fix(#342 review round-2 F5-F6): drop the posthog re-render remount + test chunk detector

- F5 [stability/regression]: the round-1 F2 fix re-rendered the root with
  <PostHogProvider><App/></PostHogProvider> after the analytics chunk loaded. In
  the ChunkLoadErrorBoundary child slot the element TYPE changes App ->
  PostHogProvider, so React does NOT reconcile in place — it REMOUNTS the whole
  App: every mount effect runs twice (websocket connect/disconnect, origin
  tracking, subscriptions) and local state / focus / scroll / in-progress input is
  lost on cloud cold-load (e.g. typing in /login before analytics loads). And it
  was USELESS: the app has ZERO consumers of the PostHog React context (no
  usePostHog / useFeatureFlag* / PostHogFeature), and PostHogProvider given an
  initialized client is a no-op — all capture goes through the posthog singleton.
  Fix: initAnalytics now inits the posthog SINGLETON only (no posthog-js/react
  import, no second render); renderApp() renders <App/> once. First paint stays
  instant, cloud analytics behavior unchanged, no remount.
- F6 [test]: exported isChunkLoadError + chunk-load-error-boundary.test.ts —
  pins the detector (ChunkLoadError name + the 3 dynamic-import failure messages,
  case-insensitive → true; null/undefined/ordinary errors → false) so a
  false-negative that re-blanks the app on a real chunk-404 is caught.

Gate: client tsc 0, chunk-load + sanitize tests 14 passed. Entry chunk unchanged.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/client/package.json

@@ -13,6 +13,7 @@
   },
   "dependencies": {
     "@ai-sdk/react": "^3.0.208",
+    "@braintree/sanitize-url": "7.1.2",
     "@atlaskit/pragmatic-drag-and-drop": "1.8.1",
     "@atlaskit/pragmatic-drag-and-drop-auto-scroll": "2.1.5",
     "@atlaskit/pragmatic-drag-and-drop-flourish": "2.0.15",
@@ -97,7 +98,6 @@
     "typescript": "5.9.3",
     "typescript-eslint": "8.57.1",
     "vite": "8.0.5",
-    "vite-plugin-compression2": "2.5.3",
     "vitest": "4.1.6"
   }
 }

apps/client/src/App.tsx

@@ -1,38 +1,72 @@
+import { lazy, Suspense } from "react";
 import { Navigate, Route, Routes } from "react-router-dom";
+import { Center, Loader } from "@mantine/core";
+import { Error404 } from "@/components/ui/error-404.tsx";
+import Layout from "@/components/layouts/global/layout.tsx";
+import { useTrackOrigin } from "@/hooks/use-track-origin";
+
+// ShareLayout is route-split: its ShareShell chrome pulls in the table of
+// contents (and thus TipTap), so keeping it out of the eager graph removes the
+// editor engine from startup for authenticated users too.
+const ShareLayout = lazy(
+  () => import("@/features/share/components/share-layout.tsx"),
+);
+
+// Auth / entry pages stay eager: they are the first paint for an unauthenticated
+// visitor (e.g. /login) and are already small, so code-splitting them would only
+// add a cold-chunk round trip to the most common cold-start path.
 import SetupWorkspace from "@/pages/auth/setup-workspace.tsx";
 import LoginPage from "@/pages/auth/login";
-import Home from "@/pages/dashboard/home";
-import Page from "@/pages/page/page";
-import AccountSettings from "@/pages/settings/account/account-settings";
-import WorkspaceMembers from "@/pages/settings/workspace/workspace-members";
-import WorkspaceSettings from "@/pages/settings/workspace/workspace-settings";
-import AiSettings from "@/pages/settings/workspace/ai-settings";
-import Groups from "@/pages/settings/group/groups";
-import GroupInfo from "./pages/settings/group/group-info";
-import Spaces from "@/pages/settings/space/spaces.tsx";
-import { Error404 } from "@/components/ui/error-404.tsx";
-import AccountPreferences from "@/pages/settings/account/account-preferences.tsx";
-import SpaceHome from "@/pages/space/space-home.tsx";
-import PageRedirect from "@/pages/page/page-redirect.tsx";
-import Layout from "@/components/layouts/global/layout.tsx";
 import InviteSignup from "@/pages/auth/invite-signup.tsx";
 import ForgotPassword from "@/pages/auth/forgot-password.tsx";
 import PasswordReset from "./pages/auth/password-reset";
-import SharedPage from "@/pages/share/shared-page.tsx";
-import Shares from "@/pages/settings/shares/shares.tsx";
-import ShareLayout from "@/features/share/components/share-layout.tsx";
+import PageRedirect from "@/pages/page/page-redirect.tsx";
 import ShareRedirect from "@/pages/share/share-redirect.tsx";
-import { useTrackOrigin } from "@/hooks/use-track-origin";
-import SpacesPage from "@/pages/spaces/spaces.tsx";
-import SpaceTrash from "@/pages/space/space-trash.tsx";
-import FavoritesPage from "@/pages/favorites/favorites-page";
-import LabelPage from "@/pages/label/label-page";
+
+// Heavy / leaf pages are route-split with React.lazy so their code (most
+// importantly the whole TipTap editor + KaTeX + lowlight grammars + drawio that
+// the page editor and the readonly share editor pull in) is fetched only when
+// the matching route is actually visited. The <Suspense> boundaries live inside
+// each Layout (around its <Outlet/>), so the app shell stays mounted while a
+// route chunk loads.
+const Home = lazy(() => import("@/pages/dashboard/home"));
+const Page = lazy(() => import("@/pages/page/page"));
+const SpaceHome = lazy(() => import("@/pages/space/space-home.tsx"));
+const SpaceTrash = lazy(() => import("@/pages/space/space-trash.tsx"));
+const SpacesPage = lazy(() => import("@/pages/spaces/spaces.tsx"));
+const FavoritesPage = lazy(() => import("@/pages/favorites/favorites-page"));
+const LabelPage = lazy(() => import("@/pages/label/label-page"));
+const SharedPage = lazy(() => import("@/pages/share/shared-page.tsx"));
+
+const AccountSettings = lazy(
+  () => import("@/pages/settings/account/account-settings"),
+);
+const AccountPreferences = lazy(
+  () => import("@/pages/settings/account/account-preferences.tsx"),
+);
+const WorkspaceSettings = lazy(
+  () => import("@/pages/settings/workspace/workspace-settings"),
+);
+const AiSettings = lazy(() => import("@/pages/settings/workspace/ai-settings"));
+const WorkspaceMembers = lazy(
+  () => import("@/pages/settings/workspace/workspace-members"),
+);
+const Groups = lazy(() => import("@/pages/settings/group/groups"));
+const GroupInfo = lazy(() => import("./pages/settings/group/group-info"));
+const Spaces = lazy(() => import("@/pages/settings/space/spaces.tsx"));
+const Shares = lazy(() => import("@/pages/settings/shares/shares.tsx"));
 
 export default function App() {
   useTrackOrigin();
 
   return (
-    <>
+    <Suspense
+      fallback={
+        <Center h="100vh">
+          <Loader size="sm" />
+        </Center>
+      }
+    >
       <Routes>
         <Route index element={<Navigate to="/home" />} />
         <Route path={"/login"} element={<LoginPage />} />
@@ -83,6 +117,6 @@ export default function App() {
 
         <Route path="*" element={<Error404 />} />
       </Routes>
-    </>
+    </Suspense>
   );
 }

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

@@ -0,0 +1,37 @@
+import { describe, it, expect } from "vitest";
+import { isChunkLoadError } from "./chunk-load-error-boundary";
+
+// The detector decides whether a caught render error is a stale-deploy chunk-404
+// (→ auto-reload to fetch the new manifest) vs a genuine app error (→ generic
+// recovery UI, no reload). A false negative on a real chunk failure re-blanks the
+// app; a false positive would auto-reload on an ordinary error. Pin both sides.
+describe("isChunkLoadError", () => {
+  it("detects the ChunkLoadError name", () => {
+    expect(isChunkLoadError({ name: "ChunkLoadError", message: "x" })).toBe(true);
+  });
+
+  it.each([
+    "Failed to fetch dynamically imported module: https://x/assets/index-abc.js",
+    "error loading dynamically imported module",
+    "Importing a module script failed.",
+  ])("detects the dynamic-import failure message %#", (message) => {
+    expect(isChunkLoadError({ name: "TypeError", message })).toBe(true);
+  });
+
+  it("is case-insensitive on the message", () => {
+    expect(
+      isChunkLoadError({ message: "FAILED TO FETCH DYNAMICALLY IMPORTED MODULE" }),
+    ).toBe(true);
+  });
+
+  it.each([
+    null,
+    undefined,
+    {},
+    { name: "TypeError", message: "Cannot read properties of undefined" },
+    { message: "Network request failed" },
+    new Error("some ordinary render error"),
+  ])("returns false for a non-chunk error %#", (err) => {
+    expect(isChunkLoadError(err)).toBe(false);
+  });
+});

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

@@ -0,0 +1,71 @@
+import { ReactNode } from "react";
+import { ErrorBoundary } from "react-error-boundary";
+import { Button, Center, Stack, Text } from "@mantine/core";
+
+const RELOAD_FLAG = "chunk-reload-attempted";
+
+// Heuristic detection of a failed dynamic import. Since the code-splitting work,
+// every route (plus Aside / AiChatWindow) is React.lazy: when a new deploy
+// replaces the hashed chunks, a tab left open on the old index.html requests a
+// chunk URL that now 404s, and React.lazy rejects. Browsers / Vite surface these
+// with a ChunkLoadError name or one of these messages.
+export function isChunkLoadError(error: unknown): boolean {
+  if (!error) return false;
+  const name = (error as { name?: string }).name ?? "";
+  const message = (error as { message?: string }).message ?? "";
+  return (
+    name === "ChunkLoadError" ||
+    /Failed to fetch dynamically imported module/i.test(message) ||
+    /error loading dynamically imported module/i.test(message) ||
+    /Importing a module script failed/i.test(message)
+  );
+}
+
+function handleError(error: unknown) {
+  if (!isChunkLoadError(error)) return;
+  // A stale-chunk 404 is cured by a full reload that re-fetches index.html and
+  // the new chunk manifest. Auto-reload once, guarding against a reload loop
+  // (e.g. a genuinely missing chunk) with a one-shot sessionStorage flag. If the
+  // flag is already set we fall through to the manual recovery UI below.
+  try {
+    if (sessionStorage.getItem(RELOAD_FLAG)) return;
+    sessionStorage.setItem(RELOAD_FLAG, "1");
+  } catch {
+    // sessionStorage unavailable (private mode / disabled): skip the automatic
+    // reload rather than risk an unguarded loop; the fallback UI still recovers.
+    return;
+  }
+  window.location.reload();
+}
+
+// Root-level boundary that sits ABOVE every route-level Suspense boundary so a
+// lazy route/component chunk failure is caught here instead of unmounting the
+// whole tree into a blank white screen. Per-feature ErrorBoundaries (page.tsx,
+// transclusion, page-embed) remain in place underneath for their local errors.
+export function ChunkLoadErrorBoundary({ children }: { children: ReactNode }) {
+  return (
+    <ErrorBoundary
+      onError={handleError}
+      fallbackRender={({ error }) => {
+        const chunk = isChunkLoadError(error);
+        return (
+          <Center h="100vh" p="md">
+            <Stack align="center" gap="sm" maw={420}>
+              <Text fw={600}>
+                {chunk ? "A new version is available" : "Something went wrong"}
+              </Text>
+              <Text size="sm" c="dimmed" ta="center">
+                {chunk
+                  ? "Please reload the page to load the latest version."
+                  : "An unexpected error occurred. Reloading the page may help."}
+              </Text>
+              <Button onClick={() => window.location.reload()}>Reload</Button>
+            </Stack>
+          </Center>
+        );
+      }}
+    >
+      {children}
+    </ErrorBoundary>
+  );
+}

