diff --git a/apps/client/public/locales/en-US/translation.json b/apps/client/public/locales/en-US/translation.json
index 89988d9b..00b4b237 100644
--- a/apps/client/public/locales/en-US/translation.json
+++ b/apps/client/public/locales/en-US/translation.json
@@ -1385,5 +1385,14 @@
   "The commented text changed since this suggestion was made; it was not applied.": "The commented text changed since this suggestion was made; it was not applied.",
   "Dismiss": "Dismiss",
   "Suggestion dismissed": "Suggestion dismissed",
-  "Failed to dismiss suggestion": "Failed to dismiss suggestion"
+  "Failed to dismiss suggestion": "Failed to dismiss suggestion",
+  "Save version": "Save version",
+  "Ctrl+S": "Ctrl+S",
+  "Version saved": "Version saved",
+  "Already saved as the latest version": "Already saved as the latest version",
+  "Agent version": "Agent version",
+  "Boundary": "Boundary",
+  "Autosave": "Autosave",
+  "Only versions": "Only versions",
+  "No saved versions yet.": "No saved versions yet."
 }
diff --git a/apps/client/public/locales/ru-RU/translation.json b/apps/client/public/locales/ru-RU/translation.json
index 0c792632..51b8e3bc 100644
--- a/apps/client/public/locales/ru-RU/translation.json
+++ b/apps/client/public/locales/ru-RU/translation.json
@@ -1248,5 +1248,14 @@
   "The commented text changed since this suggestion was made; it was not applied.": "Прокомментированный текст изменился после создания предложения; оно не было применено.",
   "Dismiss": "Не применять",
   "Suggestion dismissed": "Предложение отклонено",
-  "Failed to dismiss suggestion": "Не удалось отклонить предложение"
+  "Failed to dismiss suggestion": "Не удалось отклонить предложение",
+  "Save version": "Сохранить версию",
+  "Ctrl+S": "Ctrl+S",
+  "Version saved": "Версия сохранена",
+  "Already saved as the latest version": "Уже сохранено как последняя версия",
+  "Agent version": "Версия агента",
+  "Boundary": "Граница",
+  "Autosave": "Автосейв",
+  "Only versions": "Только версии",
+  "No saved versions yet.": "Пока нет сохранённых версий."
 }
diff --git a/apps/client/src/features/editor/atoms/editor-atoms.ts b/apps/client/src/features/editor/atoms/editor-atoms.ts
index 605a71db..7b513cc1 100644
--- a/apps/client/src/features/editor/atoms/editor-atoms.ts
+++ b/apps/client/src/features/editor/atoms/editor-atoms.ts
@@ -1,10 +1,19 @@
 import { atom } from "jotai";
 import { Editor } from "@tiptap/core";
+import type { HocuspocusProvider } from "@hocuspocus/provider";
 import { PageEditMode } from "@/features/user/types/user.types.ts";
 import type { DictationUnavailableReason } from "@/features/dictation/dictation-status";
 
 export const pageEditorAtom = atom<Editor | null>(null);
 
+// #370 — the active page's collab provider, published by the page editor so the
+// header menu can emit the "save-version" stateless signal (Cmd+S / button).
+// Null when the page is read-only / collab isn't connected. A typed initial
+// value (rather than an explicit generic) keeps jotai's overload resolution on
+// the writable PrimitiveAtom branch.
+const initialCollabProvider: HocuspocusProvider | null = null;
+export const collabProviderAtom = atom(initialCollabProvider);
+
 export const titleEditorAtom = atom<Editor | null>(null);
 
 export const readOnlyEditorAtom = atom<Editor | null>(null);
diff --git a/apps/client/src/features/editor/page-editor.tsx b/apps/client/src/features/editor/page-editor.tsx
index e1244ee5..60949e8a 100644
--- a/apps/client/src/features/editor/page-editor.tsx
+++ b/apps/client/src/features/editor/page-editor.tsx
@@ -31,11 +31,18 @@ import { useAtom, useAtomValue, useSetAtom } from "jotai";
 import useCollaborationUrl from "@/features/editor/hooks/use-collaboration-url";
 import { currentUserAtom } from "@/features/user/atoms/current-user-atom";
 import {
+  collabProviderAtom,
   currentPageEditModeAtom,
   dictationAvailabilityAtom,
   pageEditorAtom,
   yjsConnectionStatusAtom,
 } from "@/features/editor/atoms/editor-atoms";
+import { notifications } from "@mantine/notifications";
+import {
+  VERSION_SAVED_MESSAGE_TYPE,
+  type VersionSavedMessage,
+  saveVersionPending,
+} from "@/features/page-history/version-messages";
 import { asideStateAtom } from "@/components/layouts/global/hooks/atoms/sidebar-atom";
 import {
   activeCommentIdAtom,
@@ -123,6 +130,7 @@ export default function PageEditor({
 
   const [currentUser] = useAtom(currentUserAtom);
   const [, setEditor] = useAtom(pageEditorAtom);
+  const setCollabProvider = useSetAtom(collabProviderAtom);
   const [, setAsideState] = useAtom(asideStateAtom);
   const [, setActiveCommentId] = useAtom(activeCommentIdAtom);
   const [showCommentPopup, setShowCommentPopup] = useAtom(showCommentPopupAtom);
@@ -180,6 +188,24 @@ export default function PageEditor({
       const onStatelessHandler = ({ payload }: onStatelessParameters) => {
         try {
           const message = JSON.parse(payload);
+          // #370 — a version was saved somewhere; live-refresh the history panel
+          // on every client. Only the client that pressed Save (tracked by the
+          // module-level flag) shows the confirmation toast.
+          if (message?.type === VERSION_SAVED_MESSAGE_TYPE) {
+            const versionMsg = message as VersionSavedMessage;
+            queryClient.invalidateQueries({
+              queryKey: ["page-history-list"],
+            });
+            if (saveVersionPending.current) {
+              saveVersionPending.current = false;
+              notifications.show({
+                message: versionMsg.alreadySaved
+                  ? t("Already saved as the latest version")
+                  : t("Version saved"),
+              });
+            }
+            return;
+          }
           if (message?.type !== "page.updated" || !message.updatedAt) return;
           const pageData = queryClient.getQueryData<IPage>(["pages", slugId]);
           if (pageData) {
@@ -237,12 +263,16 @@ export default function PageEditor({
 
       local.on("synced", onLocalSyncedHandler);
       providersRef.current = { socket, local, remote };
+      // #370 — publish the provider so the header menu can emit save-version.
+      setCollabProvider(remote);
       setProvidersReady(true);
     } else {
+      setCollabProvider(providersRef.current.remote);
       setProvidersReady(true);
     }
     // Only destroy on final unmount
     return () => {
+      setCollabProvider(null);
       providersRef.current?.socket.destroy();
       providersRef.current?.remote.destroy();
       providersRef.current?.local.destroy();
diff --git a/apps/client/src/features/page-history/components/history-item.tsx b/apps/client/src/features/page-history/components/history-item.tsx
index bc810eca..6953a161 100644
--- a/apps/client/src/features/page-history/components/history-item.tsx
+++ b/apps/client/src/features/page-history/components/history-item.tsx
@@ -1,4 +1,11 @@
-import { Text, Group, UnstyledButton, Avatar, Tooltip } from "@mantine/core";
+import {
+  Text,
+  Group,
+  UnstyledButton,
+  Avatar,
+  Tooltip,
+  Badge,
+} from "@mantine/core";
 import { CustomAvatar } from "@/components/ui/custom-avatar.tsx";
 import { AgentAvatarStack } from "@/components/ui/agent-avatar-stack.tsx";
 import { formattedDate } from "@/lib/time";
@@ -7,10 +14,30 @@ import clsx from "clsx";
 import { IPageHistory } from "@/features/page-history/types/page.types";
 import { memo, useCallback } from "react";
 import { useSetAtom } from "jotai";
+import { useTranslation } from "react-i18next";
 import { historyAtoms } from "@/features/page-history/atoms/history-atoms.ts";
 
 const MAX_VISIBLE_AVATARS = 5;
 
