fix(#370 ): F2 terminal skip reply for empty/missing page + F1 lifecycle tests

Reviewer changes-requested on #565. F2 (real bug): a save on an empty page (or a missing page row) hung the client for the full 20s ack window and then falsely reported the collab server as unreachable + advised retry. Root cause: handleSaveVersion gated its broadcastStateless on `if (result)`, and `result` stays undefined on the two reachable early returns (isEmptyParagraphDoc and !page), so the server sent NOTHING and the client waited out its timeout. - SERVER (persistence.extension.ts): both early-return branches now record a skip reason and the tail broadcasts a terminal `version.skipped` reply (reason 'empty' | 'page-not-found'). Exactly one terminal reply per handled save. Added VERSION_SAVED/VERSION_SKIPPED message consts. - CLIENT (collaboration.ts): the predicate now matches both version.saved and version.skipped; SaveVersionResult gains {saved, skipped, reason}. An empty skip resolves to a clean {saved:false, skipped:true, reason:'empty'} (no stall); page-not-found throws an immediate, truthful error; the genuine no-reply timeout path is unchanged (that is the real "unreachable" case). A terminal reply leaves the session cached (healthy connection); only a transport failure destroys it. Kept the message-literal in-sync comments. - tool-specs.ts / pages.ts: description + docstring reflect the new result shape. F1 (coverage): added tests for the 4 previously-uncovered sendStatelessAndAwait branches — unrelated-then-real (predicate filters noise), teardown-mid-wait (rejects + removes the stateless listener, no leak), concurrent-in-flight guard — plus the F2 empty-skip / page-not-found client outcomes. Server spec gains empty-page and page-not-found terminal-reply tests. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
fix(#370 ): add savePageVersion to DocmostClientMethod union (server in-app tool parity)
2026-07-12 19:23:07 +03:00 · 2026-07-12 19:23:07 +03:00 · 2026-07-12 19:23:07 +03:00
13 changed files with 712 additions and 7 deletions
@@ -346,6 +346,9 @@ roles:
        □ Working sections ("Log", "Open Questions", "Revision") are moved to an
          appendix at the end of the document or clearly separated from the report
          body.
+        □ Once the report is complete, call save_page_version to pin the finished
+          document as a restorable named version (a checkpoint the reader can
+          return to). A repeat call after no further edits is a harmless no-op.
      Be honest about gaps. If you couldn't find something, say so — don't disguise
      a guess as a fact.
    autoStart: false
@@ -442,6 +445,7 @@ roles:
      - **The language of the notes = the main language of the call.** Technical terms — in their canonical spelling (usually Latin).
      - **Don't evaluate the participants** and don't comment on the quality of the discussion.
      - The output is the notes only, with no preambles or meta-comments, apart from targeted uncertainty marks.
+      - **Pin the result.** Once the notes are complete on the page, call save_page_version to save them as a restorable named version (a checkpoint). Calling it again after no further edits is a harmless no-op.

      ## Style example (excerpt)

@@ -345,6 +345,9 @@ roles:
        □ Working sections («Журнал», «Открытые вопросы», «Ревизия») are moved to
          an appendix at the end of the document or clearly separated from the
          report body.
+        □ Once the report is complete, call save_page_version to pin the finished
+          document as a restorable named version (a checkpoint the reader can
+          return to). A repeat call after no further edits is a harmless no-op.
      Be honest about gaps. If you couldn't find something, say so — don't disguise
      a guess as a fact.
    autoStart: false
@@ -441,6 +444,7 @@ roles:
      - **Язык конспекта = основной язык созвона.** Технические термины — в каноническом написании (обычно латиницей).
      - **Не оценивай участников** и не комментируй качество обсуждения.
      - На выходе — только конспект, без преамбул и мета-комментариев, кроме точечных пометок неуверенности.
+      - **Зафиксируй результат.** Когда конспект готов на странице, вызови save_page_version, чтобы сохранить его как именованную версию (точку восстановления). Повторный вызов без новых правок — безвредный no-op.

