);
-      }
-      return out;
-    };
-
-    if (entry.finished) {
+    if (expectLive && anchor && entry.assistantMessageId !== anchor) return null;
+    if (entry.finished && !expectLive) return null;
+    if (entry.finished && expectLive) {
      // Replay-only: the run is done, no subscriber is registered.
      return {
-        replay: sliceTail(),
+        replay: entry.frames.slice(),
        finished: true,
        start: () => undefined,
        unsubscribe: () => undefined,
@@ -383,12 +206,15 @@ export class AiChatStreamRegistryService implements OnModuleDestroy {
      pendingBytes: 0,
      overflowed: false,
      pendingEnd: false,
-      minStamp: frontier,
    };
-    // Register + snapshot in the SAME synchronous block (invariant 4). No await
-    // separates them, so a concurrently ingested frame cannot be lost/duplicated.
    entry.subscribers.add(sub);
-    const replay = sliceTail();
+    // Snapshot in the SAME synchronous block as the registration (invariant 4).
+    const replay = entry.frames.slice();
+    // CONTRACT: the caller MUST call start() in the SAME tick as this attach()
+    // returns — no await between them. While a subscriber is paused, every frame
+    // is buffered in sub.pending; a delayed start() lets a whole run accumulate
+    // there. The pendingBytes cap (see ingestFrame) is the structural backstop if
+    // that contract is ever broken (e.g. the phase-2 Redis await seam).
    return {
      replay,
      finished: false,
@@ -437,83 +263,24 @@ export class AiChatStreamRegistryService implements OnModuleDestroy {
    this.entries.clear();
  }

-  /** The synthetic `start` frame the tail is prefixed with — the source of the
-   *  run-fact (runId/chatId) on re-attach. A `start` frame does NOT reset the
-   *  client's message parts (ai@6.0.207 createStreamingUIMessageState), so it is
-   *  safe to prepend even when the sliced tail begins mid-message. */
-  private buildStartFrame(chatId: string, runId: string): string {
-    return `data: ${JSON.stringify({
-      type: 'start',
-      messageMetadata: { runId, chatId },
-    })}\n\n`;
-  }
-
-  /**
-   * The smallest step FULLY present in the ring: its smallest retained stamp, or
-   * (when the leading step was only partially evicted by an overflow) one past it.
-   * When the ring is empty it is the current step (only the live tail is coming).
-   * An attach at frontier `n` is covered ⟺ coverageFloor <= n.
-   */
-  private coverageFloor(entry: Entry): number {
-    // Empty ring: only the live tail is coming. The floor is the current step,
-    // but never below persistedFloor — a confirmed persist can rotate the ring
-    // empty while currentStamp still lags a beat behind on another connection, so
-    // max() keeps the invariant STRUCTURAL (a client with n = persistedFloor is
-    // always covered) rather than timing-dependent.
-    if (entry.frames.length === 0)
-      return Math.max(entry.currentStamp, entry.persistedFloor);
-    const min = entry.stamps[0];
-    return entry.overflowThroughStamp >= min ? min + 1 : min;
-  }
-
-  /**
-   * Buffer (step-stamped) + fan-out a single frame. The stamp is the number of
-   * finish-step frames seen BEFORE this one; a finish-step frame carries the
-   * current value and THEN increments the counter (so its stamp equals the 0-based
-   * index of the step it closes). Only frames at/above persistedFloor are buffered
-   * (already-persisted steps are on disk); the ring is then trimmed to the byte
-   * cap, an unsafe eviction opening a gap. Fan-out is always live (filtered per
-   * subscriber by its frontier).
-   */
+  /** Buffer + fan-out a single frame. See invariant/overflow semantics inline. */
  private ingestFrame(entry: Entry, frame: string): void {
-    const size = Buffer.byteLength(frame);
-    const stamp = entry.currentStamp;
-    if (frame.startsWith(FINISH_STEP_FRAME_PREFIX)) {
-      entry.currentStamp = stamp + 1;
-    }
-
-    // Buffer for replay only if this step is not already persisted+rotated away.
-    if (stamp >= entry.persistedFloor) {
+    entry.bytes += Buffer.byteLength(frame);
+    if (!entry.overflowed) {
      entry.frames.push(frame);
-      entry.stamps.push(stamp);
-      entry.bytes += size;
-      // Enforce the ring cap. Evicting a not-yet-persisted frame (stamp >=
-      // persistedFloor) opens a GAP; a leftover persisted frame (< floor) is a
-      // safe drop. Keep evicting until the ring is back under the cap.
-      while (entry.bytes > this.maxBufferBytes && entry.frames.length > 0) {
-        const evStamp = entry.stamps[0];
-        entry.bytes -= Buffer.byteLength(entry.frames[0]);
-        entry.frames.shift();
-        entry.stamps.shift();
-        if (evStamp >= entry.persistedFloor) {
-          if (evStamp > entry.overflowThroughStamp)
-            entry.overflowThroughStamp = evStamp;
-          if (!entry.overflowed) {
-            entry.overflowed = true;
-            this.logger.warn(
-              `run-stream ring overflow for run=${entry.runId}: an un-persisted ` +
-                `step was evicted to stay under ${this.maxBufferBytes}B; a late ` +
-                `attach at an evicted step will 204 until a later persist confirms`,
-            );
-          }
-        }
+      if (entry.bytes > RUN_STREAM_MAX_BUFFER_BYTES) {
+        // The crossing frame was already counted AND (below) fanned out; only the
+        // replay buffer is dropped. After overflow no more frames are buffered,
+        // but live fan-out continues.
+        entry.overflowed = true;
+        entry.frames = [];
+        this.logger.warn(
+          `run-stream buffer overflow for run=${entry.runId}; ` +
+            `late attach will 204 until the run ends`,
+        );
      }
    }
-
-    // Fan out live, filtered to each subscriber's frontier (a subscriber only
-    // wants the tail past the step it already persisted).
    for (const sub of entry.subscribers) {
-      if (stamp < sub.minStamp) continue;
      if (sub.started) {
        try {
          sub.onFrame(frame);
@@ -522,12 +289,12 @@ export class AiChatStreamRegistryService implements OnModuleDestroy {
        }
      } else {
        sub.pending.push(frame);
-        sub.pendingBytes += size;
-        if (sub.pendingBytes > this.subscriberMaxBufferedBytes) {
+        sub.pendingBytes += Buffer.byteLength(frame);
+        if (sub.pendingBytes > SUBSCRIBER_MAX_BUFFERED_BYTES) {
          // The paused subscriber's buffer overflowed — only possible if start()
-          // was delayed (the controller's drain-respecting tail write, or the
-          // phase-2 await seam). Drop it rather than buffer the whole run; on
-          // start() it degrades to an immediate end (a 204-equivalent).
+          // was delayed past the same-tick contract (the phase-2 await seam).
+          // Drop it rather than buffer the whole run; on start() it degrades to an
+          // immediate end (a 204-equivalent) instead of replaying a partial.
          sub.overflowed = true;
          sub.pending = [];
          entry.subscribers.delete(sub);
@@ -1,27 +1,19 @@
 import {
  AiChatStreamRegistryService,
-  AI_CHAT_RUN_STREAM_MAX_BUFFER_BYTES,
+  RUN_STREAM_MAX_BUFFER_BYTES,
  RUN_STREAM_RETAIN_FINISHED_MS,
+  SUBSCRIBER_MAX_BUFFERED_BYTES,
  RunStreamCallbacks,
 } from './ai-chat-stream-registry.service';

 /**
- * Unit tests for the in-memory run-stream registry (#184 phase 1.5, step-aligned
- * retention #491). The registry is the whole of the resumable-transport contract:
- * step-stamped retention, tail-only attach at the client's frontier N, the
- * confirmed-persist ring rotation (and the anti-inversion rule), the memory bound,
- * the overflow gap, paused -> live hand-off, retention, the anchor check
- * (invariant 6), and the mirror-the-done-path replace semantics (invariant 3).
+ * Unit tests for the in-memory run-stream registry (#184 phase 1.5). The registry
+ * is the whole of the resumable-transport contract: replay ordering, paused ->
+ * live hand-off, overflow, retention, the anchor check (invariant 6), and the
+ * mirror-the-done-path replace semantics (invariant 3). Every enumerated case in
+ * the issue's task 1.5 has a test here.
 */

-// Real ai@6 UI-message-stream SSE frames are `data: {json}\n\n`, one part each.
-const sse = (part: Record<string, unknown>): string =>
-  `data: ${JSON.stringify(part)}\n\n`;
-const finishStep = (): string => sse({ type: 'finish-step' });
-const textDelta = (id: string, delta: string): string =>
-  sse({ type: 'text-delta', id, delta });
-const finish = (): string => sse({ type: 'finish' });
-
 // A ReadableStream whose frames the test pushes explicitly, plus close/error.
 function makePushStream(): {
  stream: ReadableStream<string>;
@@ -66,9 +58,6 @@ function collector(): {
  };
 }

-// The tail past the synthetic start frame (replay[0] is always the start frame).
-const tail = (replay: string[]): string[] => replay.slice(1);
-
 describe('AiChatStreamRegistryService', () => {
  const CHAT = 'chat-1';
  let registry: AiChatStreamRegistryService;
@@ -82,21 +71,7 @@ describe('AiChatStreamRegistryService', () => {
    registry.onModuleDestroy();
  });

-  it('prepends a synthetic start frame carrying { runId, chatId }', async () => {
-    registry.open(CHAT, 'run-1');
-    const src = makePushStream();
-    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
-    src.push('a');
-    await flush();
-
-    const c = collector();
-    const att = (await registry.attach(CHAT, 'assist-1', 0, c.cb))!;
-    const start = JSON.parse(att.replay[0].replace(/^data: /, '').trim());
-    expect(start.type).toBe('start');
-    expect(start.messageMetadata).toEqual({ runId: 'run-1', chatId: CHAT });
-  });
-
-  it('replays the buffered tail (from frontier 0) in arrival order (live attach)', async () => {
+  it('replays frames in arrival order (live attach)', async () => {
    registry.open(CHAT, 'run-1');
    const src = makePushStream();
    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
@@ -106,13 +81,13 @@ describe('AiChatStreamRegistryService', () => {
    await flush();

    const c = collector();
-    const att = await registry.attach(CHAT, 'assist-1', 0, c.cb);
+    const att = await registry.attach(CHAT, false, undefined, c.cb);
    expect(att).not.toBeNull();
-    expect(tail(att!.replay)).toEqual(['a', 'b', 'c']);
+    expect(att!.replay).toEqual(['a', 'b', 'c']);
    expect(att!.finished).toBe(false);
  });

-  it('late attach gets the buffered prefix as tail plus the live tail', async () => {
+  it('late attach gets the full prefix as replay plus the live tail', async () => {
    registry.open(CHAT, 'run-1');
    const src = makePushStream();
    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
@@ -121,16 +96,17 @@ describe('AiChatStreamRegistryService', () => {
    await flush();

    const c = collector();
-    const att = (await registry.attach(CHAT, 'assist-1', 0, c.cb))!;
-    expect(tail(att.replay)).toEqual(['a', 'b']);
+    const att = (await registry.attach(CHAT, false, undefined, c.cb))!;
+    expect(att.replay).toEqual(['a', 'b']);
    att.start();
+    // Live tail arrives after start().
    src.push('c');
    src.push('d');
    await flush();
    expect(c.frames).toEqual(['c', 'd']);
  });

-  it('a paused subscriber receives frames buffered during pause in order, then live', async () => {
+  it('a paused subscriber receives frames buffered during pause in order, then live (no loss/reorder)', async () => {
    registry.open(CHAT, 'run-1');
    const src = makePushStream();
    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
@@ -138,45 +114,81 @@ describe('AiChatStreamRegistryService', () => {
    await flush();

    const c = collector();
-    const att = (await registry.attach(CHAT, 'assist-1', 0, c.cb))!;
-    expect(tail(att.replay)).toEqual(['a']);
+    // Attach (paused). Frames that arrive BEFORE start() must queue, not drop.
+    const att = (await registry.attach(CHAT, false, undefined, c.cb))!;
+    expect(att.replay).toEqual(['a']);
    src.push('b'); // arrives while paused -> pending
    src.push('c');
    await flush();
    expect(c.frames).toEqual([]); // nothing delivered yet (paused)
-    att.start();
+    att.start(); // drains pending in order
    expect(c.frames).toEqual(['b', 'c']);
-    src.push('d');
+    src.push('d'); // now live
    await flush();
    expect(c.frames).toEqual(['b', 'c', 'd']);
  });

  it('a run that finishes while a subscriber is paused ends it on start()', async () => {
    registry.open(CHAT, 'run-1');
-    registry.bind(CHAT, 'run-1', 'assist-1', makePushStream().stream);
    const c = collector();
-    const att = (await registry.attach(CHAT, 'assist-1', 0, c.cb))!;
+    const att = (await registry.attach(CHAT, false, undefined, c.cb))!;
+    // Terminate the run while the subscriber is still paused.
    registry.abortEntry(CHAT, 'run-1');
    expect(c.ended()).toBe(0); // paused: not ended yet
    att.start();
    expect(c.ended()).toBe(1); // start() drains + ends
  });