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

@@ -1,9 +1,10 @@
 import { AppShell, Container } from "@mantine/core";
-import React, { useEffect, useRef, useState } from "react";
+import React, { Suspense, useEffect, useRef, useState } from "react";
 import { useLocation } from "react-router-dom";
 import { useTranslation } from "react-i18next";
 import SettingsSidebar from "@/components/settings/settings-sidebar.tsx";
-import { useAtom } from "jotai";
+import { useAtom, useAtomValue } from "jotai";
+import { aiChatWindowOpenAtom } from "@/features/ai-chat/atoms/ai-chat-atom.ts";
 import {
   APP_NAVBAR_ID,
   NAVBAR_COLLAPSE_BREAKPOINT,
@@ -14,8 +15,6 @@ import {
 } from "@/components/layouts/global/hooks/atoms/sidebar-atom.ts";
 import { SpaceSidebar } from "@/features/space/components/sidebar/space-sidebar.tsx";
 import { AppHeader } from "@/components/layouts/global/app-header.tsx";
-import Aside from "@/components/layouts/global/aside.tsx";
-import AiChatWindow from "@/features/ai-chat/components/ai-chat-window.tsx";
 import GitmostGlobalBridge from "@/features/editor/gitmost/gitmost-global-bridge.tsx";
 import classes from "./app-shell.module.css";
 import { useToggleSidebar } from "@/components/layouts/global/hooks/hooks/use-toggle-sidebar.ts";
@@ -23,6 +22,21 @@ import GlobalSidebar from "@/components/layouts/global/global-sidebar.tsx";
 import { ASIDE_PANEL_ID } from "@/hooks/use-toggle-aside.tsx";
 import { MAIN_CONTENT_ID, SkipToMain } from "@/components/ui/skip-to-main.tsx";
 
+// Lazily load the AI chat window so the AI SDK runtime it pulls in is fetched
+// only after the user first opens the chat, instead of for every authenticated
+// user on load. The window itself renders null while closed, so there is no
+// behavior difference — it simply is not mounted until first opened.
+const AiChatWindow = React.lazy(
+  () => import("@/features/ai-chat/components/ai-chat-window.tsx"),
+);
+
+// The right aside hosts the comment panel and table of contents, both of which
+// pull in TipTap. It only ever renders on page routes, so lazy-loading it keeps
+// the whole editor engine out of the eager global-shell startup graph.
+const Aside = React.lazy(
+  () => import("@/components/layouts/global/aside.tsx"),
+);
+
 export default function GlobalAppShell({
   children,
 }: {
@@ -37,6 +51,15 @@ export default function GlobalAppShell({
   const [isResizing, setIsResizing] = useState(false);
   const sidebarRef = useRef(null);
 
+  // Latch: once the AI chat window has been opened, keep it mounted so an
+  // in-flight stream is never torn down. Before the first open the AI chat chunk
+  // is never fetched.
+  const aiChatOpen = useAtomValue(aiChatWindowOpenAtom);
+  const [aiChatEverOpened, setAiChatEverOpened] = useState(false);
+  useEffect(() => {
+    if (aiChatOpen) setAiChatEverOpened(true);
+  }, [aiChatOpen]);
+
   const startResizing = React.useCallback((mouseDownEvent) => {
     mouseDownEvent.preventDefault();
     setIsResizing(true);
@@ -160,13 +183,21 @@ export default function GlobalAppShell({
                   : undefined
           }
         >
-          <Aside />
+          <Suspense fallback={null}>
+            <Aside />
+          </Suspense>
         </AppShell.Aside>
       )}
     </AppShell>
-    {/* Floating AI chat window. Mounted once globally; it is position: fixed
-        and self-hides when closed, so its place in the tree is not critical. */}
-    <AiChatWindow />
+    {/* Floating AI chat window. Mounted once globally on first open; it is
+        position: fixed and self-hides when closed, so its place in the tree is
+        not critical. Kept mounted after the first open so a live stream is not
+        aborted. */}
+    {aiChatEverOpened && (
+      <Suspense fallback={null}>
+        <AiChatWindow />
+      </Suspense>
+    )}
       {/* Global gitmost native bridge: registers listSpaces / listPages /
           createPageWithRecording on window.gitmost so the native host can
           create a page with a recording even when no page editor is open. */}

apps/client/src/components/layouts/global/layout.tsx

@@ -1,5 +1,7 @@
+import { Suspense, useEffect } from "react";
 import { UserProvider } from "@/features/user/user-provider.tsx";
 import { Outlet, useParams } from "react-router-dom";
+import { Center, Loader } from "@mantine/core";
 import GlobalAppShell from "@/components/layouts/global/global-app-shell.tsx";
 import { SearchSpotlight } from "@/features/search/components/search-spotlight.tsx";
 import { useGetSpaceBySlugQuery } from "@/features/space/queries/space-query.ts";
@@ -8,10 +10,39 @@ export default function Layout() {
   const { spaceSlug } = useParams();
   const { data: space } = useGetSpaceBySlugQuery(spaceSlug);
 
+  // Warm the (now route-split) editor chunk during idle time on authenticated
+  // routes, so the first navigation to a page renders from cache instead of a
+  // cold chunk fetch. Best-effort: gated on requestIdleCallback and never blocks
+  // startup — the dynamic import mirrors the App.tsx route lazy loader so both
+  // resolve to the same chunk.
+  useEffect(() => {
+    const ric =
+      typeof window !== "undefined" && (window as any).requestIdleCallback;
+    const warm = () => {
+      // Best-effort prefetch: a failed warm-up (offline, stale 404) is harmless
+      // and must not surface as an unhandledrejection.
+      void import("@/pages/page/page").catch(() => {});
+    };
+    if (ric) {
+      const id = ric(warm);
+      return () => (window as any).cancelIdleCallback?.(id);
+    }
+    const timer = setTimeout(warm, 2000);
+    return () => clearTimeout(timer);
+  }, []);
+
   return (
     <UserProvider>
       <GlobalAppShell>
-        <Outlet />
+        <Suspense
+          fallback={
+            <Center h="60vh">
+              <Loader size="sm" />
+            </Center>
+          }
+        >
+          <Outlet />
+        </Suspense>
       </GlobalAppShell>
       <SearchSpotlight spaceId={space?.id} />
     </UserProvider>

apps/client/src/features/editor/atoms/editor-atoms.ts

@@ -1,5 +1,8 @@
 import { atom } from "jotai";
-import { Editor } from "@tiptap/core";
+// Type-only: these atoms only hold an Editor reference for typing. A value
+// import would drag the whole @tiptap/core engine into the eager graph of every
+// shell component that reads one of these atoms.
+import type { Editor } from "@tiptap/core";
 import { PageEditMode } from "@/features/user/types/user.types.ts";
 import type { DictationUnavailableReason } from "@/features/dictation/dictation-status";
 

apps/client/src/features/editor/components/drawio/drawio-menu-lazy.tsx

@@ -0,0 +1,16 @@
+import { lazy, Suspense } from "react";
+import { EditorMenuProps } from "@/features/editor/components/table/types/types.ts";
+
+// Lazily load the drawio bubble menu so it is split out of the editor chunk and
+// fetched only when an editable editor is mounted (mirrors excalidraw-menu-lazy).
+const DrawioMenu = lazy(
+  () => import("@/features/editor/components/drawio/drawio-menu.tsx"),
+);
+
+export default function DrawioMenuLazy(props: EditorMenuProps) {
+  return (
+    <Suspense fallback={null}>
+      <DrawioMenu {...props} />
+    </Suspense>
+  );
+}

apps/client/src/features/editor/components/drawio/drawio-view-lazy.tsx

@@ -0,0 +1,17 @@
+import { lazy, Suspense } from "react";
+import { NodeViewProps } from "@tiptap/react";
+
+// Lazily load the drawio node view so the heavy react-drawio embed runtime is
+// split into its own chunk and fetched only when a drawio diagram is actually
+// rendered (mirrors excalidraw-view-lazy).
+const DrawioView = lazy(
+  () => import("@/features/editor/components/drawio/drawio-view.tsx"),
+);
+
+export default function DrawioViewLazy(props: NodeViewProps) {
+  return (
+    <Suspense fallback={null}>
+      <DrawioView {...props} />
+    </Suspense>
+  );
+}

apps/client/src/features/editor/components/math/math-block-lazy.tsx

@@ -0,0 +1,19 @@
+import { lazy, Suspense } from "react";
+import { NodeViewProps } from "@tiptap/react";
+
+// Lazily load the KaTeX-backed block math view so the katex chunk is fetched
+// only when a document actually contains a math node (mirrors the mermaid/
+// excalidraw lazy pattern). The local Suspense keeps a slow katex chunk from
+// crashing or blocking the whole editor: while it loads we render the raw
+// LaTeX source as a node-sized placeholder.
+const MathBlockView = lazy(
+  () => import("@/features/editor/components/math/math-block.tsx"),
+);
+
+export default function MathBlockViewLazy(props: NodeViewProps) {
+  return (
+    <Suspense fallback={<div data-katex="true">{props.node.attrs.text}</div>}>
+      <MathBlockView {...props} />
+    </Suspense>
+  );
+}

apps/client/src/features/editor/components/math/math-inline-lazy.tsx

@@ -0,0 +1,19 @@
+import { lazy, Suspense } from "react";
+import { NodeViewProps } from "@tiptap/react";
+
+// Lazily load the KaTeX-backed inline math view so the katex chunk is fetched
+// only when a document actually contains a math node (mirrors the mermaid/
+// excalidraw lazy pattern). The local Suspense keeps a slow katex chunk from
+// crashing or blocking the whole editor: while it loads we render the raw
+// LaTeX source as a node-sized placeholder.
+const MathInlineView = lazy(
+  () => import("@/features/editor/components/math/math-inline.tsx"),
+);
+
+export default function MathInlineViewLazy(props: NodeViewProps) {
+  return (
+    <Suspense fallback={<span data-katex="true">{props.node.attrs.text}</span>}>
+      <MathInlineView {...props} />
+    </Suspense>
+  );
+}

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

@@ -81,8 +81,8 @@ import {
   createResizeHandle,
   buildResizeClasses,
 } from "@/features/editor/components/common/node-resize-handles.ts";
-import MathInlineView from "@/features/editor/components/math/math-inline.tsx";
-import MathBlockView from "@/features/editor/components/math/math-block.tsx";
+import MathInlineView from "@/features/editor/components/math/math-inline-lazy.tsx";
+import MathBlockView from "@/features/editor/components/math/math-block-lazy.tsx";
 import ImageView from "@/features/editor/components/image/image-view.tsx";
 import CalloutView from "@/features/editor/components/callout/callout-view.tsx";
 import StatusView from "@/features/editor/components/status/status-view.tsx";
@@ -90,7 +90,7 @@ import VideoView from "@/features/editor/components/video/video-view.tsx";
 import AudioView from "@/features/editor/components/audio/audio-view.tsx";
 import AttachmentView from "@/features/editor/components/attachment/attachment-view.tsx";
 import CodeBlockView from "@/features/editor/components/code-block/code-block-view.tsx";
-import DrawioView from "../components/drawio/drawio-view";
+import DrawioView from "../components/drawio/drawio-view-lazy.tsx";
 import ExcalidrawView from "@/features/editor/components/excalidraw/excalidraw-view-lazy.tsx";
 import EmbedView from "@/features/editor/components/embed/embed-view.tsx";
 import HtmlEmbedView from "@/features/editor/components/html-embed/html-embed-view.tsx";

apps/client/src/features/editor/gitmost/gitmost-global-bridge.tsx

@@ -1,8 +1,17 @@
 import { useEffect, useRef } from "react";
 import { useNavigate } from "react-router-dom";
 import { getDefaultStore } from "jotai";
-import { WebSocketStatus } from "@hocuspocus/provider";
-import { Editor } from "@tiptap/core";
+
+// Literal value of WebSocketStatus.Connected from @hocuspocus/provider. Inlined
+// so this always-mounted global bridge does not statically import
+// @hocuspocus/provider — that import pulls Yjs (and, through a shared chunk, the
+// whole TipTap engine) into the eager startup graph. yjsConnectionStatusAtom
+// already stores these raw status strings.
+const YJS_STATUS_CONNECTED = "connected";
+// Type-only: importing Editor as a type keeps @tiptap/core (the whole editor
+// engine) out of the eager global-shell graph — the bridge only uses it for
+// annotations/casts, never as a runtime value.
+import type { Editor } from "@tiptap/core";
 import {
   pageEditorAtom,
   yjsConnectionStatusAtom,
@@ -16,15 +25,19 @@ import {
   getSidebarPages,
 } from "@/features/page/services/page-service.ts";
 import { buildPageUrl } from "@/features/page/page.utils.ts";
-import {
+// Types are erased at build time, so importing them does not pull the module's
+// runtime (which drags in @tiptap + the editor-ext barrel). The actual recording
+// helpers are dynamically imported at call time inside createPageWithRecording,
+// keeping the editor engine out of the eager global-shell startup graph — the
+// bridge is mounted for every authenticated user but recording is a rare,
+// native-host-driven action.
+import type {
   GitmostBridge,
   GitmostCreatePagePayload,
   GitmostCreatePageResult,
   GitmostListPagesPayload,
   GitmostListPagesResult,
   GitmostListSpacesResult,
-  gitmostDecodePayloadToFile,
-  gitmostUploadFileToEditor,
 } from "@/features/editor/gitmost/gitmost-recording.ts";
 