      ## Пример стиля (фрагмент)

@@ -33,6 +33,6 @@ bundles:
      - en
    roles:
      - slug: researcher
-        version: 9
+        version: 10
      - slug: call-summarizer
-        version: 1
+        version: 2
@@ -736,6 +736,53 @@ describe('PersistenceExtension.onStoreDocument — Approach-A boundary snapshot'
      expect(historyQueue.remove).toHaveBeenCalledWith(PAGE_ID);
      expect(historyQueue.remove).not.toHaveBeenCalledWith(SLUG);
    });
+
+    // #370 F2 — an effectively-empty page is a REACHABLE no-op (agent calls
+    // save_page_version on a blank page): the version tx short-circuits with
+    // nothing to pin. The handler MUST still broadcast a TERMINAL reply
+    // (version.skipped, reason:'empty') so the client resolves at once instead of
+    // waiting out its 20s ack timeout and misreporting a healthy server as
+    // unreachable. MUTATION: drop the `else if (skipped)` broadcast → no terminal
+    // reply is sent → this reddens.
+    it('empty page → no version written, broadcasts a terminal version.skipped(empty)', async () => {
+      const emptyDoc = { type: 'doc', content: [{ type: 'paragraph' }] };
+      const document = ydocFor(emptyDoc);
+      pageRepo.findById.mockResolvedValue({
+        ...persistedHumanPage('IGNORED'),
+        content: emptyDoc,
+      });
+
+      await emitSave(document, 'agent');
+
+      // Nothing pinned.
+      expect(pageHistoryRepo.saveHistory).not.toHaveBeenCalled();
+      expect(pageHistoryRepo.updateHistoryKind).not.toHaveBeenCalled();
+      // But a terminal reply WAS sent so the client never times out. The flush
+      // (onStoreDocument) emits its own `page.updated`; the version.skipped is the
+      // LAST broadcast (dropping the skip branch leaves page.updated last → reds).
+      const calls = (document as any).broadcastStateless.mock.calls;
+      const msg = JSON.parse(calls[calls.length - 1][0]);
+      expect(msg).toEqual({ type: 'version.skipped', reason: 'empty' });
+    });
+
+    // #370 F2 — the page row is gone (deleted / never persisted). Same rule: a
+    // terminal reply MUST be sent (version.skipped, reason:'page-not-found') so the
+    // client surfaces a truthful "not found" immediately rather than a health
+    // timeout. onStoreDocument's own `!page` guard returns early without throwing,
+    // so the handler reaches the version tx and its `!page` skip branch.
+    it('page not found → broadcasts a terminal version.skipped(page-not-found)', async () => {
+      const document = ydocFor(doc('GONE'));
+      pageRepo.findById.mockResolvedValue(null);
+
+      await emitSave(document, 'agent');
+
+      expect(pageHistoryRepo.saveHistory).not.toHaveBeenCalled();
+      expect((document as any).broadcastStateless).toHaveBeenCalledTimes(1);
+      const msg = JSON.parse(
+        (document as any).broadcastStateless.mock.calls[0][0],
+      );
+      expect(msg).toEqual({ type: 'version.skipped', reason: 'page-not-found' });
+    });
  });

  // #370 — the in-memory idle-burst marker must be dropped on doc unload (like
@@ -68,6 +68,19 @@ export const INTENTIONAL_CLEAR_MESSAGE_TYPE = 'intentional-clear';
 */
 export const SAVE_VERSION_MESSAGE_TYPE = 'save-version';

+/**
+ * #370 F2 — wire format of the server→client REPLY to a save-version signal, sent
+ * over the same stateless channel. `version.saved` means a version was created or
+ * promoted; `version.skipped` is a TERMINAL "nothing was pinned" reply for the two
+ * reachable no-op cases (an effectively-empty page, or the page row is gone) so the
+ * client resolves at once instead of waiting out its ack timeout and misreporting a
+ * healthy server as unreachable. EXACTLY ONE of these is broadcast per handled
+ * save. The MCP client duplicates these literals (it cannot import server code) —
+ * keep the two in sync (see packages/mcp/src/lib/collaboration.ts).
+ */
+export const VERSION_SAVED_MESSAGE_TYPE = 'version.saved';
+export const VERSION_SKIPPED_MESSAGE_TYPE = 'version.skipped';
+
 /**
 * #251 — how long an intentional-clear signal stays "pending" before it is
 * ignored. The signal is set on the clearing keystroke but consumed by the
@@ -643,6 +656,10 @@ export class PersistenceExtension implements Extension {
    let result:
      | { historyId: string; kind: PageHistoryKind; alreadySaved: boolean }
      | undefined;
+    // #370 F2 — set when there is nothing to version (empty page / page gone), so
+    // the tail broadcasts a terminal `version.skipped` instead of staying silent
+    // and forcing the client to time out. Mutually exclusive with `result`.
+    let skipped: 'empty' | 'page-not-found' | undefined;

    // #370 F8-twin — the contributor set popped from Redis (destructive SPOP)
    // must be restored if the version row does not durably land. The inner
@@ -668,11 +685,20 @@ export class PersistenceExtension implements Extension {
          includeContent: true,
          trx,
        });
-        if (!page) return;
+        if (!page) {
+          // The page row is gone (deleted/never persisted). Nothing to version —
+          // record it so the tail sends a terminal skip reply (#370 F2).
+          skipped = 'page-not-found';
+          return;
+        }
        versionedPageId = page.id;
        // Never version an effectively-empty page (mirrors the processor's
-        // first-history guard); there is nothing intentional to pin.
-        if (isEmptyParagraphDoc(page.content as any)) return;
+        // first-history guard); there is nothing intentional to pin. Record the
+        // skip so the client gets a terminal reply rather than a timeout (#370 F2).
+        if (isEmptyParagraphDoc(page.content as any)) {
+          skipped = 'empty';
+          return;
+        }

        const lastHistory = await this.pageHistoryRepo.findPageLastHistory(
          page.id,
@@ -747,15 +773,26 @@ export class PersistenceExtension implements Extension {
    }
    this.idleBurstStart.delete(documentName);

+    // EXACTLY ONE terminal reply per handled save (#370 F2): a real save/promote
+    // broadcasts `version.saved`; the two no-op early returns (empty page / page
+    // gone) broadcast `version.skipped` so the client never waits out its ack
+    // timeout. A genuine failure threw above and rejected before reaching here.
    if (result) {
      document.broadcastStateless(
        JSON.stringify({
-          type: 'version.saved',
+          type: VERSION_SAVED_MESSAGE_TYPE,
          historyId: result.historyId,
          kind: result.kind,
          alreadySaved: result.alreadySaved,
        }),
      );
+    } else if (skipped) {
+      document.broadcastStateless(
+        JSON.stringify({
+          type: VERSION_SKIPPED_MESSAGE_TYPE,
+          reason: skipped,
+        }),
+      );
    }
  }

