Merge pull request 'fix(ui): collapse global sidebar to a drawer below 992px (tablet layout overflow, #291)' (#292) from fix/responsive-tablet-sidebar into develop

Reviewed-on: #292

AGENTS.md

@@ -72,7 +72,10 @@ git log -1 --format='Author: %an <%ae>%nCommitter: %cn <%ce>'
 
 ### 4. Push and PR to develop
 
-PRs always target `develop`. The `claude_code` password lives in the macOS
+PRs always target `develop`. Two different mechanisms are involved: **pushing
+commits is git-native** (the Gitea MCP cannot push local git history, so the
+branch is still pushed with `git push`), while **the PR itself is opened through
+the Gitea MCP** (see below). The `claude_code` password lives in the macOS
 keychain as a **generic password** under service `gitea-claude-code` (do not
 duplicate it as an internet-password for `gitea.vvzvlad.xyz` — that creates a
 conflict with the owner's account in the git credential helper):
@@ -94,18 +97,24 @@ git remote set-url gitea "$ORIG_URL"
 unset AGENT_PASS SAFE_PASS
 ```
 
-The PR is created via the Gitea REST API (Basic Auth as `claude_code`):
+The PR is opened through the **Gitea MCP** (server `gitea`), not `curl`/`tea` —
+the MCP authenticates in-process, so no keychain lookup or Basic-Auth is needed.
+Call `pull_request_write` with:
 
-```bash
+- `method: "create"`
-curl -s -X POST \
+- `owner: "vvzvlad"`, `repo: "gitmost"`
-  -u "claude_code:$(security find-generic-password -s gitea-claude-code -w)" \
+- `base: "develop"`, `head: "<branch>"`
-  -H "Content-Type: application/json" \
+- `title`, `body` — in the body: what was done, what is out of scope,
-  -d @pr_body.json \
+  verification results (tsc/lint/tests).
-  "https://gitea.vvzvlad.xyz/api/v1/repos/vvzvlad/gitmost/pulls"
-```
 
-`base: develop`, `head: <branch>`. In the PR body: what was done, what is out
+Manage and read PRs through the same server: `list_pull_requests`,
-of scope, verification results (tsc/lint/tests).
+`pull_request_read` (`get`, `get_diff`, `get_files`, `get_status`),
+`pull_request_review_write`.
+
+**Identity note:** the MCP acts under its **own** configured Gitea token (verify
+with `get_me`), a different account from the `claude_code` used for git
+commits/pushes in §3. Only the forge API calls (PR / issue / review) go through
+the MCP account; the commits themselves stay authored as `claude_code`.
 
 > If push fails with `User permission denied for writing`, then `claude_code`
 > lacks collaborator rights on the repo. Ask the owner to add them (once, via
@@ -152,23 +161,25 @@ below.
 | Agent user (Gitea/git) | `claude_code` |
 | Agent email | `claude_code@vvzvlad.xyz` |
 | Keychain password | `security find-generic-password -s gitea-claude-code -w` |
-| PR API | `https://gitea.vvzvlad.xyz/api/v1/repos/vvzvlad/gitmost/pulls` (here `gitmost` is the repo's real slug on the server) |
+| Forge API (PR / issue / review / reads) | **Gitea MCP** — server `gitea` (`pull_request_write`, `issue_write`, `list_pull_requests`, `pull_request_read`, `label_read`, …). Authenticated in-process; acts under its own token — check with `get_me`. Repo slug on the server is `gitmost`. |
 | Base branch | `develop` |
 | `origin` | GitHub mirror `vvzvlad/gitmost` — **do not push**, updated by the owner's CI |
 | `upstream` | The original Docmost — **never push** |
 
-## Creating issues (Gitea `tea` CLI)
+## Creating issues (Gitea MCP)
 
-Issues are filed with the official Gitea CLI `tea`, already logged in as
+File issues through the **Gitea MCP** (server `gitea`), not a CLI — call
-`claude_code` (`tea logins list` shows the `gitea` login as default):
+`issue_write` with:
 
-```bash
+- `method: "create"`
-tea issues create --repo vvzvlad/gitmost --labels feature \
+- `owner: "vvzvlad"`, `repo: "gitmost"`
-  --title '<title>' --description "$(cat body.md)"
+- `title`, `body`
-```
+- `labels` — an array of label **IDs** (numbers), *not* names. Resolve a name
+  such as `feature` to its id first with `label_read` (`method: "list"`), then
+  pass e.g. `labels: [<id>]`.
 
-> Gotcha (tea 0.14.1): the issue body flag is `--description`/`-d`, **not**
+Read issues with `list_issues`, `issue_read`, or `search_issues`. The MCP is
-> `--body` — passing `--body` fails with `flag provided but not defined: -body`.
+authenticated in-process, so no `tea`/`curl` and no keychain lookup are needed.
 
 ---
 

apps/client/src/components/layouts/global/app-header.tsx

@@ -12,6 +12,7 @@ import TopMenu from "@/components/layouts/global/top-menu.tsx";
 import { Link } from "react-router-dom";
 import { useAtom } from "jotai";
 import {
+  NAVBAR_COLLAPSE_BREAKPOINT,
   desktopSidebarAtom,
   mobileSidebarAtom,
 } from "@/components/layouts/global/hooks/atoms/sidebar-atom.ts";
@@ -53,7 +54,13 @@ export function AppHeader() {
               aria-label={t("Sidebar toggle")}
               opened={mobileOpened}
               onClick={toggleMobile}
-              hiddenFrom="sm"
+              // Must match the AppShell navbar breakpoint (md). The navbar
+              // collapses to the MOBILE drawer below md, so the mobile toggle
+              // (which flips mobileOpened) must be the one visible across the
+              // whole <md band — otherwise at 768-991 the desktop toggle showed
+              // but flipped the wrong atom, leaving the drawer unopenable (the
+              // regression from the initial sm->md navbar change).
+              hiddenFrom={NAVBAR_COLLAPSE_BREAKPOINT}
               size="sm"
             />
           </Tooltip>
@@ -63,7 +70,7 @@ export function AppHeader() {
               aria-label={t("Sidebar toggle")}
               opened={desktopOpened}
               onClick={toggleDesktop}
-              visibleFrom="sm"
+              visibleFrom={NAVBAR_COLLAPSE_BREAKPOINT}
               size="sm"
             />
           </Tooltip>

apps/client/src/components/layouts/global/global-app-shell.tsx

@@ -6,6 +6,7 @@ import SettingsSidebar from "@/components/settings/settings-sidebar.tsx";
 import { useAtom } from "jotai";
 import {
   APP_NAVBAR_ID,
+  NAVBAR_COLLAPSE_BREAKPOINT,
   asideStateAtom,
   desktopSidebarAtom,
   mobileSidebarAtom,
@@ -88,7 +89,13 @@ export default function GlobalAppShell({
       header={{ height: 45 }}
       navbar={{
         width: isSpaceRoute ? sidebarWidth : 300,
-        breakpoint: "sm",
+        // `md` (not `sm`): below 992px the fixed ~300px sidebar leaves too little
+        // room for content — the settings tables (Members/…) overflow the offset
+        // content area on tablet (~768px) and clip the Role/actions columns
+        // off-screen with no horizontal scroll. Collapsing the navbar to a toggle
+        // drawer across the whole tablet band frees the full width for content
+        // (the mobile drawer is closed by default, so nothing overlaps on load).