 // How long to wait for a freshly-navigated page's editor to mount, become
@@ -57,7 +70,7 @@ function gitmostWaitForEditor(
         !editor.isDestroyed &&
         editor.isEditable &&
         editorPageId === pageId &&
-        yjsStatus === WebSocketStatus.Connected;
+        yjsStatus === YJS_STATUS_CONNECTED;
       if (ready) {
         resolve(editor);
         return;
@@ -171,6 +184,12 @@ export default function GitmostGlobalBridge() {
           };
         }
 
+        // Load the recording helpers on demand (see the import note above). This
+        // is the only place they are needed, so the @tiptap/editor-ext code they
+        // pull in stays out of the eager startup graph.
+        const { gitmostDecodePayloadToFile, gitmostUploadFileToEditor } =
+          await import("@/features/editor/gitmost/gitmost-recording.ts");
+
         // Validate/decode the recording BEFORE creating the page so a bad
         // payload never leaves an empty junk page behind. Per the createPage
         // error contract, any decode failure collapses to "insert-failed" (the

apps/client/src/features/editor/page-editor.tsx

@@ -59,7 +59,7 @@ import {
   handlePaste,
 } from "@/features/editor/components/common/editor-paste-handler.tsx";
 import ExcalidrawMenu from "./components/excalidraw/excalidraw-menu-lazy";
-import DrawioMenu from "./components/drawio/drawio-menu";
+import DrawioMenu from "./components/drawio/drawio-menu-lazy";
 import { useCollabToken } from "@/features/auth/queries/auth-query.tsx";
 import SearchAndReplaceDialog from "@/features/editor/components/search-and-replace/search-and-replace-dialog.tsx";
 import { useDebouncedCallback, useDocumentVisibility } from "@mantine/hooks";

apps/client/src/features/share/components/share-layout.tsx

@@ -1,10 +1,20 @@
+import { Suspense } from "react";
 import { Outlet } from "react-router-dom";
+import { Center, Loader } from "@mantine/core";
 import ShareShell from "@/features/share/components/share-shell.tsx";
 
 export default function ShareLayout() {
   return (
     <ShareShell>
-      <Outlet />
+      <Suspense
+        fallback={
+          <Center h="60vh">
+            <Loader size="sm" />
+          </Center>
+        }
+      >
+        <Outlet />
+      </Suspense>
     </ShareShell>
   );
 }

apps/client/src/hooks/use-clipboard.ts

@@ -1,7 +1,7 @@
 // Source: https://github.com/mantinedev/mantine/blob/master/packages/@mantine/hooks/src/use-clipboard/use-clipboard.ts
 // polyfilled to support execCommand fallback
 import { useState } from "react";
-import { execCommandCopy } from "@docmost/editor-ext";
+import { execCommandCopy } from "@/lib/copy-to-clipboard.ts";
 
 export type UseClipboardOptions = {
   timeout?: number;

apps/client/src/lib/config.ts

@@ -1,7 +1,7 @@
 import bytes from "bytes";
 import { castToBoolean } from "@/lib/utils.tsx";
 import { AvatarIconType } from "@/features/attachments/types/attachment.types.ts";
-import { sanitizeUrl } from "@docmost/editor-ext";
+import { sanitizeUrl } from "@/lib/sanitize-url.ts";
 
 declare global {
   interface Window {

apps/client/src/lib/copy-to-clipboard.ts

@@ -0,0 +1,16 @@
+// Client-local execCommand copy fallback (previously imported from
+// @docmost/editor-ext). It lives here so the ubiquitous useClipboard / CopyButton
+// path does not pull in the editor-ext barrel — and with it the whole TipTap
+// engine — through the eager startup graph. Behavior is identical to the
+// editor-ext helper it replaces.
+export function execCommandCopy(text: string): void {
+  const textarea = document.createElement("textarea");
+  textarea.value = text;
+  textarea.style.position = "fixed";
+  textarea.style.left = "-9999px";
+  textarea.style.top = "-9999px";
+  document.body.appendChild(textarea);
+  textarea.select();
+  document.execCommand("copy");
+  document.body.removeChild(textarea);
+}

apps/client/src/lib/sanitize-url.test.ts

@@ -0,0 +1,31 @@
+import { describe, it, expect } from "vitest";
+import { sanitizeUrl } from "./sanitize-url";
+
+// `sanitizeUrl` is a byte-identical client-local copy of editor-ext's wrapper
+// around @braintree/sanitize-url: it maps the sanitizer's "about:blank" XSS
+// sentinel to "". These assertions mirror editor-ext's own security-contract
+// test so the extracted copy keeps the same guarantees.
+describe("sanitizeUrl", () => {
+  it("blocks dangerous schemes (returns empty string)", () => {
+    expect(sanitizeUrl("javascript:alert(1)")).toBe("");
+    expect(sanitizeUrl("data:text/html,<script>alert(1)</script>")).toBe("");
+    expect(sanitizeUrl("vbscript:msgbox(1)")).toBe("");
+    // Case / whitespace obfuscation must not slip past the sanitizer.
+    expect(sanitizeUrl("  JaVaScRiPt:alert(1)")).toBe("");
+  });
+
+  it("returns empty string for empty / undefined input", () => {
+    expect(sanitizeUrl(undefined)).toBe("");
+    expect(sanitizeUrl("")).toBe("");
+  });
+
+  it("allows safe https, relative file and mailto URLs", () => {
+    expect(sanitizeUrl("https://example.com/page")).toMatch(
+      /^https:\/\/example\.com\/page/,
+    );
+    expect(sanitizeUrl("/api/files/abc-123")).toBe("/api/files/abc-123");
+    expect(sanitizeUrl("mailto:user@example.com")).toBe(
+      "mailto:user@example.com",
+    );
+  });
+});

apps/client/src/lib/sanitize-url.ts

@@ -0,0 +1,15 @@
+import { sanitizeUrl as braintreeSanitizeUrl } from "@braintree/sanitize-url";
+
+// Client-local copy of editor-ext's sanitizeUrl wrapper. Importing it from the
+// editor-ext barrel dragged the whole TipTap engine into the eager startup graph
+// via the app-wide config module (getFileUrl). This keeps the exact same
+// behavior (braintree sanitize + normalize "about:blank" -> "") without that
+// dependency.
+export function sanitizeUrl(url: string | undefined): string {
+  if (!url) return "";
+
+  const sanitized = braintreeSanitizeUrl(url);
+
+  // Return an empty string instead of "about:blank".
+  return sanitized === "about:blank" ? "" : sanitized;
+}

apps/client/src/main.tsx

@@ -13,15 +13,14 @@ import { ModalsProvider } from "@mantine/modals";
 import { Notifications } from "@mantine/notifications";
 import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
 import { HelmetProvider } from "react-helmet-async";
+import { ChunkLoadErrorBoundary } from "@/components/chunk-load-error-boundary.tsx";
 import "./i18n";
-import { PostHogProvider } from "posthog-js/react";
 import {
   getPostHogHost,
   getPostHogKey,
   isCloud,
   isPostHogEnabled,
 } from "@/lib/config.ts";
-import posthog from "posthog-js";
 
 export const queryClient = new QueryClient({
   defaultOptions: {
@@ -34,31 +33,65 @@ export const queryClient = new QueryClient({
   },
 });
 
-if (isCloud() && isPostHogEnabled) {
-  posthog.init(getPostHogKey(), {
-    api_host: getPostHogHost(),
-    defaults: "2025-05-24",
-    disable_session_recording: true,
-    capture_pageleave: false,
-  });
-}
-
 const container = document.getElementById("root") as HTMLElement;
 const root = (container as any).__reactRoot ??= ReactDOM.createRoot(container);
 
-root.render(
-  <BrowserRouter>
-    <MantineProvider theme={theme} cssVariablesResolver={mantineCssResolver}>
-      <ModalsProvider>
-        <QueryClientProvider client={queryClient}>
-          <Notifications position="bottom-center" limit={3} zIndex={10000} />
-          <HelmetProvider>
-            <PostHogProvider client={posthog}>
-              <App />
-            </PostHogProvider>
-          </HelmetProvider>
-        </QueryClientProvider>
-      </ModalsProvider>
-    </MantineProvider>
-  </BrowserRouter>,
-);
+function renderApp() {
+  root.render(
+    <BrowserRouter>
+      <MantineProvider theme={theme} cssVariablesResolver={mantineCssResolver}>
+        <ModalsProvider>
+          <QueryClientProvider client={queryClient}>
+            <Notifications position="bottom-center" limit={3} zIndex={10000} />
+            <HelmetProvider>
+              {/* Root boundary above every lazy route's Suspense: a stale-chunk
+                  404 after a deploy is caught and recovered here instead of
+                  blanking the whole app. */}
+              <ChunkLoadErrorBoundary>
+                <App />
+              </ChunkLoadErrorBoundary>
+            </HelmetProvider>
+          </QueryClientProvider>
+        </ModalsProvider>
+      </MantineProvider>
+    </BrowserRouter>,
+  );
+}
+
+async function initAnalytics() {
+  // posthog-js is only pulled in for cloud deployments with analytics enabled, so
+  // self-hosted builds never download it. The gate is kept identical to the
+  // previous eager code so cloud analytics behavior is unchanged; the import is
+  // simply deferred behind it.
+  //
+  // Crucially this runs AFTER the immediate first render below, so first paint is
+  // never gated on the analytics chunk. Any failure (network, stale 404, or an
+  // ad-blocker blocking a chunk named "posthog") is swallowed so the user keeps a
+  // working app without analytics instead of a permanently blank page.
+  //
+  // NOTE: we init the posthog SINGLETON only and do NOT wrap the tree in
+  // <PostHogProvider>. The app has zero consumers of the PostHog React context
+  // (no usePostHog / useFeatureFlag* / PostHogFeature), and PostHogProvider given
+  // an already-initialized `client` is a no-op — all capture goes through the
+  // singleton. Re-rendering to attach the provider would only REMOUNT the whole
+  // App (running every mount effect twice and dropping local state / focus /
+  // in-progress input on cloud cold-load) for no functional gain.
+  if (!(isCloud() && isPostHogEnabled)) return;
+  try {
+    const { default: posthog } = await import("posthog-js");
+    posthog.init(getPostHogKey(), {
+      api_host: getPostHogHost(),
+      defaults: "2025-05-24",
+      disable_session_recording: true,
+      capture_pageleave: false,
+    });
+  } catch {
+    // Analytics failed to load — degrade gracefully; the app already rendered.
+  }
+}
+
+// Paint immediately for everyone (self-hosted stays exactly as instant as before,
+// cloud no longer blocks on the analytics import). The posthog singleton is
+// initialized after, without re-rendering the tree.
+renderApp();
+void initAnalytics();

apps/client/vite.config.ts

@@ -1,6 +1,5 @@
 import { defineConfig, loadEnv } from "vite";
 import react from "@vitejs/plugin-react";
-import { compression } from "vite-plugin-compression2";
 import * as path from "path";
 import { execSync } from "node:child_process";
 