@@ -106,6 +106,7 @@ function __assertClientCallContract(client: DocmostClientLike): void {
  void client.sharePage(s, true);
  void client.unsharePage(s);
  void client.restorePageVersion(s);
+  void client.savePageVersion(s);
  void client.transformPage(s, s, { dryRun: true });
  void client.stashPage(s);
  // --- write (image / footnote), in-app since #410 ---
@@ -58,6 +58,7 @@ type DocmostClientMethod =
  | 'sharePage'
  | 'unsharePage'
  | 'restorePageVersion'
+  | 'savePageVersion'
  | 'transformPage'
  | 'stashPage'
  // --- write (image / footnote), in-app since #410 ---
@@ -11,6 +11,7 @@ import {
  markdownToProseMirror,
  markdownToProseMirrorCanonical,
  mutatePageContent,
+  savePageVersionRealtime,
  assertYjsEncodable,
  MutationResult,
 } from "../lib/collaboration.js";
@@ -55,6 +56,7 @@ export interface IPagesMixin {
  listPageHistory(pageId: string, cursor?: string): any;
  getPageHistory(historyId: string): any;
  restorePageVersion(historyId: string): any;
+  savePageVersion(pageId: string): any;
  diffPageVersions(pageId: string, from?: string, to?: string): any;
 }

@@ -587,6 +589,24 @@ export function PagesMixin<TBase extends GConstructor<DocmostClientContext>>(Bas
    };
  }

+  /**
+   * Save an intentional NAMED version of a page's CURRENT live content (#370).
+   * The write goes over the same agent-authenticated collab session content edits
+   * use, so the server derives kind='agent' from the signed actor. Resolves a
+   * SaveVersionResult: `{ saved:true, historyId, kind, alreadySaved }` on success,
+   * or `{ saved:false, skipped:true, reason }` when the server had nothing to pin
+   * (e.g. an empty page). A stale/missing pageId throws (not a benign skip).
+   */
+  async savePageVersion(pageId: string) {
+    const collabToken = await this.getCollabTokenWithReauth();
+    const pageUuid = await this.resolvePageId(pageId);
+    // Self-heal a rejected WS handshake once (#486): re-mint the collab token and
+    // retry, symmetric to the content-write path.
+    return this.writeWithCollabAuthRetry(collabToken, (token) =>
+      savePageVersionRealtime(pageUuid, token, this.apiUrl),
+    );
+  }
+
  /**
   * Diff two versions of a page and return a Docmost-equivalent change set.
   * `from`/`to` each resolve to a ProseMirror doc:
@@ -139,7 +139,13 @@ export interface CollabProviderLike {
  unsyncedChanges: number;
  destroy(): void;
  on(event: "unsyncedChanges", handler: (data: { number: number }) => void): void;
+  on(event: "stateless", handler: (data: { payload: string }) => void): void;
  off(event: "unsyncedChanges", handler: (data: { number: number }) => void): void;
+  off(event: "stateless", handler: (data: { payload: string }) => void): void;
+  // Send a stateless (out-of-band, non-doc) message to the server. Used by the
+  // #370 explicit save-version path (payload `{type:'save-version'}`); the server
+  // replies with a broadcast `{type:'version.saved', …}` on the same channel.
+  sendStateless(payload: string): void;
 }

 /** The configuration object passed to the provider factory. */
@@ -564,6 +570,125 @@ export class CollabSession {
    });
  }