+/**
+ * #370 — map a snapshot's intentionality tier to its badge. `version: true`
+ * marks the intentional points (manual / agent); autosaves (boundary / idle /
+ * legacy null) are non-versions and get dimmed in the list.
+ */
+type HistoryKindMeta = { labelKey: string; color: string; version: boolean };
+export function historyKindMeta(kind?: string | null): HistoryKindMeta {
+  switch (kind) {
+    case "manual":
+      return { labelKey: "Saved", color: "blue", version: true };
+    case "agent":
+      return { labelKey: "Agent version", color: "violet", version: true };
+    case "boundary":
+      return { labelKey: "Boundary", color: "gray", version: false };
+    default: // "idle" | null | undefined (legacy autosave)
+      return { labelKey: "Autosave", color: "gray", version: false };
+  }
+}
+
 interface HistoryItemProps {
   historyItem: IPageHistory;
   index: number;
@@ -29,6 +56,8 @@ const HistoryItem = memo(function HistoryItem({
   isActive,
 }: HistoryItemProps) {
   const setHistoryModalOpen = useSetAtom(historyAtoms);
+  const { t } = useTranslation();
+  const kindMeta = historyKindMeta(historyItem.kind);
 
   const handleClick = useCallback(() => {
     onSelect(historyItem.id, index);
@@ -49,8 +78,20 @@ const HistoryItem = memo(function HistoryItem({
       onMouseEnter={handleMouseEnter}
       onMouseLeave={onHoverEnd}
       className={clsx(classes.history, { [classes.active]: isActive })}
+      // #370 — dim autosnapshots so intentional versions stand out.
+      style={{ opacity: kindMeta.version ? 1 : 0.55 }}
     >
-      <Text size="sm">{formattedDate(new Date(historyItem.createdAt))}</Text>
+      <Group gap={6} wrap="nowrap" justify="space-between">
+        <Text size="sm">{formattedDate(new Date(historyItem.createdAt))}</Text>
+        <Badge
+          size="xs"
+          radius="sm"
+          variant={kindMeta.version ? "filled" : "light"}
+          color={kindMeta.color}
+        >
+          {t(kindMeta.labelKey)}
+        </Badge>
+      </Group>
 
       <Group gap={6} wrap="nowrap" mt={4}>
         {hasContributors ? (
diff --git a/apps/client/src/features/page-history/components/history-list.tsx b/apps/client/src/features/page-history/components/history-list.tsx
index 4024901b..78598fb1 100644
--- a/apps/client/src/features/page-history/components/history-list.tsx
+++ b/apps/client/src/features/page-history/components/history-list.tsx
@@ -9,7 +9,7 @@ import {
   historyAtoms,
 } from "@/features/page-history/atoms/history-atoms";
 import { useAtom, useSetAtom } from "jotai";
-import { useCallback, useEffect, useMemo, useRef } from "react";
+import { useCallback, useEffect, useMemo, useRef, useState } from "react";
 import {
   Button,
   ScrollArea,
@@ -17,6 +17,8 @@ import {
   Divider,
   Loader,
   Center,
+  Switch,
+  Text,
 } from "@mantine/core";
 import { useTranslation } from "react-i18next";
 import { useHistoryRestore } from "@/features/page-history/hooks";
@@ -47,6 +49,28 @@ function HistoryList({ pageId }: Props) {
     [pageHistoryData],
   );
 
+  // #370 — "only versions" filter: hide autosnapshots (idle/boundary/legacy
+  // null), keep only intentional points (manual/agent). Filtering is over the
+  // already-loaded pages; the diff/restore still targets the true previous
+  // snapshot, so items carry their index within the FULL list.
+  const [onlyVersions, setOnlyVersions] = useState(false);
+  const isVersion = useCallback(
+    (kind?: string | null) => kind === "manual" || kind === "agent",
+    [],
+  );
+  const originalIndexById = useMemo(() => {
+    const map = new Map<string, number>();
+    historyItems.forEach((item, index) => map.set(item.id, index));
+    return map;
+  }, [historyItems]);
+  const visibleItems = useMemo(
+    () =>
+      onlyVersions
+        ? historyItems.filter((item) => isVersion(item.kind))
+        : historyItems,
+    [historyItems, onlyVersions, isVersion],
+  );
+
   const loadMoreRef = useRef<HTMLDivElement>(null);
   const prefetchTimeoutRef = useRef<ReturnType<typeof setTimeout> | null>(null);
 
@@ -128,12 +152,30 @@ function HistoryList({ pageId }: Props) {
 
   return (
     <div>
+      <Group px="xs" py={6} justify="flex-end">
+        <Switch
+          size="xs"
+          checked={onlyVersions}
+          onChange={(e) => setOnlyVersions(e.currentTarget.checked)}
+          label={t("Only versions")}
+        />
+      </Group>
+
       <ScrollArea h={620} w="100%" type="scroll" scrollbarSize={5}>
-        {historyItems.map((historyItem, index) => (
+        {onlyVersions && visibleItems.length === 0 && (
+          <Center py="md">
+            <Text size="sm" c="dimmed">
+              {t("No saved versions yet.")}
+            </Text>
+          </Center>
+        )}
+        {visibleItems.map((historyItem) => (
           <HistoryItem
             key={historyItem.id}
             historyItem={historyItem}
-            index={index}
+            // Index within the FULL list so diff/restore uses the true previous
+            // snapshot, not the previous visible one.
+            index={originalIndexById.get(historyItem.id) ?? 0}
             onSelect={handleSelect}
             onHover={handleHover}
             onHoverEnd={clearPrefetchTimeout}
diff --git a/apps/client/src/features/page-history/types/page.types.ts b/apps/client/src/features/page-history/types/page.types.ts
index a571fc99..3b110328 100644
--- a/apps/client/src/features/page-history/types/page.types.ts
+++ b/apps/client/src/features/page-history/types/page.types.ts
@@ -24,6 +24,10 @@ export interface IPageHistory {
   updatedAt: string;
   lastUpdatedBy: IPageHistoryUser;
   contributors?: IPageHistoryUser[];
+  // #370 — intentionality tier: 'manual'/'agent' are versions (intentional
+  // points), 'idle'/'boundary' are autosnapshots; null/undefined = legacy
+  // autosave. Derived server-side, drives the history badge + "versions" filter.
+  kind?: "manual" | "agent" | "idle" | "boundary" | null;
   // Provenance markers copied off the page row when the snapshot was saved.
   // `'agent'` marks a version written by the AI agent; `lastUpdatedAiChatId`
   // (when present) deep-links to the chat that produced the edit.
diff --git a/apps/client/src/features/page-history/version-messages.ts b/apps/client/src/features/page-history/version-messages.ts
new file mode 100644
index 00000000..1e944397
--- /dev/null
+++ b/apps/client/src/features/page-history/version-messages.ts
@@ -0,0 +1,28 @@
+/**
+ * #370 — page-version stateless wire formats. Kept in one place so the client
+ * emitter (Save hotkey / button) and the client listener (page-editor) agree
+ * with the server (PersistenceExtension) on the message shapes.
+ */
+
+/** Client → server: "save a version now". The server derives the tier
+ * (manual/agent) from the signed connection actor, never from this payload. */
+export const SAVE_VERSION_MESSAGE_TYPE = "save-version";
+
+/** Server → all clients: a version was saved (or promoted / already existed). */
+export const VERSION_SAVED_MESSAGE_TYPE = "version.saved";
+
+export interface VersionSavedMessage {
+  type: typeof VERSION_SAVED_MESSAGE_TYPE;
+  historyId: string;
+  kind: "manual" | "agent";
+  /** True when the latest snapshot was already a manual version (a no-op save). */
+  alreadySaved: boolean;
+}
+
+/**
+ * Cross-component coordination flag so only the client that pressed Save shows
+ * the confirmation toast, while every other client silently refreshes its
+ * history panel on the broadcast. A module-level ref avoids stale-closure
+ * pitfalls in the editor's long-lived stateless handler.
+ */
+export const saveVersionPending = { current: false };
diff --git a/apps/client/src/features/page/components/header/page-header-menu.tsx b/apps/client/src/features/page/components/header/page-header-menu.tsx
index 732d9136..438dfee4 100644
--- a/apps/client/src/features/page/components/header/page-header-menu.tsx
+++ b/apps/client/src/features/page/components/header/page-header-menu.tsx
@@ -3,6 +3,7 @@ import {
   IconArrowRight,
   IconArrowsHorizontal,
   IconClockHour4,
+  IconDeviceFloppy,
   IconDots,
   IconEye,
   IconEyeOff,
@@ -17,7 +18,7 @@ import {
   IconTrash,
   IconWifiOff,
 } from "@tabler/icons-react";
-import React, { useEffect, useRef, useState } from "react";
+import React, { useCallback, useEffect, useRef, useState } from "react";
 import { useAsideTriggerProps } from "@/hooks/use-toggle-aside.tsx";
 import { useAtom, useAtomValue } from "jotai";
 import { historyAtoms } from "@/features/page-history/atoms/history-atoms.ts";
@@ -39,9 +40,14 @@ import { Trans, useTranslation } from "react-i18next";
 import ExportModal from "@/components/common/export-modal";
 import { htmlToMarkdown } from "@docmost/editor-ext";
 import {
+  collabProviderAtom,
   pageEditorAtom,
   yjsConnectionStatusAtom,
 } from "@/features/editor/atoms/editor-atoms.ts";
+import {
+  SAVE_VERSION_MESSAGE_TYPE,
+  saveVersionPending,
+} from "@/features/page-history/version-messages.ts";
 import { formattedDate } from "@/lib/time.ts";
 import { PageEditModeToggle } from "@/features/user/components/page-state-pref.tsx";
 import MovePageModal from "@/features/page/components/move-page-modal.tsx";
@@ -72,9 +78,34 @@ export default function PageHeaderMenu({ readOnly }: PageHeaderMenuProps) {
   });
   const isDeleted = !!page?.deletedAt;
   const [workspace] = useAtom(workspaceAtom);
+  const collabProvider = useAtomValue(collabProviderAtom);
   // Community public-sharing entry point (replaces the removed EE PageShareModal)
   const workspaceSharingDisabled = workspace?.settings?.sharing?.disabled === true;
 