@@ -54,25 +53,7 @@ export default defineConfig(({ mode }) => {
       },
       APP_VERSION: JSON.stringify(resolveAppVersion(envPath)),
     },
-    plugins: [
-      react(),
-      // Emit .br and .gz next to every built asset so the server can serve the
-      // precompressed copy (see @fastify/static preCompressed in static.module.ts).
-      compression({
-        algorithms: ["brotliCompress", "gzip"],
-        // vite-plugin-compression2's default `include` only covers text-ish
-        // bundle output (js/mjs/json/css/html/svg/…). Extend it with the large
-        // VAD binaries copied from public/vad (.wasm ~26MB, .onnx ~2.3MB) so
-        // they are brotli/gzip'd once at build time and served via
-        // @fastify/static preCompressed — otherwise @fastify/compress would
-        // re-brotli them on EVERY request. The default types are repeated here
-        // because setting `include` replaces (does not extend) the default.
-        include: /\.(html|xml|css|json|js|mjs|svg|yaml|yml|toml|wasm|onnx)$/,
-        // index.html is rewritten at server boot (window.CONFIG injection); a
-        // precompressed copy would go stale — NEVER precompress it.
-        exclude: [/index\.html$/],
-      }),
-    ],
+    plugins: [react()],
     build: {
       rolldownOptions: {
         output: {
@@ -82,6 +63,20 @@ export default defineConfig(({ mode }) => {
                 name: "vendor-mantine",
                 test: /[\\/]node_modules[\\/]@mantine[\\/]/,
               },
+              // NOTE: TipTap/ProseMirror/Yjs are intentionally NOT force-grouped
+              // into a single vendor chunk. Doing so backfires: rolldown co-locates
+              // a small module shared with the (eager) react-i18next runtime into
+              // that group chunk, which then drags the whole ~590KB editor engine
+              // into the eager modulepreload graph. Left to the default splitting,
+              // the editor engine stays in lazily-loaded chunks pulled only by the
+              // route-split editor/share pages. KaTeX is safe to group (nothing
+              // eager references it).
+              // KaTeX in its own stable chunk; loaded on demand by the lazy math
+              // node views (never in the startup path).
+              {
+                name: "vendor-katex",
+                test: /[\\/]node_modules[\\/]katex[\\/]/,
+              },
             ],
           },
         },

apps/server/package.json

@@ -43,7 +43,6 @@
     "@clickhouse/client": "^1.18.2",
     "@docmost/mcp": "workspace:*",
     "@docmost/pdf-inspector": "1.9.6",
-    "@fastify/compress": "^9.0.0",
     "@fastify/cookie": "^11.0.2",
     "@fastify/multipart": "^10.0.0",
     "@fastify/static": "^9.1.3",

apps/server/src/core/attachment/attachment.controller.ts

@@ -474,19 +474,6 @@ export class AttachmentController {
     const fileSize = Number(attachment.fileSize);
     const rangeHeader = req.headers.range;
 
-    // Opt this download route out of the global @fastify/compress hook.
-    // Attachment bytes are final and mostly binary, so on-the-fly compression
-    // only burns CPU — and on the 206/Range branch it is actively corrupting:
-    // compress decides purely by Content-Type, so for a compressible mime
-    // (application/octet-stream fallback, image/svg+xml, text/*) it would gzip
-    // the byte slice and drop Content-Length while Content-Range still
-    // describes the RAW offsets and the status stays 206. A resuming client
-    // (`curl -C -`, download managers) then appends the encoded bytes as if
-    // raw and ends up with a broken file. @fastify/compress skips whenever the
-    // request carries `x-no-compression` (see its onSend hook), so setting it
-    // here covers both the 200 (full file) and 206 (range) responses.
-    req.headers['x-no-compression'] = 'true';
-
     res.header('Accept-Ranges', 'bytes');
     res.header(
       'Content-Security-Policy',

apps/server/src/integrations/static/static.module.spec.ts

@@ -1,35 +0,0 @@
-import { resolveStaticAssetHeaders } from './static.module';
-
-// Unit tests for the static-asset cache classifier extracted from the
-// @fastify/static setHeaders callback (precedent: sandbox.controller.spec.ts).
-describe('resolveStaticAssetHeaders', () => {
-  it('marks a content-hashed /assets/ file immutable and sets Vary', () => {
-    const headers = resolveStaticAssetHeaders(
-      '/app/apps/client/dist/assets/index-a1b2c3.js',
-    );
-    expect(headers['cache-control']).toBe(
-      'public, max-age=31536000, immutable',
-    );
-    expect(headers['vary']).toBe('Accept-Encoding');
-  });
-
-  it('makes index.html always revalidate (never immutable)', () => {
-    const headers = resolveStaticAssetHeaders(
-      '/app/apps/client/dist/index.html',
-    );
-    expect(headers['cache-control']).toBe(
-      'no-cache, no-store, must-revalidate',
-    );
-    expect(headers['vary']).toBe('Accept-Encoding');
-  });
-
-  it('does NOT mark a non-hashed asset immutable but still sets Vary', () => {
-    const headers = resolveStaticAssetHeaders(
-      '/app/apps/client/dist/locales/en.json',
-    );
-    // No immutable cache-control — this path keeps @fastify/static's default
-    // etag/last-modified revalidation.
-    expect(headers['cache-control']).toBeUndefined();
-    expect(headers['vary']).toBe('Accept-Encoding');
-  });
-});

apps/server/src/integrations/static/static.module.ts

@@ -5,46 +5,6 @@ import * as fs from 'node:fs';
 import fastifyStatic from '@fastify/static';
 import { EnvironmentService } from '../environment/environment.service';
 
-/**
- * Resolve the response headers for a statically served client asset.
- *
- * Extracted from the @fastify/static `setHeaders` callback so the cache
- * classification stays a pure, unit-testable function (see
- * static.module.spec.ts).
- *
- * `Vary: Accept-Encoding` is emitted for every static response because
- * @fastify/static negotiates a precompressed .br/.gz neighbour by the client's
- * Accept-Encoding but does NOT set Vary itself. Without it a shared/proxy cache
- * keyed on the URL alone could store the brotli variant and later serve it to a
- * client that only sent `Accept-Encoding: identity`/gzip → an undecodable body.
- * This matters most for the immutable /assets/ files, which proxies may keep
- * for a year.
- */
-export function resolveStaticAssetHeaders(
-  filePath: string,
-): Record<string, string> {
-  const headers: Record<string, string> = { vary: 'Accept-Encoding' };
-
-  // Content-hashed files under /assets/ never change for a given URL, so they
-  // can be cached forever and skip revalidation entirely.
-  if (filePath.includes('/assets/')) {
-    headers['cache-control'] = 'public, max-age=31536000, immutable';
-    return headers;
-  }
-
-  // index.html is rewritten at boot (window.CONFIG injection) and on every
-  // deploy — it must be revalidated on every load.
-  if (filePath.endsWith('index.html')) {
-    headers['cache-control'] = 'no-cache, no-store, must-revalidate';
-    return headers;
-  }
-
-  // Everything else (locales, vad, icons, manifest) is NOT content-hashed and
-  // changes between deploys, so it keeps @fastify/static's default
-  // etag/last-modified revalidation — do NOT mark it immutable.
-  return headers;
-}
-
 @Module({})
 export class StaticModule implements OnModuleInit {
   constructor(
@@ -108,16 +68,6 @@ export class StaticModule implements OnModuleInit {
       await app.register(fastifyStatic, {
         root: clientDistPath,
         wildcard: false,
-        // Serve the build-time .br/.gz neighbour when the client accepts it
-        // (see vite-plugin-compression2 in apps/client/vite.config.ts).
-        preCompressed: true,
-        setHeaders: (res, filePath) => {
-          for (const [name, value] of Object.entries(
-            resolveStaticAssetHeaders(filePath),
-          )) {
-            res.setHeader(name, value);
-          }
-        },
       });
 
       app.get(RENDER_PATH, (req: any, res: any) => {

apps/server/src/main.ts

@@ -10,7 +10,6 @@ import { TransformHttpResponseInterceptor } from './common/interceptors/http-res
 import { WsRedisIoAdapter } from './ws/adapter/ws-redis.adapter';
 import fastifyMultipart from '@fastify/multipart';
 import fastifyCookie from '@fastify/cookie';
-import fastifyCompress from '@fastify/compress';
 import fastifyIp from 'fastify-ip';
 import { InternalLogFilter } from './common/logger/internal-log-filter';
 import { EnvironmentService } from './integrations/environment/environment.service';
@@ -61,17 +60,6 @@ async function bootstrap() {
   await app.register(fastifyIp);
   await app.register(fastifyMultipart);
   await app.register(fastifyCookie);
-  // Compress dynamic responses (API JSON, the rewritten share-SEO HTML) when the
-  // client accepts br/gzip. @fastify/compress only compresses content-types that
-  // mime-db flags `compressible` (application/json, text/html, …); `text/event-stream`
-  // is not in mime-db, so SSE is never compressed by the allowlist. The AI-chat
-  // stream additionally hijacks the raw socket (pipeUIMessageStreamToResponse ->
-  // res.raw in ai-chat.service.ts), bypassing Fastify's reply/onSend lifecycle
-  // entirely, so this hook can never buffer that stream.
-  await app.register(fastifyCompress, {
-    // Skip tiny payloads where compression overhead outweighs the savings.
-    threshold: 1024,
-  });
 
   const environmentService = app.get(EnvironmentService);
   const frameHeader = resolveFrameHeader(

docker-compose.yml

@@ -12,11 +12,6 @@ services:
     ports:
       - "3000:3000"
     restart: unless-stopped
-    # The app already serves precompressed (brotli/gzip) static assets with
-    # long-lived cache headers and gzips dynamic API responses. For the best
-    # cold-load latency you can OPTIONALLY put a reverse proxy (caddy / nginx /
-    # traefik) in front with HTTP/2 (or HTTP/3) and brotli enabled — none is
-    # required for compression to work.
     volumes:
       - docmost:/app/data/storage
 

packages/prosemirror-markdown/src/lib/docmost-schema.ts

@@ -635,13 +635,17 @@ const Attachment = Node.create({
       },
       name: {
         default: null,
-        parseHTML: (el: HTMLElement) => el.getAttribute("data-attachment-name"),
+        // Empty-string-vs-absent idempotency (GS-EDIT-REVERT class): "" -> default.
+        parseHTML: (el: HTMLElement) =>
+          el.getAttribute("data-attachment-name") || null,
         renderHTML: (attrs: Record<string, any>) =>
           attrs.name ? { "data-attachment-name": attrs.name } : {},
       },
       mime: {
         default: null,
-        parseHTML: (el: HTMLElement) => el.getAttribute("data-attachment-mime"),
+        // Empty-string-vs-absent idempotency (GS-EDIT-REVERT class): "" -> default.
+        parseHTML: (el: HTMLElement) =>
+          el.getAttribute("data-attachment-mime") || null,
         renderHTML: (attrs: Record<string, any>) =>
           attrs.mime ? { "data-attachment-mime": attrs.mime } : {},
       },
@@ -689,7 +693,10 @@ const Video = Node.create({
       },
       alt: {
         default: null,
-        parseHTML: (el: HTMLElement) => el.getAttribute("aria-label"),
+        // Empty-string-vs-absent idempotency: coerce "" back to the default so a
+        // stray empty `aria-label` never materializes `alt: ""` on a video stored
+        // with no alt (same GS-EDIT-REVERT class as the image `alt` fix).
+        parseHTML: (el: HTMLElement) => el.getAttribute("aria-label") || null,
         renderHTML: (attrs: Record<string, any>) =>
           attrs.alt ? { "aria-label": attrs.alt } : {},
       },
@@ -864,13 +871,15 @@ const diagramAttributes = () => ({
   },
   title: {
     default: null,
-    parseHTML: (el: HTMLElement) => el.getAttribute("data-title"),
+    // Empty-string-vs-absent idempotency (GS-EDIT-REVERT class): "" -> default.
+    parseHTML: (el: HTMLElement) => el.getAttribute("data-title") || null,
     renderHTML: (attrs: Record<string, any>) =>
       attrs.title ? { "data-title": attrs.title } : {},
   },
   alt: {
     default: null,
-    parseHTML: (el: HTMLElement) => el.getAttribute("data-alt"),
+    // Empty-string-vs-absent idempotency (GS-EDIT-REVERT class): "" -> default.
+    parseHTML: (el: HTMLElement) => el.getAttribute("data-alt") || null,
     renderHTML: (attrs: Record<string, any>) =>
       attrs.alt ? { "data-alt": attrs.alt } : {},
   },
@@ -1106,7 +1115,8 @@ const Pdf = Node.create({
       },
       name: {
         default: null,
-        parseHTML: (el: HTMLElement) => el.getAttribute("data-name"),
+        // Empty-string-vs-absent idempotency (GS-EDIT-REVERT class): "" -> default.
+        parseHTML: (el: HTMLElement) => el.getAttribute("data-name") || null,
         renderHTML: (attrs: Record<string, any>) =>
           attrs.name ? { "data-name": attrs.name } : {},
       },
@@ -1491,6 +1501,29 @@ export const docmostExtensions = [
           ...parent.height,
           parseHTML: (el: HTMLElement) => el.getAttribute("height"),
         },
+        // Empty-string-vs-absent idempotency (GS-EDIT-REVERT class). `marked`
+        // renders `![](src)` as `<img alt="">`, so the stock Image `alt`
+        // parseHTML (`getAttribute("alt")`) materializes `alt: ""` on an image
+        // that was stored with NO alt (attr absent). That is a false diff against
+        // the editor-stored form (a no-alt image has alt ABSENT, not ""), so a
+        // git-sync / ai-chat touch of a page with a plain image produced phantom
+        // churn. Coerce an empty string back to the attr's default (null) so the
+        // import is idempotent. A real alt survives verbatim (`|| undefined` keeps
+        // the truthy value; the default fills the empty case). `title` is coerced
+        // the same way for the whole class, even though `marked` does not
+        // currently emit `title=""` — defence in depth against any path that does.
+        // NOTE: this DIVERGES from editor-ext's literal image `alt` parseHTML
+        // (`getAttribute("alt")`, which returns "" verbatim), but CONVERGES on
+        // editor-ext's real STORED shape: an editor image inserted without alt
+        // renders with no `alt` attribute and re-parses as absent, never "".
+        alt: {
+          ...parent.alt,
+          parseHTML: (el: HTMLElement) => el.getAttribute("alt") || null,
+        },
+        title: {
+          ...parent.title,
+          parseHTML: (el: HTMLElement) => el.getAttribute("title") || null,
+        },
       };
     },
   }).configure({ inline: false }),