+  /**
+   * Send a stateless message over the live collaboration connection and resolve
+   * with the FIRST reply whose parsed payload satisfies `predicate`, rejecting on
+   * a bounded `timeoutMs`.
+   *
+   * Used by the #370 explicit save-version path: the client sends
+   * `{type:'save-version'}` and awaits the server's broadcast
+   * `{type:'version.saved', historyId, kind, alreadySaved}`. The stateless channel
+   * (not a REST read) is deliberate — the server versions the LIVE in-memory ydoc,
+   * which the up-to-10s-stale page row would not yet reflect.
+   *
+   * `predicate` receives each incoming stateless message (already JSON-parsed) and
+   * returns the resolved value for a match or `undefined` to keep waiting; a
+   * malformed / unrelated payload is ignored. The listener is registered BEFORE
+   * the send so a fast reply is never missed.
+   *
+   * Lifecycle mirrors mutate(): it registers through `inflightReject` so a
+   * disconnect/close/auth-failure/teardown rejects THIS wait with the same
+   * connection-loss error, refuses to run on a non-ready session, fails fast on a
+   * concurrent in-flight op (the caller MUST hold the per-page lock), and re-arms
+   * the idle TTL (or self-destroys an ephemeral session) on completion.
+   *
+   * NOTE: the server broadcast carries no request-correlation id, so under a
+   * genuinely concurrent save on the SAME page (e.g. a human Cmd+S racing the
+   * agent) this resolves on whichever `version.saved` arrives first. The per-page
+   * lock serializes THIS process's saves; a cross-client race is inherent to the
+   * broadcast design and is benign (the result still describes a real save of this
+   * page's current content, and the server's save is promote-not-duplicate).
+   */
+  sendStatelessAndAwait<T>(
+    payload: string,
+    predicate: (message: any) => T | undefined,
+    timeoutMs: number,
+  ): Promise<T> {
+    // Belt-and-suspenders (acquire already validated): refuse to send on a
+    // session that is not in a live, synced, ready state.
+    if (
+      this.dead ||
+      this.state !== "ready" ||
+      this.connectionLost ||
+      !this.provider ||
+      this.provider.synced !== true
+    ) {
+      return Promise.reject(
+        new Error("Collaboration session is not in a ready state"),
+      );
+    }
+
+    // Fail-fast on concurrent use: a second overlapping op would overwrite the
+    // first's inflightReject and hang it on disconnect (same guard as mutate).
+    if (this.inflightReject) {
+      return Promise.reject(
+        new Error(
+          "stateless op already in-flight; caller must serialize (hold the page lock)",
+        ),
+      );
+    }
+
+    return new Promise<T>((resolve, reject) => {
+      let settled = false;
+      let timer: ReturnType<typeof setTimeout> | undefined;
+      let statelessHandler: ((data: { payload: string }) => void) | undefined;
+
+      const localFinish = (err: Error | null, value?: T) => {
+        if (settled) return;
+        settled = true;
+        if (timer) clearTimeout(timer);
+        if (statelessHandler && this.provider) {
+          try {
+            this.provider.off("stateless", statelessHandler);
+          } catch (e) {}
+        }
+        this.inflightReject = undefined;
+        if (err) reject(err);
+        else resolve(value as T);
+        // Post-settle lifecycle, identical to mutate's localFinish.
+        if (this.ephemeral) {
+          this.destroy("ephemeral op complete");
+        } else if (!this.dead) {
+          this.armIdle();
+        }
+      };
+
+      // Register so a disconnect/close/auth-failure/teardown rejects THIS op with
+      // the connection-loss error text (the `settled` guard makes a racing
+      // teardown + normal resolve safe — first one wins).
+      this.inflightReject = (e: Error) => localFinish(e);
+
+      // Register the reply listener BEFORE sending so a fast server broadcast is
+      // never missed.
+      statelessHandler = (data: { payload: string }) => {
+        if (settled) return;
+        let message: any;
+        try {
+          message = JSON.parse(data.payload);
+        } catch {
+          return; // unrelated / malformed stateless message — keep waiting
+        }
+        const matched = predicate(message);
+        if (matched !== undefined) localFinish(null, matched);
+      };
+      this.provider!.on("stateless", statelessHandler);
+
+      timer = setTimeout(() => {
+        localFinish(
+          new Error(
+            `Timeout waiting for a stateless reply from the collaboration server ${this.hint()}`,
+          ),
+        );
+      }, timeoutMs);
+
+      try {
+        this.provider!.sendStateless(payload);
+      } catch (e) {
+        localFinish(e instanceof Error ? e : new Error(String(e)));
+      }
+    });
+  }
+
  /** (Re)arm the idle TTL so the clock starts from the most recent activity. */
  armIdle(): void {
    if (this.dead || this.ephemeral) return;
@@ -324,6 +324,146 @@ export async function mutatePageContent(
  });
 }