+        breakpoint: NAVBAR_COLLAPSE_BREAKPOINT,
         collapsed: {
           mobile: !mobileOpened,
           desktop: !desktopOpened,
@@ -97,7 +104,7 @@ export default function GlobalAppShell({
       aside={
         isPageRoute && {
           width: 420,
-          breakpoint: "sm",
+          breakpoint: "md",
           collapsed: { mobile: !isAsideOpen, desktop: !isAsideOpen },
         }
       }

apps/client/src/components/layouts/global/hooks/atoms/sidebar-atom.ts

@@ -7,6 +7,13 @@ import { atom } from "jotai";
 // would create a shell -> chat-window -> shell import cycle).
 export const APP_NAVBAR_ID = "app-shell-navbar";
 
+// Single source of truth for the navbar collapse breakpoint. The AppShell navbar
+// `breakpoint` and BOTH burger toggles' `hiddenFrom`/`visibleFrom` MUST use this
+// exact value: if they drift, the sidebar becomes unreachable on tablet widths
+// (the round-1 regression of #292). Kept here so the shell and the header share
+// one constant the compiler enforces, instead of three hand-synced string literals.
+export const NAVBAR_COLLAPSE_BREAKPOINT = "md";
+
 export const mobileSidebarAtom = atom<boolean>(false);
 
 export const desktopSidebarAtom = atomWithWebStorage<boolean>(

apps/client/src/features/editor/extensions/custom-typography.test.ts

@@ -0,0 +1,231 @@
+import { describe, it, expect } from "vitest";
+import { Editor } from "@tiptap/core";
+import { Document } from "@tiptap/extension-document";
+import { Paragraph } from "@tiptap/extension-paragraph";
+import { Text } from "@tiptap/extension-text";
+import { ySyncPluginKey } from "@tiptap/y-tiptap";
+import {
+  CustomTypography,
+  undoGuardKey,
+  findChangedRange,
+  mapRangeThroughChange,
+} from "./custom-typography";
+
+/**
+ * PR #296 — the collab-safe typography undo-guard is exercised through the REAL
+ * editor path: a fresh Editor with the CustomTypography extension, transactions
+ * tagged exactly the way prosemirror-history / y-tiptap tag undo & remote
+ * changes (`setMeta("history$", …)` and `setMeta(ySyncPluginKey, …)`), plus
+ * direct unit tests of the two pure diff helpers. No hand-poke of plugin state.
+ *
+ * ARMING MECHANISM (verified against custom-typography.ts source):
+ *   - A transaction arms the guard only when it is BOTH history/remote
+ *     (`getMeta("history$")` truthy, or `isChangeOrigin` via the ySync meta)
+ *     AND an undo/redo (`getMeta("history$")` truthy, or ySync
+ *     `isUndoRedoOperation`), AND its whole-doc diff is a REPLACE
+ *     (change.oldTo > change.from && change.newTo > change.from).
+ *   - `history$` is the stringified PluginKey of the single prosemirror-history
+ *     plugin; ProseMirror stores meta under `key.key`, so setMeta("history$")
+ *     in a test is read identically by the extension's getMeta("history$").
+ */
+
+const singlePara = (text: string) => ({
+  type: "doc",
+  content: [{ type: "paragraph", content: [{ type: "text", text }] }],
+});
+
+const makeEditor = (text: string) =>
+  new Editor({
+    extensions: [Document, Paragraph, Text, CustomTypography],
+    content: singlePara(text),
+  });
+
+// Build a before/after EditorState pair by applying one plain transaction.
+const mutate = (text: string, apply: (tr: any, schema: any) => void) => {
+  const editor = new Editor({
+    extensions: [Document, Paragraph, Text],
+    content: singlePara(text),
+  });
+  const before = editor.state;
+  const tr = before.tr;
+  apply(tr, before.schema);
+  editor.view.dispatch(tr);
+  const after = editor.state;
+  return { before, after, editor };
+};
+
+describe("findChangedRange", () => {
+  it("returns null for identical docs", () => {
+    const editor = new Editor({
+      extensions: [Document, Paragraph, Text],
+      content: singlePara("hello"),
+    });
+    expect(findChangedRange(editor.state, editor.state)).toBeNull();
+    editor.destroy();
+  });
+
+  it("returns the minimal range for a normal middle insertion", () => {
+    // "hello world" (text at 1..12); insert "there " at pos 6.
+    const { before, after, editor } = mutate("hello world", (tr) =>
+      tr.insertText("there ", 6),
+    );
+    expect(findChangedRange(before, after)).toEqual({
+      from: 6,
+      oldTo: 6,
+      newTo: 12,
+    });
+    editor.destroy();
+  });
+
+  it("normalizes the INSERTION overlapping-bounds branch (repeated content)", () => {
+    // Insert one more 'a' into "aaaaa" at pos 3. findDiffStart lands at the end
+    // (6) while findDiffEnd reports an end BEFORE it ({a:1,b:2}); both ends must
+    // be pushed forward by the same delta -> a non-degenerate range.
+    const { before, after, editor } = mutate("aaaaa", (tr) =>
+      tr.insertText("a", 3),
+    );
+    const change = findChangedRange(before, after)!;
+    expect(change).toEqual({ from: 6, oldTo: 6, newTo: 7 });
+    // Invariant the guard logic relies on: never degenerate.
+    expect(change.from).toBeLessThanOrEqual(change.oldTo);
+    expect(change.from).toBeLessThanOrEqual(change.newTo);
+    editor.destroy();
+  });
+
+  it("normalizes the DELETION overlapping-bounds branch (F2 fix)", () => {
+    // Delete one repeated 'a' from the middle of "aaaaa" ([3,4)). Here
+    // findDiffEnd reports newTo < start, the symmetric case the old one-sided
+    // normalization missed -> it used to yield a degenerate range (newTo < from).
+    const { before, after, editor } = mutate("aaaaa", (tr) => tr.delete(3, 4));
+    const change = findChangedRange(before, after)!;
+    expect(change).toEqual({ from: 5, oldTo: 6, newTo: 5 });
+    // The whole point of F2: from <= newTo (and from <= oldTo) still holds.
+    expect(change.from).toBeLessThanOrEqual(change.newTo);
+    expect(change.from).toBeLessThanOrEqual(change.oldTo);
+    editor.destroy();
+  });
+
+  it("normalizes a multi-char repeated deletion (F2 fix)", () => {
+    const { before, after, editor } = mutate("aaaaa", (tr) => tr.delete(2, 4));
+    const change = findChangedRange(before, after)!;
+    expect(change).toEqual({ from: 4, oldTo: 6, newTo: 4 });
+    expect(change.from).toBeLessThanOrEqual(change.newTo);
+    editor.destroy();
+  });
+});
+
+describe("mapRangeThroughChange", () => {
+  const range = { from: 5, to: 10 };
+
+  it("RELEASES on a strict intersection (edit inside the guarded range)", () => {
+    // change straddles the interior of the guard.