+  // #370 — explicit "save a version" (Cmd+S / Save button). One path for the
+  // human; the server derives the tier from the signed actor. Readers can't save
+  // (the button is hidden and the collab connection is read-only server-side).
+  const handleSaveVersion = useCallback(() => {
+    if (readOnly || !collabProvider) return;
+    // Flag this client as the initiator so only it shows the confirmation toast;
+    // a safety timeout clears it if no broadcast comes back (e.g. offline).
+    saveVersionPending.current = true;
+    window.setTimeout(() => {
+      saveVersionPending.current = false;
+    }, 5000);
+    collabProvider.sendStateless(
+      JSON.stringify({ type: SAVE_VERSION_MESSAGE_TYPE }),
+    );
+  }, [readOnly, collabProvider]);
+
+  // mod+S must also block the browser's "Save page" dialog. `triggerOnContent-
+  // Editable` + empty ignore-list so it fires while typing in the editor/title.
+  useHotkeys(
+    [["mod+S", handleSaveVersion, { preventDefault: true }]],
+    [],
+    true,
+  );
+
   useHotkeys(
     [
       [
@@ -133,15 +164,16 @@ export default function PageHeaderMenu({ readOnly }: PageHeaderMenuProps) {
         </ActionIcon>
       </Tooltip>
 
-      <PageActionMenu readOnly={readOnly} />
+      <PageActionMenu readOnly={readOnly} onSaveVersion={handleSaveVersion} />
     </>
   );
 }
 
 interface PageActionMenuProps {
   readOnly?: boolean;
+  onSaveVersion?: () => void;
 }
-function PageActionMenu({ readOnly }: PageActionMenuProps) {
+function PageActionMenu({ readOnly, onSaveVersion }: PageActionMenuProps) {
   const { t } = useTranslation();
   const [, setHistoryModalOpen] = useAtom(historyAtoms);
   const clipboard = useClipboard({ timeout: 500 });
@@ -302,6 +334,20 @@ function PageActionMenu({ readOnly }: PageActionMenuProps) {
             </Group>
           </Menu.Item>
 
+          {!readOnly && (
+            <Menu.Item
+              leftSection={<IconDeviceFloppy size={16} />}
+              onClick={onSaveVersion}
+              rightSection={
+                <Text size="xs" c="dimmed">
+                  {t("Ctrl+S")}
+                </Text>
+              }
+            >
+              {t("Save version")}
+            </Menu.Item>
+          )}
+
           <Menu.Item
             leftSection={<IconHistory size={16} />}
             onClick={openHistoryModal}
diff --git a/apps/server/src/collaboration/constants.ts b/apps/server/src/collaboration/constants.ts
index 8ce8c825..315d70ba 100644
--- a/apps/server/src/collaboration/constants.ts
+++ b/apps/server/src/collaboration/constants.ts
@@ -1,3 +1,29 @@
-export const HISTORY_INTERVAL = 5 * 60 * 1000;
-export const HISTORY_FAST_INTERVAL = 60 * 1000;
-export const HISTORY_FAST_THRESHOLD = 5 * 60 * 1000;
+/**
+ * #370 — page-history intentionality tiers. Domain of `page_history.kind`.
+ *   - 'manual' / 'agent'  → Tier 1 versions (intentional points)
+ *   - 'idle' / 'boundary' → Tier 0 autosnapshots (safety net)
+ * A legacy `null` kind is treated as an autosave.
+ */
+export type PageHistoryKind = 'manual' | 'agent' | 'idle' | 'boundary';
+
+/**
+ * #370 — trailing idle-flush windows. A page's pending idle snapshot is
+ * re-armed on every store and fires this long after edits go quiet, so a burst
+ * of edits collapses into a single autosnapshot instead of one-per-store. Human
+ * sessions are noisier and less risky, so they flush less often than the agent.
+ */
+export const IDLE_INTERVAL_USER = 60 * 60 * 1000; // 60m
+export const IDLE_INTERVAL_AGENT = 15 * 60 * 1000; // 15m
+
+/**
+ * #370 — max-wait ceiling for the idle flush. Pure trailing debounce starves the
+ * safety net: hocuspocus stores at least every ~45s, so a CONTINUOUS editing
+ * session would re-arm the trailing timer forever and never take an idle
+ * snapshot until edits finally go quiet (up to IDLE_INTERVAL_USER = 60m). This
+ * ceiling bounds the actual wait from the FIRST edit of a burst, so an idle
+ * snapshot fires at least this often during a long unbroken session — restoring
+ * a recovery point cadence closer to the old heuristic without one-per-store
+ * noise. Mirrors hocuspocus's own maxDebounce idea.
+ */
+export const IDLE_MAX_WAIT_USER = 10 * 60 * 1000; // 10m
+export const IDLE_MAX_WAIT_AGENT = 5 * 60 * 1000; // 5m
diff --git a/apps/server/src/collaboration/extensions/compute-history-job.spec.ts b/apps/server/src/collaboration/extensions/compute-history-job.spec.ts
index aa21f14f..cd1d3711 100644
--- a/apps/server/src/collaboration/extensions/compute-history-job.spec.ts
+++ b/apps/server/src/collaboration/extensions/compute-history-job.spec.ts
@@ -1,84 +1,93 @@
+import { computeHistoryJob, resolveSource } from './persistence.extension';
 import {
-  computeHistoryJob,
-  resolveSource,
-} from './persistence.extension';
-import {
-  HISTORY_FAST_INTERVAL,
-  HISTORY_FAST_THRESHOLD,
-  HISTORY_INTERVAL,
+  IDLE_INTERVAL_AGENT,
+  IDLE_INTERVAL_USER,
+  IDLE_MAX_WAIT_AGENT,
+  IDLE_MAX_WAIT_USER,
 } from '../constants';
 
-// A fixed clock + fixed createdAt make pageAge deterministic.
-const NOW = 1_700_000_000_000;
 const PAGE_ID = '550e8400-e29b-41d4-a716-446655440000';
 