+/**
+ * Stateless-channel message types for the #370 explicit save-version handshake.
+ * These MUST match the server constants in
+ * apps/server/src/collaboration/extensions/persistence.extension.ts
+ * (SAVE_VERSION_MESSAGE_TYPE and the VERSION_SAVED / VERSION_SKIPPED replies) —
+ * the mcp package cannot import server code, so the literals are duplicated here.
+ * KEEP THE TWO SIDES IN SYNC: the server broadcasts exactly ONE terminal reply per
+ * handled save (`version.saved` for a real save/promote, `version.skipped` for a
+ * reachable no-op — an empty page or a missing page row); the client must match
+ * BOTH or it waits out the ack timeout on the skip case and misreports a healthy
+ * server as unreachable (#370 F2).
+ */
+const SAVE_VERSION_MESSAGE_TYPE = "save-version";
+const VERSION_SAVED_MESSAGE_TYPE = "version.saved";
+const VERSION_SKIPPED_MESSAGE_TYPE = "version.skipped";
+
+/**
+ * Bounded wait for the server's terminal reply after we ask it to save a version.
+ * The server flushes the live ydoc through its store path and writes a history row
+ * inside a DB transaction before broadcasting, so allow the same headroom as a
+ * persistence ack; reject (do NOT hang) past it. A timeout here means NO reply at
+ * all arrived — the genuine "collab server unreachable/overloaded" case — as
+ * distinct from a `version.skipped` reply, which resolves immediately.
+ */
+const SAVE_VERSION_ACK_TIMEOUT_MS = 20000;
+
+/**
+ * The resolved outcome of an explicit save-version, surfaced to the tool caller.
+ * `saved:true` → a version was created or promoted (historyId/kind/alreadySaved
+ * are present). `saved:false` → the server had nothing to pin (a reachable no-op,
+ * e.g. an empty page); `skipped` + `reason` explain why. A page-not-found reply is
+ * NOT represented here — it is surfaced as a thrown error (a bad/stale pageId).
+ */
+export interface SaveVersionResult {
+  saved: boolean;
+  historyId?: string;
+  kind?: string;
+  alreadySaved?: boolean;
+  skipped?: boolean;
+  reason?: string;
+}
+
+/**
+ * Parsed terminal reply the predicate hands back to savePageVersionRealtime. Kept
+ * internal: it carries the page-not-found case (mapped to a thrown error, never a
+ * returned result) that SaveVersionResult deliberately does not model.
+ */
+type SaveVersionReply =
+  | { outcome: "saved"; historyId: string; kind: string; alreadySaved: boolean }
+  | { outcome: "skipped"; reason: string };
+
+/** Match the server's terminal reply (version.saved / version.skipped), ignoring
+ *  any unrelated / cross-page stateless message so the wait is not resolved by
+ *  noise. Returns `undefined` to keep waiting (#370 F1 predicate coverage). */
+function matchSaveVersionReply(message: any): SaveVersionReply | undefined {
+  if (!message || typeof message !== "object") return undefined;
+  if (message.type === VERSION_SAVED_MESSAGE_TYPE) {
+    return {
+      outcome: "saved",
+      historyId: String(message.historyId),
+      kind: String(message.kind),
+      alreadySaved: !!message.alreadySaved,
+    };
+  }
+  if (message.type === VERSION_SKIPPED_MESSAGE_TYPE) {
+    return { outcome: "skipped", reason: String(message.reason ?? "unknown") };
+  }
+  return undefined;
+}
+
+/**
+ * Save an intentional version of a page's CURRENT live collaboration content
+ * (#370). Runs under the per-page lock, acquires the SAME cached CollabSession the
+ * content writes use (#400) — so it authenticates with the caller's agent collab
+ * token, and the server derives kind='agent' from that signed actor — then sends a
+ * `{type:'save-version'}` stateless message and awaits the server's terminal reply
+ * (`version.saved` or `version.skipped`) on the same channel.
+ *
+ * Deliberately does NOT read `pages.content` over REST: the versioned content is
+ * the live in-memory ydoc, which the debounced (up-to-10s-stale) page row would
+ * not yet reflect. The stateless round-trip is what makes the save exact.
+ *
+ * Outcomes:
+ *   - a real save/promote → `{ saved:true, historyId, kind, alreadySaved }`;
+ *   - the server had nothing to pin (empty page) → `{ saved:false, skipped:true,
+ *     reason:'empty' }` — a clean, immediate no-op, NOT a stall;
+ *   - the page row is gone (a stale/bad pageId) → a thrown error, immediate and
+ *     truthful (not the health-timeout path);
+ *   - no reply within the timeout → a thrown timeout error (the genuine "server
+ *     unreachable/overloaded" case).
+ *
+ * On a TRANSPORT failure (timeout / disconnect) the session is destroyed so the
+ * next call reconnects fresh; a page-not-found is a healthy-connection terminal
+ * reply, so the session is left cached. A save is safe to retry — the server
+ * promotes-not-duplicates an identical latest version — so the caller (and its
+ * agent) may re-issue it without risking a duplicate heavy history row.
+ */
+export async function savePageVersionRealtime(
+  pageId: PageId,
+  collabToken: string,
+  baseUrl: string,
+): Promise<SaveVersionResult> {
+  return withPageLock(pageId, async () => {
+    const session = await acquireCollabSession(pageId, collabToken, baseUrl);
+    let reply: SaveVersionReply;
+    try {
+      reply = await session.sendStatelessAndAwait<SaveVersionReply>(
+        JSON.stringify({ type: SAVE_VERSION_MESSAGE_TYPE }),
+        matchSaveVersionReply,
+        SAVE_VERSION_ACK_TIMEOUT_MS,
+      );
+    } catch (e) {
+      // TRANSPORT failure (no reply within the timeout, or a disconnect): drop the
+      // session so the next call reconnects fresh.
+      session.destroy("save-version failed");
+      throw e;
+    }