packages/prosemirror-markdown/test/roundtrip-stability.helper.ts

@@ -0,0 +1,443 @@
+/**
+ * Reusable round-trip-STABILITY matrix helper (fixtures-first).
+ *
+ * A single stored node authored WITHOUT a given string attribute (attr
+ * absent / undefined) must not gain a phantom EMPTY-STRING value after a
+ * markdown round-trip — the "empty-string-vs-absent" churn class. This helper,
+ * given a node spec, drives a matrix of attribute combinations through the REAL
+ * converter (`convertProseMirrorToMarkdown` -> `markdownToProseMirror`) and
+ * asserts byte-stability on two contours:
+ *
+ *   1. RAW round-trip: for the node under test, every attribute the round-trip
+ *      materializes must equal what the INPUT authored — an authored attr keeps
+ *      its value, an ABSENT attr may only reappear at its SCHEMA DEFAULT. If an
+ *      absent attr comes back as a NON-default value (e.g. `alt: ""` where the
+ *      default is `null`), that is an instability and is reported precisely as
+ *      `type.attr: absent -> "<got>"`. This is the contour git-sync / stored
+ *      JSON diffs on, so masking it only in `canonicalize` would leave the noise.
+ *
+ *   2. CANONICAL round-trip: `canonicalizeContent(original)` must deep-equal
+ *      `canonicalizeContent(roundtrip)` (a second, semantic contour).
+ *
+ * The ONLY normalization the helper treats as allowed (not an instability) is
+ * the DOCUMENTED numeric width/height/size/aspectRatio -> string coercion the
+ * converter performs on purpose (a stored numeric `640` re-parses via
+ * `getAttribute` as the string `"640"`). It is encoded here as an explicit
+ * per-spec `numericStringAttrs` set applied to BOTH contours, NOT a silent skip.
+ *
+ * The helper is node-type agnostic: image and the whole media family share the
+ * `align !== "center"` predicate + `<!--name {…}-->` comment machinery, so one
+ * matrix guards the shared class.
+ */
+import { getSchema } from "@tiptap/core";
+import {
+  convertProseMirrorToMarkdown,
+  markdownToProseMirror,
+  canonicalizeContent,
+  docmostExtensions,
+} from "../src/lib/index.js";
+import { firstDivergence } from "./roundtrip-helpers.js";
+
+/** One attribute's two probe values. */
+export interface AttrMatrixEntry {
+  /** Attribute name on the node. */
+  attr: string;
+  /**
+   * The "default" pick. `undefined` means the attribute is OMITTED entirely
+   * (the absent case — the one that can materialize an empty string on import).
+   * A concrete value is authored verbatim.
+   */
+  default: unknown;
+  /** A representative NON-default value to exercise (must survive verbatim). */
+  nonDefault: unknown;
+  /**
+   * Marks the attr as a member of the EMPTY-STRING class the fix targets: a
+   * string attr whose schema default is `null`/absent and whose parseHTML
+   * coerces `"" -> default` (image/drawio `alt`+`title`, video `alt` via
+   * aria-label, pdf/attachment `name`, attachment `mime`). Set true to also
+   * drive the THIRD-STATE convergence case (see runConvergenceCase) for this
+   * attr. Attrs whose default is NOT null (e.g. embed `provider`, default "")
+   * or that are not `""`-coerced (control attrs) are left unset.
+   */
+  emptyStringClass?: boolean;
+}
+
+/** A node type + the attribute matrix to sweep for it. */
+export interface NodeStabilitySpec {
+  /** Node type (e.g. "image", "video"). */
+  type: string;
+  /** Attributes always present on the node (e.g. `{ src: "/i.png" }`). */
+  baseAttrs?: Record<string, unknown>;
+  /** Attributes to sweep at default and non-default. */
+  attrMatrix: AttrMatrixEntry[];
+  /**
+   * Attributes whose numeric -> string coercion on round-trip is DOCUMENTED and
+   * intentional; compared modulo `String(x)` on both sides. Defaults to the
+   * converter's known sizing set.
+   */
+  numericStringAttrs?: string[];
+}
+
+/** A single unstable finding, legible enough to tie a gate-lock to. */
+export interface Instability {
+  type: string;
+  attr: string;
+  /** What the input authored: the literal value, or the ABSENT sentinel. */
+  authored: unknown | typeof ABSENT;
+  /** What the round-trip produced. */
+  got: unknown;
+  /** What a stable round-trip should have produced (authored value or default). */
+  expected: unknown;
+}
+
+/** One matrix cell's result. */
+export interface ComboResult {
+  label: string;
+  authored: Record<string, unknown>;
+  /** RAW-contour instabilities on the node under test. */
+  raw: Instability[];
+  /** CANONICAL-contour divergence (path + values) or null when equal. */
+  canonical: { path: string; a: unknown; b: unknown } | null;
+  /** True when the node type failed to round-trip at all (structural loss). */
+  missing: boolean;
+  md: string;
+}
+
+/** Whole-matrix report for one node spec. */
+export interface MatrixReport {
+  type: string;
+  combos: ComboResult[];
+}
+
+/** Sentinel marking an attribute the input did NOT author. */
+export const ABSENT = Symbol("ABSENT");
+
+const DEFAULT_NUMERIC_STRING_ATTRS = [
+  "width",
+  "height",
+  "size",
+  "aspectRatio",
+];
+
+// The ProseMirror schema the converter targets — its attribute `default`s are
+// the authoritative "what an absent attr should re-materialize as" oracle.
+const schema = getSchema(docmostExtensions);
+
+/** Read the schema default for every attribute of a node type. */
+function schemaDefaults(type: string): Record<string, unknown> {
+  const specAttrs = (schema.nodes[type]?.spec?.attrs ?? {}) as Record<
+    string,
+    { default: unknown }
+  >;
+  const out: Record<string, unknown> = {};
+  for (const [k, v] of Object.entries(specAttrs)) out[k] = v.default;
+  return out;
+}
+
+/** Find the first node of a given type anywhere in a PM doc tree. */
+function findFirst(node: any, type: string): any {
+  if (node && node.type === type) return node;
+  for (const child of node?.content ?? []) {
+    const hit = findFirst(child, type);
+    if (hit) return hit;
+  }
+  return null;
+}
+
+/** Coerce a scalar for the documented numeric->string comparison. */
+const numStr = (x: unknown): unknown => (x == null ? x : String(x));
+
+/**
+ * Enumerate the cartesian product of the matrix: every attribute independently
+ * at its default (index 0) or non-default (index 1) pick. The all-default
+ * corner is included (the baseline). Small by construction (2^N over a handful
+ * of at-risk string attrs).
+ */
+function enumerateCombos(matrix: AttrMatrixEntry[]): number[][] {
+  let combos: number[][] = [[]];
+  for (let i = 0; i < matrix.length; i++) {
+    const next: number[][] = [];
+    for (const c of combos) {
+      next.push([...c, 0]);
+      next.push([...c, 1]);
+    }
+    combos = next;
+  }
+  return combos;
+}
+
+/** Build the authored attrs for one combo pick vector. */
+function authoredAttrs(
+  spec: NodeStabilitySpec,
+  picks: number[],
+): Record<string, unknown> {
+  const attrs: Record<string, unknown> = { ...(spec.baseAttrs ?? {}) };
+  spec.attrMatrix.forEach((entry, i) => {
+    if (picks[i] === 1) {
+      attrs[entry.attr] = entry.nonDefault;
+    } else if (entry.default !== undefined) {
+      attrs[entry.attr] = entry.default;
+    }
+    // default === undefined -> OMIT the attr entirely (the absent case).
+  });
+  return attrs;
+}
+
+/** Human-readable label for a combo (which attrs are at non-default). */
+function comboLabel(spec: NodeStabilitySpec, picks: number[]): string {
+  const on = spec.attrMatrix
+    .filter((_, i) => picks[i] === 1)
+    .map((e) => e.attr);
+  return on.length === 0 ? "<all-default>" : on.join("+");
+}
+
+/**
+ * Run the full stability matrix for one node spec and return a structured
+ * report (does NOT throw — the caller asserts, so a failure can print the whole
+ * report). Every combo runs the real export->import pipeline once.
+ */
+export async function runStabilityMatrix(
+  spec: NodeStabilitySpec,
+): Promise<MatrixReport> {
+  const numericStringAttrs = new Set(
+    spec.numericStringAttrs ?? DEFAULT_NUMERIC_STRING_ATTRS,
+  );
+  const defaults = schemaDefaults(spec.type);
+  const combos: ComboResult[] = [];
+
+  for (const picks of enumerateCombos(spec.attrMatrix)) {
+    const authored = authoredAttrs(spec, picks);
+    const doc = { type: "doc", content: [{ type: spec.type, attrs: authored }] };
+    const md = convertProseMirrorToMarkdown(doc);
+    const rt = await markdownToProseMirror(md);
+    const node = findFirst(rt, spec.type);
+
+    const result: ComboResult = {
+      label: comboLabel(spec, picks),
+      authored,
+      raw: [],
+      canonical: null,
+      missing: node == null,
+      md,
+    };
+
+    if (node != null) {
+      // RAW contour: every materialized attr must equal the authored value, or
+      // (for an absent attr) the schema default — modulo the documented numeric
+      // string coercion.
+      const rtAttrs = (node.attrs ?? {}) as Record<string, unknown>;
+      for (const key of Object.keys(rtAttrs)) {
+        const authoredHas = Object.prototype.hasOwnProperty.call(authored, key);