-// Build a minimal page whose age (NOW - createdAt) is exactly `ageMs`.
-const pageAged = (ageMs: number) => ({
-  id: PAGE_ID,
-  createdAt: new Date(NOW - ageMs),
-});
+const page = { id: PAGE_ID };
 
-describe('computeHistoryJob', () => {
-  it('agent edit → delay MUST be 0 and job id is source-keyed', () => {
-    // INVARIANT (§15 H2 / persistence.extension): the agent delay MUST stay 0.
-    // The worker re-reads the page row at run time, so any non-zero delay risks
-    // snapshotting content a later human edit has already overwritten. This is
-    // the load-bearing assertion of this spec — do not relax it.
-    const { jobId, delay } = computeHistoryJob(pageAged(0), 'agent', NOW);
-    expect(delay).toBe(0);
-    expect(jobId).toBe(`${PAGE_ID}-agent`);
-  });
-
-  it('agent edit on an OLD page is still delay 0 (age never applies to agents)', () => {
-    // Even when the page is far older than the fast threshold, the agent path
-    // must short-circuit to 0 — age-based debounce is a human-only concern.
-    const { jobId, delay } = computeHistoryJob(
-      pageAged(HISTORY_FAST_THRESHOLD + 60_000),
-      'agent',
-      NOW,
-    );
-    expect(delay).toBe(0);
-    expect(jobId).toBe(`${PAGE_ID}-agent`);
-  });
-
-  it('human edit on a YOUNG page (age < threshold) → fast interval, bare job id', () => {
-    const { jobId, delay } = computeHistoryJob(
-      pageAged(HISTORY_FAST_THRESHOLD - 1),
-      'user',
-      NOW,
-    );
-    expect(delay).toBe(HISTORY_FAST_INTERVAL);
+describe('computeHistoryJob (#370 — shared trailing idle pipeline)', () => {
+  it('human edit → user idle window, bare page.id job', () => {
+    // Humans and the agent now share ONE idle job per page (jobId = page.id).
+    // The agent's old delay=0 fast path is GONE — intentional agent points now
+    // arrive via the explicit save-version signal, not a zero-delay snapshot.
+    const { jobId, delay } = computeHistoryJob(page, 'user');
+    expect(delay).toBe(IDLE_INTERVAL_USER);
     expect(jobId).toBe(PAGE_ID);
   });
 
-  it('human edit on an OLD page (age > threshold) → standard interval', () => {
-    const { jobId, delay } = computeHistoryJob(
-      pageAged(HISTORY_FAST_THRESHOLD + 1),
-      'user',
-      NOW,
-    );
-    expect(delay).toBe(HISTORY_INTERVAL);
+  it('agent edit → agent idle window (shorter), still the bare page.id job', () => {
+    const { jobId, delay } = computeHistoryJob(page, 'agent');
+    expect(delay).toBe(IDLE_INTERVAL_AGENT);
+    // No `-agent` suffix anymore: the agent joins the common idle pipeline.
     expect(jobId).toBe(PAGE_ID);
   });
 
-  it('boundary: pageAge EXACTLY === threshold takes the slow branch (the `<` is strict)', () => {
-    // Off-by-one guard: the condition is `pageAge < HISTORY_FAST_THRESHOLD`, so
-    // an age of exactly the threshold is NOT "fast" — it must use HISTORY_INTERVAL.
-    const { delay } = computeHistoryJob(
-      pageAged(HISTORY_FAST_THRESHOLD),
-      'user',
-      NOW,
-    );
-    expect(delay).toBe(HISTORY_INTERVAL);
+  it('agent flushes sooner than a human', () => {
+    expect(IDLE_INTERVAL_AGENT).toBeLessThan(IDLE_INTERVAL_USER);
   });
 
-  it('treats any non-"agent" source string as human', () => {
-    // resolveSource only ever yields 'agent' | 'user', but guard the contract:
-    // the agent branch keys strictly on === 'agent'.
-    const { jobId, delay } = computeHistoryJob(pageAged(0), 'user', NOW);
-    expect(delay).toBe(HISTORY_FAST_INTERVAL);
+  it('treats any non-"agent" source string as human (keys strictly on === agent)', () => {
+    const { jobId, delay } = computeHistoryJob(page, 'user');
+    expect(delay).toBe(IDLE_INTERVAL_USER);
     expect(jobId).toBe(PAGE_ID);
   });
+
+  // #370 review round-1 WARNING: the max-wait ceiling prevents autosnapshot
+  // starvation during a continuous editing session (the trailing timer would
+  // otherwise re-arm forever and never fire).
+  describe('max-wait ceiling', () => {
+    const T0 = 1_000_000; // arbitrary fixed epoch for deterministic tests
+
+    it('early in the burst, the full trailing interval is used', () => {
+      // 1 minute into the burst: remaining budget (10m - 1m = 9m) still exceeds
+      // nothing that clamps it below the interval only if interval > remaining.
+      // For USER, interval 60m > remaining 9m, so delay clamps to the remaining.
+      const { delay } = computeHistoryJob(page, 'user', T0, T0 + 60_000);
+      expect(delay).toBe(IDLE_MAX_WAIT_USER - 60_000);
+    });
+
+    it('never waits longer than the max-wait budget from the burst start', () => {
+      // A store arriving right at the ceiling → delay 0 (fire promptly).
+      const { delay } = computeHistoryJob(
+        page,
+        'user',
+        T0,
+        T0 + IDLE_MAX_WAIT_USER,
+      );
+      expect(delay).toBe(0);
+    });
+
+    it('past the ceiling never returns a negative delay', () => {
+      const { delay } = computeHistoryJob(
+        page,
+        'user',
+        T0,
+        T0 + IDLE_MAX_WAIT_USER + 5 * 60_000,
+      );
+      expect(delay).toBe(0);
+    });
+
+    it('the agent ceiling is shorter than the user ceiling', () => {
+      expect(IDLE_MAX_WAIT_AGENT).toBeLessThan(IDLE_MAX_WAIT_USER);
+      const { delay } = computeHistoryJob(
+        page,
+        'agent',
+        T0,
+        T0 + IDLE_MAX_WAIT_AGENT,
+      );
+      expect(delay).toBe(0);
+    });
+
+    it('without a burstStart there is no ceiling (backward-compatible)', () => {
+      expect(computeHistoryJob(page, 'user').delay).toBe(IDLE_INTERVAL_USER);
+      expect(computeHistoryJob(page, 'agent').delay).toBe(IDLE_INTERVAL_AGENT);
+    });
+  });
 });
 
 describe('resolveSource (truth table)', () => {
diff --git a/apps/server/src/collaboration/extensions/persistence-store.spec.ts b/apps/server/src/collaboration/extensions/persistence-store.spec.ts
index e707290f..73dbbe3c 100644
--- a/apps/server/src/collaboration/extensions/persistence-store.spec.ts
+++ b/apps/server/src/collaboration/extensions/persistence-store.spec.ts
@@ -40,11 +40,12 @@ describe('PersistenceExtension.onStoreDocument — Approach-A boundary snapshot'
   let pageHistoryRepo: {
     saveHistory: jest.Mock;
     findPageLastHistory: jest.Mock;
+    updateHistoryKind: jest.Mock;
   };
   let aiQueue: { add: jest.Mock };
-  let historyQueue: { add: jest.Mock };
+  let historyQueue: { add: jest.Mock; remove: jest.Mock };
   let notificationQueue: { add: jest.Mock };
-  let collabHistory: { addContributors: jest.Mock };
+  let collabHistory: { addContributors: jest.Mock; popContributors: jest.Mock };
   let transclusionService: {
     syncPageTransclusions: jest.Mock;
     syncPageReferences: jest.Mock;
@@ -93,13 +94,22 @@ describe('PersistenceExtension.onStoreDocument — Approach-A boundary snapshot'
     pageHistoryRepo = {
       saveHistory: jest.fn().mockImplementation(async () => {
         callOrder.push('saveHistory');
+        return { id: 'history-1' };
       }),
       findPageLastHistory: jest.fn().mockResolvedValue(null),
+      updateHistoryKind: jest.fn().mockResolvedValue(undefined),
     };
     aiQueue = { add: jest.fn().mockResolvedValue(undefined) };
-    historyQueue = { add: jest.fn().mockResolvedValue(undefined) };
+    historyQueue = {
+      add: jest.fn().mockResolvedValue(undefined),
+      // #370 — enqueuePageHistory now removes any pending idle job before re-adding.
+      remove: jest.fn().mockResolvedValue(undefined),
+    };
     notificationQueue = { add: jest.fn().mockResolvedValue(undefined) };
-    collabHistory = { addContributors: jest.fn().mockResolvedValue(undefined) };
+    collabHistory = {
+      addContributors: jest.fn().mockResolvedValue(undefined),
+      popContributors: jest.fn().mockResolvedValue([]),
+    };
     transclusionService = {
       syncPageTransclusions: jest.fn().mockResolvedValue(undefined),
       syncPageReferences: jest.fn().mockResolvedValue(undefined),
@@ -165,6 +175,50 @@ describe('PersistenceExtension.onStoreDocument — Approach-A boundary snapshot'
     expect(pageRepo.updatePage.mock.calls[0][0].lastUpdatedSource).toBe('user');
   });
 