+    // A terminal reply arrived over a healthy connection — do NOT destroy the
+    // session; interpret the outcome.
+    if (reply.outcome === "skipped") {
+      if (reply.reason === "page-not-found") {
+        // A resolved pageId that the collab server no longer holds (deleted, or a
+        // stale id). Surface it immediately and truthfully, not as a health error.
+        throw new Error(
+          `savePageVersion: page ${pageId} was not found on the collaboration ` +
+            `server (it may have been deleted) — nothing was saved.`,
+        );
+      }
+      // Reachable benign no-op (e.g. an empty page): a clean result, not a throw.
+      return { saved: false, skipped: true, reason: reply.reason };
+    }
+    return {
+      saved: true,
+      historyId: reply.historyId,
+      kind: reply.kind,
+      alreadySaved: reply.alreadySaved,
+    };
+  });
+}
+
 /**
 * Replace the live content of a page over the collaboration websocket.
 * Accepts a ready ProseMirror JSON document; the caller controls whether
@@ -44,7 +44,7 @@ export const ROUTING_PROSE =
  "EDIT: fix wording/typos/numbers -> editPageText (find/replace inside blocks, no node id needed). Edit a block -> getNode(markdown) -> edit the markdown -> patchNode(markdown) (by attrs.id from getOutline; the markdown fragment may be several blocks — a 1->N section rewrite in one call, the first block keeps the id). Reach for patchNode's `node`-JSON only for fine attr/mark work; a table cell with spans/colors/fixed width -> the table tools (patchNode markdown refuses it). Add a block -> insertNode (markdown, before/after a block by attrs.id or by anchor text, or append; `node` for raw JSON or bare table structure). Remove a block -> deleteNode (by attrs.id). Tables -> tableGet / tableUpdateCell / tableInsertRow / tableDeleteRow (address by \"#<index>\" from getOutline; table nodes have no attrs.id). Images -> insertImage (add from a web URL) / replaceImage (swap an existing image). Draw.io diagrams -> PREFER the high-level semantic tools that hide coordinates/styles: drawioFromGraph (architecture/cloud/network diagrams — describe nodes/groups/edges by kind+icon, the server picks layout, colors and verified icons; hints layer/sameLayerAs/pinned and layout:full|incremental|none) and drawioFromMermaid (standard flowcharts — write Mermaid, get an editable diagram). For targeted tweaks of an existing diagram use drawioEditCells (id-based add/update/delete with cascade delete + baseHash lock). Raw mxGraph XML via drawioCreate/drawioUpdate is the escape-hatch for exotic/wireframe diagrams; drawioGet reads a diagram as mxGraph XML + a hash (pass it as baseHash to drawioUpdate/drawioEditCells for optimistic locking). Before authoring raw XML, drawioShapes (look up verified stencil style-strings so a shape name never renders as an empty box) and drawioGuide (on-demand authoring reference: skeleton/layout/containers/icons-aws/icons-azure), and pass layout:\"elk\" to drawioCreate/drawioUpdate to auto-place nodes. Footnotes -> insertFootnote. Bulk/structural rewrite -> updatePageJson (full ProseMirror replace) or updatePageMarkdown (full plain-Markdown body replace, re-imported — block ids regenerate); prefer the granular tools above to avoid resending the whole ~100KB+ document. Complex/scripted rewrite (multiple coordinated edits, renumbering) -> docmostTransform: write a JS `(doc, ctx) => doc` transform, preview the diff with dryRun (default), then apply with dryRun:false; ctx.helpers includes commentsToFootnotes for turning inline comments into numbered footnotes.\n" +
  "PAGES: new -> createPage (Markdown). Rename (title only) -> renamePage. Move -> movePage. Delete -> deletePage (SOFT delete — the page goes to trash and is restorable; nothing is permanent). Copy/replace a page's whole content from another page (server-side, no document through the model) -> copyPageContent. Sharing -> sharePage / unsharePage / listShares; sharePage makes the page PUBLICLY accessible — do it only when explicitly asked.\n" +
  "COMMENTS: createComment is always inline and requires an EXACT selection — contiguous text from a single block, <=250 chars (fails rather than leaving an unanchored comment); reply to a thread via parentCommentId. Propose a concrete text fix for one-click human approval -> createComment with suggestedText (the exact plain-text replacement for the selection; the selection must then be UNIQUE in the page — extend it with context if needed); prefer this over editing directly when the change is subjective or needs the author's sign-off. Manage -> listComments, updateComment, resolveComment (resolve/reopen, reversible — prefer over delete to close), deleteComment, checkNewComments.\n" +
-  "HISTORY: review what changed -> diffPageVersions (a historyId vs current, or two versions). List saved versions -> listPageHistory. Undo a bad edit -> restorePageVersion (writes a past version back as current; itself revertible). Export a page to self-contained Docmost Markdown (with comment anchors) -> exportPageMarkdown.";
+  "HISTORY: review what changed -> diffPageVersions (a historyId vs current, or two versions). List saved versions -> listPageHistory. Undo a bad edit -> restorePageVersion (writes a past version back as current; itself revertible). Pin the page's CURRENT content as a restorable named checkpoint when you finish a coherent editing pass -> savePageVersion (kind derived server-side as an agent version; an identical-to-last save is promoted/no-op'd, so a redundant call is harmless). Export a page to self-contained Docmost Markdown (with comment anchors) -> exportPageMarkdown.";

 /**
 * Non-tool camelCase identifiers that legitimately appear in ROUTING_PROSE:
@@ -218,6 +218,7 @@ const TOOL_FAMILY: Record<string, Family> = {
  diffPageVersions: "HISTORY",
  listPageHistory: "HISTORY",
  restorePageVersion: "HISTORY",
+  savePageVersion: "HISTORY",
  exportPageMarkdown: "HISTORY",
  // importPageMarkdown is now inAppOnly (#411) — it is not registered on the
  // external MCP host, so it no longer appears in the generated inventory.
@@ -93,6 +93,7 @@ export type DocmostClientLike = Pick<
  | 'sharePage'
  | 'unsharePage'
  | 'restorePageVersion'
+  | 'savePageVersion'
  | 'stashPage'
  | 'insertFootnote'
  | 'insertImage'
@@ -743,6 +744,30 @@ export const SHARED_TOOL_SPECS = {
      client.restorePageVersion(historyId as string),
  },

+  savePageVersion: {
+    mcpName: 'savePageVersion',
+    inAppKey: 'savePageVersion',
+    writeClass: 'write',
+    description:
+      'Save an intentional, NAMED version (kind=agent) of the page\'s CURRENT ' +
+      'live content — a restorable checkpoint pinned into its history. Call it ' +
+      'when you have FINISHED a coherent editing pass (not after every small ' +
+      'edit), so the reader can see and roll back to the state you left. The ' +
+      'version type is derived SERVER-SIDE from your signed agent identity (you ' +
+      'cannot mislabel it); a save whose content is IDENTICAL to the last saved ' +
+      'version is promoted/no-op\'d server-side, so a redundant call is harmless ' +
+      'and never duplicates a version. Returns { saved:true, historyId, kind, ' +
+      'alreadySaved } on success, or { saved:false, skipped:true, reason:\'empty\' } ' +
+      'when the page had nothing to pin (e.g. it was empty).',
+    tier: 'deferred',
+    catalogLine:
+      'savePageVersion — pin the page\'s current content as a named agent version (restorable checkpoint).',
+    buildShape: (z) => ({
+      pageId: z.string().min(1),
+    }),
+    execute: (client, { pageId }) => client.savePageVersion(pageId as string),
+  },
+
  // --- markdown round-trip ---

  importPageMarkdown: {
@@ -0,0 +1,300 @@
+import { test, beforeEach, afterEach, mock } from "node:test";
+import assert from "node:assert/strict";
+import { EventEmitter } from "node:events";
+
+import {
+  acquireCollabSession,
+  destroyAllSessions,
+  __setCollabProviderFactory,
+} from "../../build/lib/collab-session.js";
+import { savePageVersionRealtime } from "../../build/lib/collaboration.js";
+
+// #370 — unit coverage for the MCP client transport of the explicit save-version.
+// There is no collaboration server in the test env, so a fake HocuspocusProvider
+// drives the stateless round-trip: it auto-completes the connect/sync handshake on
+// a microtask (like the real provider), records sends, and either auto-broadcasts a
+// configured reply (`opts.reply`) or lets the test emit stateless messages /
+// disconnects by hand (`_emitStateless` / `_disconnect`) to exercise the predicate
+// filter, the teardown-mid-wait path, and the timeout.
+class FakeProvider extends EventEmitter {
+  static instances = [];
+
+  static reset() {
+    FakeProvider.instances = [];
+  }
+
+  static last() {
+    return FakeProvider.instances[FakeProvider.instances.length - 1];
+  }
+
+  constructor(config, opts = {}) {
+    super();
+    this.config = config;
+    this.synced = false;
+    this.unsyncedChanges = 0;
+    this.destroyed = false;
+    this.sent = [];
+    this.opts = opts;
+    FakeProvider.instances.push(this);
+    // Real HocuspocusProvider fires onSynced asynchronously after the handshake;
+    // a microtask reproduces that without depending on timers (so mock.timers on
+    // setTimeout does not stall the connect).
+    queueMicrotask(() => {
+      if (this.destroyed) return;
+      this.config.onConnect?.();
+      this.synced = true;
+      this.config.onSynced?.();
+    });
+  }
+
+  destroy() {
+    this.destroyed = true;
+  }
+
+  sendStateless(payload) {
+    this.sent.push(payload);
+    const reply = this.opts.reply;
+    if (!reply) return; // silent → the caller times out, or the test drives it
+    // Broadcast the configured server reply on a microtask, mirroring
+    // document.broadcastStateless landing back on this provider's `stateless` event.
+    queueMicrotask(() => {
+      if (this.destroyed) return;
+      this.emit("stateless", { payload: JSON.stringify(reply) });
+    });
+  }
+
+  // --- test drivers ---
+  _emitStateless(obj) {
+    this.emit("stateless", { payload: JSON.stringify(obj) });
+  }
+  _disconnect() {
+    this.config.onDisconnect?.();
+  }
+}
+
+const ENV_KEYS = [
+  "MCP_COLLAB_SESSION_IDLE_MS",
+  "MCP_COLLAB_SESSION_MAX_AGE_MS",
+  "MCP_COLLAB_SESSION_MAX_ENTRIES",
+  "MCP_COLLAB_TOKEN_TTL_MS",
+];
+let savedEnv;
+
+beforeEach(() => {
+  savedEnv = {};
+  for (const k of ENV_KEYS) savedEnv[k] = process.env[k];
+  FakeProvider.reset();
+});
+
+afterEach(() => {
+  destroyAllSessions();
+  __setCollabProviderFactory(null);
+  mock.timers.reset();
+  for (const k of ENV_KEYS) {
+    if (savedEnv[k] === undefined) delete process.env[k];
+    else process.env[k] = savedEnv[k];
+  }
+});
+
+const PAGE_A = "11111111-1111-4111-8111-111111111111";
+const PAGE_B = "22222222-2222-4222-8222-222222222222";
+const PAGE_C = "33333333-3333-4333-8333-333333333333";
+const PAGE_D = "44444444-4444-4444-8444-444444444444";
+const PAGE_E = "55555555-5555-4555-8555-555555555555";
+const PAGE_F = "66666666-6666-4666-8666-666666666666";
+
+// --- happy paths (resolve with the server's terminal reply) -----------------
+
+test("saved: resolves { saved:true, historyId, kind, alreadySaved }", async () => {
+  __setCollabProviderFactory(
+    (config) =>
+      new FakeProvider(config, {
+        reply: {
+          type: "version.saved",
+          historyId: "hist-42",
+          kind: "agent",
+          alreadySaved: false,
+        },
+      }),
+  );
+
+  const result = await savePageVersionRealtime(PAGE_A, "collab-tok", "http://host/api");
+
+  assert.deepEqual(result, {
+    saved: true,
+    historyId: "hist-42",
+    kind: "agent",
+    alreadySaved: false,
+  });
+  // The client actually asked the server to save a version (the stateless send).
+  assert.deepEqual(
+    FakeProvider.last().sent.map((p) => JSON.parse(p)),
+    [{ type: "save-version" }],
+  );
+});
+
+test("saved: surfaces alreadySaved=true (promote-not-dup / no-op save)", async () => {
+  __setCollabProviderFactory(
+    (config) =>
+      new FakeProvider(config, {
+        reply: {
+          type: "version.saved",
+          historyId: "hist-7",
+          kind: "manual",
+          alreadySaved: true,
+        },
+      }),
+  );
+
+  const result = await savePageVersionRealtime(PAGE_B, "collab-tok", "http://host/api");
+
+  assert.deepEqual(result, {
+    saved: true,
+    historyId: "hist-7",
+    kind: "manual",
+    alreadySaved: true,
+  });
+});
+
+// --- F2: terminal SKIP replies (no timeout, no false "unreachable") ---------
+
+test("F2 skip: an empty-page reply resolves to a clean { saved:false, skipped:true, reason:'empty' } — no timeout", async () => {
+  __setCollabProviderFactory(
+    (config) =>
+      new FakeProvider(config, {
+        reply: { type: "version.skipped", reason: "empty" },
+      }),
+  );
+
+  const result = await savePageVersionRealtime(PAGE_C, "collab-tok", "http://host/api");
+
+  assert.deepEqual(result, { saved: false, skipped: true, reason: "empty" });
+});
+
+test("F2 skip: a page-not-found reply throws an immediate, truthful error (not the health-timeout path)", async () => {
+  __setCollabProviderFactory(
+    (config) =>
+      new FakeProvider(config, {
+        reply: { type: "version.skipped", reason: "page-not-found" },
+      }),
+  );
+
+  await assert.rejects(
+    savePageVersionRealtime(PAGE_D, "collab-tok", "http://host/api"),
+    /was not found on the collaboration server/,
+  );
+});
+
+// --- F1 (a): predicate filters unrelated messages, resolves on the real reply ---
+
+test("F1(a) unrelated-then-real: an unrelated stateless message does NOT resolve; the later version.saved does", async () => {
+  __setCollabProviderFactory((config) => new FakeProvider(config, {})); // manual drive
+
+  const p = savePageVersionRealtime(PAGE_E, "collab-tok", "http://host/api");
+  // Let acquire's handshake + the stateless send complete so the listener is armed.
+  await new Promise((r) => setImmediate(r));
+  const provider = FakeProvider.last();
+
+  // Noise first: an unrelated stateless type (e.g. another feature's broadcast).
+  provider._emitStateless({ type: "something-else", historyId: "NOPE" });
+  // The wait must still be pending — a microtask turn would have resolved it if the
+  // predicate wrongly matched.
+  let settledEarly = false;
+  p.then(() => (settledEarly = true)).catch(() => (settledEarly = true));
+  await new Promise((r) => setImmediate(r));
+  assert.equal(settledEarly, false, "resolved on an unrelated stateless message");
+
+  // Now the real reply arrives → it resolves with that payload.
+  provider._emitStateless({
+    type: "version.saved",
+    historyId: "h-real",
+    kind: "agent",
+    alreadySaved: false,
+  });
+  const result = await p;
+  assert.deepEqual(result, {
+    saved: true,
+    historyId: "h-real",
+    kind: "agent",
+    alreadySaved: false,
+  });
+});
+
+// --- F1 (b): teardown mid-wait rejects AND removes the stateless listener -----
+
+test("F1(b) teardown mid-wait: a disconnect rejects the wait with the connection-loss error AND removes the stateless listener (no leak)", async () => {
+  __setCollabProviderFactory((config) => new FakeProvider(config, {})); // silent
+
+  const session = await acquireCollabSession(PAGE_F, "collab-tok", "http://host/api");
+  const provider = FakeProvider.last();
+
+  const p = session.sendStatelessAndAwait(
+    JSON.stringify({ type: "save-version" }),
+    (m) => (m && m.type === "version.saved" ? m : undefined),
+    20000,
+  );
+  // Swallow the eventual rejection so it does not race the assertions below.
+  p.catch(() => {});
+  await new Promise((r) => setImmediate(r));
+
+  // The wait armed exactly one stateless listener.
+  assert.equal(
+    provider.listenerCount("stateless"),
+    1,
+    "the wait must register one stateless listener",
+  );
+
+  // A disconnect tears the session down mid-wait.
+  provider._disconnect();
+
+  await assert.rejects(p, /connection closed before the update was persisted/);
+  // The listener was removed on teardown — dropping provider.off() reds this.
+  assert.equal(
+    provider.listenerCount("stateless"),
+    0,
+    "the stateless listener leaked after teardown",
+  );
+});
+
+// --- F1 (c): concurrent-in-flight guard fails fast, no cross-wiring -----------
+
+test("F1(c) concurrent guard: a second sendStatelessAndAwait while one is in flight fails fast", async () => {
+  __setCollabProviderFactory((config) => new FakeProvider(config, {})); // silent
+
+  const session = await acquireCollabSession(PAGE_A, "collab-tok", "http://host/api");
+
+  const first = session.sendStatelessAndAwait(
+    JSON.stringify({ type: "save-version" }),
+    (m) => (m && m.type === "version.saved" ? m : undefined),
+    20000,
+  );
+  first.catch(() => {}); // it stays pending until afterEach destroys the session
+
+  await assert.rejects(
+    session.sendStatelessAndAwait(
+      JSON.stringify({ type: "save-version" }),
+      (m) => (m && m.type === "version.saved" ? m : undefined),
+      20000,
+    ),
+    /already in-flight/,
+  );
+});
+
+// --- timeout: NO reply at all is the genuine "server unreachable" path --------
+
+test("timeout: rejects on a bounded timeout when the server never replies", async () => {
+  __setCollabProviderFactory((config) => new FakeProvider(config, {})); // silent
+
+  mock.timers.enable({ apis: ["setTimeout"] });
+  const p = savePageVersionRealtime(PAGE_B, "collab-tok", "http://host/api");
+  // Swallow the eventual rejection so an unhandled-rejection does not race the tick.
+  p.catch(() => {});
+
+  // Flush the (microtask-driven) connect handshake + the stateless send so the
+  // ack timer is armed before we advance the clock.
+  await new Promise((r) => setImmediate(r));
+  // Advance well past the 20s ack window; the connect timer (25s) does not fire.
+  mock.timers.tick(20000 + 100);
+
+  await assert.rejects(p, /Timeout waiting for a stateless reply/);
+});