+        const expected = authoredHas ? authored[key] : defaults[key];
+        let got = rtAttrs[key];
+        let exp = expected;
+        if (numericStringAttrs.has(key)) {
+          got = numStr(got);
+          exp = numStr(exp);
+        }
+        if (firstDivergence(got, exp) !== null) {
+          result.raw.push({
+            type: spec.type,
+            attr: key,
+            authored: authoredHas ? authored[key] : ABSENT,
+            got: rtAttrs[key],
+            expected,
+          });
+        }
+      }
+
+      // CANONICAL contour: canonical forms deep-equal, modulo the same numeric
+      // string coercion (applied to both trees so a documented coercion is not
+      // counted as a divergence).
+      const ca = normalizeNumeric(canonicalizeContent(doc), numericStringAttrs);
+      const cb = normalizeNumeric(canonicalizeContent(rt), numericStringAttrs);
+      result.canonical = firstDivergence(ca, cb);
+    }
+
+    combos.push(result);
+  }
+
+  return { type: spec.type, combos };
+}
+
+/**
+ * Deep-copy a canonical tree, coercing the documented numeric->string attrs to
+ * their string form so an intentional `640 -> "640"` coercion is not reported
+ * as a canonical divergence. Only touches the listed attribute keys.
+ */
+function normalizeNumeric(node: any, attrs: Set<string>): any {
+  if (Array.isArray(node)) return node.map((n) => normalizeNumeric(n, attrs));
+  if (node === null || typeof node !== "object") return node;
+  const out: Record<string, unknown> = {};
+  for (const key of Object.keys(node)) {
+    if (key === "attrs" && node.attrs && typeof node.attrs === "object") {
+      const a: Record<string, unknown> = {};
+      for (const [k, v] of Object.entries(node.attrs)) {
+        a[k] = attrs.has(k) ? numStr(v) : v;
+      }
+      out.attrs = a;
+    } else {
+      out[key] = normalizeNumeric(node[key], attrs);
+    }
+  }
+  return out;
+}
+
+/** Flatten a report to just its unstable combos (for a terse assertion). */
+export function unstableCombos(report: MatrixReport): ComboResult[] {
+  return report.combos.filter(
+    (c) => c.missing || c.raw.length > 0 || c.canonical !== null,
+  );
+}
+
+// ---------------------------------------------------------------------------
+// THIRD STATE: an EXPLICITLY-STORED empty string on a string attr.
+//
+// The matrix above sweeps TWO states per string attr: absent/default and a
+// non-default value — and asserts FIRST-pass byte-stability for both. There is
+// a third, degenerate state the matrix does NOT cover: the attr stored as a
+// LITERAL `""`. This is DISTINCT from "the node never had the attr": a user
+// types an alt in the editor, then deletes it, and Tiptap's
+// `updateAttributes({ alt: "" })` persists a literal `alt: ""` in the stored
+// JSON. There is no absent-vs-"" distinction in the DOM once serialized, so the
+// fix's `getAttribute("alt") || null` coercion canonicalizes BOTH to the
+// default (`null`).
+//
+// Consequence — and this is CORRECT, not a bug: a doc carrying an explicit `""`
+// converges to the default on the FIRST round-trip (a ONE-TIME diff: `"" ->
+// null`), then is byte-stable from the SECOND round-trip on (idempotent). So
+// this state must be pinned with a DIFFERENT contract than the matrix's:
+//   - do NOT assert first-pass byte-stability (the first pass legitimately
+//     changes `""` -> default), and
+//   - DO assert the first pass converges to the default AND the second pass is
+//     idempotent (rt2 deep-equals rt1).
+//
+// A future sync/QA pass diffing stored pages will see this one-time `"" -> null`
+// normalization exactly once per affected node; it is the converter canon, not
+// corruption, and must not be flagged as data loss.
+// ---------------------------------------------------------------------------
+
+/** Result of the third-state ("explicit empty string") convergence probe. */
+export interface ConvergenceResult {
+  type: string;
+  attr: string;
+  /** The schema default the attr must converge to on pass 1 (null / absent). */
+  expectedDefault: unknown;
+  /** rt1's materialized value for the attr — must equal `expectedDefault`. */
+  firstPassValue: unknown;
+  /** True when the node round-tripped AND rt1 converged the attr to default. */
+  convergedToDefault: boolean;
+  /** rt1-vs-rt2 divergence; MUST be null (idempotent from pass 2 on). */
+  secondPassDivergence: { path: string; a: unknown; b: unknown } | null;
+  /** True when the node type failed to round-trip at all (structural loss). */
+  missing: boolean;
+}
+
+/** Round-trip a full PM doc through the real converter once. */
+async function roundtripDoc(doc: any): Promise<any> {
+  return markdownToProseMirror(convertProseMirrorToMarkdown(doc));
+}
+
+/**
+ * Third-state convergence probe for one string attr of the empty-string class.
+ *
+ * (a) builds a doc with the attr EXPLICITLY set to `""` (baseAttrs + `""`),
+ * (b) rt1 = roundtrip(doc); asserts rt1's attr equals the schema default — the
+ *     documented ONE-TIME `"" -> default` normalization (NOT byte-stable vs the
+ *     `""` input, so first-pass stability is deliberately NOT asserted here),
+ * (c) rt2 = roundtrip(rt1); asserts rt2 deep-equals rt1 — idempotent from the
+ *     second round-trip on.
+ *
+ * Returns a structured result (does NOT throw) so the caller can assert and
+ * print. Reusable across the whole node family: drive it for every attr flagged
+ * `emptyStringClass` on every spec (see convergenceCasesFor / the test driver).
+ */
+export async function runConvergenceCase(
+  spec: NodeStabilitySpec,
+  attr: string,
+): Promise<ConvergenceResult> {
+  const expectedDefault = schemaDefaults(spec.type)[attr];
+
+  // (a) The degenerate third state: attr persisted as a LITERAL "".
+  const authored = { ...(spec.baseAttrs ?? {}), [attr]: "" };
+  const doc = { type: "doc", content: [{ type: spec.type, attrs: authored }] };
+
+  // (b) First round-trip: "" must normalize to the default (a one-time diff).
+  const rt1 = await roundtripDoc(doc);
+  const node1 = findFirst(rt1, spec.type);
+  const firstPassValue = node1?.attrs?.[attr];
+  const convergedToDefault =
+    node1 != null && firstDivergence(firstPassValue, expectedDefault) === null;
+
+  // (c) Second round-trip: must be byte-stable (rt2 deep-equals rt1). We compare
+  // the WHOLE docs — both are converter OUTPUTS already in the same materialized
+  // form (numeric attrs are strings on both sides), so no numeric normalization
+  // is needed here, unlike the raw/canonical contours above.
+  const rt2 = node1 != null ? await roundtripDoc(rt1) : rt1;
+  const secondPassDivergence =
+    node1 != null ? firstDivergence(rt1, rt2) : null;
+
+  return {
+    type: spec.type,
+    attr,
+    expectedDefault,
+    firstPassValue,
+    convergedToDefault,
+    secondPassDivergence,
+    missing: node1 == null,
+  };
+}
+
+/** The attrs of a spec flagged as members of the empty-string class. */
+export function convergenceCasesFor(spec: NodeStabilitySpec): string[] {
+  return spec.attrMatrix
+    .filter((e) => e.emptyStringClass)
+    .map((e) => e.attr);
+}
+
+/** True when a convergence result honours the "converges once, then stable" contract. */
+export function convergenceOk(r: ConvergenceResult): boolean {
+  return !r.missing && r.convergedToDefault && r.secondPassDivergence === null;
+}
+
+/** Render a convergence result as a legible one-liner for a failed assertion. */
+export function formatConvergence(r: ConvergenceResult): string {
+  if (r.missing) return `${r.type}.${r.attr}: DID-NOT-ROUND-TRIP`;
+  const parts: string[] = [];
+  if (!r.convergedToDefault) {
+    parts.push(
+      `pass1 did NOT converge: got ${JSON.stringify(r.firstPassValue)} (expected default ${JSON.stringify(r.expectedDefault)})`,
+    );
+  }
+  if (r.secondPassDivergence) {
+    parts.push(
+      `pass2 NOT idempotent @ ${r.secondPassDivergence.path}: ${JSON.stringify(r.secondPassDivergence.a)} vs ${JSON.stringify(r.secondPassDivergence.b)}`,
+    );
+  }
+  const status = parts.length === 0 ? "converges-once-then-stable" : parts.join("; ");
+  return `${r.type}.${r.attr}: ${status}`;
+}
+
+/** Render a report as a legible multi-line string for a failed assertion. */
+export function formatReport(report: MatrixReport): string {
+  const lines: string[] = [`node "${report.type}":`];
+  for (const c of report.combos) {
+    const flags: string[] = [];
+    if (c.missing) flags.push("DID-NOT-ROUND-TRIP");
+    for (const i of c.raw) {
+      const authored =
+        i.authored === ABSENT ? "absent" : JSON.stringify(i.authored);
+      flags.push(
+        `RAW ${i.type}.${i.attr}: ${authored} -> ${JSON.stringify(i.got)} (expected ${JSON.stringify(i.expected)})`,
+      );
+    }
+    if (c.canonical) {
+      flags.push(
+        `CANON @ ${c.canonical.path}: ${JSON.stringify(c.canonical.a)} vs ${JSON.stringify(c.canonical.b)}`,
+      );
+    }
+    const status = flags.length === 0 ? "stable" : flags.join("; ");
+    lines.push(`  [${c.label}] ${status}`);
+  }
+  return lines.join("\n");
+}