+  // #370 review round-1 SUGGESTION: the boundary was GENERALIZED from a
+  // user→agent special-case to ANY lastUpdatedSource transition. These pin the
+  // generalized behaviour it was rebuilt for.
+  describe('generalized boundary — any source transition', () => {
+    // Same persisted page but with an explicit prior source.
+    const pageWithPriorSource = (prior: string | null) => ({
+      ...persistedHumanPage('NEW CONTENT'),
+      lastUpdatedSource: prior,
+    });
+
+    it('agent→user transition fires the boundary (pins the prior agent revision)', async () => {
+      const document = ydocFor(doc('NEW CONTENT'));
+      pageRepo.findById.mockResolvedValue(pageWithPriorSource('agent'));
+      pageHistoryRepo.findPageLastHistory.mockResolvedValue(null);
+
+      await ext.onStoreDocument(buildData(document, 'user') as any);
+
+      expect(pageHistoryRepo.saveHistory).toHaveBeenCalledTimes(1);
+      expect(callOrder).toEqual(['saveHistory', 'updatePage']);
+      expect(pageRepo.updatePage.mock.calls[0][0].lastUpdatedSource).toBe('user');
+    });
+
+    it('git→user transition fires the boundary (git-sync overwrite is a source change)', async () => {
+      const document = ydocFor(doc('NEW CONTENT'));
+      pageRepo.findById.mockResolvedValue(pageWithPriorSource('git'));
+      pageHistoryRepo.findPageLastHistory.mockResolvedValue(null);
+
+      await ext.onStoreDocument(buildData(document, 'user') as any);
+
+      expect(pageHistoryRepo.saveHistory).toHaveBeenCalledTimes(1);
+      expect(callOrder).toEqual(['saveHistory', 'updatePage']);
+    });
+
+    it('a null prior source (first-ever edit) does NOT fire the boundary', async () => {
+      const document = ydocFor(doc('NEW CONTENT'));
+      pageRepo.findById.mockResolvedValue(pageWithPriorSource(null));
+
+      await ext.onStoreDocument(buildData(document, 'agent') as any);
+
+      expect(pageHistoryRepo.saveHistory).not.toHaveBeenCalled();
+      expect(pageRepo.updatePage).toHaveBeenCalledTimes(1);
+    });
+  });
+
   it('idempotency: unchanged content → no updatePage, no history, no queues', async () => {
     // The Y.Doc content equals the persisted content deeply → early skip.
     // A Y.Doc round-trip normalizes attrs (e.g. paragraph indent), so derive
@@ -469,4 +523,125 @@ describe('PersistenceExtension.onStoreDocument — Approach-A boundary snapshot'
     // Contributors keyed by the UUID so they match the PAGE_HISTORY job (page.id).
     expect(collabHistory.addContributors.mock.calls[0][0]).toBe(PAGE_ID);
   });
+
+  // #370 — explicit save-version (Cmd+S / agent save tool) over the stateless
+  // seam. The tier is derived from the SIGNED connection actor, the store path
+  // is reused, and promote-not-dup avoids duplicating heavy content rows.
+  describe('save-version (#370)', () => {
+    const emitSave = (document: any, actor: 'user' | 'agent') =>
+      ext.onStateless({
+        connection: {
+          readOnly: false,
+          context: { user: { id: USER_ID, name: 'Alice' }, actor },
+        } as any,
+        documentName: `page.${PAGE_ID}`,
+        document: document as any,
+        payload: JSON.stringify({ type: 'save-version' }),
+      } as any);
+
+    // findById returns a page whose content already equals the live doc, so the
+    // store path is a no-op and we isolate the versioning decision.
+    const pageMatchingDoc = (document: any) => ({
+      ...persistedHumanPage('IGNORED'),
+      content: TiptapTransformer.fromYdoc(document, 'default'),
+    });
+
+    it('human save with no prior snapshot → writes a manual version + broadcasts', async () => {
+      const document = ydocFor(doc('VERSION ME'));
+      pageRepo.findById.mockResolvedValue(pageMatchingDoc(document));
+      pageHistoryRepo.findPageLastHistory.mockResolvedValue(null);
+
+      await emitSave(document, 'user');
+
+      expect(pageHistoryRepo.saveHistory).toHaveBeenCalledTimes(1);
+      expect(pageHistoryRepo.saveHistory.mock.calls[0][1]).toEqual(
+        expect.objectContaining({ kind: 'manual' }),
+      );
+      // The pending idle autosnapshot is cancelled by the explicit version.
+      expect(historyQueue.remove).toHaveBeenCalledWith(PAGE_ID);
+      const msg = JSON.parse(
+        (document as any).broadcastStateless.mock.calls.at(-1)[0],
+      );
+      expect(msg).toMatchObject({
+        type: 'version.saved',
+        kind: 'manual',
+        alreadySaved: false,
+      });
+    });
+
+    it('agent save derives kind=agent from the signed actor', async () => {
+      const document = ydocFor(doc('AGENT VERSION'));
+      pageRepo.findById.mockResolvedValue(pageMatchingDoc(document));
+      pageHistoryRepo.findPageLastHistory.mockResolvedValue(null);
+
+      await emitSave(document, 'agent');
+
+      expect(pageHistoryRepo.saveHistory.mock.calls.at(-1)[1]).toEqual(
+        expect.objectContaining({ kind: 'agent' }),
+      );
+    });
+
+    it('promote-not-dup: latest snapshot is an autosave with identical content → upgrades in place', async () => {
+      const document = ydocFor(doc('SAME'));
+      const page = pageMatchingDoc(document);
+      pageRepo.findById.mockResolvedValue(page);
+      pageHistoryRepo.findPageLastHistory.mockResolvedValue({
+        id: 'auto-1',
+        content: page.content,
+        kind: 'idle',
+      });
+
+      await emitSave(document, 'user');
+
+      // No heavy new content row — the existing autosave is promoted to manual.
+      expect(pageHistoryRepo.updateHistoryKind).toHaveBeenCalledWith(
+        'auto-1',
+        'manual',
+        expect.anything(),
+      );
+      expect(pageHistoryRepo.saveHistory).not.toHaveBeenCalled();
+      const msg = JSON.parse(
+        (document as any).broadcastStateless.mock.calls.at(-1)[0],
+      );
+      expect(msg).toMatchObject({ historyId: 'auto-1', alreadySaved: false });
+    });
+
+    it('no-op when the latest snapshot is already a manual version of this content', async () => {
+      const document = ydocFor(doc('ALREADY SAVED'));
+      const page = pageMatchingDoc(document);
+      pageRepo.findById.mockResolvedValue(page);
+      pageHistoryRepo.findPageLastHistory.mockResolvedValue({
+        id: 'ver-1',
+        content: page.content,
+        kind: 'manual',
+      });
+
+      await emitSave(document, 'user');
+
+      expect(pageHistoryRepo.updateHistoryKind).not.toHaveBeenCalled();
+      expect(pageHistoryRepo.saveHistory).not.toHaveBeenCalled();
+      const msg = JSON.parse(
+        (document as any).broadcastStateless.mock.calls.at(-1)[0],
+      );
+      expect(msg).toMatchObject({ alreadySaved: true, kind: 'manual' });
+    });
+
+    it('a read-only connection cannot save a version', async () => {
+      const document = ydocFor(doc('READER'));
+      pageRepo.findById.mockResolvedValue(pageMatchingDoc(document));
+
+      await ext.onStateless({
+        connection: {
+          readOnly: true,
+          context: { user: { id: USER_ID }, actor: 'user' },
+        } as any,
+        documentName: `page.${PAGE_ID}`,
+        document: document as any,
+        payload: JSON.stringify({ type: 'save-version' }),
+      } as any);
+
+      expect(pageHistoryRepo.saveHistory).not.toHaveBeenCalled();
+      expect(pageHistoryRepo.updateHistoryKind).not.toHaveBeenCalled();
+    });
+  });
 });
diff --git a/apps/server/src/collaboration/extensions/persistence.extension.ts b/apps/server/src/collaboration/extensions/persistence.extension.ts
index 35310cf4..3c4de6cb 100644
--- a/apps/server/src/collaboration/extensions/persistence.extension.ts
+++ b/apps/server/src/collaboration/extensions/persistence.extension.ts
@@ -36,9 +36,11 @@ import {
 import { Page } from '@docmost/db/types/entity.types';
 import { CollabHistoryService } from '../services/collab-history.service';
 import {
-  HISTORY_FAST_INTERVAL,
-  HISTORY_FAST_THRESHOLD,
-  HISTORY_INTERVAL,
+  IDLE_INTERVAL_AGENT,
+  IDLE_INTERVAL_USER,
+  IDLE_MAX_WAIT_AGENT,
+  IDLE_MAX_WAIT_USER,
+  PageHistoryKind,
 } from '../constants';
 import { TransclusionService } from '../../core/page/transclusion/transclusion.service';
 import { observeCollabStore } from '../../integrations/metrics/metrics.registry';
@@ -51,6 +53,16 @@ import { observeCollabStore } from '../../integrations/metrics/metrics.registry'
  */
 export const INTENTIONAL_CLEAR_MESSAGE_TYPE = 'intentional-clear';
 