+    expect(
+      mapRangeThroughChange(range, { from: 6, oldTo: 8, newTo: 7 }),
+    ).toBeNull();
+  });
+
+  it("does NOT release on a boundary touch at the guard END", () => {
+    // Edit begins exactly at range.to (10): from < to is false -> no intersect.
+    expect(
+      mapRangeThroughChange(range, { from: 10, oldTo: 10, newTo: 12 }),
+    ).toEqual(range);
+  });
+
+  it("does NOT release on a boundary touch at the guard START", () => {
+    // Edit ends exactly at range.from (5): oldTo > from is false -> no intersect;
+    // it is treated as a change fully before, shifting the guard.
+    expect(
+      mapRangeThroughChange(range, { from: 3, oldTo: 5, newTo: 8 }),
+    ).toEqual({ from: 8, to: 13 });
+  });
+
+  it("SHIFTS the guard for a change fully before it", () => {
+    // Insert 2 chars entirely before the range (oldTo 3 <= from 5): +2 delta.
+    expect(
+      mapRangeThroughChange(range, { from: 2, oldTo: 3, newTo: 5 }),
+    ).toEqual({ from: 7, to: 12 });
+  });
+
+  it("leaves the guard untouched for a change fully after it", () => {
+    expect(
+      mapRangeThroughChange(range, { from: 12, oldTo: 14, newTo: 16 }),
+    ).toBe(range);
+  });
+});
+
+describe("undo-guard arming (integration)", () => {
+  it("arms {from, to:newTo} on a LOCAL undo-replace (history meta)", () => {
+    // Undo of an em-dash substitution: "a—b" restored to "a--b" — the em-dash
+    // (pos 2..3) is REPLACED by "--", tagged with the history plugin's meta.
+    const editor = makeEditor("a—b");
+    const { state } = editor;
+    const tr = state.tr
+      .replaceWith(2, 3, state.schema.text("--"))
+      .setMeta("history$", { redo: false });
+    editor.view.dispatch(tr);
+
+    expect(editor.state.doc.textContent).toBe("a--b");
+    // from = diff start (2), to = newTo = end of the inserted "--" (4).
+    expect(undoGuardKey.getState(editor.state)).toEqual({ from: 2, to: 4 });
+    editor.destroy();
+  });
+
+  it("does NOT arm on a REMOTE change-origin replace (no undo meta)", () => {
+    // Same replace, but tagged only as a y-sync remote change: history/remote
+    // yes, undo/redo NO -> must not arm.
+    const editor = makeEditor("a—b");
+    const { state } = editor;
+    const tr = state.tr
+      .replaceWith(2, 3, state.schema.text("--"))
+      .setMeta(ySyncPluginKey, { isChangeOrigin: true });
+    editor.view.dispatch(tr);
+
+    expect(editor.state.doc.textContent).toBe("a--b");
+    expect(undoGuardKey.getState(editor.state)).toBeNull();
+    editor.destroy();
+  });
+
+  it("does NOT arm on an ordinary local edit", () => {
+    const editor = makeEditor("a—b");
+    editor.view.dispatch(
+      editor.state.tr.replaceWith(2, 3, editor.state.schema.text("--")),
+    );
+    expect(undoGuardKey.getState(editor.state)).toBeNull();
+    editor.destroy();
+  });
+});
+
+describe("undo-guard release / shift (integration)", () => {
+  it("RELEASES when a later edit lands inside the guarded region", () => {
+    const editor = makeEditor("a—b");
+    editor.view.dispatch(
+      editor.state.tr
+        .replaceWith(2, 3, editor.state.schema.text("--"))
+        .setMeta("history$", { redo: false }),
+    );
+    const guard = undoGuardKey.getState(editor.state)!;
+    expect(guard).toEqual({ from: 2, to: 4 });
+
+    // Type a character inside the restored region -> guard is dropped.
+    editor.view.dispatch(editor.state.tr.insertText("x", guard.from + 1));
+    expect(undoGuardKey.getState(editor.state)).toBeNull();
+    editor.destroy();
+  });
+
+  it("keeps and SHIFTS the guard when a later edit lands before it", () => {
+    const editor = makeEditor("zz a—b");
+    // "zz a—b": em-dash at pos 5; replace the 'a' at 4..5 with "--" to arm.
+    editor.view.dispatch(
+      editor.state.tr
+        .replaceWith(4, 5, editor.state.schema.text("--"))
+        .setMeta("history$", { redo: false }),
+    );
+    const guard = undoGuardKey.getState(editor.state)!;
+    expect(guard).toEqual({ from: 4, to: 6 });
+
+    // Insert one char at the very start (before the guard) -> guard shifts +1.
+    editor.view.dispatch(editor.state.tr.insertText("Q", 1));
+    expect(undoGuardKey.getState(editor.state)).toEqual({ from: 5, to: 7 });
+    editor.destroy();
+  });
+});

apps/client/src/features/editor/extensions/custom-typography.ts

@@ -0,0 +1,193 @@
+import { InputRule } from "@tiptap/core";
+import {
+  Plugin,
+  PluginKey,
+  type EditorState,
+  type Transaction,
+} from "@tiptap/pm/state";
+import { Typography } from "@tiptap/extension-typography";
+import { isChangeOrigin } from "@tiptap/extension-collaboration";
+import { ySyncPluginKey } from "@tiptap/y-tiptap";
+
+// Region restored by the latest undo — while it is intact, typography
+// input rules overlapping it must not fire again.
+interface UndoGuardRange {
+  from: number;
+  to: number;
+}
+
+// Exported for tests: the plugin key lets a test read the armed guard state,
+// and the two pure helpers below are unit-tested directly.
+export const undoGuardKey = new PluginKey<UndoGuardRange | null>(
+  "typographyUndoGuard",
+);
+
+// prosemirror-history does not export its plugin key, so template-editor
+// undo/redo is detected via the stable stringified key. Only one
+// PluginKey("history") exists in the dependency tree, so "history$" is stable.
+const HISTORY_META = "history$";
+
+const isUndoRedoTransaction = (tr: Transaction): boolean => {
+  if (tr.getMeta(HISTORY_META)) {
+    return true;
+  }
+  // Read yjs undo/redo meta via the real ySyncPluginKey object (imported, not
+  // a fragile stringified key), which y-tiptap sets on Y.UndoManager changes.
+  const ySyncMeta = tr.getMeta(ySyncPluginKey) as
+    | { isUndoRedoOperation?: boolean }
+    | undefined;
+  return !!ySyncMeta?.isUndoRedoOperation;
+};
+
+interface DocChange {
+  from: number;
+  oldTo: number;
+  newTo: number;
+}
+
+// Compute the minimal changed region between two docs. yjs undo/redo (and any
+// remote change) arrives as a whole-document replace step, so the transaction
+// step maps are useless — diff the docs to recover the real minimal change.
+// Returns null when the docs are identical.
+export const findChangedRange = (
+  oldState: EditorState,
+  newState: EditorState,
+): DocChange | null => {
+  const start = oldState.doc.content.findDiffStart(newState.doc.content);
+  const end = oldState.doc.content.findDiffEnd(newState.doc.content);
+  if (start == null || end == null) {
+    return null;
+  }
+  let { a: oldTo, b: newTo } = end;
+  // findDiffEnd can report an end BEFORE the diff start when the changed text
+  // abuts repeated content (insertion -> oldTo<start, deletion -> newTo<start).
+  // Push both ends forward by the same delta so the range stays non-degenerate
+  // (from <= oldTo and from <= newTo), matching ProseMirror's own diff bounds.
+  const minTo = Math.min(oldTo, newTo);
+  if (minTo < start) {
+    const delta = start - minTo;
+    oldTo += delta;
+    newTo += delta;
+  }
+  return { from: start, oldTo, newTo };
+};
+
+// Map an armed guard range across a single document change described by a diff.
+// Returns null when the change touches the guarded text itself (the restored
+// substitution was edited, so the guard must be released).
+export const mapRangeThroughChange = (
+  range: UndoGuardRange,
+  change: DocChange,
+): UndoGuardRange | null => {
+  // Strict intersection: an edit exactly at a guard boundary (e.g. the user
+  // typing the suppressed space right after the restored text, or deleting it)
+  // must NOT drop the guard.
+  if (change.from < range.to && change.oldTo > range.from) {
+    return null;
+  }
+  // Change fully before the guard: shift the guard by the length delta.
+  if (change.oldTo <= range.from) {
+    const delta = change.newTo - change.oldTo;
+    return { from: range.from + delta, to: range.to + delta };
+  }
+  // Change fully after the guard: positions are unaffected.
+  return range;
+};
+
+// Detect history/remote transactions that may arrive as a whole-document
+// replace step: prosemirror-history undo/redo, or any yjs remote-origin change
+// (isChangeOrigin is the canonical predicate already used across the app).
+const isHistoryOrRemoteTransaction = (tr: Transaction): boolean =>
+  !!tr.getMeta(HISTORY_META) || isChangeOrigin(tr);
+
+export const CustomTypography = Typography.extend({
+  addProseMirrorPlugins() {
+    return [
+      ...(this.parent?.() ?? []),
+      new Plugin({
+        key: undoGuardKey,
+        state: {
+          init: () => null,
+          apply(tr, prev, oldState, newState): UndoGuardRange | null {
+            if (tr.docChanged && isHistoryOrRemoteTransaction(tr)) {
+              const change = findChangedRange(oldState, newState);
+              if (change == null) {
+                // Attribute-only or otherwise content-neutral change: keep the
+                // guard.
+                return prev;
+              }
+              // Arm the guard only when the LOCAL user's undo/redo REPLACED text
+              // (deleted + inserted) — the signature of reverting an input-rule
+              // substitution. Pure insertions/deletions and remote peer edits
+              // must not arm it.
+              if (
+                isUndoRedoTransaction(tr) &&
+                change.oldTo > change.from &&
+                change.newTo > change.from
+              ) {
+                return { from: change.from, to: change.newTo };
+              }
+              // Non-arming history/remote change: map the existing guard through
+              // the real diff instead of the (whole-document) step map.
+              if (!prev) {
+                return null;
+              }
+              return mapRangeThroughChange(prev, change);
+            }
+            if (!prev) {
+              return null;
+            }
+            if (!tr.docChanged) {
+              return prev;
+            }
+            // Ordinary local edit: minimal step maps are accurate and cheap.
+            let range: UndoGuardRange | null = prev;
+            for (const stepMap of tr.mapping.maps) {
+              const { from: rangeFrom, to: rangeTo } = range;
+              let touched = false;
+              stepMap.forEach((fromA, toA) => {
+                if (fromA < rangeTo && toA > rangeFrom) {
+                  touched = true;
+                }
+              });
+              if (touched) {
+                range = null;
+                break;
+              }
+              range = {
+                from: stepMap.map(rangeFrom, 1),
+                to: stepMap.map(rangeTo, -1),
+              };
+            }
+            return range && range.to > range.from ? range : null;
+          },
+        },
+      }),
+    ];
+  },
+
+  addInputRules() {
+    // Wrap every typography rule: skip it when its match overlaps the text
+    // just restored by undo, so an undone substitution is not re-applied.
+    return (this.parent?.() ?? []).map(
+      (rule) =>
+        new InputRule({
+          find: rule.find,
+          undoable: rule.undoable,
+          handler: (props) => {
+            const guard = undoGuardKey.getState(props.state);
+            if (
+              guard &&
+              props.range.from < guard.to &&
+              props.range.to > guard.from
+            ) {
+              // Returning null skips this rule and lets the typed character
+              // be inserted as plain text.
+              return null;
+            }
+            return rule.handler(props);
+          },
+        }),
+    );
+  },
+});

apps/client/src/features/editor/extensions/extensions.ts

@@ -6,7 +6,7 @@ import { TaskList, TaskItem } from "@tiptap/extension-list";
 import { Placeholder, CharacterCount, UndoRedo } from "@tiptap/extensions";
 import { Superscript } from "@tiptap/extension-superscript";
 import SubScript from "@tiptap/extension-subscript";
-import { Typography } from "@tiptap/extension-typography";
+import { CustomTypography } from "./custom-typography";
 import { TextStyle } from "@tiptap/extension-text-style";
 import { Color } from "@tiptap/extension-color";
 import { Youtube } from "@tiptap/extension-youtube";
@@ -245,7 +245,9 @@ export const mainExtensions = [
       return ReactMarkViewRenderer(SpoilerView);
     },
   }),
-  Typography,
+  // Typography with an undo guard: does not re-apply a substitution the user
+  // just undid (e.g. Ctrl+Z on "1/2" -> "½" followed by another space).
+  CustomTypography,
   TrailingNode,
   GlobalDragHandle.configure({
     customNodes: ["transclusionSource", "transclusionReference", "pageEmbed"],

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

@@ -1,5 +1,9 @@
 import { describe, it, expect } from "vitest";
-import { normalizeTableColumnWidths } from "./markdown-clipboard";
+import { htmlToMarkdown } from "@docmost/editor-ext";
+import {
+  normalizeTableColumnWidths,
+  classifyClipboardSelection,
+} from "./markdown-clipboard";
 
 // normalizeTableColumnWidths mutates a DOM subtree (jsdom provides document).
 function root(html: string): HTMLElement {
@@ -124,3 +128,171 @@ describe("normalizeTableColumnWidths", () => {
     ).toEqual([null, null]);
   });
 });
+
+describe("classifyClipboardSelection", () => {
+  it("serializes a list of 2+ items as markdown", () => {
+    expect(
+      classifyClipboardSelection([{ name: "bulletList", childCount: 2 }]),
+    ).toEqual({ asMarkdown: true, wrapBareRows: false });
+  });
+
+  it("leaves a single-item list as plain text", () => {
+    expect(
+      classifyClipboardSelection([{ name: "bulletList", childCount: 1 }]),
+    ).toEqual({ asMarkdown: false, wrapBareRows: false });
+  });
+
+  it("serializes a whole table without wrapping bare rows", () => {
+    expect(
+      classifyClipboardSelection([{ name: "table", childCount: 3 }]),
+    ).toEqual({ asMarkdown: true, wrapBareRows: false });
+  });
+
+  it("serializes a partial cell selection (bare rows) and flags wrapping", () => {
+    expect(
+      classifyClipboardSelection([
+        { name: "tableRow", childCount: 2 },
+        { name: "tableRow", childCount: 2 },
+      ]),
+    ).toEqual({ asMarkdown: true, wrapBareRows: true });
+  });
+
+  it("leaves plain paragraphs as plain text", () => {
+    expect(
+      classifyClipboardSelection([{ name: "paragraph", childCount: 1 }]),
+    ).toEqual({ asMarkdown: false, wrapBareRows: false });
+  });
+
+  it("does not wrap when rows are mixed with other block types", () => {
+    expect(
+      classifyClipboardSelection([
+        { name: "tableRow", childCount: 2 },
+        { name: "paragraph", childCount: 1 },
+      ]),
+    ).toEqual({ asMarkdown: false, wrapBareRows: false });
+  });
+});
+
+// Output-level tests for the table clipboard regression: copying a table must
+// yield a real GFM pipe table, NOT one-value-per-line concatenated cells.
+// These exercise the actual markdown produced by htmlToMarkdown (the same
+// serializer step the clipboardTextSerializer runs), so they pin the OUTPUT
+// shape that the classifier-flag tests above do not cover.
+describe("table clipboard markdown output (htmlToMarkdown)", () => {
+  // Trim each line and drop blanks so structural assertions are whitespace-robust.
+  function lines(md: string): string[] {
+    return md
+      .split("\n")
+      .map((l) => l.trim())
+      .filter((l) => l.length > 0);
+  }
+
+  // A GFM separator row like "| --- | --- |" (any number of columns), tolerant
+  // of the padding turndown emits.
+  function isSeparatorRow(line: string): boolean {
+    const compact = line.replace(/\s+/g, "");
+    return /^\|(?:-{3,}\|)+$/.test(compact);
+  }
+
+  // Split a pipe-delimited row into trimmed cell values.
+  function cells(line: string): string[] {
+    return line
+      .replace(/^\|/, "")
+      .replace(/\|$/, "")
+      .split("|")
+      .map((c) => c.trim());
+  }
+
+  it("serializes a header-less partial cell selection (bare rows) as a valid GFM pipe table", () => {
+    // Mirror the serializer's `wrapBareRows` branch exactly: bare <tr> nodes are
+    // wrapped in <table><tbody> and htmlToMarkdown(div.innerHTML) is called.
+    // See markdown-clipboard.ts clipboardTextSerializer:
+    //   const table = document.createElement("table");
+    //   const tbody = document.createElement("tbody");
+    //   tbody.appendChild(fragment); table.appendChild(tbody);
+    //   div.appendChild(table);
+    //   return htmlToMarkdown(div.innerHTML);
+    const div = document.createElement("div");
+    const table = document.createElement("table");
+    const tbody = document.createElement("tbody");
+    for (const [c1, c2] of [
+      ["a", "b"],
+      ["c", "d"],
+    ]) {
+      const tr = document.createElement("tr");
+      const td1 = document.createElement("td");
+      td1.textContent = c1;
+      const td2 = document.createElement("td");
+      td2.textContent = c2;
+      tr.appendChild(td1);
+      tr.appendChild(td2);
+      tbody.appendChild(tr);
+    }
+    table.appendChild(tbody);
+    div.appendChild(table);
+
+    const md = htmlToMarkdown(div.innerHTML);
+    const ls = lines(md);
+
+    // Valid GFM: a header/data separator row is present (an empty header is
+    // synthesized by the GFM turndown plugin for a header-less table — fine).
+    expect(ls.some(isSeparatorRow)).toBe(true);
+    // NOT the old broken "one value per line" shape: every line is pipe-delimited
+    // and no line is a bare cell value on its own.
+    expect(ls.every((l) => l.includes("|"))).toBe(true);
+    expect(md).not.toMatch(/^\s*(a|b|c|d)\s*$/m);
+    // The cell values land in real pipe-delimited data rows.
+    const dataRows = ls.filter((l) => !isSeparatorRow(l)).map(cells);
+    expect(dataRows).toContainEqual(["a", "b"]);
+    expect(dataRows).toContainEqual(["c", "d"]);
+  });
+
+  it("serializes a whole table with a header row as a proper GFM table (headline regression)", () => {
+    // Mirror the serializer's non-wrap branch: the full <table> node is appended
+    // directly (div.appendChild(fragment)) and htmlToMarkdown(div.innerHTML) runs.
+    const div = document.createElement("div");
+    const table = document.createElement("table");
+
+    const thead = document.createElement("thead");
+    const headerRow = document.createElement("tr");
+    for (const h of ["Name", "Age"]) {
+      const th = document.createElement("th");
+      th.textContent = h;
+      headerRow.appendChild(th);
+    }
+    thead.appendChild(headerRow);
+    table.appendChild(thead);
+
+    const tbody = document.createElement("tbody");
+    for (const [name, age] of [
+      ["Alice", "30"],
+      ["Bob", "25"],
+    ]) {
+      const tr = document.createElement("tr");
+      const td1 = document.createElement("td");
+      td1.textContent = name;
+      const td2 = document.createElement("td");
+      td2.textContent = age;
+      tr.appendChild(td1);
+      tr.appendChild(td2);
+      tbody.appendChild(tr);
+    }
+    table.appendChild(tbody);
+    div.appendChild(table);
+
+    const md = htmlToMarkdown(div.innerHTML);
+    const ls = lines(md);
+
+    // Proper GFM structure: separator row + all rows pipe-delimited.
+    expect(ls.some(isSeparatorRow)).toBe(true);
+    expect(ls.every((l) => l.includes("|"))).toBe(true);
+
+    const rows = ls.filter((l) => !isSeparatorRow(l)).map(cells);
+    // Header row comes first, followed by both data rows.
+    expect(rows[0]).toEqual(["Name", "Age"]);
+    expect(rows).toContainEqual(["Alice", "30"]);
+    expect(rows).toContainEqual(["Bob", "25"]);
+    // Headline regression: the table is NOT concatenated one-value-per-line.
+    expect(md).not.toMatch(/^\s*(Name|Age|Alice|Bob|30|25)\s*$/m);
+  });
+});

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

@@ -27,24 +27,36 @@ export const MarkdownClipboard = Extension.create({
         key: new PluginKey("markdownClipboard"),
         props: {
           clipboardTextSerializer: (slice) => {
-            const listTypes = ["bulletList", "orderedList", "taskList"];
+            const topLevelNodes: { name: string; childCount: number }[] = [];
-            let topLevelCount = 0;
-            let hasList = false;
             slice.content.forEach((node) => {
-              if (listTypes.includes(node.type.name)) {
+              topLevelNodes.push({
-                hasList = true;
+                name: node.type.name,
-                topLevelCount += node.childCount;
+                childCount: node.childCount,
-              } else {
+              });
-                topLevelCount++;
-              }
             });
 
-            if (!hasList || topLevelCount < 2) return null;
+            const { asMarkdown, wrapBareRows } =
+              classifyClipboardSelection(topLevelNodes);
+            if (!asMarkdown) return null;
 
             const div = document.createElement("div");
             const serializer = DOMSerializer.fromSchema(this.editor.schema);
             const fragment = serializer.serializeFragment(slice.content);
+
+            if (wrapBareRows) {
+              // A partial table cell-selection serializes to bare <tr> nodes
+              // (prosemirror-tables returns the whole `table` node only when the
+              // entire table is selected). Bare <tr> would be foster-parented
+              // away by the HTML parser inside htmlToMarkdown, so wrap them in
+              // <table><tbody> first for the GFM turndown rule to detect them.
+              const table = document.createElement("table");
+              const tbody = document.createElement("tbody");
+              tbody.appendChild(fragment);
+              table.appendChild(tbody);
+              div.appendChild(table);
+            } else {
               div.appendChild(fragment);
+            }
             return htmlToMarkdown(div.innerHTML);
           },
           handlePaste: (view, event, slice) => {
@@ -153,6 +165,55 @@ export const MarkdownClipboard = Extension.create({
   },
 });
 
+/**
+ * Decide whether a copied slice's plain-text clipboard payload should be
+ * serialized as Markdown (instead of ProseMirror's default text serializer,
+ * which joins block leaves with newlines — the "one value per line" bug for
+ * tables).
+ *
+ * Serialize as Markdown for structured content:
+ *  - lists with 2+ total items (a single copied bullet stays literal text);
+ *  - a whole table (top-level `table` node);
+ *  - a partial table cell-selection, which prosemirror-tables copies as bare
+ *    `tableRow` nodes (only a full-table selection yields a `table` node).
+ *
+ * `wrapBareRows` flags the bare-rows case so the caller wraps the serialized
+ * <tr> nodes in <table><tbody> before the HTML->Markdown step. Plain paragraphs
+ * return asMarkdown=false so a simple text copy stays literal, and internal
+ * copy/paste keeps using the richer text/html clipboard payload.
+ */
+export function classifyClipboardSelection(
+  nodes: { name: string; childCount: number }[],
+): { asMarkdown: boolean; wrapBareRows: boolean } {
+  const listTypes = ["bulletList", "orderedList", "taskList"];
+  let topLevelCount = 0;
+  let hasList = false;
+  let hasTable = false;
+  let tableRowCount = 0;
+  let nonRowCount = 0;
+
+  for (const node of nodes) {
+    if (listTypes.includes(node.name)) {
+      hasList = true;
+      topLevelCount += node.childCount;
+      nonRowCount++;
+    } else {
+      if (node.name === "table") hasTable = true;
+      if (node.name === "tableRow") tableRowCount++;
+      else nonRowCount++;
+      topLevelCount++;
+    }
+  }
+
+  // Bare tableRow nodes at the top level only occur for a partial cell
+  // selection; a slice never mixes bare rows with other block types, so
+  // "every top-level node is a row" is a safe signal to wrap-and-serialize.
+  const wrapBareRows = tableRowCount > 0 && nonRowCount === 0;
+  const asMarkdown =
+    (hasList && topLevelCount >= 2) || hasTable || wrapBareRows;
+  return { asMarkdown, wrapBareRows };
+}
+
 /**
  * Reorder/dedup the footnotes of a SELF-CONTAINED pasted markdown block to the
  * canonical invariant (the live footnoteSyncPlugin never reorders an existing

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

@@ -303,6 +303,11 @@ describe('buildSystemPrompt page-changed note (#274)', () => {
     expect(prompt).toContain(NOTE_MARKER);
     expect(prompt).toContain('-old line');
     expect(prompt).toContain('+new line');
+    // Strengthened note (#274): instructs a fresh re-read via getPage and steers
+    // the agent toward small, targeted edits instead of a full-page overwrite.
+    expect(prompt).toContain('getPage');
+    expect(prompt.toLowerCase()).toContain('targeted');
+    expect(prompt).toContain('editPageText');
     // Inside the safety sandwich: the trailing SAFETY block follows the note.
     expect(prompt.lastIndexOf(SAFETY_MARKER)).toBeGreaterThan(
       prompt.indexOf(NOTE_MARKER),

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

@@ -85,11 +85,17 @@ const INTERRUPT_NOTE =
 const PAGE_CHANGED_NOTE =
   'NOTE: The user edited the open page AFTER your last response in this ' +
   'conversation, so any copy of that page you produced or remember from earlier ' +
-  'is now STALE. The unified diff below shows exactly what changed since you last ' +
+  'is now STALE and must not be reused. Before you edit the page, you MUST first ' +
-  'spoke (lines starting with "-" were removed, "+" were added) and is the source ' +
+  're-read its current content with the getPage tool and base your work on that ' +
-  'of truth. Preserve the user\'s edits: build on the current page, do not revert ' +
+  'live version — never on your earlier copy or on the transcript. The unified ' +
-  'or overwrite their changes. If you need the full up-to-date page, re-read it ' +
+  'diff below shows exactly what the user changed since you last spoke (lines ' +
-  'with the getPage tool before editing.';
+  'starting with "-" were removed, "+" were added) and is the source of truth. ' +
+  'Preserve every one of the user\'s edits: make the smallest change that ' +
+  'satisfies the request using the targeted edit tools (editPageText, patchNode, ' +
+  'insertNode, deleteNode) rather than replacing the whole page, and do not ' +
+  'revert, drop, or overwrite anything the user changed. If a full rewrite is ' +
+  'truly unavoidable, start from the current getPage content and carry over all ' +
+  'of the user\'s edits.';
 
 /**
  * Sanitize a value interpolated into a prompt XML-ish attribute (e.g.

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

@@ -356,6 +356,32 @@ describe('flushAssistant', () => {
     expect(flushed.toolCalls).not.toBeNull();
     expect(flushed.metadata.error).toBe('boom');
   });
+
+  // #274 observability: the page-change diff the agent saw this turn is persisted
+  // to metadata.pageChanged when a non-empty diff was injected, and omitted when
+  // the diff is empty/whitespace or the arg is not supplied.
+  it('persists metadata.pageChanged when a non-empty diff was injected', () => {
+    const f = flushAssistant([], '', 'completed', {
+      pageChanged: { title: 'Doc', diff: '@@ -1 +1 @@\n-old\n+new' },
+    });
+    expect(f.metadata.pageChanged).toEqual({
+      title: 'Doc',
+      diff: '@@ -1 +1 @@\n-old\n+new',
+    });
+  });
+
+  it('omits metadata.pageChanged for an empty/whitespace diff or a missing arg', () => {
+    const whitespace = flushAssistant([], '', 'completed', {
+      pageChanged: { title: 'Doc', diff: '   \n  ' },
+    });
+    expect('pageChanged' in whitespace.metadata).toBe(false);
+
+    const nullArg = flushAssistant([], '', 'completed', { pageChanged: null });
+    expect('pageChanged' in nullArg.metadata).toBe(false);
+
+    const omitted = flushAssistant([], '', 'streaming');
+    expect('pageChanged' in omitted.metadata).toBe(false);
+  });
 });
 
 /**

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

@@ -685,7 +685,7 @@ export class AiChatService implements OnModuleInit {
     // no-op (guarded below) so the turn still streams to the user.
     let assistantId: string | undefined;
     try {
-      const seed = flushAssistant([], '', 'streaming');
+      const seed = flushAssistant([], '', 'streaming', { pageChanged });
       const seeded = await this.aiChatMessageRepo.insert({
         chatId,
         workspaceId: workspace.id,
@@ -720,7 +720,7 @@ export class AiChatService implements OnModuleInit {
         await this.aiChatMessageRepo.update(
           assistantId,
           workspace.id,
-          flushAssistant(capturedSteps, '', 'streaming'),
+          flushAssistant(capturedSteps, '', 'streaming', { pageChanged }),
           { onlyIfStreaming: true },
         );
       } catch (err) {
@@ -860,6 +860,7 @@ export class AiChatService implements OnModuleInit {
               // resolved from the admin-configured provider settings (in
               // closure scope here). Omitted/0 = no limit.
               maxContextTokens: resolved?.chatContextWindow,
+              pageChanged,
             }),
           );
           // Lifecycle: release the external MCP clients leased for this turn.
@@ -911,6 +912,7 @@ export class AiChatService implements OnModuleInit {
           await finalizeAssistant(
             flushAssistant(capturedSteps, inProgressText, 'error', {
               error: errorText,
+              pageChanged,
             }),
           );
           await closeExternalClients();
@@ -940,7 +942,9 @@ export class AiChatService implements OnModuleInit {
               `steps=${steps.length}`,
           );
           await finalizeAssistant(
-            flushAssistant(capturedSteps, inProgressText, 'aborted'),
+            flushAssistant(capturedSteps, inProgressText, 'aborted', {
+              pageChanged,
+            }),
           );
           await closeExternalClients();
           // Advance the page snapshot even on abort (#274): an agent edit that
@@ -1506,6 +1510,7 @@ export function flushAssistant(
     contextTokens?: number;
     maxContextTokens?: number;
     error?: string;
+    pageChanged?: { title: string; diff: string } | null;
   },
 ): AssistantFlush {
   const finished = capturedSteps ?? [];
@@ -1538,6 +1543,15 @@ export function flushAssistant(
   if (extra?.maxContextTokens)
     metadata.maxContextTokens = extra.maxContextTokens;
   if (extra?.error) metadata.error = extra.error;
+  // Persist the page-change diff the agent saw this turn (#274 observability),
+  // so history / the Markdown export can show what the user changed. Only when
+  // a non-empty diff was actually injected into the prompt this turn.
+  if (extra?.pageChanged && extra.pageChanged.diff?.trim().length) {
+    metadata.pageChanged = {
+      title: extra.pageChanged.title,
+      diff: extra.pageChanged.diff,
+    };
+  }
 
   return {
     content: stepsText + trailing,

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

@@ -269,6 +269,168 @@ describe('buildChatMarkdown (server) — structure', () => {
     expect(md).toContain('**⚠️ Error:** 401: Unauthorized');
   });
 
+  // #274 observability: an assistant row whose turn started with a user edit to
+  // the open page carries metadata.pageChanged = { title, diff }; the export
+  // renders the diff the agent saw, before the message body.
+  it('renders the persisted page-change diff block for an assistant row', () => {
+    const md = buildChatMarkdown({
+      title: 'T',
+      chatId: 'c',
+      rows: [
+        row({
+          role: 'assistant',
+          content: 'answer',
+          metadata: {
+            pageChanged: { title: 'Doc', diff: '@@ -1 +1 @@\n-old\n+new' },
+          } as never,
+        }),
+      ],
+    });
+    expect(md).toContain(
+      'The user edited this page before this turn; the diff the agent saw:',
+    );
+    expect(md).toContain('("Doc")');
+    expect(md).toContain('-old');
+    expect(md).toContain('+new');
+    // The diff sits before the message body (chronological: change, then reply).
+    expect(md.indexOf('-old')).toBeLessThan(md.indexOf('answer'));
+  });
+
+  it('does not render the page-change block when metadata.pageChanged is absent', () => {
+    const md = buildChatMarkdown({
+      title: 'T',
+      chatId: 'c',
+      rows: [row({ role: 'assistant', content: 'answer' })],
+    });
+    expect(md).not.toContain(
+      'The user edited this page before this turn; the diff the agent saw:',
+    );
+  });
+
+  // #288 F1/F2: an empty page title must render the BARE heading with no
+  // `("…")` suffix (the `pc.title ? … : …` false branch).
+  it('renders the page-change heading with no title suffix when title is empty', () => {
+    const md = buildChatMarkdown({
+      title: 'T',
+      chatId: 'c',
+      rows: [
+        row({
+          role: 'assistant',
+          content: 'answer',
+          metadata: {
+            pageChanged: { title: '', diff: '@@ -1 +1 @@\n-old\n+new' },
+          } as never,
+        }),
+      ],
+    });
+    // Bare heading, single line, no parenthesized title.
+    expect(md).toContain(
+      '> **📝 The user edited this page before this turn; the diff the agent saw:**',
+    );
+    expect(md).not.toContain('("');
+    expect(md).toContain('-old');
+  });
+
+  // #288 F1: the page title is UNTRUSTED cross-user data, so a title carrying a
+  // newline / backtick / `"` / `<`/`>` must be neutralized by escapeAttr before
+  // it is interpolated into the `> **…**` blockquote heading — otherwise it
+  // could break the blockquote onto multiple lines or inject markup/HTML into
+  // the downloaded .md. escapeAttr strips `<>"` and collapses whitespace runs to
+  // a single space, so `Ev"il\n> `x` <b>` becomes ``Evil `x` b``.
+  it('escapes an untrusted page title in the page-change heading', () => {
+    const md = buildChatMarkdown({
+      title: 'T',
+      chatId: 'c',
+      rows: [
+        row({
+          role: 'assistant',
+          content: 'answer',
+          metadata: {
+            pageChanged: {
+              title: 'Ev"il\n> `x` <b>',
+              diff: '@@ -1 +1 @@\n-old\n+new',
+            },
+          } as never,
+        }),
+      ],
+    });
+    // The heading stays a single blockquote line with the escaped title.
+    expect(md).toContain(
+      '> **📝 The user edited this page before this turn; the diff the agent saw: ("Evil `x` b")**',
+    );
+    // No raw attribute/markup breakers survived from the title.
+    expect(md).not.toContain('Ev"il');
+    expect(md).not.toContain('<b>');
+  });
+
+  // #288 review F1: escapeAttr ALONE is insufficient for this MARKDOWN sink —
+  // link/image syntax survives it. A cross-user title with `![x](url)` /
+  // `[phish](url)` must NOT become a working remote image or clickable link in
+  // the downloaded .md; markdownHeadingSafe backslash-escapes `[`/`]` so both are
+  // inert. (Non-vacuous: fails against the escapeAttr-only version, which left
+  // `](https://` intact.)
+  it('neutralizes markdown link/image syntax in an untrusted page title', () => {
+    const md = buildChatMarkdown({
+      title: 'T',
+      chatId: 'c',
+      rows: [
+        row({
+          role: 'assistant',
+          content: 'answer',
+          metadata: {
+            pageChanged: {
+              title:
+                '![x](https://attacker.example/t.png) and [click](https://phish.example)',
+              diff: '@@ -1 +1 @@\n-old\n+new',
+            },
+          } as never,
+        }),
+      ],
+    });
+    // No WORKING image/link syntax survives — the `[…]` sits escaped as `\[…\]`,
+    // so the unescaped `![x](` image and `[click](` link markers are gone. (We
+    // deliberately do NOT assert `not.toContain('](https://')`: after escaping the
+    // literal `\](https://` still contains `](https://` as a raw substring — that
+    // check would false-fail even though the link is inert.)
+    expect(md).not.toContain('![x](');
+    expect(md).not.toContain('[click](');
+    // The brackets are backslash-escaped, so `[text](url)`/`![text](url)` are inert.
+    expect(md).toContain('\\[');
+    expect(md).toContain('\\]');
+    // The heading stays a SINGLE blockquote line (no newline injected).
+    const headingLine = md
+      .split('\n')
+      .find((l) => l.includes('the diff the agent saw:'));
+    expect(headingLine).toBeDefined();
+    expect(headingLine).toContain('\\[x\\]');
+    expect(headingLine).toContain('\\[click\\]');
+  });
+
+  // #288 internal review Finding 2: a NON-empty title made up entirely of
+  // escapeAttr breakers (`<>"`) escapes to '' — the ternary must then fall to the
+  // BARE heading with NO `("…")` suffix. Locks the ternary-on-escaped-value
+  // behavior (distinct from the empty-string input test above).
+  it('renders the bare heading for a title that escapes to empty', () => {
+    const md = buildChatMarkdown({
+      title: 'T',
+      chatId: 'c',
+      rows: [
+        row({
+          role: 'assistant',
+          content: 'answer',
+          metadata: {
+            pageChanged: { title: '<>"', diff: '@@ -1 +1 @@\n-old\n+new' },
+          } as never,
+        }),
+      ],
+    });
+    expect(md).toContain(
+      '> **📝 The user edited this page before this turn; the diff the agent saw:**',
+    );
+    expect(md).not.toContain('("');
+    expect(md).toContain('-old');
+  });
+
   it('escapes embedded triple-backtick fences with a longer delimiter', () => {
     const md = buildChatMarkdown({
       title: 'T',

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

@@ -15,6 +15,7 @@
  */
 
 import type { AiChatMessage } from '@docmost/db/types/entity.types';
+import { escapeAttr } from './ai-chat.prompt';
 
 /** Supported export label languages. Defaults to English. */
 export type ExportLang = 'en' | 'ru';
@@ -63,6 +64,7 @@ const LABELS: Record<
     tools: Record<string, string>;
     ranTool: (name: string) => string;
     stillGenerating: string;
+    pageEditedByUser: string;
   }
 > = {
   en: {
@@ -83,6 +85,8 @@ const LABELS: Record<
     ranTool: (name) => `Ran tool ${name}`,
     stillGenerating:
       'This message is still being generated — the export captured a partial, in-progress response.',
+    pageEditedByUser:
+      'The user edited this page before this turn; the diff the agent saw:',
   },
   ru: {
     untitled: 'Без названия',
@@ -102,9 +106,29 @@ const LABELS: Record<
     ranTool: (name) => `Выполнил инструмент ${name}`,
     stillGenerating:
       'Это сообщение всё ещё генерируется — экспорт захватил частичный, незавершённый ответ.',
+    pageEditedByUser:
+      'Пользователь изменил страницу перед этим ходом; дифф, который видел агент:',
   },
 };
 
+/**
+ * Make an untrusted title safe to interpolate into a Markdown blockquote
+ * HEADING. escapeAttr() neutralizes the XML/HTML breakers (`<` `>` `"`) and
+ * collapses whitespace for the PROMPT sink (`page="…"`), but this export sink is
+ * MARKDOWN — link/image syntax survives escapeAttr. So additionally backslash-
+ * escape `[` and `]`: that disables both `[text](url)` links and `![text](url)`
+ * images, so a cross-user title like `![x](http://evil)` or `[phish](http://evil)`
+ * cannot inject a remote (auto-loading) image or a clickable link into the
+ * downloaded .md disguised as a trusted system annotation. A bare `(url)` with no
+ * preceding `[]` is inert Markdown, so brackets are the only security-critical
+ * characters here. (We leave backticks to escapeAttr's whitespace pass — a title
+ * shown as inline code cannot escape the blockquote line or load a resource, so
+ * it is not a security concern for this sink.)
+ */
+function markdownHeadingSafe(title: string): string {
+  return escapeAttr(title).replace(/[[\]]/g, (m) => `\\${m}`);
+}
+
 /** True for AI SDK tool parts (static `tool-*` or `dynamic-tool`). */
 function isToolPart(type: string): boolean {
   return type.startsWith('tool-') || type === 'dynamic-tool';
@@ -208,6 +232,23 @@ function rowParts(row: AiChatMessage): ExportPart[] {
     : [{ type: 'text', text: row.content ?? '' }];
 }
 
+/** The persisted page-change diff the agent saw this turn (#274), when any. */
+function pageChangedOf(
+  row: AiChatMessage,
+): { title: string; diff: string } | undefined {
+  const meta = (row.metadata ?? {}) as {
+    pageChanged?: { title?: string; diff?: string };
+  };
+  const pc = meta.pageChanged;
+  if (pc && typeof pc.diff === 'string' && pc.diff.trim().length > 0) {
+    return {
+      title: typeof pc.title === 'string' ? pc.title : '',
+      diff: pc.diff,
+    };
+  }
+  return undefined;
+}
+
 /**
  * Serialize a chat to a Markdown string from its persisted rows. Source = DB
  * ONLY (no live client state). A row whose `status` is still 'streaming' is an
@@ -266,6 +307,26 @@ export function buildChatMarkdown(args: {
       blocks.push(`<!-- ${iso} -->`);
     }
 
+    // Page-change observability (#274): show the diff the agent saw at the start
+    // of this turn, before its response, so the export reflects the stale-page
+    // warning the model received.
+    const pc = pageChangedOf(row);
+    if (pc) {
+      // The page title is UNTRUSTED cross-user data (a collaborative page's title
+      // controllable by another user). escapeAttr() alone (the prompt sink) is
+      // INSUFFICIENT here: this is a MARKDOWN sink, so we neutralize link/image
+      // syntax too (backslash-escaping `[`/`]`) before interpolating it into this
+      // `> **…**` blockquote heading — otherwise `![x](url)` / `[phish](url)` would
+      // inject a remote image or clickable link into the downloaded .md. An
+      // all-`<>"` title escapes to empty and correctly falls to the bare heading.
+      // The diff body is already safe via fence(). (#288 review F1.)
+      const safeTitle = markdownHeadingSafe(pc.title);
+      const heading = safeTitle
+        ? `${L.pageEditedByUser} ("${safeTitle}")`
+        : L.pageEditedByUser;
+      blocks.push(`> **📝 ${heading}**\n\n${fence(pc.diff, 'diff')}`);
+    }
+
     blocks.push(...renderMessageParts(rowParts(row), lang));
 
     // A still-'streaming' row is an interrupted/in-progress turn captured by the