packages/prosemirror-markdown/test/roundtrip-stability.test.ts

@@ -0,0 +1,164 @@
+import { describe, expect, it } from "vitest";
+import {
+  runStabilityMatrix,
+  unstableCombos,
+  formatReport,
+  runConvergenceCase,
+  convergenceCasesFor,
+  convergenceOk,
+  formatConvergence,
+  type NodeStabilitySpec,
+} from "./roundtrip-stability.helper.js";
+
+// ---------------------------------------------------------------------------
+// Round-trip STABILITY matrix for image + the media family.
+//
+// Guards the "empty-string-vs-absent" churn class (GS-EDIT-REVERT family): a
+// stored node authored WITHOUT a string attr (alt/title/caption/aria-label/...)
+// must not gain a phantom `attr: ""` after `markdownToProseMirror(convert…)`.
+// Each spec sweeps the at-risk string attrs at DEFAULT (absent) and at a real
+// NON-default value; the helper asserts both the RAW round-trip (attrs equal the
+// input's, modulo the documented numeric width/height/size/aspectRatio -> string
+// coercion) and the CANONICAL round-trip (canonical forms deep-equal).
+//
+// The image + media family share the `align !== "center"` predicate and the
+// `<!--name {…}-->` comment machinery, so one matrix guards the shared class.
+// align is NOT part of this class (it round-trips correctly) and is not swept.
+// ---------------------------------------------------------------------------
+
+const SPECS: NodeStabilitySpec[] = [
+  {
+    // Image carries the most at-risk string attrs. `alt` is the one marked
+    // materializes as `<img alt="">` on `![](src)` import (the real bug); title
+    // and caption are covered as the same class. attachmentId is a string attr
+    // that must stay absent when unset (control).
+    type: "image",
+    baseAttrs: { src: "/i.png" },
+    attrMatrix: [
+      { attr: "alt", default: undefined, nonDefault: "a real alt text", emptyStringClass: true },
+      { attr: "title", default: undefined, nonDefault: "a real title", emptyStringClass: true },
+      { attr: "caption", default: undefined, nonDefault: "a real caption" },
+      { attr: "attachmentId", default: undefined, nonDefault: "att-42" },
+    ],
+  },
+  {
+    // Video's `alt` rides the `aria-label` attribute (media aria-label at risk).
+    type: "video",
+    baseAttrs: { src: "/v.mp4" },
+    attrMatrix: [
+      { attr: "alt", default: undefined, nonDefault: "a clip", emptyStringClass: true },
+      { attr: "attachmentId", default: undefined, nonDefault: "att-1" },
+    ],
+  },
+  {
+    // Audio carries no alt/title; attachmentId is its only optional string attr.
+    type: "audio",
+    baseAttrs: { src: "/a.mp3" },
+    attrMatrix: [
+      { attr: "attachmentId", default: undefined, nonDefault: "att-2" },
+    ],
+  },
+  {
+    // pdf: link-form media. `name` (filename) is its at-risk string attr.
+    type: "pdf",
+    baseAttrs: { src: "/d.pdf" },
+    attrMatrix: [
+      { attr: "name", default: undefined, nonDefault: "report.pdf", emptyStringClass: true },
+      { attr: "attachmentId", default: undefined, nonDefault: "att-3" },
+    ],
+  },
+  {
+    // attachment: link-form media (file card). `name` + `mime` string attrs.
+    type: "attachment",
+    baseAttrs: { url: "/f.zip" },
+    attrMatrix: [
+      { attr: "name", default: undefined, nonDefault: "bundle.zip", emptyStringClass: true },
+      { attr: "mime", default: undefined, nonDefault: "application/zip", emptyStringClass: true },
+      { attr: "attachmentId", default: undefined, nonDefault: "att-4" },
+    ],
+  },
+  {
+    // embed: link-form media. `provider` is its at-risk string attr (schema
+    // default ""). embed's numeric width/height defaults (800/600) are a SEPARATE,
+    // documented limitation OUTSIDE the empty-string class: they are not in
+    // canonicalize's KNOWN_DEFAULTS, so an ABSENT width/height re-imports as the
+    // 800/600 default and diverges canonically (see the note in canonicalize.ts).
+    // That is canonicalize-owned and out of scope here, so we author the
+    // dimensions at their defaults (as real editor embeds carry them) to keep this
+    // guard focused on the empty-string/provider class.
+    // provider's schema default is "" (NOT null), so a re-imported "" is the
+    // correct value, not a phantom — it is outside the null-default empty-string
+    // class. We author it at its "" default (the default pick) so the sweep still
+    // asserts a non-default provider ("youtube") round-trips, without tripping the
+    // canonicalize KNOWN_DEFAULTS gap for embed's non-null defaults.
+    type: "embed",
+    baseAttrs: { src: "https://example.com/x", width: 800, height: 600 },
+    attrMatrix: [
+      { attr: "provider", default: "", nonDefault: "youtube" },
+    ],
+  },
+  {
+    // drawio: image-form diagram. `title` + `alt` string attrs (data-title/-alt).
+    type: "drawio",
+    baseAttrs: { src: "blob:drawio" },
+    attrMatrix: [
+      { attr: "title", default: undefined, nonDefault: "flow chart", emptyStringClass: true },
+      { attr: "alt", default: undefined, nonDefault: "an alt", emptyStringClass: true },
+      { attr: "attachmentId", default: undefined, nonDefault: "att-5" },
+    ],
+  },
+  {
+    // excalidraw: image-form diagram, same shared diagramAttributes set.
+    type: "excalidraw",
+    baseAttrs: { src: "blob:excalidraw" },
+    attrMatrix: [
+      { attr: "title", default: undefined, nonDefault: "sketch", emptyStringClass: true },
+      { attr: "alt", default: undefined, nonDefault: "an alt", emptyStringClass: true },
+      { attr: "attachmentId", default: undefined, nonDefault: "att-6" },
+    ],
+  },
+];
+
+describe("round-trip stability matrix (image + media family)", () => {
+  for (const spec of SPECS) {
+    it(`${spec.type}: no attr materializes an empty-string / phantom value`, async () => {
+      const report = await runStabilityMatrix(spec);
+      const unstable = unstableCombos(report);
+      // On failure, print the WHOLE matrix so which (attr, value) combos are
+      // unstable is legible.
+      expect(unstable, `\n${formatReport(report)}\n`).toEqual([]);
+    });
+  }
+});
+
+// ---------------------------------------------------------------------------
+// THIRD STATE: an attr EXPLICITLY stored as a literal "" (GS-EDIT-REVERT: a user
+// typed alt/title/name/... then deleted it, so Tiptap persisted `attr: ""` — a
+// value DISTINCT from "attr was never set"). Unlike the absent case above, this
+// state is NOT first-pass byte-stable: the fix's `"" -> default` coercion is a
+// deliberate ONE-TIME normalization on the FIRST sync round-trip, stable
+// thereafter. We therefore assert a DIFFERENT contract — "converges to default
+// on pass 1, then idempotent from pass 2 on" — for every empty-string-class attr
+// across the whole node family (image/video/pdf/attachment/drawio/excalidraw).
+//
+// IMPORTANT for a future sync/QA pass: the pass-1 `"" -> null` diff is the
+// converter canon, not corruption. It appears at most once per affected node and
+// must NOT be flagged as "the converter is losing/corrupting page data".
+// ---------------------------------------------------------------------------
+describe("round-trip third state: explicit empty string converges once, then idempotent", () => {
+  for (const spec of SPECS) {
+    for (const attr of convergenceCasesFor(spec)) {
+      it(`${spec.type}.${attr}: "" normalizes to default on pass 1, byte-stable from pass 2`, async () => {
+        const r = await runConvergenceCase(spec, attr);
+        // Pass 1 must converge "" -> the schema default (the one-time diff) and
+        // pass 2 (roundtrip of pass-1 output) must be byte-stable. formatConvergence
+        // prints exactly which half failed.
+        expect(convergenceOk(r), `\n${formatConvergence(r)}\n`).toBe(true);
+        // Spell the contract out explicitly so the intent is legible in the test:
+        expect(r.convergedToDefault, `\n${formatConvergence(r)}\n`).toBe(true);
+        expect(r.firstPassValue).toEqual(r.expectedDefault);
+        expect(r.secondPassDivergence, `\n${formatConvergence(r)}\n`).toBeNull();
+      });
+    }
+  }
+});

pnpm-lock.yaml

@@ -269,6 +269,9 @@ importers:
       '@atlaskit/pragmatic-drag-and-drop-live-region':
         specifier: 1.3.4
         version: 1.3.4
+      '@braintree/sanitize-url':
+        specifier: 7.1.2
+        version: 7.1.2
       '@casl/react':
         specifier: 5.0.1
         version: 5.0.1(@casl/ability@6.8.0)(react@18.3.1)
@@ -501,9 +504,6 @@ importers:
       vite:
         specifier: 8.0.5
         version: 8.0.5(@types/node@22.19.1)(esbuild@0.28.0)(jiti@2.4.2)(less@4.2.0)(sugarss@5.0.1(postcss@8.5.14))(terser@5.39.0)(tsx@4.21.0)(yaml@2.8.3)
-      vite-plugin-compression2:
-        specifier: 2.5.3
-        version: 2.5.3
       vitest:
         specifier: 4.1.6
         version: 4.1.6(@opentelemetry/api@1.9.0)(@types/node@22.19.1)(@vitest/coverage-v8@4.1.6)(happy-dom@20.8.9)(jsdom@25.0.0)(vite@8.0.5(@types/node@22.19.1)(esbuild@0.28.0)(jiti@2.4.2)(less@4.2.0)(sugarss@5.0.1(postcss@8.5.14))(terser@5.39.0)(tsx@4.21.0)(yaml@2.8.3))
@@ -543,9 +543,6 @@ importers:
       '@docmost/pdf-inspector':
         specifier: 1.9.6
         version: 1.9.6
-      '@fastify/compress':
-        specifier: ^9.0.0
-        version: 9.0.0
       '@fastify/cookie':
         specifier: ^11.0.2
         version: 11.0.2
@@ -2700,9 +2697,6 @@ packages:
   '@fastify/busboy@3.1.1':
     resolution: {integrity: sha512-5DGmA8FTdB2XbDeEwc/5ZXBl6UbBAyBOOLlPuBnZ/N1SwdH9Ii+cOX3tBROlDgcTXxjOYnLMVoKk9+FXAw0CJw==}
 
-  '@fastify/compress@9.0.0':
-    resolution: {integrity: sha512-PZRg+ut5xd/ubsGPWfoPNryoCOtEdHboIWpDieTUHov1gKdLitF8mRmT3JbqNnRbelQXSNXUsIpakAEKR6AcTQ==}
-
   '@fastify/cookie@11.0.2':
     resolution: {integrity: sha512-GWdwdGlgJxyvNv+QcKiGNevSspMQXncjMZ1J8IvuDQk0jvkzgWWZFNC2En3s+nHndZBGV8IbLwOI/sxCZw/mzA==}
 
@@ -4496,15 +4490,6 @@ packages:
   '@rolldown/pluginutils@1.0.0-rc.7':
     resolution: {integrity: sha512-qujRfC8sFVInYSPPMLQByRh7zhwkGFS4+tyMQ83srV1qrxL4g8E2tyxVVyxd0+8QeBM1mIk9KbWxkegRr76XzA==}
 
-  '@rollup/pluginutils@5.4.0':
-    resolution: {integrity: sha512-MfPp06CjRLfXQ3wY0R8vJDYBy/MvVcc9OulEfR0B8Iv9ko+GCNaRZ+EpJYFl27LhKsZK0o420sYCRHCjfCgeUg==}
-    engines: {node: '>=14.0.0'}
-    peerDependencies:
-      rollup: ^1.20.0||^2.0.0||^3.0.0||^4.0.0
-    peerDependenciesMeta:
-      rollup:
-        optional: true
-
   '@selderee/plugin-htmlparser2@0.11.0':
     resolution: {integrity: sha512-P33hHGdldxGabLFjPPpaTxVolMrzrcegejx+0GxjrIb9Zv48D8yAIA/QTDR2dFl7Uz7urX8aX6+5bCZslr+gWQ==}
 
@@ -5694,10 +5679,6 @@ packages:
     resolution: {integrity: sha512-/XrFJgzQQQHpti1raDJC6m4ws6aNktmjBlhk8Fdlk7LwCEuDoieEJJY9OFHjfiFJFFRM2tK+Ky/IsfbbmlMu1w==}
     engines: {node: ^22.22.2 || ^24.15.0 || >=26.0.0}
 
-  abort-controller@3.0.0:
-    resolution: {integrity: sha512-h8lQ8tacZYnR3vNQTgibj+tODHI5/+l06Au2Pcriv/Gmet0eaj4TwWH41sO9wnHDiQsEj19q0drzdWdeAHtweg==}
-    engines: {node: '>=6.5'}
-
   abstract-logging@2.0.1:
     resolution: {integrity: sha512-2BjRTZxTPvheOvGbBslFSYOUkr+SjPtOnrLP33f+VIWLzezQpZcqVg7ja3L4dBXmzzgwT+a029jRx5PCi3JuiA==}
 
@@ -6077,9 +6058,6 @@ packages:
   buffer@5.7.1:
     resolution: {integrity: sha512-EHcyIPBQ4BSGlvjB16k5KgAJ27CIsHY/2JBmCRReo48y9rQ3MaUzWX3KVlBa4U7MyX02HdVj0K7C3WaB3ju7FQ==}
 
-  buffer@6.0.3:
-    resolution: {integrity: sha512-FTiCpNxtwiZZHEZbcbTIcZjERVICn9yq/pDFkTl95/AxzD1naBctN7YO68riM/gLSDY7sdrMby8hofADYuuqOA==}
-
   bullmq@5.76.10:
     resolution: {integrity: sha512-LWve7SpQjYSpCP2GEsWmoyzTz2H37L8HRmSTu3YihYsTOr5kJxrfEX6aEV7m6eskEMWXSHZYTMZepX6qNaH6CQ==}
     engines: {node: '>=12.22.0'}
@@ -6835,9 +6813,6 @@ packages:
     resolution: {integrity: sha512-KIN/nDJBQRcXw0MLVhZE9iQHmG68qAVIBg9CqmUYjmQIhgij9U5MFvrqkUL5FbtyyzZuOeOt0zdeRe4UY7ct+A==}
     engines: {node: '>= 0.4'}
 
-  duplexify@3.7.1:
-    resolution: {integrity: sha512-07z8uv2wMyS51kKhD1KsdXJg5WQ6t93RneqRxUHnskXVtlYYkLqM0gqStQZ3pj073g687jPCHrqNfCzawLYh5g==}
-
   ecdsa-sig-formatter@1.0.11:
     resolution: {integrity: sha512-nagl3RYrbNv6kQkeJIpt6NJZy8twLB/2vtz6yN9Z4vRKHN4/QZJIEbqohALSgwKdnksuY3k5Addp5lg8sVoVcQ==}
 
@@ -7081,9 +7056,6 @@ packages:
     resolution: {integrity: sha512-MMdARuVEQziNTeJD8DgMqmhwR11BRQ/cBP+pLtYdSTnf3MIO8fFeiINEbX36ZdNlfU/7A9f3gUw49B3oQsvwBA==}
     engines: {node: '>=4.0'}
 
-  estree-walker@2.0.2:
-    resolution: {integrity: sha512-Rfkk/Mp/DL7JVje3u18FxFujQlTNR2q6QfMSMB7AvCBx91NGj/ba3kCfza0f6dVDbw7YlRf/nDrn7pQrCCyQ/w==}
-
   estree-walker@3.0.3:
     resolution: {integrity: sha512-7RUKfXgSMMkzt6ZuXmqapOurLGPPfgj6l9uRZ7lRGolvk0y2yocc35LdcxKC5PQZdn2DMqioAQ2NoWcrTKmm6g==}
 
@@ -7095,10 +7067,6 @@ packages:
     resolution: {integrity: sha512-aIL5Fx7mawVa300al2BnEE4iNvo1qETxLrPI/o05L7z6go7fCw1J6EQmbK4FmJ2AS7kgVF/KEZWufBfdClMcPg==}
     engines: {node: '>= 0.6'}
 