+/**
+ * #370 — wire format of the client→server "save a version" signal. Sent by the
+ * human (Cmd+S / Save button) and by the agent's explicit save tool over the
+ * SAME stateless channel. The intentionality tier ('manual' vs 'agent') is
+ * derived SERVER-SIDE from the signed connection actor, never from this
+ * payload, so a version's type is unforgeable. The document is taken from the
+ * connection (not the payload), so the signal cannot be aimed at another page.
+ */
+export const SAVE_VERSION_MESSAGE_TYPE = 'save-version';
+
 /**
  * #251 — how long an intentional-clear signal stays "pending" before it is
  * ignored. The signal is set on the clearing keystroke but consumed by the
@@ -87,35 +99,39 @@ export function resolveSource(
 }
 
 /**
- * Compute the BullMQ job id + delay for a page-history snapshot job. Pure so
- * the data-loss-sensitive timing arithmetic is unit-testable; `now` is injected
- * (caller passes `Date.now()`) for determinism.
+ * #370 — compute the BullMQ job id + delay for a page's trailing idle-flush
+ * autosnapshot. Pure so the timing is unit-testable.
  *
- * - Agent edits: delay 0 and a source-keyed job id `${page.id}-agent`. The
- *   delay MUST stay 0 — the worker re-reads the page row at run time, so any
- *   delay risks reading content a later human edit has already overwritten
- *   (mis-tagged snapshot). 0 minimizes that window. The `-agent` suffix keeps
- *   the job from coalescing with the bare-page.id human job.
- * - Human edits: age-based debounce so rapid human edits coalesce into one
- *   snapshot; job id is the bare `page.id`.
- *
- * BullMQ forbids ':' in custom job ids (Redis key separator), so '-' is used;
- * page.id is a UUID, so `${page.id}-agent` cannot collide with a human job.
+ * Both humans and the agent now share ONE idle pipeline (the agent's old
+ * `delay=0` fast path is gone — intentional agent points arrive via the
+ * explicit save-version signal instead). The job id is the bare `page.id`, so a
+ * page has at most one pending idle job; the caller removes-and-re-adds it on
+ * every store to keep it debounced to the trailing edge of an edit burst. The
+ * window differs by source only: the agent flushes sooner than a human.
  */
 export function computeHistoryJob(
-  page: Pick<Page, 'id' | 'createdAt'>,
+  page: Pick<Page, 'id'>,
   source: string,
-  now: number,
+  // Epoch ms of the FIRST edit in the current burst (when the pending idle job
+  // was first armed). Used to enforce the max-wait ceiling so a continuous
+  // editing session cannot re-arm the trailing timer forever. `now` is injectable
+  // for tests; both default to a live clock / no ceiling when omitted.
+  burstStart?: number,
+  now: number = Date.now(),
 ): { jobId: string; delay: number } {
   const isAgent = source === 'agent';
-  const pageAge = now - new Date(page.createdAt).getTime();
-  const delay = isAgent
-    ? 0
-    : pageAge < HISTORY_FAST_THRESHOLD
-      ? HISTORY_FAST_INTERVAL
-      : HISTORY_INTERVAL;
-  const jobId = isAgent ? `${page.id}-agent` : page.id;
-  return { jobId, delay };
+  const interval = isAgent ? IDLE_INTERVAL_AGENT : IDLE_INTERVAL_USER;
+  const maxWait = isAgent ? IDLE_MAX_WAIT_AGENT : IDLE_MAX_WAIT_USER;
+
+  let delay = interval;
+  if (burstStart !== undefined) {
+    // Time already elapsed since the burst's first edit; the snapshot must fire
+    // no later than `maxWait` after that, so shrink the trailing delay to the
+    // remaining budget (never negative, so BullMQ fires it promptly).
+    const remaining = burstStart + maxWait - now;
+    delay = Math.max(0, Math.min(interval, remaining));
+  }
+  return { jobId: page.id, delay };
 }
 
 @Injectable()
@@ -127,6 +143,11 @@ export class PersistenceExtension implements Extension {
   // coalescing window" per document and OR it across all edits in the window,
   // so the snapshot is marked 'agent' regardless of who wrote last.
   private agentTouched: Map<string, boolean> = new Map();
+  // #370 — epoch ms of the FIRST edit in the current idle-flush burst, per page.
+  // Set when the pending idle job is first armed (empty entry), read to enforce
+  // the max-wait ceiling in computeHistoryJob, and cleared when the idle job is
+  // consumed/cancelled so the next burst starts a fresh window.
+  private idleBurstStart: Map<string, number> = new Map();
   // #251 — per-document "intentional clear pending" flags. Keyed by
   // documentName, value = expiry timestamp (ms). Set by onStateless when the
   // client reports a deliberate clear; consumed once by the next
@@ -326,20 +347,19 @@ export class PersistenceExtension implements Extension {
             //this.logger.debug('Contributors error:' + err?.['message']);
           }
 
-          // Approach A — boundary snapshot before the agent's first edit.
-          // When this store is the agent's and the page's currently persisted
-          // state was authored by a human, pin that human state as its own
-          // history version BEFORE the agent overwrites it. `page` still holds
-          // the OLD content/provenance here, so saveHistory(page) captures the
-          // pre-agent state tagged 'user'. The agent's new content is
-          // snapshotted later by the debounced PAGE_HISTORY job ('agent'). Skip
-          // if the prior state is already agent-authored (boundary already
-          // pinned on the user->agent transition), if the page is effectively
-          // empty, or if the latest existing snapshot already equals this human
-          // state (avoid duplicates).
+          // #370 — boundary snapshot on ANY source transition. When the store
+          // flips the page's provenance (user↔agent↔git), pin the OUTGOING
+          // state as its own history version BEFORE the incoming source
+          // overwrites it. `page` still holds the OLD content/provenance here,
+          // so saveHistory(page) captures the pre-transition state tagged with
+          // its own source, kind='boundary'. The incoming content is snapshotted
+          // later by the debounced idle job. Skip if the page is effectively
+          // empty or if the latest existing snapshot already equals this state
+          // (the shared isDeepStrictEqual gate — avoids duplicates). Generalizing
+          // beyond the old user→agent special-case also covers git-sync for free.
           if (
-            lastUpdatedSource === 'agent' &&
-            page.lastUpdatedSource !== 'agent'
+            page.lastUpdatedSource &&
+            page.lastUpdatedSource !== lastUpdatedSource
           ) {
             // pageHistory.pageId is uuid-typed; use page.id (never the doc-name
             // slugId) so a `page.<slugId>` doc cannot throw 22P02 here (#260).
@@ -347,15 +367,13 @@ export class PersistenceExtension implements Extension {
               page.id,
               { includeContent: true, trx },
             );
-            const humanBaselineMissing =
+            const baselineMissing =
               !lastHistory ||
               !isDeepStrictEqual(lastHistory.content, page.content);
-            if (
-              !isEmptyParagraphDoc(page.content as any) &&
-              humanBaselineMissing
-            ) {
+            if (!isEmptyParagraphDoc(page.content as any) && baselineMissing) {
               await this.pageHistoryRepo.saveHistory(page, {
                 contributorIds: page.contributorIds ?? undefined,
+                kind: 'boundary',
                 trx,
               });
             }
@@ -480,6 +498,14 @@ export class PersistenceExtension implements Extension {
       return; // unrelated / malformed stateless message
     }
 
+    // #370 — explicit "save a version" (human Cmd+S / agent save tool). Edit
+    // rights are already enforced by the readOnly reject above (a reader can't
+    // create a version), exactly as intentional-clear requires.
+    if (message?.type === SAVE_VERSION_MESSAGE_TYPE) {
+      await this.handleSaveVersion(data);
+      return;
+    }
+
     if (message?.type !== INTENTIONAL_CLEAR_MESSAGE_TYPE) return;
 
     this.intentionalClear.set(
@@ -488,6 +514,117 @@ export class PersistenceExtension implements Extension {
     );
   }
 
+  /**
+   * #370 — persist an intentional version from the live in-memory ydoc.
+   *
+   * One stateless path serves BOTH the human and the agent; the tier is derived
+   * SERVER-SIDE from the signed connection actor ('agent' → 'agent', anything
+   * else → 'manual'), so the version type cannot be spoofed by the client. We
+   * take the fresh ydoc from the collab process memory and run it through the
+   * EXISTING store path first (so pages.content/ydoc reflect the exact content
+   * being versioned — a REST endpoint would race the up-to-10s-stale page row),
+   * then snapshot it into page_history with the intentional kind.
+   *
+   * Promote-not-dup: if the latest history row already holds this exact content
+   * and it is an autosave (idle/boundary/legacy-null), upgrade its kind in place
+   * instead of duplicating a heavy content row; if it is already 'manual', it is
+   * a no-op (the client shows an "already saved" toast). Otherwise a fresh
+   * version row is written, popping the aggregated contributors from Redis.
+   */
+  private async handleSaveVersion(data: onStatelessPayload): Promise<void> {
+    const { connection, document, documentName } = data;
+    const context = connection?.context;
+    const pageId = getPageId(documentName);
+    // Unforgeable: 'agent' only for a signed agent connection, else 'manual'.
+    const kind: PageHistoryKind =
+      context?.actor === 'agent' ? 'agent' : 'manual';
+
+    // Flush the live ydoc through the normal store path so the page row + ydoc
+    // hold exactly what we are about to version (also fires the idle enqueue we
+    // supersede below, plus any source-transition boundary). onStoreDocument
+    // only needs document/documentName/context.
+    await this.onStoreDocument({
+      document,
+      documentName,
+      context,
+    } as onStoreDocumentPayload);
+
+    let result:
+      | { historyId: string; kind: PageHistoryKind; alreadySaved: boolean }
+      | undefined;
+
+    await executeTx(this.db, async (trx) => {
+      const page = await this.pageRepo.findById(pageId, {
+        withLock: true,
+        includeContent: true,
+        trx,
+      });
+      if (!page) return;
+      // Never version an effectively-empty page (mirrors the processor's
+      // first-history guard); there is nothing intentional to pin.
+      if (isEmptyParagraphDoc(page.content as any)) return;
+
+      const lastHistory = await this.pageHistoryRepo.findPageLastHistory(
+        page.id,
+        { includeContent: true, trx },
+      );
+
+      if (
+        lastHistory &&
+        isDeepStrictEqual(lastHistory.content, page.content)
+      ) {
+        // Content is already snapshotted. Promote-not-dup.
+        if (lastHistory.kind === 'manual') {
+          result = {
+            historyId: lastHistory.id,
+            kind: 'manual',
+            alreadySaved: true,
+          };
+          return;
+        }
+        await this.pageHistoryRepo.updateHistoryKind(
+          lastHistory.id,
+          kind,
+          trx,
+        );
+        result = { historyId: lastHistory.id, kind, alreadySaved: false };
+        return;
+      }
+
+      // Fresh version row. Pop the contributors aggregated since the last
+      // snapshot (SPOP); restore them if the write fails so they aren't lost.
+      const contributorIds = await this.collabHistory.popContributors(page.id);
+      try {
+        const saved = await this.pageHistoryRepo.saveHistory(page, {
+          contributorIds,
+          kind,
+          trx,
+        });
+        result = { historyId: saved.id, kind, alreadySaved: false };
+      } catch (err) {
+        await this.collabHistory.addContributors(page.id, contributorIds);
+        throw err;
+      }
+    });
+
+    // Housekeeping: this explicit version supersedes the page's pending idle
+    // autosnapshot, so cancel it (delayed job → remove() just deletes it) and
+    // end the current idle burst so the next edit starts a fresh max-wait window.
+    await this.historyQueue.remove(pageId).catch(() => undefined);
+    this.idleBurstStart.delete(pageId);
+
+    if (result) {
+      document.broadcastStateless(
+        JSON.stringify({
+          type: 'version.saved',
+          historyId: result.historyId,
+          kind: result.kind,
+          alreadySaved: result.alreadySaved,
+        }),
+      );
+    }
+  }
+
   async onChange(data: onChangePayload) {
     const documentName = data.documentName;
     const userId = data.context?.user?.id;
@@ -545,17 +682,39 @@ export class PersistenceExtension implements Extension {
     page: Page,
     lastUpdatedSource: string,
   ): Promise<void> {
-    // Job id + delay arithmetic lives in the pure `computeHistoryJob` (see its
-    // doc comment for the agent-delay-0 / age-based-debounce invariants).
+    // #370 — trailing idle debounce with a max-wait ceiling. One pending idle
+    // job per page (jobId = page.id); on every store we remove the pending
+    // delayed job and re-add it, so the snapshot lands `delay` after edits go
+    // quiet rather than once per store (precedent: workspace.service.ts).
+    // remove() on a delayed job simply deletes it (0 if absent, no throw); if the
+    // job is already ACTIVE and the remove is a no-op, the add still de-dups and
+    // the processor's isDeepStrictEqual gate collapses the duplicate content.
+    //
+    // The FIRST arm of a burst records `burstStart`; computeHistoryJob shrinks
+    // the delay to the remaining max-wait budget from that point, so a continuous
+    // session cannot re-arm the trailing timer forever and starve the snapshot.
+    // A burst marker older than the (larger, USER) max-wait means the previous
+    // idle job has already fired — start a fresh window instead of firing
+    // immediately on the next edit.
+    const now = Date.now();
+    let burstStart = this.idleBurstStart.get(page.id);
+    if (burstStart === undefined || now - burstStart >= IDLE_MAX_WAIT_USER) {
+      burstStart = now;
+      this.idleBurstStart.set(page.id, burstStart);
+    }
+
     const { jobId, delay } = computeHistoryJob(
       page,
       lastUpdatedSource,
-      Date.now(),
+      burstStart,
+      now,
     );
 
+    await this.historyQueue.remove(jobId).catch(() => undefined);
+
     await this.historyQueue.add(
       QueueJob.PAGE_HISTORY,
-      { pageId: page.id } as IPageHistoryJob,
+      { pageId: page.id, kind: 'idle' } as IPageHistoryJob,
       { jobId, delay },
     );
   }
diff --git a/apps/server/src/collaboration/processors/history.processor.spec.ts b/apps/server/src/collaboration/processors/history.processor.spec.ts
index bdcf846e..ecd44248 100644
--- a/apps/server/src/collaboration/processors/history.processor.spec.ts
+++ b/apps/server/src/collaboration/processors/history.processor.spec.ts
@@ -134,7 +134,7 @@ describe('HistoryProcessor.process', () => {
     );
     expect(pageHistoryRepo.saveHistory).toHaveBeenCalledWith(
       expect.objectContaining({ id: PAGE_ID }),
-      { contributorIds: ['u1', 'u2'] },
+      { contributorIds: ['u1', 'u2'], kind: 'idle' },
     );
     expect(generalQueue.add).toHaveBeenCalledWith(
       QueueJob.PAGE_BACKLINKS,
diff --git a/apps/server/src/collaboration/processors/history.processor.ts b/apps/server/src/collaboration/processors/history.processor.ts
index 6f26d3fa..3fde25e4 100644
--- a/apps/server/src/collaboration/processors/history.processor.ts
+++ b/apps/server/src/collaboration/processors/history.processor.ts
@@ -78,7 +78,11 @@ export class HistoryProcessor extends WorkerHost implements OnModuleDestroy {
             page.workspaceId,
           );
 
-          await this.pageHistoryRepo.saveHistory(page, { contributorIds });
+          // #370 — every job on this queue is a trailing idle-flush autosnapshot.
+          await this.pageHistoryRepo.saveHistory(page, {
+            contributorIds,
+            kind: job.data.kind ?? 'idle',
+          });
           this.logger.debug(`History created for page: ${pageId}`);
         } catch (err) {
           await this.collabHistory.addContributors(pageId, contributorIds);
diff --git a/apps/server/src/database/migrations/20260705T120000-page-history-kind.ts b/apps/server/src/database/migrations/20260705T120000-page-history-kind.ts
new file mode 100644
index 00000000..c2292e6f
--- /dev/null
+++ b/apps/server/src/database/migrations/20260705T120000-page-history-kind.ts
@@ -0,0 +1,27 @@
+import { type Kysely } from 'kysely';
+
+/**
+ * #370 — page-versioning intentionality tier on a history snapshot.
+ *
+ * Adds `page_history.kind`, the three-tier "how intentional was this snapshot"
+ * marker that lets versions (intentional points) be told apart from autosaves:
+ *   - 'manual'   — a human explicitly saved a version (Cmd+S / Save button)
+ *   - 'agent'    — the AI agent explicitly saved a version
+ *   - 'idle'     — trailing idle-flush autosnapshot (safety net)
+ *   - 'boundary' — autosnapshot pinned on a source transition (user↔agent↔git)
+ *
+ * Nullable with NO default (mirrors last_updated_source in the agent-provenance
+ * migration): legacy rows predate the marker and read back as `null`, which the
+ * client renders as a plain autosave. Stored as a short varchar to stay
+ * forward-compatible without an enum migration.
+ */
+export async function up(db: Kysely<any>): Promise<void> {
+  await db.schema
+    .alterTable('page_history')
+    .addColumn('kind', 'varchar(20)', (col) => col)
+    .execute();
+}
+
+export async function down(db: Kysely<any>): Promise<void> {
+  await db.schema.alterTable('page_history').dropColumn('kind').execute();
+}
diff --git a/apps/server/src/database/repos/page/page-history.repo.ts b/apps/server/src/database/repos/page/page-history.repo.ts
index e6ba1d61..6eb5b145 100644
--- a/apps/server/src/database/repos/page/page-history.repo.ts
+++ b/apps/server/src/database/repos/page/page-history.repo.ts
@@ -13,6 +13,7 @@ import { jsonArrayFrom, jsonObjectFrom } from 'kysely/helpers/postgres';
 import { ExpressionBuilder, sql } from 'kysely';
 import { DB } from '@docmost/db/types/db';
 import { resolveAgentProvenance } from '../agent-provenance';
+import { PageHistoryKind } from '../../../collaboration/constants';
 
 /**
  * Role-resolution subquery for a page-history row's bound AI chat (#300). Joins
@@ -46,6 +47,9 @@ export class PageHistoryRepo {
     'lastUpdatedById',
     'lastUpdatedSource',
     'lastUpdatedAiChatId',
+    // #370 — intentionality tier ('manual' | 'agent' | 'idle' | 'boundary');
+    // null on legacy rows (= autosave). Selected so callers can read/promote it.
+    'kind',
     'contributorIds',
     'spaceId',
     'workspaceId',
@@ -85,9 +89,15 @@ export class PageHistoryRepo {
 
   async saveHistory(
     page: Page,
-    opts?: { contributorIds?: string[]; trx?: KyselyTransaction },
-  ): Promise<void> {
-    await this.insertPageHistory(
+    opts?: {
+      contributorIds?: string[];
+      // #370 — intentionality tier for this snapshot. Omitted → null (legacy
+      // autosave semantics). Callers derive it server-side, never from a client.
+      kind?: PageHistoryKind;
+      trx?: KyselyTransaction;
+    },
+  ): Promise<PageHistory> {
+    return await this.insertPageHistory(
       {
         pageId: page.id,
         slugId: page.slugId,
@@ -99,6 +109,7 @@ export class PageHistoryRepo {
         // Copy the provenance marker off the page row, as for lastUpdatedById.
         lastUpdatedSource: page.lastUpdatedSource,
         lastUpdatedAiChatId: page.lastUpdatedAiChatId,
+        kind: opts?.kind ?? null,
         contributorIds: opts?.contributorIds,
         spaceId: page.spaceId,
         workspaceId: page.workspaceId,
@@ -107,6 +118,25 @@ export class PageHistoryRepo {
     );
   }
 
+  /**
+   * #370 — promote an existing snapshot's intentionality tier in place. Used by
+   * the manual-save "promote-not-dup" path: when the latest history row already
+   * holds the exact content being versioned, we upgrade its `kind` instead of
+   * duplicating a heavy content row.
+   */
+  async updateHistoryKind(
+    pageHistoryId: string,
+    kind: PageHistoryKind,
+    trx?: KyselyTransaction,
+  ): Promise<void> {
+    const db = dbOrTx(this.db, trx);
+    await db
+      .updateTable('pageHistory')
+      .set({ kind })
+      .where('id', '=', pageHistoryId)
+      .execute();
+  }
+
   async findPageHistoryByPageId(pageId: string, pagination: PaginationOptions) {
     const query = this.db
       .selectFrom('pageHistory')
diff --git a/apps/server/src/database/types/db.d.ts b/apps/server/src/database/types/db.d.ts
index bf5a9663..69294d32 100644
--- a/apps/server/src/database/types/db.d.ts
+++ b/apps/server/src/database/types/db.d.ts
@@ -280,6 +280,7 @@ export interface PageHistory {
   createdAt: Generated<Timestamp>;
   icon: string | null;
   id: Generated<string>;
+  kind: string | null;
   lastUpdatedAiChatId: string | null;
   lastUpdatedById: string | null;
   lastUpdatedSource: string | null;
diff --git a/apps/server/src/integrations/queue/constants/queue.interface.ts b/apps/server/src/integrations/queue/constants/queue.interface.ts
index 19445944..f95e5eda 100644
--- a/apps/server/src/integrations/queue/constants/queue.interface.ts
+++ b/apps/server/src/integrations/queue/constants/queue.interface.ts
@@ -20,6 +20,10 @@ export interface IStripeSeatsSyncJob {
 
 export interface IPageHistoryJob {
   pageId: string;
+  // #370 — intentionality tier the worker stamps on the snapshot. All jobs on
+  // this queue are trailing idle-flush autosnapshots, so this is 'idle' (absent
+  // → treated as 'idle' by the processor).
+  kind?: 'idle';
 }
 
 /**