-  it('anchor mismatch returns null (and null before bind sets assistantMessageId)', async () => {
+  it('finished + expect=live returns a replay WITHOUT registering a subscriber', async () => {
+    registry.open(CHAT, 'run-1');
+    const src = makePushStream();
+    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
+    src.push('a');
+    src.push('b');
+    src.close();
+    await flush();
+
+    const c = collector();
+    const att = (await registry.attach(CHAT, true, undefined, c.cb))!;
+    expect(att.finished).toBe(true);
+    expect(att.replay).toEqual(['a', 'b']);
+    // No subscriber registered: start()/unsubscribe are no-ops and the entry has
+    // zero subscribers.
+    const entry = (registry as any).entries.get(CHAT);
+    expect(entry.subscribers.size).toBe(0);
+    att.start();
+    expect(c.frames).toEqual([]);
+  });
+
+  it('finished WITHOUT expect=live returns null', async () => {
+    registry.open(CHAT, 'run-1');
+    const src = makePushStream();
+    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
+    src.push('a');
+    src.close();
+    await flush();
+
+    const c = collector();
+    expect(await registry.attach(CHAT, false, undefined, c.cb)).toBeNull();
+  });
+
+  it('anchor mismatch with expect=live returns null (and null before bind sets assistantMessageId)', async () => {
    registry.open(CHAT, 'run-1');
    const c = collector();
    // Before bind: assistantMessageId is undefined -> mismatches any anchor.
-    expect(await registry.attach(CHAT, 'assist-1', 0, c.cb)).toBeNull();
+    expect(
+      await registry.attach(CHAT, true, 'assist-1', c.cb),
+    ).toBeNull();

    const src = makePushStream();
    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
    src.push('a');
    await flush();
    // Wrong anchor -> null (cross-run replay forbidden, invariant 6).
-    expect(await registry.attach(CHAT, 'other-id', 0, c.cb)).toBeNull();
+    expect(await registry.attach(CHAT, true, 'other-id', c.cb)).toBeNull();
  });

-  it('matching anchor attaches', async () => {
+  it('matching anchor with expect=live attaches', async () => {
    registry.open(CHAT, 'run-1');
    const src = makePushStream();
    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
@@ -184,39 +196,73 @@ describe('AiChatStreamRegistryService', () => {
    await flush();

    const c = collector();
-    const att = await registry.attach(CHAT, 'assist-1', 0, c.cb);
+    const att = await registry.attach(CHAT, true, 'assist-1', c.cb);
    expect(att).not.toBeNull();
-    expect(tail(att!.replay)).toEqual(['a']);
+    expect(att!.replay).toEqual(['a']);
  });

-  it('a throwing onFrame ejects only that subscriber; the ingest loop stays alive', async () => {
+  it('overflow: attach returns null, but the LIVE subscriber keeps receiving (incl. the crossing frame)', async () => {
    registry.open(CHAT, 'run-1');
    const src = makePushStream();
    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);

-    const bad = collector();
-    const badAtt = (await registry.attach(CHAT, 'assist-1', 0, {
-      onFrame: () => {
-        throw new Error('boom');
-      },
-      onEnd: bad.cb.onEnd,
-    }))!;
-    badAtt.start();
+    // A live (started) subscriber attached before the flood.
+    const c = collector();
+    const att = (await registry.attach(CHAT, false, undefined, c.cb))!;
+    att.start();

-    const good = collector();
-    const goodAtt = (await registry.attach(CHAT, 'assist-1', 0, good.cb))!;
-    goodAtt.start();
-
-    src.push('a'); // bad throws on this frame -> ejected
-    src.push('b'); // good still receives both
+    // Cap-relative so it survives a buffer-cap change (#430): a quarter-cap frame
+    // means 5 frames comfortably exceed the replay cap; the last one crosses.
+    const chunk = 'x'.repeat(Math.floor(RUN_STREAM_MAX_BUFFER_BYTES / 4));
+    for (let i = 0; i < 5; i++) src.push(chunk + i);
    await flush();

    const entry = (registry as any).entries.get(CHAT);
-    expect(entry.subscribers.size).toBe(1);
-    expect(good.frames).toEqual(['a', 'b']);
+    expect(entry.overflowed).toBe(true);
+    expect(entry.bytes).toBeGreaterThan(RUN_STREAM_MAX_BUFFER_BYTES);
+    // The live subscriber received ALL 5 frames, including the crossing one.
+    expect(c.frames).toHaveLength(5);
+    expect(c.frames[4]).toBe(chunk + 4);
+
+    // A NEW attach after overflow gets null (replay buffer is gone).
+    const c2 = collector();
+    expect(await registry.attach(CHAT, false, undefined, c2.cb)).toBeNull();
  });

-  it('open() over a LIVE entry ends started subscribers once; a late done never touches the new entry (invariant 3)', async () => {
+  it('a paused subscriber whose pending buffer overflows is dropped and ends on start(); other subscribers keep receiving', async () => {
+    registry.open(CHAT, 'run-1');
+    const src = makePushStream();
+    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
+
+    // A: paused (start() deliberately delayed to simulate the phase-2 await seam).
+    const a = collector();
+    const attA = (await registry.attach(CHAT, false, undefined, a.cb))!;
+    // B: live (started) — its delivery must be unaffected by A's overflow.
+    const b = collector();
+    const attB = (await registry.attach(CHAT, false, undefined, b.cb))!;
+    attB.start();
+
+    // Cap-relative so it survives a buffer-cap change (#430): a quarter-of-the-
+    // per-subscriber-cap frame means 5 frames exceed A's paused-pending cap while
+    // B streams every frame live.
+    const chunk = 'x'.repeat(Math.floor(SUBSCRIBER_MAX_BUFFERED_BYTES / 4));
+    for (let i = 0; i < 5; i++) src.push(chunk + i);
+    await flush();
+
+    const entry = (registry as any).entries.get(CHAT);
+    // A was dropped from the subscriber set on overflow; B (started) remains.
+    expect(entry.subscribers.size).toBe(1);
+    expect(a.frames).toEqual([]); // paused + overflowed: nothing was delivered
+    // B received every frame live (delivery unaffected by A's overflow).
+    expect(b.frames).toHaveLength(5);
+
+    // A's start() (arriving late) degrades to an immediate end, not a partial replay.
+    attA.start();
+    expect(a.frames).toEqual([]);
+    expect(a.ended()).toBe(1);
+  });
+
+  it('open() over a LIVE entry ends started subscribers exactly once and a late done does not touch the new entry (invariant 3)', async () => {
    registry.open(CHAT, 'run-1');
    const src = makePushStream();
    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
@@ -224,20 +270,23 @@ describe('AiChatStreamRegistryService', () => {
    await flush();

    const c = collector();
-    const att = (await registry.attach(CHAT, 'assist-1', 0, c.cb))!;
-    att.start();
+    const att = (await registry.attach(CHAT, false, undefined, c.cb))!;
+    att.start(); // started subscriber on run-1

+    // run-2 starts on the same chat while run-1's tee is still reading.
    registry.open(CHAT, 'run-2');
-    expect(c.ended()).toBe(1);
+    expect(c.ended()).toBe(1); // exactly one onEnd from the replace

    const newEntry = (registry as any).entries.get(CHAT);
    expect(newEntry.runId).toBe('run-2');
    expect(newEntry.finished).toBe(false);

+    // The old tee now completes: its late done must NOT double-end nor delete the
+    // new entry.
    src.push('b');
    src.close();
    await flush();
-    expect(c.ended()).toBe(1);
+    expect(c.ended()).toBe(1); // still exactly one
    const still = (registry as any).entries.get(CHAT);
    expect(still).toBe(newEntry);
    expect(still.runId).toBe('run-2');
@@ -250,6 +299,7 @@ describe('AiChatStreamRegistryService', () => {
    src.push('a');
    await flush();
    const entry = (registry as any).entries.get(CHAT);
+    // Frames were NOT ingested (bind bailed), assistantMessageId untouched.
    expect(entry.frames).toEqual([]);
    expect(entry.assistantMessageId).toBeUndefined();
  });
@@ -260,276 +310,32 @@ describe('AiChatStreamRegistryService', () => {
    const entry = (registry as any).entries.get(CHAT);
    expect(entry.finished).toBe(false);
  });
-});

-/**
- * #491 step-stamped retention: the boundary detector, tail-only slicing at the
- * client's frontier N, the confirmed-persist rotation (+ anti-inversion), the
- * overflow gap, the memory bound, and the finished-retained tail. All observable
- * against the REAL registry driven through open/bind/ingest.
- */
-describe('AiChatStreamRegistryService step-aligned retention (#491)', () => {
-  const CHAT = 'chat-s';
-  let registry: AiChatStreamRegistryService;
-
-  beforeEach(() => {
-    registry = new AiChatStreamRegistryService();
-    jest.spyOn((registry as any).logger, 'warn').mockImplementation(() => {});
-  });
-  afterEach(() => registry.onModuleDestroy());
-
-  const entryOf = () => (registry as any).entries.get(CHAT);
-
-  it('stamps frames by finish-step count, aligned with stepsPersisted', async () => {
+  it('a throwing onFrame ejects only that subscriber; the ingest loop stays alive', async () => {
    registry.open(CHAT, 'run-1');
    const src = makePushStream();
    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
-    // step 0 content, its finish-step, step 1 content, its finish-step, finish.
-    src.push(textDelta('t0', 'a')); // stamp 0
-    src.push(finishStep()); // stamp 0 (the finish-step frame carries the pre value)
-    src.push(textDelta('t1', 'b')); // stamp 1
-    src.push(finishStep()); // stamp 1
-    src.push(finish()); // stamp 2
-    await flush();
-    const e = entryOf();
-    expect(e.stamps).toEqual([0, 0, 1, 1, 2]);
-    expect(e.currentStamp).toBe(2);
-  });

-  it('does NOT treat a text delta that merely quotes "finish-step" as a boundary', async () => {
-    registry.open(CHAT, 'run-1');
-    const src = makePushStream();
-    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
-    // A model that literally types "type":"finish-step" — JSON-escaped in the frame.
-    src.push(textDelta('t0', '"type":"finish-step"'));
-    await flush();
-    expect(entryOf().currentStamp).toBe(0); // no false boundary
-  });
+    const bad = collector();
+    const badAtt = (await registry.attach(CHAT, false, undefined, {
+      onFrame: () => {
+        throw new Error('boom');
+      },
+      onEnd: bad.cb.onEnd,
+    }))!;
+    badAtt.start();

-  it('tail-only: attach at N slices frames with stamp >= N', async () => {
-    registry.open(CHAT, 'run-1');
-    const src = makePushStream();
-    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
-    src.push(textDelta('t0', 'a')); // 0
-    src.push(finishStep()); // 0
-    src.push(textDelta('t1', 'b')); // 1
-    src.push(finishStep()); // 1
-    src.push(textDelta('t2', 'c')); // 2 (in-progress)
+    const good = collector();
+    const goodAtt = (await registry.attach(CHAT, false, undefined, good.cb))!;
+    goodAtt.start();
+
+    src.push('a'); // bad throws on this frame -> ejected
+    src.push('b'); // good still receives both
    await flush();

-    const c = collector();
-    // Client persisted 2 steps -> wants the tail from step 2.
-    const att = (await registry.attach(CHAT, 'assist-1', 2, c.cb))!;
-    expect(tail(att.replay)).toEqual([textDelta('t2', 'c')]);
-  });
-
-  it('attach in the MIDDLE of a step (N between finish-steps) slices from that step', async () => {
-    registry.open(CHAT, 'run-1');
-    const src = makePushStream();
-    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
-    src.push(textDelta('t0', 'a')); // 0
-    src.push(finishStep()); // 0
-    src.push(textDelta('t1', 'b1')); // 1
-    src.push(textDelta('t1', 'b2')); // 1 (still step 1, no finish-step yet)
-    await flush();
-
-    const c = collector();
-    const att = (await registry.attach(CHAT, 'assist-1', 1, c.cb))!;
-    // Step 0's frames are dropped from the tail; the whole in-progress step 1 is kept.
-    expect(tail(att.replay)).toEqual([textDelta('t1', 'b1'), textDelta('t1', 'b2')]);
-  });
-
-  it('rotates the ring ONLY on a confirmed persist (drops stamp < N)', async () => {
-    registry.open(CHAT, 'run-1');
-    const src = makePushStream();
-    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
-    src.push(textDelta('t0', 'a')); // 0
-    src.push(finishStep()); // 0
-    src.push(textDelta('t1', 'b')); // 1
-    await flush();
-    expect(entryOf().stamps).toEqual([0, 0, 1]);
-
-    // Confirm step 0 persisted (stepsPersisted = 1) -> drop stamp < 1.
-    registry.confirmPersistedStep(CHAT, 'run-1', 1);
-    expect(entryOf().stamps).toEqual([1]);
-    expect(entryOf().persistedFloor).toBe(1);
-  });
-
-  it('persist FAILED but the ring still fits -> attach SUCCEEDS and the tail includes step N', async () => {
-    registry.open(CHAT, 'run-1');
-    const src = makePushStream();
-    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
-    src.push(textDelta('t0', 'a')); // 0
-    src.push(finishStep()); // 0
-    src.push(textDelta('t1', 'b')); // 1 (step 1's persist FAILED -> no confirm)
-    await flush();
-    // No confirmPersistedStep for step 1: the ring still holds step 1.
-
-    const c = collector();
-    // Client's last successful persist was step 0 -> stepsPersisted = 1.
-    const att = await registry.attach(CHAT, 'assist-1', 1, c.cb);
-    expect(att).not.toBeNull();
-    expect(tail(att!.replay)).toEqual([textDelta('t1', 'b')]); // includes step 1
-  });
-
-  it('persist failed AND the ring overflowed past N -> 204 (coverage gap)', async () => {
-    registry.open(CHAT, 'run-1');
-    const src = makePushStream();
-    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
-    // Step 0: a fat step that blows past the cap with NO persist confirmation.
-    const big = 'x'.repeat(Math.floor(AI_CHAT_RUN_STREAM_MAX_BUFFER_BYTES / 2));
-    src.push(textDelta('t0', big)); // 0
-    src.push(textDelta('t0', big)); // 0
-    src.push(textDelta('t0', big)); // 0 -> overflow evicts stamp-0 frames
-    await flush();
-    const e = entryOf();
-    expect(e.overflowed).toBe(true);
-    expect(e.bytes).toBeLessThanOrEqual(registry.maxBufferBytes);
-
-    // A client at frontier 0 falls at/below an evicted step -> gap -> null.
-    const c = collector();
-    expect(await registry.attach(CHAT, 'assist-1', 0, c.cb)).toBeNull();
-  });
-
-  it('stale N (client seed lagged behind a rotation) -> 204; after a refetch (larger N) -> success', async () => {
-    registry.open(CHAT, 'run-1');
-    const src = makePushStream();
-    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
-    src.push(textDelta('t0', 'a')); // 0
-    src.push(finishStep()); // 0
-    src.push(textDelta('t1', 'b')); // 1
-    src.push(finishStep()); // 1
-    src.push(textDelta('t2', 'c')); // 2
-    await flush();
-    // Server confirmed steps 0 and 1 -> rotate away stamp < 2.
-    registry.confirmPersistedStep(CHAT, 'run-1', 2);
-    expect(entryOf().stamps).toEqual([2]);
-
-    // A client whose seed still says stepsPersisted = 1 -> below minStamp -> 204.
-    const stale = collector();
-    expect(await registry.attach(CHAT, 'assist-1', 1, stale.cb)).toBeNull();
-
-    // It refetches (now stepsPersisted = 2) and re-attaches -> success.
-    const fresh = collector();
-    const att = await registry.attach(CHAT, 'assist-1', 2, fresh.cb);
-    expect(att).not.toBeNull();
-    expect(tail(att!.replay)).toEqual([textDelta('t2', 'c')]);
-  });
-
-  it('overflow gap CLEARS once a later persist rotates out the holey steps', async () => {
-    registry.open(CHAT, 'run-1');
-    const src = makePushStream();
-    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
-    const big = 'x'.repeat(Math.floor(AI_CHAT_RUN_STREAM_MAX_BUFFER_BYTES / 2));
-    src.push(textDelta('t0', big)); // 0
-    src.push(textDelta('t0', big)); // 0
-    src.push(finishStep()); // 0 (still stamp 0)
-    src.push(textDelta('t1', 'small')); // 1
-    src.push(finishStep()); // 1
-    src.push(textDelta('t2', 'c')); // 2
-    await flush();
-    expect(entryOf().overflowed).toBe(true);
-
-    // Late persist confirms steps 0..1 -> rotates out the holey step-0 frames.
-    registry.confirmPersistedStep(CHAT, 'run-1', 2);
-    // A client at frontier 2 is now cleanly covered (the hole was below it).
-    const c = collector();
-    const att = await registry.attach(CHAT, 'assist-1', 2, c.cb);
-    expect(att).not.toBeNull();
-    expect(tail(att!.replay)).toEqual([textDelta('t2', 'c')]);
-  });
-
-  it('finished-retained + N = N_final -> empty tail plus the finish frame', async () => {
-    registry.open(CHAT, 'run-1');
-    const src = makePushStream();
-    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
-    src.push(textDelta('t0', 'a')); // 0
-    src.push(finishStep()); // 0
-    src.push(finish()); // 1  (N_final = 1)
-    src.close();
-    await flush();
-    // The last step's per-step persist confirmed stepsPersisted = 1.
-    registry.confirmPersistedStep(CHAT, 'run-1', 1);
-
-    const c = collector();
-    const att = (await registry.attach(CHAT, 'assist-1', 1, c.cb))!;
-    expect(att.finished).toBe(true);
-    // Empty step tail; just the finish frame so the client's SDK closes the stream.
-    expect(tail(att.replay)).toEqual([finish()]);
-    // No subscriber registered for a finished run.
-    expect(entryOf().subscribers.size).toBe(0);
-  });
-
-  it('#491 regression (#137/#161 dup): a PARAMETERLESS attach (n=null) to a finished NON-rotated run -> 204, but n=0 still gets the tail', async () => {
-    // A finished, non-rotated run: frames present, coverageFloor 0. A missing `n`
-    // (null — a legacy/parameterless tab that never stripped its transcript) must
-    // 204 -> poll, NOT receive the whole tail it would append (duplicate). A
-    // tail-aware client (n=0 present) still resumes.
-    registry.open(CHAT, 'run-1');
-    const src = makePushStream();
-    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
-    src.push(textDelta('t0', 'a')); // 0
-    src.push(finishStep()); // 0
-    src.push(finish()); // 1
-    src.close();
-    await flush();
-    // NOT rotated (no confirmPersistedStep) -> stamps[0]=0, coverageFloor=0.
-    // MUTATION-VERIFY: revert the `finished && n === null -> null` gate (default n
-    // to 0) and the parameterless attach below serves the full tail instead of 204.
-    expect(await registry.attach(CHAT, 'assist-1', null, collector().cb)).toBeNull();
-    // A tail-aware client at frontier 0 IS served (the distinction: null != 0).
-    const tailAware = await registry.attach(CHAT, 'assist-1', 0, collector().cb);
-    expect(tailAware).not.toBeNull();
-    expect(tailAware!.finished).toBe(true);
-  });
-
-  it('confirmPersistedStep is monotonic and identity-checked', async () => {
-    registry.open(CHAT, 'run-1');
-    const src = makePushStream();
-    registry.bind(CHAT, 'run-1', 'assist-1', src.stream);
-    src.push(textDelta('t0', 'a'));
-    src.push(finishStep());
-    src.push(textDelta('t1', 'b'));
-    await flush();
-    registry.confirmPersistedStep(CHAT, 'run-1', 1);
-    expect(entryOf().persistedFloor).toBe(1);
-    // A stale lower count is ignored.
-    registry.confirmPersistedStep(CHAT, 'run-1', 0);
-    expect(entryOf().persistedFloor).toBe(1);
-    // A foreign runId is ignored.
-    registry.confirmPersistedStep(CHAT, 'WRONG', 5);
-    expect(entryOf().persistedFloor).toBe(1);
-  });
-
-  it('MEMORY BOUND: 5 parallel marathon runs each stream well past 32MB; each ring stays <= the cap', async () => {
-    const cap = registry.maxBufferBytes;
-    const chats = ['m0', 'm1', 'm2', 'm3', 'm4'];
-    const srcs = chats.map((chat) => {
-      registry.open(chat, `run-${chat}`);
-      const s = makePushStream();
-      registry.bind(chat, `run-${chat}`, `assist-${chat}`, s.stream);
-      return s;
-    });
-    // ~256KB frames; 160 per chat = 40MB streamed each, well past the old 32MB.
-    // Interleave a finish-step every 8 frames so steps advance realistically. No
-    // persist confirmation -> the ONLY thing keeping memory bounded is the cap.
-    const frame = 'y'.repeat(256 * 1024);
-    for (let batch = 0; batch < 20; batch++) {
-      for (let i = 0; i < 8; i++) {
-        for (const s of srcs) s.push(textDelta('t', frame));
-      }
-      for (const s of srcs) s.push(finishStep());
-      await flush(); // drain the pump so queues never hold a whole run
-    }
-    let total = 0;
-    for (const chat of chats) {
-      const e = (registry as any).entries.get(chat);
-      expect(e.bytes).toBeLessThanOrEqual(cap);
-      total += e.bytes;
-    }
-    // Total retained across all 5 runs is bounded by 5x the per-run cap — the old
-    // registry would have retained ~5x40MB = 200MB here.
-    expect(total).toBeLessThanOrEqual(cap * chats.length);
+    const entry = (registry as any).entries.get(CHAT);
+    expect(entry.subscribers.size).toBe(1); // bad ejected, good remains
+    expect(good.frames).toEqual(['a', 'b']);
  });
 });

@@ -555,7 +361,7 @@ describe('AiChatStreamRegistryService retention timers', () => {

  it('a finished entry is removed after the retention window', () => {
    registry.open(CHAT, 'run-1');
-    registry.abortEntry(CHAT, 'run-1');
+    registry.abortEntry(CHAT, 'run-1'); // finalize -> retention armed
    expect((registry as any).entries.get(CHAT)).toBeDefined();
    jest.advanceTimersByTime(RUN_STREAM_RETAIN_FINISHED_MS + 1);
    expect((registry as any).entries.get(CHAT)).toBeUndefined();
@@ -563,18 +369,20 @@ describe('AiChatStreamRegistryService retention timers', () => {

  it('retention deletes ONLY its own entry (invariant 2)', () => {
    registry.open(CHAT, 'run-1');
-    registry.abortEntry(CHAT, 'run-1');
+    registry.abortEntry(CHAT, 'run-1'); // arm retention for entry A
+    // Simulate the race where the key was replaced without clearing A's timer.
    const sentinel = { marker: true };
    (registry as any).entries.set(CHAT, sentinel);
    jest.advanceTimersByTime(RUN_STREAM_RETAIN_FINISHED_MS + 1);
+    // A's timer saw entries.get(CHAT) !== A, so it did NOT delete the successor.
    expect((registry as any).entries.get(CHAT)).toBe(sentinel);
  });

  it('open() over a retained entry clears its timer and the successor survives', () => {
    registry.open(CHAT, 'run-1');
-    registry.abortEntry(CHAT, 'run-1');
+    registry.abortEntry(CHAT, 'run-1'); // retained, timer armed
    const clearSpy = jest.spyOn(global, 'clearTimeout');
-    registry.open(CHAT, 'run-2');
+    registry.open(CHAT, 'run-2'); // must clear run-1's retain timer
    expect(clearSpy).toHaveBeenCalled();
    jest.advanceTimersByTime(RUN_STREAM_RETAIN_FINISHED_MS + 1);
    const entry = (registry as any).entries.get(CHAT);
@@ -8,12 +8,10 @@ import { SUBSCRIBER_MAX_BUFFERED_BYTES } from './ai-chat-stream-registry.service
 import type { User, Workspace } from '@docmost/db/types/entity.types';

 /**
- * Wiring spec for the #184 phase 1.5 attach endpoint (tail-only #491)
+ * Wiring spec for the #184 phase 1.5 attach endpoint
 * (`GET /ai-chat/runs/:chatId/stream`). Owner-gated via assertOwnedChat; the
- * registry is mocked so this exercises ONLY the controller's tail-write/live/204/
- * cleanup wiring against a fake raw socket. The attach signature is now
- * `(chatId, anchor, n, cb)` — the client hands its persisted step frontier `n`
- * and its assistant row id `anchor`. Constructor order is (aiChatService,
+ * registry is mocked so this exercises ONLY the controller's replay/live/204/
+ * cleanup wiring against a fake raw socket. Constructor order is (aiChatService,
 * aiChatRunService, aiChatRepo, aiChatMessageRepo, aiTranscription, pageRepo,
 * streamRegistry, environment).
 */
@@ -88,8 +86,8 @@ describe('AiChatController attach endpoint (#184 phase 1.5)', () => {
      attach: jest.fn(
        (
          _chatId: string,
+          _live: boolean,
          _anchor: string | undefined,
-          _n: number,
          cb: RunStreamCallbacks,
        ) => {
          capturedCb = cb;
@@ -158,7 +156,7 @@ describe('AiChatController attach endpoint (#184 phase 1.5)', () => {
    expect(res.hijack).not.toHaveBeenCalled();
  });

-  it('threads anchor and the numeric frontier n through to the registry', async () => {
+  it('threads expect=live and anchor through to the registry', async () => {
    const { controller, streamRegistry } = makeController({
      chat: owned,
      attachment: null,
@@ -167,8 +165,8 @@ describe('AiChatController attach endpoint (#184 phase 1.5)', () => {
    const { req } = makeReq();
    await controller.attachRunStream(
      'c1',
+      'live',
      'anchor-1',
-      '2',
      req,
      res,
      user,
@@ -176,44 +174,13 @@ describe('AiChatController attach endpoint (#184 phase 1.5)', () => {
    );
    expect(streamRegistry.attach).toHaveBeenCalledWith(
      'c1',
+      true,
      'anchor-1',
-      2, // parsed to a number
      expect.anything(),
    );
  });

-  it('#491: an ABSENT/invalid n passes null (not 0) so a finished run 204s (not-tail-aware)', async () => {
-    // Distinguishing a MISSING `n` from `n=0` is the #137/#161 dup guard: a
-    // parameterless/legacy tab must be handed null (-> the registry 204s a finished
-    // run) rather than frontier 0 (which would serve a finished non-rotated run's
-    // whole tail). MUTATION-VERIFY: revert to `Number(n) || 0` and this asserts 0.
-    const { controller, streamRegistry } = makeController({
-      chat: owned,
-      attachment: null,
-    });
-    for (const bad of [undefined, '', 'abc']) {
-      streamRegistry.attach.mockClear();
-      const { res } = makeRawRes();
-      const { req } = makeReq();
-      await controller.attachRunStream(
-        'c1',
-        undefined,
-        bad,
-        req,
-        res,
-        user,
-        workspace,
-      );
-      expect(streamRegistry.attach).toHaveBeenCalledWith(
-        'c1',
-        undefined,
-        null,
-        expect.anything(),
-      );
-    }
-  });
-
-  it('#491: a PRESENT n=0 passes 0 (tail-aware, distinct from absent)', async () => {
+  it('passes expect=false when the query is absent', async () => {
    const { controller, streamRegistry } = makeController({
      chat: owned,
      attachment: null,
@@ -223,7 +190,7 @@ describe('AiChatController attach endpoint (#184 phase 1.5)', () => {
    await controller.attachRunStream(
      'c1',
      undefined,
-      '0',
+      undefined,
      req,
      res,
      user,
@@ -231,8 +198,8 @@ describe('AiChatController attach endpoint (#184 phase 1.5)', () => {
    );
    expect(streamRegistry.attach).toHaveBeenCalledWith(
      'c1',
+      false,
      undefined,
-      0,
      expect.anything(),
    );
  });
@@ -278,8 +245,8 @@ describe('AiChatController attach endpoint (#184 phase 1.5)', () => {
    const { req } = makeReq();
    await controller.attachRunStream(
      'c1',
+      'live',
      'a1',
-      '1',
      req,
      res,
      user,
@@ -1,108 +0,0 @@
-import { ForbiddenException } from '@nestjs/common';
-import { AiChatController } from './ai-chat.controller';
-import type { User, Workspace } from '@docmost/db/types/entity.types';
-
-/**
- * Wiring spec for the #491 delta-poll endpoint (`POST /ai-chat/messages/delta`).
- * Owner-gated via assertOwnedChat (same gate as the other reads), NOT flag-gated.
- * The run fact rides IN the delta response (no separate /run poll). Hand-rolled
- * mocks — no Nest graph, no DB. Constructor order: (aiChatService,
- * aiChatRunService, aiChatRepo, aiChatMessageRepo, aiTranscription, pageRepo).
- */
-describe('AiChatController POST /ai-chat/messages/delta (#491)', () => {
-  const user = { id: 'u1' } as User;
-  const workspace = { id: 'ws1' } as Workspace;
-
-  function makeController(opts: {
-    chat?: unknown;
-    delta?: { rows: unknown[]; cursor: string };
-    run?: unknown;
-  }) {
-    const aiChatRunService = {
-      getLatestForChat: jest.fn().mockResolvedValue(opts.run),
-    };
-    const aiChatRepo = {
-      findById: jest.fn().mockResolvedValue(opts.chat),
-    };
-    const aiChatMessageRepo = {
-      findByChatUpdatedAfter: jest
-        .fn()
-        .mockResolvedValue(opts.delta ?? { rows: [], cursor: 'C1' }),
-    };
-    const controller = new AiChatController(
-      {} as never,
-      aiChatRunService as never,
-      aiChatRepo as never,
-      aiChatMessageRepo as never,
-      {} as never,
-      {} as never,
-    );
-    return { controller, aiChatRunService, aiChatRepo, aiChatMessageRepo };
-  }
-
-  it('owner-gates: a chat the user does not own throws, never reaching the repo', async () => {
-    const { controller, aiChatMessageRepo, aiChatRunService } = makeController({
-      chat: { id: 'c1', creatorId: 'someone-else' },
-    });
-    await expect(
-      controller.getMessagesDelta({ chatId: 'c1' }, user, workspace),
-    ).rejects.toBeInstanceOf(ForbiddenException);
-    expect(aiChatMessageRepo.findByChatUpdatedAfter).not.toHaveBeenCalled();
-    expect(aiChatRunService.getLatestForChat).not.toHaveBeenCalled();
-  });
-
-  it('returns { rows, cursor, run:{id,status} } with the run fact inlined', async () => {
-    const rows = [{ id: 'm1' }];
-    const { controller } = makeController({
-      chat: { id: 'c1', creatorId: 'u1' },
-      delta: { rows, cursor: 'C2' },
-      run: { id: 'r1', status: 'running', error: 'ignored', stepCount: 3 },
-    });
-    const res = await controller.getMessagesDelta(
-      { chatId: 'c1', cursor: 'C1' },
-      user,
-      workspace,
-    );
-    expect(res).toEqual({
-      rows,
-      cursor: 'C2',
-      // ONLY id + status — never the whole run row.
-      run: { id: 'r1', status: 'running' },
-    });
-  });
-
-  it('run is null when the chat has never had a run', async () => {
-    const { controller } = makeController({
-      chat: { id: 'c1', creatorId: 'u1' },
-      run: undefined,
-    });
-    const res = await controller.getMessagesDelta(
-      { chatId: 'c1' },
-      user,
-      workspace,
-    );
-    expect(res.run).toBeNull();
-  });
-
-  it('passes cursor through, defaulting a missing cursor to null (first poll)', async () => {
-    const { controller, aiChatMessageRepo } = makeController({
-      chat: { id: 'c1', creatorId: 'u1' },
-    });
-    await controller.getMessagesDelta({ chatId: 'c1' }, user, workspace);
-    expect(aiChatMessageRepo.findByChatUpdatedAfter).toHaveBeenCalledWith(
-      'c1',
-      'ws1',
-      null,
-    );
-    await controller.getMessagesDelta(
-      { chatId: 'c1', cursor: 'CX' },
-      user,
-      workspace,
-    );
-    expect(aiChatMessageRepo.findByChatUpdatedAfter).toHaveBeenLastCalledWith(
-      'c1',
-      'ws1',
-      'CX',
-    );
-  });
-});
@@ -51,7 +51,6 @@ import {
  ChatIdDto,
  ExportChatDto,
  GeneratePageTitleDto,
-  GetChatDeltaDto,
  GetChatMessagesDto,
  GetRunDto,
  RenameChatDto,
@@ -64,47 +63,6 @@ import {
  SUBSCRIBER_MAX_BUFFERED_BYTES,
 } from './ai-chat-stream-registry.service';
 import { startSseHeartbeat } from './sse-resilience';
-
-/**
- * Write the attach TAIL to the hijacked socket in chunks that RESPECT drain
- * (#491): each `write()` that returns false (the kernel buffer is full) is awaited
- * on the next 'drain' before continuing. The old code wrote the whole buffer
- * synchronously, which — with the pre-#491 32MB ring — spiked memory (half the
- * OOM). Bails immediately if the socket ended/errored mid-write. Frames that the
- * paused registry subscriber buffers while this awaits are delivered by start().
- */
-async function writeTailRespectingDrain(
-  raw: {
-    write(chunk: string): boolean;
-    writableEnded?: boolean;
-    destroyed?: boolean;
-    once(event: string, cb: () => void): unknown;
-    removeListener?(event: string, cb: () => void): unknown;
-  },
-  frames: string[],
-): Promise<void> {
-  for (const frame of frames) {
-    if (raw.writableEnded || raw.destroyed) return;
-    const ok = raw.write(frame);
-    if (!ok) {
-      // Kernel buffer full — wait for drain (or an early close/error) before the
-      // next chunk, so a slow reader never forces the whole tail into memory.
-      // Remove ALL three listeners once any fires, so a many-chunk tail with
-      // repeated backpressure never leaks (MaxListenersExceededWarning).
-      await new Promise<void>((resolve) => {
-        const finish = (): void => {
-          raw.removeListener?.('drain', finish);
-          raw.removeListener?.('close', finish);
-          raw.removeListener?.('error', finish);
-          resolve();
-        };
-        raw.once('drain', finish);
-        raw.once('close', finish);
-        raw.once('error', finish);
-      });
-    }
-  }
-}
 import { EnvironmentService } from '../../integrations/environment/environment.service';

 /**
@@ -191,46 +149,6 @@ export class AiChatController {
    );
  }

-  /**
-   * Delta poll (#491) — the degraded-poll fallback's payload. Returns the chat's
-   * message rows changed since `cursor` (a DB-clock timestamp from the previous
-   * poll), a FRESH cursor, AND the current run fact `{ id, status } | null`. This
-   * replaces the old degraded poll that refetched ALL infinite-query pages (full
-   * parts) every 2.5s: the client seeds once and thereafter merges only the
-   * deltas by id (the overlap window guarantees repeats — the merge is idempotent,
-   * see mergeById). The run fact rides IN the delta (a separate /run poll would
-   * double the poll QPS), so the client FSM gets the run's status on the same tick.
-   * Owner-gated via assertOwnedChat (same gate as the other read endpoints).
-   */
-  @HttpCode(HttpStatus.OK)
-  @Post('messages/delta')
-  async getMessagesDelta(
-    @Body() dto: GetChatDeltaDto,
-    @AuthUser() user: User,
-    @AuthWorkspace() workspace: Workspace,
-  ): Promise<{
-    rows: AiChatMessage[];
-    cursor: string;
-    run: { id: string; status: string } | null;
-  }> {
-    await this.assertOwnedChat(dto.chatId, user, workspace);
-    const { rows, cursor } =
-      await this.aiChatMessageRepo.findByChatUpdatedAfter(
-        dto.chatId,
-        workspace.id,
-        dto.cursor ?? null,
-      );
-    const run = await this.aiChatRunService.getLatestForChat(
-      dto.chatId,
-      workspace.id,
-    );
-    return {
-      rows,
-      cursor,
-      run: run ? { id: run.id, status: run.status } : null,
-    };
-  }
-
  /**
   * Export a chat to Markdown (#183). The DB is the single source of truth: the
   * whole transcript is loaded (oldest -> newest) and rendered server-side. Now
@@ -331,25 +249,19 @@ export class AiChatController {
  }

  /**
-   * Attach to a chat's live run stream from the client's step frontier (#184 phase
-   * 1.5, tail-only #491). A late/reloaded tab hands the server the step count it
-   * has PERSISTED (`n` = the seeded row's `metadata.stepsPersisted`) and its
-   * assistant row id (`anchor`); the registry answers with the TAIL past step `n`
-   * (a synthetic `start` frame + the buffered frames stamped >= n) and then the
-   * live tail. Owner-gated via assertOwnedChat (same gate as getRun). When there
-   * is nothing to resume — no entry, a ring that does not cover the client's
-   * frontier (overflow gap, or the client's seed lagged a rotation), or an anchor
-   * that pins a DIFFERENT run (invariant 6) — the endpoint answers 204, the ONLY
-   * "nothing to resume" signal the AI SDK's reconnect accepts (it maps 204 to a
-   * silent no-op); the client then refetches (a larger n) and re-attaches. With
-   * AI_CHAT_RESUMABLE_STREAM off the registry is never populated, so attach always
-   * 204s.
+   * Attach to a chat's live run stream (#184 phase 1.5). A late/reloaded tab
+   * replays the frames buffered so far and then follows the live tail as a normal
+   * streamer. Owner-gated via assertOwnedChat (same gate as getRun). When there is
+   * nothing to resume — no entry, a finished run without expect=live, an
+   * overflowed buffer, or an anchor that pins a DIFFERENT run — the endpoint
+   * answers 204, the ONLY "nothing to resume" signal the AI SDK's reconnect
+   * accepts (it maps 204 to a silent no-op). With AI_CHAT_RESUMABLE_STREAM off the
+   * registry is never populated, so attach always 204s.
   *
-   * The step marker `n` comes ONLY from the client — the server never reads the
-   * row to derive it, because a server-side n from a stale seed would open a
-   * silent one-step hole. The tail is written to the socket in CHUNKS respecting
-   * drain (writeTailRespectingDrain): the old code synchronously blasted the whole
-   * buffer, which — with the old 32MB cap — was half the OOM.
+   * `expect=live` opts into replaying a finished-but-retained run (safe only when
+   * the client stripped the streaming tail); `anchor` is the client's assistant
+   * row id, which must match this run's (invariant 6) or a foreign run's
+   * transcript would be replayed into the store.
   */
  @SkipTransform()
  @UseGuards(JwtAuthGuard, UserThrottlerGuard)
@@ -357,49 +269,39 @@ export class AiChatController {
  @Get('runs/:chatId/stream')
  async attachRunStream(
    @Param('chatId', new ParseUUIDPipe()) chatId: string,
+    @Query('expect') expect: string | undefined,
    @Query('anchor') anchor: string | undefined,
-    @Query('n') n: string | undefined,
    @Req() req: FastifyRequest,
    @Res() res: FastifyReply,
    @AuthUser() user: User,
    @AuthWorkspace() workspace: Workspace,
  ): Promise<void> {
    await this.assertOwnedChat(chatId, user, workspace); // same gate as getRun
-    // The client's persisted step frontier. #491: distinguish a MISSING/invalid `n`
-    // (null — a NOT-tail-aware, legacy/parameterless tab expecting the old
-    // "finished -> 204 -> poll" contract) from `n=0` (a tail-aware client with
-    // nothing persisted yet). Passing 0 for a missing `n` would serve a finished,
-    // non-rotated run's WHOLE tail and a parameterless client would append it onto
-    // the steps it already shows -> #137/#161 duplicate. null makes the registry
-    // 204 such a finished run (see attach); a tail-aware n=0 still resumes.
-    const frontier: number | null =
-      n === undefined || n === '' || !Number.isFinite(Number(n))
-        ? null
-        : Math.max(0, Number(n));
-    // The per-subscriber backpressure cap tracks the (env-tunable) ring cap.
-    const subscriberCap =
-      this.streamRegistry?.subscriberMaxBufferedBytes ??
-      SUBSCRIBER_MAX_BUFFERED_BYTES;
    let stopHeartbeat: () => void = () => undefined;
-    const attachment = await this.streamRegistry?.attach(chatId, anchor, frontier, {
-      onFrame: (frame) => {
-        // Backpressure guard: 2x the ring cap, so the initial tail burst alone
-        // can never trip it; only a genuinely stalled socket can.
-        try {
-          if (res.raw.writableLength > subscriberCap) {
-            res.raw.destroy(); // 'close' fires -> unsubscribe below
-            return;
+    const attachment = await this.streamRegistry?.attach(
+      chatId,
+      expect === 'live',
+      anchor,
+      {
+        onFrame: (frame) => {
+          // Backpressure guard: 2x the replay cap, so the initial replay burst
+          // alone can never trip it; only a genuinely stalled socket can.
+          try {
+            if (res.raw.writableLength > SUBSCRIBER_MAX_BUFFERED_BYTES) {
+              res.raw.destroy(); // 'close' fires -> unsubscribe below
+              return;
+            }
+            if (!res.raw.writableEnded) res.raw.write(frame);
+          } catch {
+            res.raw.destroy();
          }
-          if (!res.raw.writableEnded) res.raw.write(frame);
-        } catch {
-          res.raw.destroy();
-        }
+        },
+        onEnd: () => {
+          stopHeartbeat();
+          if (!res.raw.writableEnded) res.raw.end();
+        },
      },
-      onEnd: () => {
-        stopHeartbeat();
-        if (!res.raw.writableEnded) res.raw.end();
-      },
-    });
+    );
    if (!attachment) {
      res.status(204).send(); // the ONLY "nothing to resume" signal the SDK accepts
      return;
@@ -428,16 +330,13 @@ export class AiChatController {
        // deliberately NO Connection/Keep-Alive (hop-by-hop; Safari/HTTP2)
      });
      res.raw.flushHeaders?.();
-      // Write the tail in chunks respecting drain (not a synchronous blast, which
-      // was half the OOM). Frames the paused subscriber buffers meanwhile are
-      // drained by start() below; its cap is the backstop for a stalled socket.
-      await writeTailRespectingDrain(res.raw, attachment.replay);
+      for (const frame of attachment.replay) res.raw.write(frame);
      if (attachment.finished) {
-        if (!res.raw.writableEnded) res.raw.end();
+        res.raw.end();
        return;
      }
      stopHeartbeat = startSseHeartbeat(res.raw, 15_000);
-      attachment.start(); // drain pending accumulated during the tail write, go live
+      attachment.start(); // drain pending accumulated during replay, go live
    } catch {
      attachment.unsubscribe();
      stopHeartbeat();
@@ -1543,39 +1543,30 @@ export class AiChatService implements OnModuleInit, OnModuleDestroy {
      // Per-step (non-terminal) update: persist the finished steps the moment a
      // step ends. Tolerant — a failed update is logged and swallowed so it never
      // throws into the stream. Keeps status 'streaming'.
-      //
-      // #491: it now SIGNALS its outcome — the persisted `stepsPersisted` count on
-      // a CONFIRMED write, or null when it was skipped/failed. The caller rotates
-      // the run-stream registry ring ONLY on a non-null return (a confirmed
-      // persist), so a failed persist never rotates away a step nobody has (the
-      // classic inversion bug); a failure just makes the ring cover more.
-      const updateStreaming = async (): Promise<number | null> => {
-        if (!assistantId) return null;
+      const updateStreaming = async (): Promise<void> => {
+        if (!assistantId) return;
        // Cheap short-circuit once the turn is finalized (see `finalized` below).
        // The AUTHORITATIVE guard is `onlyIfStreaming` on the UPDATE: a late
        // fire-and-forget step update could still be in flight on another pool
        // connection when finalize runs, so the SQL `WHERE status='streaming'`
        // (not this flag) is what prevents it clobbering the terminal row.
-        if (finalized) return null;
-        // Build the flush ONCE so the returned count is EXACTLY the persisted
-        // `stepsPersisted` (both derive from capturedSteps.length at this instant).
-        const flushed = flushAssistant(capturedSteps, '', 'streaming', {
-          pageChanged,
-          partsCache,
-        });
-        const stepsPersisted = flushed.metadata.stepsPersisted as number;
+        if (finalized) return;
        try {
-          await this.aiChatMessageRepo.update(assistantId, workspace.id, flushed, {
-            onlyIfStreaming: true,
-          });
-          return stepsPersisted;
+          await this.aiChatMessageRepo.update(
+            assistantId,
+            workspace.id,
+            flushAssistant(capturedSteps, '', 'streaming', {
+              pageChanged,
+              partsCache,
+            }),
+            { onlyIfStreaming: true },
+          );
        } catch (err) {
          this.logger.warn(
            `Failed to update streaming assistant row: ${
              err instanceof Error ? err.message : 'unknown error'
            }`,
          );
-          return null;
        }
      };

@@ -1751,24 +1742,7 @@ export class AiChatService implements OnModuleInit, OnModuleDestroy {
            // this point still recovers the step. Not awaited here (never block the
            // stream), but SERIALIZED via stepUpdateChain so the writes commit in
            // step order; updateStreaming is error-tolerant (logs + swallows).
-            // #491: on a CONFIRMED persist, rotate the run-stream registry ring to
-            // drop the now-on-disk steps (stamp < stepsPersisted). Gated on the
-            // resumable flag (same as open/bind) and identity-checked in the
-            // registry; a null return (skipped/failed) rotates NOTHING (auto-safe).
-            stepUpdateChain = stepUpdateChain.then(async () => {
-              const persisted = await updateStreaming();
-              if (
-                persisted != null &&
-                runId &&
-                this.environment?.isAiChatResumableStreamEnabled?.()
-              ) {
-                this.streamRegistry?.confirmPersistedStep(
-                  chatId,
-                  runId,
-                  persisted,
-                );
-              }
-            });
+            stepUpdateChain = stepUpdateChain.then(() => updateStreaming());
            // #184: persist the run's progress (finished-step count). Fire-and-
            // forget; the hook swallows its own errors.
            if (runId) runHooks?.onStep?.(runId, capturedSteps.length);
@@ -2917,18 +2891,6 @@ export function flushAssistant(
    // `parts`). Old rows have no marker and the legacy { output } shape; a
    // dual-shape query branches on this. Old rows are deliberately NOT migrated.
    toolTraceVersion: 2,
-    // #491 STEP MARKER: the number of FINISHED steps whose parts are in THIS row,
-    // written by the SAME flush that builds `parts` (atomically — they are both
-    // derived from `finished`, so the marker can NEVER disagree with the persisted
-    // parts). This is the step-alignment anchor the resume stack builds on:
-    // - the registry rotates its retention ring only on a CONFIRMED persist of
-    //   step N (commit 3);
-    // - attach slices the tail at "step > N" from the client's persisted seed.
-    // It is NOT `run.stepCount`: recordStep is fire-and-forget and NOT atomic with
-    // the parts write, so stepCount could race ahead of the persisted parts
-    // (seed↔marker drift). The in-progress trailing text (an error/abort partial,
-    // or a mid-stream flush) is NOT a finished step and is excluded from the count.
-    stepsPersisted: finished.length,
  };
  // finishReason: prefer an explicit one; else derive a sensible value from the
  // terminal status (so onError/onAbort records keep their historical reason).
@@ -1,65 +0,0 @@
-import { flushAssistant } from './ai-chat.service';
-
-/**
- * #491 STEP MARKER — `metadata.stepsPersisted` is written by the SAME flush that
- * builds `metadata.parts`, so the marker can never disagree with the persisted
- * parts (the step-alignment anchor the resume stack builds on). These are
- * PROPERTY tests: they assert the marker tracks the number of FINISHED steps for
- * every flush shape.
- */
-
-// A finished step carrying one line of text and one tool call/result.
-function step(i: number) {
-  return {
-    text: `step ${i}`,
-    toolCalls: [
-      { toolCallId: `c${i}`, toolName: 'getPage', input: { id: `p${i}` } },
-    ],
-    toolResults: [
-      { toolCallId: `c${i}`, toolName: 'getPage', output: { title: `T${i}` } },
-    ],
-  };
-}
-
-describe('flushAssistant step marker (#491)', () => {
-  it('seed (no steps) → stepsPersisted 0', () => {
-    const f = flushAssistant([], '', 'streaming');
-    expect(f.metadata.stepsPersisted).toBe(0);
-  });
-
-  it('PROPERTY: stepsPersisted equals the number of FINISHED steps, for any N', () => {
-    for (let n = 0; n <= 6; n++) {
-      const steps = Array.from({ length: n }, (_, i) => step(i));
-      const f = flushAssistant(steps, '', 'streaming');
-      expect(f.metadata.stepsPersisted).toBe(n);
-      // ...and the parts actually contain those N steps' text (marker agrees with
-      // the persisted parts — the atomicity the whole design relies on).
-      const parts = f.metadata.parts as Array<Record<string, unknown>>;
-      const textParts = parts.filter((p) => p.type === 'text');
-      expect(textParts).toHaveLength(n);
-    }
-  });
-
-  it('an in-progress trailing partial does NOT increment the marker', () => {
-    // 2 finished steps + a partial (not-yet-finished) trailing text: the marker
-    // counts only the CONFIRMED step boundaries, not the partial.
-    const f = flushAssistant([step(0), step(1)], 'partial third step', 'error', {
-      error: 'boom',
-    });
-    expect(f.metadata.stepsPersisted).toBe(2);
-    // The partial text IS persisted in parts (so the user sees it), but it is not a
-    // counted step.
-    const parts = f.metadata.parts as Array<Record<string, unknown>>;
-    expect(parts[parts.length - 1]).toEqual({
-      type: 'text',
-      text: 'partial third step',
-    });
-  });
-
-  it('terminal completed flush counts all finished steps', () => {
-    const f = flushAssistant([step(0), step(1), step(2)], '', 'completed', {
-      finishReason: 'stop',
-    });
-    expect(f.metadata.stepsPersisted).toBe(3);
-  });
-});
@@ -1,10 +1,4 @@
-import {
-  IsISO8601,
-  IsOptional,
-  IsString,
-  MaxLength,
-  MinLength,
-} from 'class-validator';
+import { IsOptional, IsString, MaxLength, MinLength } from 'class-validator';

 /** Identify a chat by id (workspace-scoped on the server). */
 export class ChatIdDto {
@@ -43,24 +37,6 @@ export class GetChatMessagesDto {
  cursor?: string;
 }

-/**
- * Delta poll (#491): pull the chat's rows changed since `cursor` (a DB-clock
- * timestamp from the previous poll) plus the current run fact — the degraded-poll
- * fallback's payload, replacing the full infinite-query refetch. Omit `cursor` on
- * the first poll (returns just a fresh cursor to start the chain).
- */
-export class GetChatDeltaDto {
-  @IsString()
-  chatId: string;
-
-  // ISO-8601 timestamp echoed from the previous poll's response. Validated as
-  // ISO-8601 (not a bare string): a malformed cursor would otherwise reach the
-  // `::timestamptz` cast in findByChatUpdatedAfter and 500 instead of a clean 400.
-  @IsOptional()
-  @IsISO8601()
-  cursor?: string;
-}
-
 /** Resolve the chat bound to a document (the page's most-recent owned chat). */
 export class BoundChatDto {
  @IsString()
@@ -1,27 +0,0 @@
-import { type Kysely } from 'kysely';
-
-/**
- * #370 — page-versioning intentionality tier on a history snapshot.
- *
- * Adds `page_history.kind`, the three-tier "how intentional was this snapshot"
- * marker that lets versions (intentional points) be told apart from autosaves:
- *   - 'manual'   — a human explicitly saved a version (Cmd+S / Save button)
- *   - 'agent'    — the AI agent explicitly saved a version
- *   - 'idle'     — trailing idle-flush autosnapshot (safety net)
- *   - 'boundary' — autosnapshot pinned on a source transition (user↔agent↔git)
- *
- * Nullable with NO default (mirrors last_updated_source in the agent-provenance
- * migration): legacy rows predate the marker and read back as `null`, which the
- * client renders as a plain autosave. Stored as a short varchar to stay
- * forward-compatible without an enum migration.
- */
-export async function up(db: Kysely<any>): Promise<void> {
-  await db.schema
-    .alterTable('page_history')
-    .addColumn('kind', 'varchar(20)', (col) => col)
-    .execute();
-}
-
-export async function down(db: Kysely<any>): Promise<void> {
-  await db.schema.alterTable('page_history').dropColumn('kind').execute();
-}
@@ -1,280 +0,0 @@
-import { randomUUID } from 'crypto';
-import { CamelCasePlugin, Kysely, sql } from 'kysely';
-import { PostgresJSDialect } from 'kysely-postgres-js';
-// NOT a default import: the project tsconfig is `module: commonjs` with NO
-// esModuleInterop, so `import postgres from 'postgres'` compiles to
-// `postgres_1.default(...)` and the CJS `postgres` export has no `.default` —
-// it threw in beforeAll, was swallowed as "DB unreachable", and SILENTLY voided
-// all six tests. Mirror the working integration harness (test/integration/db.ts).
-import * as postgres from 'postgres';
-import { AiChatMessageRepo } from './ai-chat-message.repo';
-import { AiChatRunRepo } from './ai-chat-run.repo';
-
-/**
- * #491 delta-poll — OBSERVABLE-PROPERTY tests against a LIVE Postgres (the local
- * gitmost test DB, docker `gitmost-test-pg` on :5432), not "rows through a mock"
- * (a mock cannot observe the DB clock nor the overlap-window race — the very
- * things that matter here). Drives the REAL repo methods (`findByChatUpdatedAfter`,
- * the now()-stamped `update`) and asserts:
- *   1. delta-relevant writes stamp `updatedAt` from the DB clock, not the app clock
- *      (proven by faking the process clock far into the future and observing the
- *      stamp stays on real DB time);
- *   2. the poll returns only rows changed after the cursor, ordered, with a fresh
- *      DB-clock cursor;
- *   3. the "committed late but stamped earlier than the cursor" RACE is caught by
- *      the overlap window (a naive `updatedAt > cursor` would MISS it);
- *   4. the overlap GUARANTEES repeats across close polls — the contract behind the
- *      client's idempotent merge (mergeById).
- *
- * INTEGRATION lane (`*.int-spec.ts`): runs under `test:int`, whose global-setup
- * DROPS + RE-CREATES + MIGRATES `docmost_test`, so the real `ai_chat_messages` /
- * `ai_chat_runs` tables EXIST here. (It was previously a `.spec.ts` defaulting to
- * the UNmigrated dev `docmost`; in the CI unit lane — where `WAL_TEST_DATABASE_URL`
- * is unset and only `test:int` migrates — that meant 5/6 ERROR
- * `relation "ai_chat_messages" does not exist`, silently voiding coverage of the
- * risky cursor/overlap logic. Renaming to `.int-spec.ts` + defaulting the DSN to
- * `docmost_test` fixes the CI fidelity.)
- *
- * FK triggers are bypassed (`session_replication_role = replica`) so synthetic
- * chat/workspace ids need no parent fixtures; a single pooled connection (max 1)
- * keeps that session setting for every query. SKIPS cleanly when the DB is
- * unreachable so a DB-less CI never breaks.
- */
-const CONN =
-  process.env.WAL_TEST_DATABASE_URL ??
-  process.env.TEST_DATABASE_URL ??
-  'postgresql://docmost:docmost_dev_pw@localhost:5432/docmost_test';
-
-let db: Kysely<any>;
-let sqlClient: ReturnType<typeof postgres>;
-let msgRepo: AiChatMessageRepo;
-let runRepo: AiChatRunRepo;
-let reachable = false;
-
-const workspaceId = randomUUID();
-const chatId = randomUUID();
-
-beforeAll(async () => {
-  try {
-    sqlClient = postgres(CONN, { max: 1, onnotice: () => {} });
-    db = new Kysely<any>({
-      dialect: new PostgresJSDialect({ postgres: sqlClient }),
-      plugins: [new CamelCasePlugin()],
-    });
-    // Single connection keeps this session-scoped bypass for the whole suite.
-    await sql`set session_replication_role = replica`.execute(db);
-    await sql`select 1`.execute(db);
-    reachable = true;
-  } catch (err) {
-    reachable = false;
-    // A genuine connection failure (ECONNREFUSED etc.) is a legitimate skip on a
-    // DB-less CI. A PROGRAMMING error (bad import, typo, driver misuse) must NOT
-    // masquerade as "DB unreachable" and silently void the whole suite (that is
-    // exactly the bug that hid this spec's zero coverage) — rethrow it so the
-    // suite fails LOUDLY.
-    const msg = String((err as Error)?.message ?? err);
-    if (
-      !/ECONNREFUSED|ENOTFOUND|ETIMEDOUT|EHOSTUNREACH|connect|terminating|password|authentication|role .* does not exist|database .* does not exist/i.test(
-        msg,
-      )
-    ) {
-      throw err;
-    }
-  }
-  msgRepo = new AiChatMessageRepo(db as never);
-  runRepo = new AiChatRunRepo(db as never);
-});
-
-afterAll(async () => {
-  if (db) {
-    try {
-      await db
-        .deleteFrom('aiChatMessages')
-        .where('workspaceId', '=', workspaceId)
-        .execute();
-      await db
-        .deleteFrom('aiChatRuns')
-        .where('workspaceId', '=', workspaceId)
-        .execute();
-    } catch {
-      /* best-effort cleanup */
-    }
-    await db.destroy();
-  }
-});
-
-afterEach(() => {
-  jest.useRealTimers();
-});
-
-async function seedMessage(overrides: Record<string, unknown> = {}) {
-  return msgRepo.insert({
-    chatId,
-    workspaceId,
-    userId: null as never,
-    role: 'assistant',
-    content: 'x',
-    status: 'streaming',
-    ...overrides,
-  } as never);
-}
-
-async function dbNow(): Promise<string> {
-  const r = await sql<{ now: Date }>`select now() as now`.execute(db);
-  return r.rows[0].now.toISOString();
-}
-
-// Fake ONLY the Date object (so in-process `new Date()`/`Date.now()` jump), while
-// leaving every TIMER function real. Faking timers wholesale freezes postgres.js's
-// internal connection/query timers, so the awaited DB round-trip would hang the
-// test (and the afterAll cleanup) at the jest 5s cap. With Date-only faking the
-// query resolves normally, and we still prove the stamp is the DB clock (not the
-// skewed process clock).
-function fakeDateOnly(iso: string): void {
-  jest.useFakeTimers({
-    doNotFake: [
-      'hrtime',
-      'nextTick',
-      'performance',
-      'queueMicrotask',
-      'requestAnimationFrame',
-      'cancelAnimationFrame',
-      'requestIdleCallback',
-      'cancelIdleCallback',
-      'setImmediate',
-      'clearImmediate',
-      'setInterval',
-      'clearInterval',
-      'setTimeout',
-      'clearTimeout',
-    ],
-    now: new Date(iso),
-  });
-}
-
-const maybe = (name: string, fn: () => Promise<void>) =>
-  it(name, async () => {
-    if (!reachable) {
-      console.warn(`SKIP (${name}): test DB unreachable at ${CONN}`);
-      return;
-    }
-    await fn();
-  });
-
-describe('AiChatMessageRepo.findByChatUpdatedAfter (#491 delta poll)', () => {
-  maybe('null cursor returns no rows and a fresh DB-clock cursor', async () => {
-    const before = await dbNow();
-    const { rows, cursor } = await msgRepo.findByChatUpdatedAfter(
-      chatId,
-      workspaceId,
-      null,
-    );
-    expect(rows).toEqual([]);
-    expect(new Date(cursor).getTime()).toBeGreaterThanOrEqual(
-      new Date(before).getTime(),
-    );
-  });
-
-  maybe('returns only rows changed after the cursor', async () => {
-    const { cursor: c0 } = await msgRepo.findByChatUpdatedAfter(
-      chatId,
-      workspaceId,
-      null,
-    );
-    const m = await seedMessage();
-    const { rows, cursor: c1 } = await msgRepo.findByChatUpdatedAfter(
-      chatId,
-      workspaceId,
-      c0,
-    );
-    expect(rows.map((r) => r.id)).toContain(m.id);
-    // Cursor is monotonic (advances).
-    expect(new Date(c1).getTime()).toBeGreaterThanOrEqual(
-      new Date(c0).getTime(),
-    );
-  });
-
-  maybe(
-    'RACE: a row stamped BEFORE the cursor but seen after is caught by the overlap',
-    async () => {
-      // Cursor taken now; then a row appears whose updatedAt is 2s in the PAST
-      // (committed late on another connection but stamped earlier). A naive
-      // `updatedAt > cursor` would MISS it; the 5s overlap window catches it.
-      const cursor = await dbNow();
-      const m = await seedMessage();
-      await sql`update ai_chat_messages set updated_at = now() - interval '2 seconds' where id = ${m.id}`.execute(
-        db,
-      );
-      const { rows } = await msgRepo.findByChatUpdatedAfter(
-        chatId,
-        workspaceId,
-        cursor,
-      );
-      expect(rows.map((r) => r.id)).toContain(m.id);
-    },
-  );
-
-  maybe(
-    'overlap GUARANTEES repeats across close polls (idempotent-merge contract)',
-    async () => {
-      const { cursor: c0 } = await msgRepo.findByChatUpdatedAfter(
-        chatId,
-        workspaceId,
-        null,
-      );
-      const m = await seedMessage();
-      const first = await msgRepo.findByChatUpdatedAfter(
-        chatId,
-        workspaceId,
-        c0,
-      );
-      expect(first.rows.map((r) => r.id)).toContain(m.id);
-      // Immediately re-poll with the JUST-returned cursor: the row is still within
-      // the overlap window, so it is returned AGAIN — the client MUST dedupe by id.
-      const second = await msgRepo.findByChatUpdatedAfter(
-        chatId,
-        workspaceId,
-        first.cursor,
-      );
-      expect(second.rows.map((r) => r.id)).toContain(m.id);
-    },
-  );
-
-  maybe(
-    'update() stamps updatedAt from the DB clock, not the app clock',
-    async () => {
-      const m = await seedMessage();
-      // Skew the PROCESS clock ~73 years into the future (Date only). If the stamp
-      // came from `new Date()` the row would read year 2099; sql now() keeps it on
-      // DB time.
-      fakeDateOnly('2099-01-01T00:00:00Z');
-      const updated = await msgRepo.update(m.id, workspaceId, {
-        content: 'y',
-      });
-      jest.useRealTimers();
-      expect(updated).toBeDefined();
-      expect(new Date(updated!.updatedAt).getFullYear()).toBeLessThan(2099);
-    },
-  );
-
-  maybe(
-    'run update() also stamps updatedAt from the DB clock',
-    async () => {
-      const run = await runRepo.insert({
-        chatId,
-        workspaceId,
-        createdBy: null as never,
-        trigger: 'user',
-        status: 'running',
-        stepCount: 0,
-      } as never);
-      fakeDateOnly('2099-01-01T00:00:00Z');
-      const updated = await runRepo.update(run.id, workspaceId, {
-        stepCount: 1,
-      });
-      jest.useRealTimers();
-      expect(updated).toBeDefined();
-      expect(new Date(updated!.updatedAt).getFullYear()).toBeLessThan(2099);
-    },
-  );
-});
@@ -25,20 +25,6 @@ const SWEEP_STREAMING_STALE_MS = 10 * 60 * 1000; // 10 minutes
 // into memory; far above any realistic transcript length.
 const FIND_ALL_BY_CHAT_LIMIT = 5000;

-// Delta-poll overlap (#491): the poll query reaches this far BEHIND the client's
-// echoed cursor, so a row that committed with an `updatedAt` marginally before the
-// previous cursor was taken (on another autocommit connection) is still caught.
-// Sized well above realistic single-row commit skew; the client merge is
-// idempotent by id (mergeById), so the guaranteed repeats the overlap produces are
-// harmless.
-export const DELTA_POLL_OVERLAP_SECONDS = 5;
-
-// Hard cap on rows one delta poll returns — a safety bound (a poll should carry a
-// handful of just-changed rows, never a whole transcript). Ordered by (updatedAt,
-// id) asc, so on the pathological overflow the OLDEST changes win and the newest
-// are picked up by the next poll (its cursor did not advance past them).
-export const DELTA_POLL_MAX_ROWS = 500;
-
@Injectable()
 export class AiChatMessageRepo {
  private readonly logger = new Logger(AiChatMessageRepo.name);
@@ -153,72 +139,6 @@ export class AiChatMessageRepo {
      .executeTakeFirst();
  }

-  /**
-   * Delta read (#491) for the degraded poll: the chat's messages whose row
-   * changed AFTER the client's `cursor`, plus a FRESH cursor taken from the DB
-   * clock. Replaces the old "refetch ALL infinite-query pages every 2.5s with
-   * full parts" poll — the client seeds once (findByChat) and thereafter pulls
-   * only the deltas and merges them by id (mergeById).
-   *
-   * Cursor: a DB-clock timestamp (now()) the client echoes back each poll. All
-   * delta-relevant writes stamp `updatedAt` with now() (see `update` /
-   * `finalizeOwner`), so this is a SINGLE monotonic axis. The query overlaps the
-   * cursor by DELTA_POLL_OVERLAP_SECONDS to catch a row committed with an
-   * `updatedAt` marginally BEFORE the previous cursor was taken on another
-   * connection (single-row autocommit UPDATEs; no long transactions). The overlap
-   * GUARANTEES occasional REPEATS, so the client merge MUST be idempotent by id.
-   *
-   * `cursor === null` (first poll after the full seed) returns NO rows — there is
-   * nothing "new" relative to a just-loaded seed — only the fresh cursor to start
-   * the delta chain. The fresh cursor is read AFTER the rows, so it is >= every
-   * returned row's `updatedAt` (they were read strictly earlier) — a row that
-   * commits between the rows-read and the cursor-read is at most
-   * DELTA_POLL_OVERLAP_SECONDS behind the returned cursor, so the next poll's
-   * overlap window always re-includes it (no miss).
-   */
-  async findByChatUpdatedAfter(
-    chatId: string,
-    workspaceId: string,
-    cursor: string | null,
-  ): Promise<{ rows: AiChatMessage[]; cursor: string }> {
-    if (cursor === null) {
-      const nowRow = await sql<{ now: Date }>`select now() as now`.execute(
-        this.db,
-      );
-      return { rows: [], cursor: nowRow.rows[0].now.toISOString() };
-    }
-    // Overlap the client cursor by DELTA_POLL_OVERLAP_SECONDS, computed in SQL off
-    // the echoed cursor so the whole comparison stays on the DB clock.
-    const rows = await this.db
-      .selectFrom('aiChatMessages')
-      .select(this.baseFields)
-      .where('chatId', '=', chatId)
-      .where('workspaceId', '=', workspaceId)
-      .where('deletedAt', 'is', null)
-      .where(
-        'updatedAt',
-        '>',
-        sql<Date>`${cursor}::timestamptz - make_interval(secs => ${DELTA_POLL_OVERLAP_SECONDS})`,
-      )
-      .orderBy('updatedAt', 'asc')
-      .orderBy('id', 'asc')
-      .limit(DELTA_POLL_MAX_ROWS)
-      .execute();
-    // When the page filled (pathological overflow), DO NOT advance the cursor to
-    // now(): that would skip the changed rows past the cap that this poll did not
-    // return. Resume from the last returned row's updatedAt instead (the next
-    // poll's overlap re-includes ties by id). In the normal case the fresh DB-clock
-    // now() is the cursor.
-    if (rows.length === DELTA_POLL_MAX_ROWS) {
-      return {
-        rows,
-        cursor: rows[rows.length - 1].updatedAt.toISOString(),
-      };
-    }
-    const nowRow = await sql<{ now: Date }>`select now() as now`.execute(this.db);
-    return { rows, cursor: nowRow.rows[0].now.toISOString() };
-  }
-
  async insert(
    insertable: InsertableAiChatMessage,
    trx?: KyselyTransaction,
@@ -252,13 +172,7 @@ export class AiChatMessageRepo {
    const db = dbOrTx(this.db, opts?.trx);
    let query = db
      .updateTable('aiChatMessages')
-      // #491: stamp `updatedAt` from the DB clock (sql now()), NOT the app clock
-      // (new Date()). The delta-poll cursor (findByChatUpdatedAfter) is a single
-      // DB-clock axis; a per-step 'streaming' UPDATE stamped with the app clock
-      // would be a SECOND, skewed clock source and could leave a row's updatedAt
-      // just under a cursor taken from now() on another connection — an
-      // independent source of delta MISSES. All delta-relevant writes use now().
-      .set({ ...(patch as Record<string, unknown>), updatedAt: sql`now()` })
+      .set({ ...(patch as Record<string, unknown>), updatedAt: new Date() })
      .where('id', '=', id)
      .where('workspaceId', '=', workspaceId);
    // Concurrency guard (#183 review): a per-step 'streaming' update must NEVER
@@ -300,9 +214,7 @@ export class AiChatMessageRepo {
    const db = dbOrTx(this.db, trx);
    return db
      .updateTable('aiChatMessages')
-      // #491: DB-clock stamp (see `update`) — this terminal write flips the row's
-      // status, which the delta poll must observe on the shared now() cursor axis.
-      .set({ ...(patch as Record<string, unknown>), updatedAt: sql`now()` })
+      .set({ ...(patch as Record<string, unknown>), updatedAt: new Date() })
      .where('id', '=', id)
      .where('workspaceId', '=', workspaceId)
      .where((eb) =>
@@ -337,9 +249,7 @@ export class AiChatMessageRepo {
      .set({
        status,
        metadata: sql`coalesce(metadata, '{}'::jsonb) || jsonb_build_object('finalizeFailed', true)`,
-        // #491: DB-clock stamp (see `update`) so a reconcile status flip lands on
-        // the same now() cursor axis the delta poll reads.
-        updatedAt: sql`now()`,
+        updatedAt: new Date(),
      })
      .where('id', '=', id)
      .where('workspaceId', '=', workspaceId)
@@ -397,9 +307,7 @@ export class AiChatMessageRepo {
      .set({
        status: 'aborted',
        metadata: sql`coalesce(m.metadata, '{}'::jsonb) || jsonb_build_object('finalizeFailed', true)`,
-        // #491: DB-clock stamp (see `update`). The staleness WHERE below stays on
-        // the app clock — a >minutes window makes the ms-scale skew irrelevant.
-        updatedAt: sql`now()`,
+        updatedAt: new Date(),
      })
      .where('m.status', '=', 'streaming')
      .where('m.updatedAt', '<', staleBefore)
@@ -443,8 +351,7 @@ export class AiChatMessageRepo {
      .set({
        status: 'aborted',
        metadata: sql`coalesce(metadata, '{}'::jsonb) || jsonb_build_object('finalizeFailed', true)`,
-        // #491: DB-clock stamp (see `update`). Staleness WHERE stays app-clock.
-        updatedAt: sql`now()`,
+        updatedAt: new Date(),
      })
      .where('status', '=', 'streaming')
      .where('updatedAt', '<', staleBefore)
@@ -62,17 +62,10 @@ describe('AiChatRunRepo.sweepRunning', () => {
    // ...but a fresh 'running' run (updatedAt = now) must NOT be skipped: no
    // updatedAt predicate at all on the boot path.
    expect(rec.wheres.some(([col]) => col === 'updatedAt')).toBe(false);
-    // It flips to 'aborted' and stamps finishedAt + updatedAt. #491: the stamps
-    // are now DB-clock `sql now()` expressions (raw builders), NOT app-clock
-    // `new Date()`, so the run row shares the delta poll's single now() cursor axis
-    // — assert they are present and are the sql raw-builder objects (not a Date,
-    // not undefined).
-    expect(rec.set?.status).toBe('aborted');
-    for (const stamp of ['finishedAt', 'updatedAt'] as const) {
-      expect(rec.set?.[stamp]).toBeDefined();
-      expect(rec.set?.[stamp]).not.toBeInstanceOf(Date);
-      expect(typeof rec.set?.[stamp]).toBe('object');
-    }
+    // It flips to 'aborted' and stamps finishedAt.
+    expect(rec.set).toEqual(
+      expect.objectContaining({ status: 'aborted', finishedAt: expect.any(Date) }),
+    );
  });

  it('phase-2 path: an explicit staleMs reintroduces the updatedAt window', async () => {
@@ -136,11 +136,7 @@ export class AiChatRunRepo {
    const db = dbOrTx(this.db, trx);
    return db
      .updateTable('aiChatRuns')
-      // #491: DB-clock stamp (sql now()) so the run row shares the delta poll's
-      // single now() cursor axis with the assistant message rows — a run-status
-      // change (the run fact the delta carries) must never sit on a skewed app
-      // clock relative to the message updatedAt cursor.
-      .set({ ...(patch as Record<string, unknown>), updatedAt: sql`now()` })
+      .set({ ...(patch as Record<string, unknown>), updatedAt: new Date() })
      .where('id', '=', id)
      .where('workspaceId', '=', workspaceId)
      .returning(this.baseFields)
@@ -166,15 +162,14 @@ export class AiChatRunRepo {
    trx?: KyselyTransaction,
  ): Promise<AiChatRun | undefined> {
    const db = dbOrTx(this.db, trx);
+    const now = new Date();
    return db
      .updateTable('aiChatRuns')
      .set({
        status: patch.status,
        error: patch.error,
-        // #491: DB-clock stamps (finished_at + updated_at) so the terminal run
-        // fact lands on the delta poll's now() cursor axis.
-        finishedAt: sql`now()`,
-        updatedAt: sql`now()`,
+        finishedAt: now,
+        updatedAt: now,
      })
      .where('id', '=', id)
      .where('workspaceId', '=', workspaceId)
@@ -197,8 +192,7 @@ export class AiChatRunRepo {
    const db = dbOrTx(this.db, trx);
    return db
      .updateTable('aiChatRuns')
-      // #491: DB-clock stamps (see `update`).
-      .set({ stopRequestedAt: sql`now()`, updatedAt: sql`now()` })
+      .set({ stopRequestedAt: new Date(), updatedAt: new Date() })
      .where('id', '=', id)
      .where('workspaceId', '=', workspaceId)
      .where('status', 'in', ACTIVE_RUN_STATUSES as unknown as string[])
@@ -255,14 +249,13 @@ export class AiChatRunRepo {
    trx?: KyselyTransaction,
  ): Promise<number> {
    const db = dbOrTx(this.db, trx);
+    const now = new Date();
    let query = db
      .updateTable('aiChatRuns')
      .set({
        status: 'aborted',
-        // #491: DB-clock stamps (see `update`). The staleness WHERE below stays on
-        // the app clock — a >minutes window makes the ms-scale skew irrelevant.
-        finishedAt: sql`now()`,
-        updatedAt: sql`now()`,
+        finishedAt: now,
+        updatedAt: now,
        error: sql`coalesce(error, ${'Run interrupted by a server restart.'})`,
      })
      .where('status', 'in', ACTIVE_RUN_STATUSES as unknown as string[]);
@@ -270,7 +263,7 @@ export class AiChatRunRepo {
    // sibling replica's live run is never aborted. Omitted on the phase-1 boot
    // sweep -> unconditional.
    if (typeof opts.staleMs === 'number') {
-      const staleBefore = new Date(Date.now() - opts.staleMs);
+      const staleBefore = new Date(now.getTime() - opts.staleMs);
      query = query.where('updatedAt', '<', staleBefore);
    }
    const rows = await query.returning('id').execute();
@@ -13,7 +13,6 @@ import { jsonArrayFrom, jsonObjectFrom } from 'kysely/helpers/postgres';
 import { ExpressionBuilder, sql } from 'kysely';
 import { DB } from '@docmost/db/types/db';
 import { resolveAgentProvenance } from '../agent-provenance';
-import { PageHistoryKind } from '../../../collaboration/constants';

 /**
 * Role-resolution subquery for a page-history row's bound AI chat (#300). Joins
@@ -47,9 +46,6 @@ export class PageHistoryRepo {
    'lastUpdatedById',
    'lastUpdatedSource',
    'lastUpdatedAiChatId',
-    // #370 — intentionality tier ('manual' | 'agent' | 'idle' | 'boundary');
-    // null on legacy rows (= autosave). Selected so callers can read/promote it.
-    'kind',
    'contributorIds',
    'spaceId',
    'workspaceId',
@@ -89,15 +85,9 @@ export class PageHistoryRepo {

  async saveHistory(
    page: Page,
-    opts?: {
-      contributorIds?: string[];
-      // #370 — intentionality tier for this snapshot. Omitted → null (legacy
-      // autosave semantics). Callers derive it server-side, never from a client.
-      kind?: PageHistoryKind;
-      trx?: KyselyTransaction;
-    },
-  ): Promise<PageHistory> {
-    return await this.insertPageHistory(
+    opts?: { contributorIds?: string[]; trx?: KyselyTransaction },
+  ): Promise<void> {
+    await this.insertPageHistory(
      {
        pageId: page.id,
        slugId: page.slugId,
@@ -109,7 +99,6 @@ export class PageHistoryRepo {
        // Copy the provenance marker off the page row, as for lastUpdatedById.
        lastUpdatedSource: page.lastUpdatedSource,
        lastUpdatedAiChatId: page.lastUpdatedAiChatId,
-        kind: opts?.kind ?? null,
        contributorIds: opts?.contributorIds,
        spaceId: page.spaceId,
        workspaceId: page.workspaceId,
@@ -118,25 +107,6 @@ export class PageHistoryRepo {
    );
  }

-  /**
-   * #370 — promote an existing snapshot's intentionality tier in place. Used by
-   * the manual-save "promote-not-dup" path: when the latest history row already
-   * holds the exact content being versioned, we upgrade its `kind` instead of
-   * duplicating a heavy content row.
-   */
-  async updateHistoryKind(
-    pageHistoryId: string,
-    kind: PageHistoryKind,
-    trx?: KyselyTransaction,
-  ): Promise<void> {
-    const db = dbOrTx(this.db, trx);
-    await db
-      .updateTable('pageHistory')
-      .set({ kind })
-      .where('id', '=', pageHistoryId)
-      .execute();
-  }
-
  async findPageHistoryByPageId(pageId: string, pagination: PaginationOptions) {
    const query = this.db
      .selectFrom('pageHistory')
@@ -280,7 +280,6 @@ export interface PageHistory {
  createdAt: Generated<Timestamp>;
  icon: string | null;
  id: Generated<string>;
-  kind: string | null;
  lastUpdatedAiChatId: string | null;
  lastUpdatedById: string | null;
  lastUpdatedSource: string | null;
@@ -20,10 +20,6 @@ export interface IStripeSeatsSyncJob {

 export interface IPageHistoryJob {
  pageId: string;
-  // #370 — intentionality tier the worker stamps on the snapshot. All jobs on
-  // this queue are trailing idle-flush autosnapshots, so this is 'idle' (absent
-  // → treated as 'idle' by the processor).
-  kind?: 'idle';
 }

 /**
@@ -30,13 +30,11 @@ import {
 * tees the SSE frames into it via `consumeSseStream` while stamping the DB row id
 * via `generateMessageId` (both gated on runId + the resumable flag).
 *
- * Proven here (tail-only #491): a finished run attached at its persisted frontier
- * N_final delivers only the TAIL past N (a synthetic `start` carrying the run-fact
- * + the terminal `finish`/`[DONE]`) — the step content below N lives in the seeded
- * DB row, NOT the ring; the anchor check (invariant 6); an attach opened BEFORE the
- * first frame follows the live stream from frame 0; an explicit stop surfaces
- * `{"type":"abort"}` + `[DONE]` + end to the subscriber; and the legacy (non-run)
- * path tees nothing.
+ * Proven here: a finished run's replay is the full frame sequence incl `[DONE]`
+ * with `start.messageId` == the seeded DB row id; the anchor check (invariant 6);
+ * an attach opened BEFORE the first frame follows the live stream from frame 0; an
+ * explicit stop surfaces `{"type":"abort"}` + `[DONE]` + end to the subscriber;
+ * and the legacy (non-run) path tees nothing.
 */

 const sleep = (ms: number) => new Promise((r) => setTimeout(r, ms));
@@ -135,16 +133,14 @@ function liveSink(): {
  };
 }

-// Parse the first `start` frame's JSON out of a `data: {...}` sequence.
-function parseStartFrame(
-  frames: string[],
-): { messageId?: string; messageMetadata?: any } | undefined {
+// The SSE `start` frame carries the message id; pull it out of a `data: {...}`.
+function parseStartMessageId(frames: string[]): string | undefined {
  for (const f of frames) {
    const m = /^data: (\{.*\})\s*$/m.exec(f.trim());
    if (!m) continue;
    try {
      const json = JSON.parse(m[1]);
-      if (json.type === 'start') return json;
+      if (json.type === 'start') return json.messageId;
    } catch {
      /* not this frame */
    }
@@ -274,7 +270,7 @@ describe('AiChatService run-stream attach [integration]', () => {
    await destroyTestDb();
  });

-  it('run-wrapped, tail-only: a finished run at N_final delivers the run-fact start + finish/[DONE]; the step content lives in the seeded row', async () => {
+  it('run-wrapped: replay is the full frame sequence incl [DONE], start.messageId == the seeded DB row id', async () => {
    const chatId = (await createChat(db, { workspaceId, creatorId: userId })).id;
    const registry = new AiChatStreamRegistryService();
    const runService = new AiChatRunService(runRepo, {
@@ -304,37 +300,27 @@ describe('AiChatService run-stream attach [integration]', () => {
        );
      });
      const rowId = await assistantRowId(chatId);
-      // The client reads its persisted step frontier N from the seeded row.
-      const row: any = await msgRepo.findById(rowId, workspaceId);
-      const nFinal = row.metadata.stepsPersisted as number;
-      expect(nFinal).toBe(1); // a single finished step
-      // The step content is in the SEEDED row (parts/content), not the ring.
-      expect(JSON.stringify(row.metadata.parts)).toContain('Hello');

-      // Attach at N_final with the correct anchor: the tail past step 1 is just
-      // the terminal frames; step 0's 'Hello' is BELOW the frontier (seeded).
+      // Finished-run replay with expect=live + the correct anchor.
      const sink = liveSink();
-      const att = await registry.attach(chatId, rowId, nFinal, sink.cb);
+      const att = await registry.attach(chatId, true, rowId, sink.cb);
      expect(att).not.toBeNull();
      expect(att!.finished).toBe(true);
-      // The synthetic start frame carries the run-fact (runId/chatId), the source
-      // of the run-fact on re-attach.
-      const start = parseStartFrame(att!.replay);
-      expect(start?.messageMetadata).toMatchObject({
-        runId: box.runId,
-        chatId,
-      });
-      // The terminal marker is delivered so the client's SDK closes the stream.
+      // The tee captured frames (consumeSseStream was wired).
+      expect(att!.replay.length).toBeGreaterThan(0);
+      // generateMessageId stamped the DB row id onto the streamed start frame.
+      expect(parseStartMessageId(att!.replay)).toBe(rowId);
+      // The full sequence includes the streamed text and the terminal marker.
+      const joined = att!.replay.join('');
+      expect(joined).toContain('Hello');
      expect(att!.replay.some((f) => f.includes('[DONE]'))).toBe(true);
-      // 'Hello' (step 0, below the frontier) is NOT re-streamed — it is seeded.
-      expect(att!.replay.some((f) => f.includes('Hello'))).toBe(false);
    } finally {
      registry.onModuleDestroy();
      await cleanup();
    }
  });

-  it('anchor mismatch returns null (invariant 6)', async () => {
+  it('anchor mismatch with expect=live returns null (invariant 6)', async () => {
    const chatId = (await createChat(db, { workspaceId, creatorId: userId })).id;
    const registry = new AiChatStreamRegistryService();
    const runService = new AiChatRunService(runRepo, {
@@ -361,7 +347,7 @@ describe('AiChatService run-stream attach [integration]', () => {
      const sink = liveSink();
      // A foreign anchor must NOT replay this run's transcript.
      expect(
-        await registry.attach(chatId, 'a-different-run-row', 1, sink.cb),
+        await registry.attach(chatId, true, 'a-different-run-row', sink.cb),
      ).toBeNull();
    } finally {
      registry.onModuleDestroy();
@@ -390,11 +376,8 @@ describe('AiChatService run-stream attach [integration]', () => {
    try {
      // Attach while the entry exists (opened at begin) but before any frame.
      const sink = liveSink();
-      const att = (await registry.attach(chatId, undefined, 0, sink.cb))!;
-      // Nothing streamed yet -> the tail is just the synthetic start frame; the
-      // whole live stream (start..DONE) follows via onFrame after start().
-      expect(att.replay).toHaveLength(1);
-      expect(att.replay[0]).toContain('"type":"start"');
+      const att = (await registry.attach(chatId, false, undefined, sink.cb))!;
+      expect(att.replay).toEqual([]); // nothing streamed yet -> replay from 0
      att.start(); // go live (drains nothing, then follows)

      // Now emit the whole turn.
@@ -465,7 +448,7 @@ describe('AiChatService run-stream attach [integration]', () => {
    });
    try {
      const sink = liveSink();
-      const att = (await registry.attach(chatId, undefined, 0, sink.cb))!;
+      const att = (await registry.attach(chatId, false, undefined, sink.cb))!;
      att.start();

      // Give streamText a beat to begin consuming the partial output.
@@ -543,9 +526,7 @@ describe('AiChatService run-stream attach [integration]', () => {
      expect(entry).toBeDefined();
      expect(entry.finished).toBe(true);
      const sink = liveSink();
-      // Finished with an EMPTY ring (aborted before any frame) -> null -> the
-      // client degrades to poll instead of hanging on an empty stream.
-      expect(await registry.attach(chatId, undefined, 0, sink.cb)).toBeNull();
+      expect(await registry.attach(chatId, false, undefined, sink.cb)).toBeNull();
    } finally {
      registry.onModuleDestroy();
      await cleanup();
@@ -575,8 +556,8 @@ describe('AiChatService run-stream attach [integration]', () => {
      });
      const sink = liveSink();
      // No entry was ever opened; attach always yields null.
-      expect(await registry.attach(chatId, undefined, 0, sink.cb)).toBeNull();
-      expect(await registry.attach(chatId, 'anything', 1, sink.cb)).toBeNull();
+      expect(await registry.attach(chatId, false, undefined, sink.cb)).toBeNull();
+      expect(await registry.attach(chatId, true, 'anything', sink.cb)).toBeNull();
    } finally {
      registry.onModuleDestroy();
      await cleanup();
@@ -1,162 +0,0 @@
-import { randomUUID } from 'node:crypto';
-import { Queue, Worker } from 'bullmq';
-import { PersistenceExtension } from '../../src/collaboration/extensions/persistence.extension';
-
-/**
- * #370 — integration property of the idle-snapshot pipeline against REAL BullMQ.
- *
- * This is deliberately NOT a unit test of computeHistoryJob (that lives in
- * compute-history-job.spec.ts). The point here is the OBSERVABLE end-to-end
- * behaviour of the production `enqueuePageHistory` remove-then-add debounce
- * driving a real Redis-backed delayed queue + worker (the #431→#439 class: a
- * locally-correct function whose queue/timer property was never exercised):
- *
- *   - a CONTINUOUS burst of stores lasting several caps yields periodic idle
- *     snapshots — at least one per max-wait cap, NOT one-per-store; and
- *   - an INTERMITTENT burst (a few stores, then quiet) yields exactly ONE
- *     trailing snapshot.
- *
- * We shrink the idle windows to milliseconds (jest.mock of collaboration
- * constants) so real BullMQ delayed jobs actually promote within the test —
- * fake timers cannot advance Redis's own delayed-set clock, so the intervals
- * must be real but tiny. The production method under test is called verbatim.
- */
-
-// NOTE: jest.mock is hoisted above the module's const initializers, so its
-// factory cannot close over MAX_WAIT_MS/INTERVAL_MS — the literals are inlined
-// here and MUST stay in sync with the consts below (a single source of truth is
-// impossible across the hoist boundary).
-jest.mock('../../src/collaboration/constants', () => {
-  const actual = jest.requireActual('../../src/collaboration/constants');
-  return {
-    ...actual,
-    IDLE_MAX_WAIT_USER: 300,
-    IDLE_MAX_WAIT_AGENT: 300,
-    IDLE_INTERVAL_USER: 1000,
-    IDLE_INTERVAL_AGENT: 1000,
-  };
-});
-
-// Mirrors the mocked IDLE_MAX_WAIT_* above (IDLE_INTERVAL_* is 1000 > this, so
-// the max-wait ceiling is what actually governs the trailing delay).
-const MAX_WAIT_MS = 300;
-
-const REDIS_CONNECTION = {
-  host: process.env.TEST_REDIS_HOST ?? '127.0.0.1',
-  port: Number(process.env.TEST_REDIS_PORT ?? 6379),
-};
-
-const sleep = (ms: number) => new Promise((r) => setTimeout(r, ms));
-
-describe('#370 idle-snapshot pipeline (real BullMQ)', () => {
-  let queue: Queue;
-  let worker: Worker;
-  let extension: PersistenceExtension;
-  // Every processed snapshot, tagged by pageId so the two scenarios stay isolated.
-  const processed: Array<{ pageId: string; kind: string; at: number }> = [];
-  const queueName = `history-idle-int-${randomUUID()}`;
-
-  beforeAll(async () => {
-    queue = new Queue(queueName, {
-      connection: REDIS_CONNECTION,
-      // Mirror the production default (BullModule.forRoot removeOnComplete): the
-      // enqueue idiom relies on the jobId being freed once a job completes so the
-      // next burst can re-arm the same id.
-      defaultJobOptions: { removeOnComplete: true, removeOnFail: true },
-    });
-    await queue.waitUntilReady();
-
-    worker = new Worker(
-      queueName,
-      async (job) => {
-        processed.push({
-          pageId: job.data?.pageId,
-          kind: job.data?.kind,
-          at: Date.now(),
-        });
-      },
-      { connection: REDIS_CONNECTION },
-    );
-    await worker.waitUntilReady();
-
-    // Construct the real extension; only historyQueue (5th ctor arg) and the
-    // internal idleBurstStart map are exercised by enqueuePageHistory, so the
-    // other collaborators can be null — the constructor only assigns fields.
-    extension = new PersistenceExtension(
-      null as any, // pageRepo
-      null as any, // pageHistoryRepo
-      null as any, // db
-      null as any, // aiQueue
-      queue as any, // historyQueue
-      null as any, // notificationQueue
-      null as any, // collabHistory
-      null as any, // transclusionService
-    );
-  });
-
-  afterAll(async () => {
-    // Force-close and fully drain so no BullMQ background activity (delayed-set
-    // polling, blocking BRPOPLPUSH) bleeds into later suites in this single
-    // shared jest worker (maxWorkers: 1).
-    await worker?.close(true).catch(() => undefined);
-    await queue?.obliterate({ force: true }).catch(() => undefined);
-    await queue?.close();
-    // Let the redis sockets settle before the next suite starts.
-    await sleep(150);
-  });
-
-  const arm = (pageId: string) =>
-    (extension as any).enqueuePageHistory({ id: pageId }, 'user');
-
-  it('continuous burst over several caps → periodic idle snapshots (≥1 per cap, not one-per-store)', async () => {
-    const pageId = randomUUID();
-    const runMs = 6 * MAX_WAIT_MS; // ~6 caps of unbroken editing
-    // Store cadence that does NOT evenly divide the cap: real hocuspocus stores
-    // are not aligned to cap boundaries, so a boundary job promotes in the gap
-    // before the next store's remove(). A cap-aligned cadence would instead land
-    // a store exactly on every boundary and lose the snapshot to the documented
-    // remove-vs-active race — an artefact of the test clock, not the pipeline.
-    const stepMs = 70;
-    const stores = Math.floor(runMs / stepMs);
-
-    const start = Date.now();
-    let count = 0;
-    while (Date.now() - start < runMs) {
-      await arm(pageId);
-      count++;
-      await sleep(stepMs);
-    }
-    // Let the final armed job flush.
-    await sleep(2 * MAX_WAIT_MS);
-
-    const snaps = processed.filter((p) => p.pageId === pageId);
-
-    // Every autosnapshot is an idle-kind row.
-    expect(snaps.every((s) => s.kind === 'idle')).toBe(true);
-    // Periodic: at least one per cap over a multi-cap burst (lower-bounded loosely
-    // to stay robust; the property is "fires at least every cap", not a single
-    // trailing snapshot).
-    expect(snaps.length).toBeGreaterThanOrEqual(3);
-    // But NOT one-per-store: ~`stores` stores were issued; the debounce must
-    // collapse them to a small multiple of the cap count, nowhere near per-store.
-    expect(snaps.length).toBeLessThanOrEqual(Math.ceil(stores / 2));
-  });
-
-  it('intermittent burst (a few stores, then quiet) → exactly ONE trailing snapshot', async () => {
-    const pageId = randomUUID();
-
-    // A short burst well within a single cap window, then silence.
-    await arm(pageId);
-    await sleep(40);
-    await arm(pageId);
-    await sleep(40);
-    await arm(pageId);
-
-    // Wait comfortably past the cap so the single pending trailing job fires.
-    await sleep(4 * MAX_WAIT_MS);
-
-    const snaps = processed.filter((p) => p.pageId === pageId);
-    expect(snaps).toHaveLength(1);
-    expect(snaps[0].kind).toBe('idle');
-  });
-});
@@ -387,7 +387,7 @@ bucketByDay(sessions, tz):
 факты ниже — ground truth, можно дозапросить файлы через gitea MCP по указанному SHA):

 - `page_history.kind` — `varchar(20)`, NULLABLE, БЕЗ дефолта (migration
-  `20260707T120000-page-history-kind.ts`). Домен: `manual`/`agent`/`idle`/`boundary`;
+  `20260705T120000-page-history-kind.ts`). Домен: `manual`/`agent`/`idle`/`boundary`;
  legacy `null` = автосейв (`collaboration/constants.ts`, `PageHistoryKind`).
 - `kind` УЖЕ включён в `PageHistoryRepo.baseFields` (`page-history.repo.ts`) — читается всеми
  выборками истории. `saveHistory({kind})` и `updateHistoryKind(id, kind)` существуют.
Author	SHA1	Message	Date
vvzvlad	220142bef6	Merge pull request 'fix(page-tree/dnd): drop-раскрытие + guard от потери детей (#523 )' (#532 ) from fix/523-tree-dnd into fix/525-insert-unloaded Reviewed-on: #532	2026-07-12 05:08:42 +03:00
agent_coder	0af7eb30c3	docs(page-tree): correct isUnloadedBranch comment — no DnD-guard consumer (#525 review) The comment falsely listed a 'DnD move guard' consumer; no DnD path routes through the predicate (local DnD/create-page use the raw index-based insert). List the real consumers (handleToggle + realtime insertByPosition/placeByPosition) and note the local raw-insert path as a #525 follow-up. Comment-only. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>	2026-07-12 04:13:49 +03:00
agent_coder	27d51303ba	fix(page-tree/dnd): drag авто-раскрытие — задержка 2с, не раскрывать при drop внутрь + guard от потери детей и сигнал «уехало сюда» Пять точечных клиентских правок (дизайн из адверсариального разбора #523): 1. Задержка hover-раскрытия при drag: `AUTO_EXPAND_MS` 500 → 2000 мс, чтобы проведение курсора через дерево не раскрывало ряды — только осознанное удержание. 2. Не раскрывать цель при drop внутрь (make-child): удалена строка `onToggle(target, true)` в `onDrop` (drop оставляет узел свёрнутым; раскрытие только по hover-hold). Восстановление раскрытости самого source не тронуто. 3. Guard от потери детей в `handleMove` (обязателен вместе с п.2): раньше эта же `onToggle` была ЕДИНСТВЕННЫМ триггером корректирующего lazy-load. `treeModel.move` материализует `target.children = [source]`; для НЕзагруженной цели (предикат gate `treeModel.isUnloadedBranch`) это скрыло бы остальных серверных детей папки (класс #159 #1). Теперь для незагруженной make-child-цели оптимистичное дерево строится БЕЗ материализации source: source удаляется из старого родителя, цели ставится `hasChildren:true`; gate остаётся взведён и раскрытие догружает полный набор. Для загруженной цели поведение прежнее (append сохраняет детей). 4. Инвалидация крошек: `updateCacheOnMovePage` инвалидирует `["breadcrumbs", pageId]` — guard делает `remove(source)`, и для текущей открытой страницы `findBreadcrumbPath` промахивается → крошки показывали бы старого родителя до refocus. 5. Сигнал «уехало сюда»: транзиентный teal-пульс на строке при make-child-drop в свёрнутую цель (узел НЕ раскрывается), отдельный `data-landed-child` + `DROP_LANDED_HIGHLIGHT_MS`, таймер чистится при анмаунте; уважает prefers-reduced-motion. Тесты: `handleMove` — незагруженная make-child-цель не материализует `[source]` (мутация guard'а краснит), загруженная цель append'ит и сохраняет детей, genuinely-empty лист материализует; инвалидация `["breadcrumbs", pageId]`. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>	2026-07-12 01:15:02 +03:00
agent_coder	c765483947	fix(page-tree/realtime): insertByPosition теряет непоказанных детей — предикат «незагружено» приведён к gate `insertByPosition` считал узел незагруженным только при `children === undefined`, но канонический незагруженный вид в этом коде — `children: []` с `hasChildren: true` (его ставит `pageToTreeNode`, к нему сбрасывает свёрнутые ветки `pruneCollapsedChildren`). Для реального незагруженного узла guard `=== undefined` не срабатывал → в пустой список вставлялся `[node]` → lazy-load gate видел `length !== 0` и не догружал остальных серверных детей папки (скрыты до полной перезагрузки) — тот же класс потери данных #159 #1. - Новый общий предикат `treeModel.isUnloadedBranch(node)`: `hasChildren === true && (children == null \|\| children.length === 0)` — единый источник истины для «отложить ли фетч/материализацию». - `insertByPosition` использует его вместо `=== undefined`; для действительно пустой папки (`hasChildren: false`) вставка первого ребёнка сохраняется. - gate в `handleToggle` (`space-tree.tsx`) переведён на тот же хелпер, чтобы предикаты больше не разъезжались (R3). Тесты: юнит на `isUnloadedBranch`; `insertByPosition` не материализует `[node]` в `children:[]`+`hasChildren:true` (и оставляет ветку незагруженной), но вставляет в genuinely-empty. Мутация: старый `=== undefined` предикат краснит эти тесты (в т.ч. на уровне `applyMoveTreeNode`). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>	2026-07-12 01:06:42 +03:00