-  event-target-shim@5.0.1:
-    resolution: {integrity: sha512-i/2XbnSz/uxRCU6+NdVJgKWDTM427+MqYbkQzD321DuCQJUqOuJKIA0IM2+W2xtYHdKOmZ4dR6fExsd4SXL+WQ==}
-    engines: {node: '>=6'}
-
   eventemitter2@6.4.9:
     resolution: {integrity: sha512-JEPTiaOt9f04oa6NOkc4aH+nVp5I3wEjpHbIPqfgCdD5v5bUzy7xQqwcVO2aDQgOWhI28da57HksMrzK9HlRxg==}
 
@@ -9108,9 +9076,6 @@ packages:
   peberminta@0.9.0:
     resolution: {integrity: sha512-XIxfHpEuSJbITd1H3EeQwpcZbTLHc+VVr8ANI9t5sit565tsI4/xK3KWTUFE2e6QiangUkh3B0jihzmGnNrRsQ==}
 
-  peek-stream@1.1.3:
-    resolution: {integrity: sha512-FhJ+YbOSBb9/rIl2ZeE/QHEsWn7PqNYt8ARAY3kIgNGOk13g9FGyIY6JIl/xB/3TFRVoTv5as0l11weORrTekA==}
-
   pend@1.2.0:
     resolution: {integrity: sha512-F3asv42UuXchdzt+xXqfW1OGlVBe+mxa2mqI0pg5yAHZPvFmY3Y6drSf/GQ1A86WgWEN9Kzh/WrgKa6iGcHXLg==}
 
@@ -9356,10 +9321,6 @@ packages:
   process-warning@5.0.0:
     resolution: {integrity: sha512-a39t9ApHNx2L4+HBnQKqxxHNs1r7KF+Intd8Q/g1bUh6q0WIp9voPXJ/x0j+ZL45KF1pJd9+q2jLIRMfvEshkA==}
 
-  process@0.11.10:
-    resolution: {integrity: sha512-cdGef/drWFoydD1JsMzuFf8100nZl+GT+yacc2bEced5f9Rjk4z+WtFUTBu9PhOi9j/jfmBPu0mMEY4wIdAF8A==}
-    engines: {node: '>= 0.6.0'}
-
   prompts@2.4.2:
     resolution: {integrity: sha512-NxNv/kLguCA7p3jE8oL2aEBsrJWgAakBpgmgK6lpPWV+WuOmY6r2/zbAVnP+T8bQlA0nzHXSJSJW0Hq7ylaD2Q==}
     engines: {node: '>= 6'}
@@ -9651,10 +9612,6 @@ packages:
     resolution: {integrity: sha512-9u/sniCrY3D5WdsERHzHE4G2YCXqoG5FTHUiCC4SIbr6XcLZBY05ya9EKjYek9O5xOAwjGq+1JdGBAS7Q9ScoA==}
     engines: {node: '>= 6'}
 
-  readable-stream@4.7.0:
-    resolution: {integrity: sha512-oIGGmcpTLwPga8Bn6/Z75SVaH1z5dUut2ibSyAMVhmUggWpmDn2dapB0n7f8nwaSiRtepAsfJyfXIO5DCVAODg==}
-    engines: {node: ^12.22.0 || ^14.17.0 || >=16.0.0}
-
   readdirp@3.6.0:
     resolution: {integrity: sha512-hOS089on8RduqdbhvQ5Z37A0ESjsqz6qnRcffsMU3495FuTdqSm+7bhJ29JvIOsBDEEnan5DPu9t3To9VRlMzA==}
     engines: {node: '>=8.10.0'}
@@ -10043,9 +10000,6 @@ packages:
   stream-browserify@3.0.0:
     resolution: {integrity: sha512-H73RAHsVBapbim0tU2JwwOiXUj+fikfiaoYAKHF3VJfA0pe2BCzkhAHBlLG6REzE+2WNZcxOXjK7lkso+9euLA==}
 
-  stream-shift@1.0.3:
-    resolution: {integrity: sha512-76ORR0DO1o1hlKwTbi/DM3EXWGf3ZJYO8cXX5RJwnul2DEg2oyoZyjLNoQM8WsvZiFKCRfC1O0J7iCvie3RZmQ==}
-
   strict-event-emitter-types@2.0.0:
     resolution: {integrity: sha512-Nk/brWYpD85WlOgzw5h173aci0Teyv8YdIAEtV+N88nDB0dLlazZyJMIsN6eo1/AR61l+p6CJTG1JIyFaoNEEA==}
 
@@ -10186,9 +10140,6 @@ packages:
     resolution: {integrity: sha512-g9ljZiwki/LfxmQADO3dEY1CbpmXT5Hm2fJ+QaGKwSXUylMybePR7/67YW7jOrrvjEgL1Fmz5kzyAjWVWLlucg==}
     engines: {node: '>=6'}
 
-  tar-mini@0.2.0:
-    resolution: {integrity: sha512-+qfUHz700DWnRutdUsxRRVZ38G1Qr27OetwaMYTdg8hcPxf46U0S1Zf76dQMWRBmusOt2ZCK5kbIaiLkoGO7WQ==}
-
   tar-stream@2.2.0:
     resolution: {integrity: sha512-ujeqbceABgwMZxEJnk2HDY2DlnUZ+9oEcb1KzTVfYHio0UE6dG71n60d8D2I4qNvleWrrXpmjpt7vZeF1LnMZQ==}
     engines: {node: '>=6'}
@@ -10229,9 +10180,6 @@ packages:
     resolution: {integrity: sha512-nt6AMGKW1p/70DF/hGBdJB57B8Tspmbp5gfJ8ilhLnt7kkr2ye7hzD6NVG8GGErk2HWF34igrL2CXmNIkzKqKw==}
     engines: {node: '>=18'}
 
-  through2@2.0.5:
-    resolution: {integrity: sha512-/mrRod8xqpA+IHSLyGCQ2s8SPHiCDEeQJSep1jqLYeEUClOFG2Qsh+4FU6G9VeqpZnGW/Su8LQGc4YKni5rYSQ==}
-
   tiny-invariant@1.3.3:
     resolution: {integrity: sha512-+FbBPE1o9QAYvviau/qC5SE3caw21q3xkvWKBtja5vgqOWIHHJ3ioaq1VPfn/Szqctz2bU/oYeKd9/z5BL+PVg==}
 
@@ -10637,9 +10585,6 @@ packages:
     resolution: {integrity: sha512-BNGbWLfd0eUPabhkXUVm0j8uuvREyTh5ovRa/dyow/BqAbZJyC+5fU+IzQOzmAKzYqYRAISoRhdQr3eIZ/PXqg==}
     engines: {node: '>= 0.8'}
 
-  vite-plugin-compression2@2.5.3:
-    resolution: {integrity: sha512-ItPgqQWkcnBbVw7is9OKwiZ8v6+ju9rYROl5Lp6QfQDEx/d55AwJQb/KLpsQqsU9HoigYBsZ8tK6I02UwJNvEw==}
-
   vite@8.0.5:
     resolution: {integrity: sha512-nmu43Qvq9UopTRfMx2jOYW5l16pb3iDC1JH6yMuPkpVbzK0k+L7dfsEDH4jRgYFmsg0sTAqkojoZgzLMlwHsCQ==}
     engines: {node: ^20.19.0 || >=22.12.0}
@@ -12979,15 +12924,6 @@ snapshots:
 
   '@fastify/busboy@3.1.1': {}
 
-  '@fastify/compress@9.0.0':
-    dependencies:
-      '@fastify/accept-negotiator': 2.0.1
-      fastify-plugin: 5.1.0
-      mime-db: 1.54.0
-      minipass: 7.1.3
-      peek-stream: 1.1.3
-      readable-stream: 4.7.0
-
   '@fastify/cookie@11.0.2':
     dependencies:
       cookie: 1.1.1
@@ -15003,12 +14939,6 @@ snapshots:
 
   '@rolldown/pluginutils@1.0.0-rc.7': {}
 
-  '@rollup/pluginutils@5.4.0':
-    dependencies:
-      '@types/estree': 1.0.9
-      estree-walker: 2.0.2
-      picomatch: 4.0.4
-
   '@selderee/plugin-htmlparser2@0.11.0':
     dependencies:
       domhandler: 5.0.3
@@ -16382,10 +16312,6 @@ snapshots:
 
   abbrev@5.0.0: {}
 
-  abort-controller@3.0.0:
-    dependencies:
-      event-target-shim: 5.0.1
-
   abstract-logging@2.0.1: {}
 
   accepts@1.3.8:
@@ -16832,11 +16758,6 @@ snapshots:
       base64-js: 1.5.1
       ieee754: 1.2.1
 
-  buffer@6.0.3:
-    dependencies:
-      base64-js: 1.5.1
-      ieee754: 1.2.1
-
   bullmq@5.76.10:
     dependencies:
       cron-parser: 4.9.0
@@ -17590,13 +17511,6 @@ snapshots:
       es-errors: 1.3.0
       gopd: 1.2.0
 
-  duplexify@3.7.1:
-    dependencies:
-      end-of-stream: 1.4.4
-      inherits: 2.0.4
-      readable-stream: 2.3.8
-      stream-shift: 1.0.3
-
   ecdsa-sig-formatter@1.0.11:
     dependencies:
       safe-buffer: 5.2.1
@@ -18023,8 +17937,6 @@ snapshots:
 
   estraverse@5.3.0: {}
 
-  estree-walker@2.0.2: {}
-
   estree-walker@3.0.3:
     dependencies:
       '@types/estree': 1.0.9
@@ -18033,8 +17945,6 @@ snapshots:
 
   etag@1.8.1: {}
 
-  event-target-shim@5.0.1: {}
-
   eventemitter2@6.4.9: {}
 
   eventemitter3@4.0.7: {}
@@ -20298,12 +20208,6 @@ snapshots:
 
   peberminta@0.9.0: {}
 
-  peek-stream@1.1.3:
-    dependencies:
-      buffer-from: 1.1.2
-      duplexify: 3.7.1
-      through2: 2.0.5
-
   pend@1.2.0: {}
 
   perfect-freehand@1.2.0: {}
@@ -20575,8 +20479,6 @@ snapshots:
 
   process-warning@5.0.0: {}
 
-  process@0.11.10: {}
-
   prompts@2.4.2:
     dependencies:
       kleur: 3.0.3
@@ -20993,14 +20895,6 @@ snapshots:
       string_decoder: 1.3.0
       util-deprecate: 1.0.2
 
-  readable-stream@4.7.0:
-    dependencies:
-      abort-controller: 3.0.0
-      buffer: 6.0.3
-      events: 3.3.0
-      process: 0.11.10
-      string_decoder: 1.3.0
-
   readdirp@3.6.0:
     dependencies:
       picomatch: 2.3.2
@@ -21454,8 +21348,6 @@ snapshots:
       inherits: 2.0.4
       readable-stream: 3.6.2
 
-  stream-shift@1.0.3: {}
-
   strict-event-emitter-types@2.0.0: {}
 
   string-length@4.0.2:
@@ -21616,8 +21508,6 @@ snapshots:
 
   tapable@2.3.0: {}
 
-  tar-mini@0.2.0: {}
-
   tar-stream@2.2.0:
     dependencies:
       bl: 4.1.0
@@ -21663,11 +21553,6 @@ snapshots:
 
   throttleit@2.1.0: {}
 
-  through2@2.0.5:
-    dependencies:
-      readable-stream: 2.3.8
-      xtend: 4.0.2
-
   tiny-invariant@1.3.3: {}
 
   tinybench@2.9.0: {}
@@ -22072,13 +21957,6 @@ snapshots:
 
   vary@1.1.2: {}
 
-  vite-plugin-compression2@2.5.3:
-    dependencies:
-      '@rollup/pluginutils': 5.4.0
-      tar-mini: 0.2.0
-    transitivePeerDependencies:
-      - rollup
-
   vite@8.0.5(@types/node@20.19.43)(esbuild@0.28.0)(jiti@2.4.2)(less@4.2.0)(sugarss@5.0.1(postcss@8.5.14))(terser@5.39.0)(tsx@4.21.0)(yaml@2.8.3):
     dependencies:
       lightningcss: 1.32.0
@@ -22459,7 +22337,8 @@ snapshots:
 
   xpath@0.0.34: {}
 
-  xtend@4.0.2: {}
+  xtend@4.0.2:
+    optional: true
 
   y-indexeddb@9.0.12(yjs@13.6.30(patch_hash=1ceeb66dba1f86545c98a3ff7f5152aff9b35caf409091cef9caedb5e65c8810)):
     dependencies: