diff --git a/.changeset/collaboration-presence-avatars-i18n-3440.md b/.changeset/collaboration-presence-avatars-i18n-3440.md
new file mode 100644
index 0000000000..fbbba18f7f
--- /dev/null
+++ b/.changeset/collaboration-presence-avatars-i18n-3440.md
@@ -0,0 +1,53 @@
+---
+'@object-ui/collaboration': patch
+'@object-ui/i18n': patch
+---
+
+Localize `PresenceAvatars` — the avatar stack's accessible name and tooltips follow the session language (objectui#3440)
+
+objectui#3424 wired `@object-ui/collaboration` up to `@object-ui/i18n` but only
+converted `CommentThread`. `PresenceAvatars` in the same package kept three
+English literals, and it is not a dormant export — the console renders it in
+two places: `app-shell/src/layout/AppHeader.tsx` (tenant presence beside the
+lifecycle badge) and `app-shell/src/views/RecordDetailView.tsx` (who else is on
+this record). A `zh` session got them in English.
+
+The three sites:
+
+- the group's `aria-label`, `` `${n} user${n !== 1 ? 's' : ''} present` ``;
+- the overflow badge's tooltip, `` `${n} more user${n !== 1 ? 's' : ''}` ``;
+- each avatar's tooltip, `` `${name} (${status})` ``.
+
+The first one is the whole control as far as a screen reader is concerned: the
+stack renders images and initials and nothing else, so there was no other
+accessible name to fall back on.
+
+As with the comment count in #3424, the first two carried a second defect on
+top of being untranslated — the plural **rule** was compiled into the component.
+Both produced correct *English* (each has a real singular branch, so this is
+not the "1 items" defect objectui#3423 fixed on the tab badge), but
+`n !== 1 ? 's' : ''` is English grammar in a render path and no locale could
+apply its own. Both now use the repo's **two-key** plural convention
+(`collaboration.presentUserCount`/`presentUserCountOne`,
+`collaboration.moreUserCount`/`moreUserCountOne`) rather than an i18next
+`_one`/`_other` pair, with the count interpolated as a string so i18next skips
+its own plural resolution. German is what witnesses the move: "1 anwesender
+Benutzer" vs "2 anwesende Benutzer" inflects the adjective, which the deleted
+ternary could not have produced for any pack.
+
+The avatar tooltip becomes a single `collaboration.userStatusTitle` key
+(`{{name}} ({{status}})`) so the parentheses and their spacing belong to the
+translation — the CJK packs drop the space English puts before `(`, matching
+their existing `edited: '(已编辑)'`.
+
+Its `status` is a **display-layer** translation
+(`collaboration.statusActive` / `statusIdle` / `statusAway`): the
+`PresenceUser['status']` enum value stays raw data everywhere it is stored,
+compared or passed around — including the `statusColors` lookup — and is
+translated only at this render exit. A status outside the declared union
+renders as itself, the raw string: presence users arrive from a host-supplied
+`PresenceSource` transport, so an unmapped value is reachable at runtime
+whatever the type says, and the fallback invents nothing rather than leaving an
+empty bracket pair.
+
+Eight new keys, added to all ten locale packs with real translations.
diff --git a/packages/collaboration/src/PresenceAvatars.tsx b/packages/collaboration/src/PresenceAvatars.tsx
index 7aa7eb8552..b843421537 100644
--- a/packages/collaboration/src/PresenceAvatars.tsx
+++ b/packages/collaboration/src/PresenceAvatars.tsx
@@ -8,6 +8,10 @@
 
 import React, { useMemo } from 'react';
 import type { PresenceUser } from './usePresence';
+import {
+  useCollaborationTranslation,
+  type CollaborationTranslate,
+} from './useCollaborationTranslation';
 
 export interface PresenceAvatarsProps {
   /** Present users */
@@ -34,6 +38,41 @@ const statusColors: Record<PresenceUser['status'], string> = {
   away: '#94a3b8',
 };
 
+/**
+ * Display-layer translation key per presence status (objectui#3440).
+ *
+ * The status enum is DATA: `'active' | 'idle' | 'away'` is what
+ * {@link PresenceUser} carries, what the transport pushes and what
+ * `statusColors` above keys off. Nothing about that changes — this map exists
+ * only at the render exit, the one place the value stops being an identifier
+ * and becomes copy inside a tooltip.
+ *
+ * Typed `Record< string, string >` rather than
+ * `Record< PresenceUser['status'], string >` on purpose. Presence users arrive
+ * from a host-supplied `PresenceSource` (a WebSocket/SSE transport the package
+ * does not own — see `PresenceProvider`), so a status outside the union is
+ * reachable at runtime however strict the type is. An unmapped value renders
+ * as ITSELF, the raw string: no invented label, and no empty parenthesis where
+ * a status used to be.
+ */
+const statusLabelKeys: Record<string, string> = {
+  active: 'collaboration.statusActive',
+  idle: 'collaboration.statusIdle',
+  away: 'collaboration.statusAway',
+};
+
+/**
+ * Resolve a status value to its display copy, falling back to the raw value.
+ *
+ * Takes `t` as a parameter (same shape as `CommentThread`'s `formatTimestamp`)
+ * so this helper cannot drift from whichever half of the union — real i18next
+ * `t` or the English defaults map — the component is running under.
+ */
+function statusLabel(status: string, t: CollaborationTranslate): string {
+  const key = statusLabelKeys[status];
+  return key ? t(key) : status;
+}
+
 function getInitials(name: string): string {
   return name
     .split(' ')
@@ -48,6 +87,11 @@ function getInitials(name: string): string {
  *
  * Displays user avatars (or initials) in an overlapping stack,
  * with optional status indicators and a "+N" overflow badge.
+ *
+ * Every user-visible string resolves through `useCollaborationTranslation`
+ * (objectui#3440). The stack is images and initials only, so its `aria-label`
+ * is the entire control as far as a screen reader is concerned — leaving it in
+ * English left a `zh` console announcing its avatar group in English.
  */
 export function PresenceAvatars({
   users,
@@ -56,6 +100,7 @@ export function PresenceAvatars({
   showStatus = true,
   className,
 }: PresenceAvatarsProps): React.ReactElement {
+  const { t } = useCollaborationTranslation();
   const px = sizeMap[size];
   const overlapOffset = Math.round(px * 0.3);
   const fontSize = Math.round(px * 0.35);
@@ -113,13 +158,29 @@ export function PresenceAvatars({
     style: containerStyle,
     className,
     role: 'group',
-    'aria-label': `${users.length} user${users.length !== 1 ? 's' : ''} present`,
+    // Two keys instead of an English `s` glued on at render time. The old
+    // `` `${n} user${n !== 1 ? 's' : ''} present` `` produced correct *English*
+    // — the defect is that the plural RULE was compiled into the component, so
+    // no locale could apply its own (ru needs three forms, ja needs none, and
+    // neither could ever be expressed). Same treatment as the comment count in
+    // objectui#3424.
+    'aria-label': t(
+      users.length === 1
+        ? 'collaboration.presentUserCountOne'
+        : 'collaboration.presentUserCount',
+      { count: String(users.length) },
+    ),
   },
     // Overflow badge (rendered first because of row-reverse)
     overflowCount > 0 && React.createElement('div', {
       key: 'overflow',
       style: overflowStyle,
-      title: `${overflowCount} more user${overflowCount !== 1 ? 's' : ''}`,
+      title: t(
+        overflowCount === 1
+          ? 'collaboration.moreUserCountOne'
+          : 'collaboration.moreUserCount',
+        { count: String(overflowCount) },
+      ),
     }, `+${overflowCount}`),
     // Avatars
     reversedVisible.map((user, idx) =>
@@ -130,7 +191,14 @@ export function PresenceAvatars({
           backgroundColor: user.color,
           marginLeft: idx > 0 || overflowCount > 0 ? `-${overlapOffset}px` : '0',
         },
-        title: `${user.userName} (${user.status})`,
+        // The parentheses live in the translation, not in the component, so a
+        // translator owns the whole shape — spacing included: the CJK packs
+        // drop the space English puts before `(`, which a component-side
+        // `` `${name} (${status})` `` could never let them do.
+        title: t('collaboration.userStatusTitle', {
+          name: user.userName,
+          status: statusLabel(user.status, t),
+        }),
       },
         user.avatar
           ? React.createElement('img', {
diff --git a/packages/collaboration/src/__tests__/presence-avatars-i18n.test.tsx b/packages/collaboration/src/__tests__/presence-avatars-i18n.test.tsx
new file mode 100644
index 0000000000..3fc33e2242
--- /dev/null
+++ b/packages/collaboration/src/__tests__/presence-avatars-i18n.test.tsx
@@ -0,0 +1,259 @@
+/**
+ * ObjectUI
+ * Copyright (c) 2024-present ObjectStack Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+/**
+ * `PresenceAvatars` speaks the session language — objectui#3440 (follow-up to
+ * #3424, which wired the package up but only converted `CommentThread`).
+ *
+ * This is not a dormant export: the console renders it in two places under
+ * whatever language the session is in — `app-shell/src/layout/AppHeader.tsx`
+ * (tenant presence next to the lifecycle badge) and
+ * `app-shell/src/views/RecordDetailView.tsx` (who else is on this record).
+ * The stack itself is images and initials, so its `aria-label` IS the control
+ * as far as a screen reader is concerned, and it announced "4 users present"
+ * inside a Chinese console.
+ *
+ * ── Directions: predicted BEFORE running ──────────────────────────────────
+ * Reverting `PresenceAvatars.tsx` to `origin/main` and keeping this file turns
+ * every `zh` / `de` / `ru` / `ja` case RED and leaves the `en` cases GREEN.
+ *
+ * The `en` cases being green on BOTH sides is the invariant, not a gap. The
+ * English `origin/main` produced was already correct — `` `${n} user${n !== 1
+ * ? 's' : ''} present` `` has a real singular branch, so this is NOT the "1
+ * items" defect objectui#3423 fixed on the tab badge. What was wrong is that
+ * the plural RULE was compiled into the component: `n !== 1 ? 's' : ''` is
+ * English grammar in a render path, and no locale could ever apply its own.
+ * The `de` cases below are what pin the rule having MOVED — German inflects
+ * the adjective, so "1 anwesender Benutzer" vs "2 anwesende Benutzer" differ
+ * in a way the deleted ternary could not express under any locale pack. `ru`
+ * pins a language that needs three forms and `ja` one that needs none.
+ *
+ * The provider-less English fallback is asserted in
+ * `presence-avatars-no-provider-fallback.test.tsx` and cannot live here: see
+ * that file's header for the react-i18next module-global instance reason.
+ */
+
+import type { ComponentProps } from 'react';
+import { describe, it, expect, afterEach } from 'vitest';
+import { render, screen, cleanup } from '@testing-library/react';
+import { I18nProvider, en } from '@object-ui/i18n';
+import { PresenceAvatars } from '../PresenceAvatars';
+import { COLLAB_DEFAULT_TRANSLATIONS } from '../useCollaborationTranslation';
+import type { PresenceUser } from '../usePresence';
+
+const at = '2026-01-01T00:00:00.000Z';
+
+/** Three statuses across the visible slots, so all three enum values render. */
+const users: PresenceUser[] = [
+  { userId: 'u_alice', userName: 'Alice Chen', color: '#e74c3c', status: 'active', lastActivity: at },
+  { userId: 'u_bob', userName: 'Bob Ito', color: '#3498db', status: 'idle', lastActivity: at },
+  { userId: 'u_carol', userName: 'Carol Diaz', color: '#2ecc71', status: 'away', lastActivity: at },
+  { userId: 'u_dan', userName: 'Dan Meyer', color: '#f39c12', status: 'active', lastActivity: at },
+  { userId: 'u_eve', userName: 'Eve Novak', color: '#9b59b6', status: 'idle', lastActivity: at },
+];
+
+function renderStack(
+  language: string,
+  overrides: Partial<ComponentProps<typeof PresenceAvatars>> = {},
+) {
+  return render(
+    <I18nProvider config={{ defaultLanguage: language, detectBrowserLanguage: false }}>
+      <PresenceAvatars users={users} maxVisible={3} showStatus {...overrides} />
+    </I18nProvider>,
+  );
+}
+
+/** The avatar group's accessible name — the only name this control has. */
+const groupLabel = () => screen.getByRole('group').getAttribute('aria-label');
+
+afterEach(() => cleanup());
+
+describe('PresenceAvatars group label (objectui#3440)', () => {
+  it('announces the present-user count in English under an en session', () => {
+    renderStack('en');
+
+    expect(groupLabel()).toBe('5 users present');
+  });
+
+  it('announces the present-user count in Chinese under a zh session', () => {
+    renderStack('zh');
+
+    expect(groupLabel()).toBe('5 人在线');
+    // The English literal is gone, not merely shadowed.
+    expect(screen.queryByLabelText('5 users present')).toBeNull();
+  });
+
+  it('announces a one-user stack with a real singular under an en session', () => {
+    renderStack('en', { users: [users[0]] });
+
+    expect(groupLabel()).toBe('1 user present');
+  });
+
+  /**
+   * The plural-rule pin. German inflects the attributive adjective, so the
+   * singular and plural differ in a way `n !== 1 ? 's' : ''` could not have
+   * produced for any locale — the rule now lives in the pack, not the render
+   * path.
+   */
+  it('applies German adjective inflection, which the deleted ternary could not', () => {
+    renderStack('de', { users: [users[0]] });
+    expect(groupLabel()).toBe('1 anwesender Benutzer');
+    cleanup();
+
+    renderStack('de');
+    expect(groupLabel()).toBe('5 anwesende Benutzer');
+  });
+
+  /** A language that needs three forms; the pack picks, not the component. */
+  it('uses the Russian pack’s own singular / general forms', () => {
+    renderStack('ru', { users: [users[0]] });
+    expect(groupLabel()).toBe('Присутствует 1 пользователь');
+    cleanup();
+
+    renderStack('ru');
+    expect(groupLabel()).toBe('Присутствует пользователей: 5');
+  });
+
+  /** A language that needs none — one form for both, and no stray `s`. */
+  it('keeps one Japanese form for both counts', () => {
+    renderStack('ja', { users: [users[0]] });
+    expect(groupLabel()).toBe('オンライン 1 人');
+    cleanup();
+
+    renderStack('ja');
+    expect(groupLabel()).toBe('オンライン 5 人');
+  });
+});
+
+describe('PresenceAvatars overflow badge (objectui#3440)', () => {
+  it('labels the +N badge in the session language, plural and singular', () => {
+    renderStack('en');
+    expect(screen.getByTitle('2 more users')).toBeTruthy();
+    cleanup();
+
+    renderStack('en', { users: users.slice(0, 4) });
+    expect(screen.getByTitle('1 more user')).toBeTruthy();
+  });
+
+  it('labels the +N badge in Chinese under a zh session', () => {
+    renderStack('zh');
+
+    expect(screen.getByTitle('另有 2 人')).toBeTruthy();
+    expect(screen.queryByTitle('2 more users')).toBeNull();
+  });
+
+  it('applies German inflection to the +N badge too', () => {
+    renderStack('de', { users: users.slice(0, 4) });
+    expect(screen.getByTitle('1 weiterer Benutzer')).toBeTruthy();
+    cleanup();
+
+    renderStack('de');
+    expect(screen.getByTitle('2 weitere Benutzer')).toBeTruthy();
+  });
+});
+
+describe('PresenceAvatars status tooltip (objectui#3440)', () => {
+  it('renders name and status in English under an en session', () => {
+    renderStack('en');
+
+    expect(screen.getByTitle('Alice Chen (active)')).toBeTruthy();
+    expect(screen.getByTitle('Bob Ito (idle)')).toBeTruthy();
+    expect(screen.getByTitle('Carol Diaz (away)')).toBeTruthy();
+  });
+
+  /**
+   * The status is a display-layer translation: the raw enum value is data and
+   * stays untouched everywhere except this render exit. The bracket shape is
+   * part of the translation too, so each pack owns its own spacing — `zh`
+   * drops the space English puts before `(`, matching that pack's existing
+   * `edited: '(已编辑)'`, instead of inheriting English-shaped glue.
+   */
+  it('translates the status enum for display under a zh session', () => {
+    renderStack('zh');
+
+    expect(screen.getByTitle('Alice Chen(活跃)')).toBeTruthy();
+    expect(screen.getByTitle('Bob Ito(空闲)')).toBeTruthy();
+    expect(screen.getByTitle('Carol Diaz(离开)')).toBeTruthy();
+    // Neither the English enum value nor the English bracket glue survives.
+    expect(screen.queryByTitle('Alice Chen (active)')).toBeNull();
+    expect(screen.queryByTitle('Alice Chen (活跃)')).toBeNull();
+  });
+
+  it('translates the status enum under a de session', () => {
+    renderStack('de');
+
+    expect(screen.getByTitle('Alice Chen (aktiv)')).toBeTruthy();
+    expect(screen.getByTitle('Bob Ito (inaktiv)')).toBeTruthy();
+    expect(screen.getByTitle('Carol Diaz (abwesend)')).toBeTruthy();
+  });
+
+  /**
+   * Presence users arrive from a host-supplied transport, so a status outside
+   * the declared union is reachable at runtime whatever the type says. It must
+   * render as ITSELF — not as an invented label, not as a raw i18n key, and
+   * not as an empty bracket pair.
+   */
+  it('falls back to the raw value for a status outside the union', () => {
+    const offUnion = {
+      ...users[0],
+      status: 'online' as PresenceUser['status'],
+    };
+    renderStack('zh', { users: [offUnion] });
+
+    expect(screen.getByTitle('Alice Chen(online)')).toBeTruthy();
+    expect(screen.queryByTitle('Alice Chen()')).toBeNull();
+    expect(screen.queryByTitle(/collaboration\.status/)).toBeNull();
+  });
+
+  it('keeps the tooltip when status dots are hidden', () => {
+    // `showStatus` governs the coloured dot, not the accessible copy — the
+    // tooltip is the only place a status is readable at all.
+    renderStack('zh', { showStatus: false });
+
+    expect(screen.getByTitle('Alice Chen(活跃)')).toBeTruthy();
+  });
+});
+
+describe('the collaboration defaults map mirrors the en pack (objectui#3440)', () => {
+  /**
+   * `useCollaborationTranslation`'s docblock states that
+   * `COLLAB_DEFAULT_TRANSLATIONS` "must stay byte-identical to the `en` locale
+   * pack's `collaboration` namespace". Nothing enforced it, and this change
+   * adds eight keys to BOTH places — the exact shape that drifts. A key added
+   * to only one of them is invisible at runtime: with a provider the pack
+   * wins, without one the map does, so each path looks fine on its own.
+   *
+   * Only the `collaboration.` prefix is compared; the four `common.*` entries
+   * are deliberately borrowed from the shared namespace.
+   */
+  it('agrees key-for-key and value-for-value with en.collaboration', () => {
+    const fromMap = Object.fromEntries(
+      Object.entries(COLLAB_DEFAULT_TRANSLATIONS)
+        .filter(([k]) => k.startsWith('collaboration.'))
+        .map(([k, v]) => [k.slice('collaboration.'.length), v]),
+    );
+
+    expect(fromMap).toEqual({ ...en.collaboration });
+  });
+
+  it('carries the eight presence keys this change added', () => {
+    for (const key of [
+      'presentUserCount',
+      'presentUserCountOne',
+      'moreUserCount',
+      'moreUserCountOne',
+      'userStatusTitle',
+      'statusActive',
+      'statusIdle',
+      'statusAway',
+    ]) {
+      expect(en.collaboration).toHaveProperty(key);
+      expect(COLLAB_DEFAULT_TRANSLATIONS).toHaveProperty(`collaboration.${key}`);
+    }
+  });
+});
diff --git a/packages/collaboration/src/__tests__/presence-avatars-no-provider-fallback.test.tsx b/packages/collaboration/src/__tests__/presence-avatars-no-provider-fallback.test.tsx
new file mode 100644
index 0000000000..2abe4112ef
--- /dev/null
+++ b/packages/collaboration/src/__tests__/presence-avatars-no-provider-fallback.test.tsx
@@ -0,0 +1,160 @@
+/**
+ * ObjectUI
+ * Copyright (c) 2024-present ObjectStack Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+/**
+ * Every string objectui#3440 moved out of `PresenceAvatars` still resolves to
+ * ENGLISH when no `I18nProvider` is mounted.
+ *
+ * `PresenceAvatars` is an exported component and its host may mount no ObjectUI
+ * shell at all. Routing a literal through `t()` without a working default is
+ * exactly how an accessible name turns into a raw dotted key
+ * (`collaboration.presentUserCount`) in someone else's app — silently, because
+ * `fallbackLng: 'en'` never fires when there is no i18next instance to fall
+ * back inside of. `COLLAB_DEFAULT_TRANSLATIONS` is what has to hold here.
+ *
+ * ── Directions: predicted BEFORE running ──────────────────────────────────
+ * **Every** assertion in this file is GREEN on BOTH sides of the change. That
+ * is the invariant, not a missing test: the English copy is byte-identical
+ * before and after (`origin/main`'s ternary already produced a correct
+ * singular), so a flip here would mean the copy moved. What this file catches
+ * is a break introduced by *this* change — a key wired into the component but
+ * missing or misspelled in `COLLAB_DEFAULT_TRANSLATIONS` goes red here and
+ * nowhere else, because the provider-backed file resolves against the locale
+ * packs instead.
+ *
+ * The one genuinely new English string is the status tooltip's fallback for an
+ * off-union status: `origin/main` interpolated the raw value directly, and it
+ * still must.
+ *
+ * ── Why this is its own FILE, not a describe block ────────────────────────
+ * `createI18n` calls `instance.use(initReactI18next)`, which registers that
+ * instance as react-i18next's **module-global default**. The registration
+ * survives unmount and `cleanup()`. So the moment any test in a file mounts
+ * `<I18nProvider config={{ defaultLanguage: 'zh' }}>`, every later "no
+ * provider" render in that same file silently resolves against the Chinese
+ * instance — a file that looks green while asserting nothing, or a baffling
+ * red where a provider-less stack renders 中文.
+ *
+ * Vitest's `dom` project runs with `isolate: true`, so a file that never mounts
+ * a provider gets a genuinely clean global. Keep it that way: **do not import
+ * or mount `I18nProvider` here.**
+ */
+
+import { describe, it, expect, afterEach } from 'vitest';
+import { render, screen, cleanup } from '@testing-library/react';
+import { PresenceAvatars } from '../PresenceAvatars';
+import { COLLAB_DEFAULT_TRANSLATIONS } from '../useCollaborationTranslation';
+import type { PresenceUser } from '../usePresence';
+
+const at = '2026-01-01T00:00:00.000Z';
+
+const users: PresenceUser[] = [
+  { userId: 'u_alice', userName: 'Alice Chen', color: '#e74c3c', status: 'active', lastActivity: at },
+  { userId: 'u_bob', userName: 'Bob Ito', color: '#3498db', status: 'idle', lastActivity: at },
+  { userId: 'u_carol', userName: 'Carol Diaz', color: '#2ecc71', status: 'away', lastActivity: at },
+  { userId: 'u_dan', userName: 'Dan Meyer', color: '#f39c12', status: 'active', lastActivity: at },
+  { userId: 'u_eve', userName: 'Eve Novak', color: '#9b59b6', status: 'idle', lastActivity: at },
+];
+
+function renderBare(overrides: Record<string, unknown> = {}) {
+  return render(<PresenceAvatars users={users} maxVisible={3} showStatus {...overrides} />);
+}
+
+const groupLabel = () => screen.getByRole('group').getAttribute('aria-label');
+
+afterEach(() => cleanup());
+
+describe('PresenceAvatars with no I18nProvider — English fallback (objectui#3440)', () => {
+  it('names the avatar group in English, plural and singular', () => {
+    renderBare();
+    expect(groupLabel()).toBe('5 users present');
+    cleanup();
+
+    renderBare({ users: [users[0]] });
+    expect(groupLabel()).toBe('1 user present');
+    expect(screen.queryByLabelText('1 users present')).toBeNull();
+  });
+
+  it('labels the overflow badge in English, plural and singular', () => {
+    renderBare();
+    expect(screen.getByTitle('2 more users')).toBeTruthy();
+    cleanup();
+
+    renderBare({ users: users.slice(0, 4) });
+    expect(screen.getByTitle('1 more user')).toBeTruthy();
+    expect(screen.queryByTitle('1 more users')).toBeNull();
+  });
+
+  it('renders every status enum value as English display copy', () => {
+    renderBare();
+
+    expect(screen.getByTitle('Alice Chen (active)')).toBeTruthy();
+    expect(screen.getByTitle('Bob Ito (idle)')).toBeTruthy();
+    expect(screen.getByTitle('Carol Diaz (away)')).toBeTruthy();
+  });
+
+  it('falls back to the raw value for a status outside the union', () => {
+    renderBare({ users: [{ ...users[0], status: 'online' as PresenceUser['status'] }] });
+
+    expect(screen.getByTitle('Alice Chen (online)')).toBeTruthy();
+  });
+
+  /**
+   * The failure mode this whole file exists to catch: a key wired into the
+   * component but absent from the defaults map renders as its own dotted name
+   * — here inside an `aria-label`, where nothing on screen would show it.
+   */
+  it('never renders a raw i18n key or an unsubstituted placeholder', () => {
+    const { container } = renderBare();
+
+    const names = [
+      groupLabel() ?? '',
+      ...[...container.querySelectorAll('[title]')].map((el) => el.getAttribute('title') ?? ''),
+    ].join(' | ');
+
+    expect(names).not.toMatch(/collaboration\.\w+/);
+    expect(names).not.toMatch(/\{\{\w+\}\}/);
+  });
+});
+
+describe('COLLAB_DEFAULT_TRANSLATIONS covers the presence stack', () => {
+  /**
+   * The defaults map is the only English copy left in the package, so an
+   * absent key would make the assertions above pass for the wrong reason: a
+   * key that resolves to itself still "renders" something.
+   */
+  it('has real English copy for every presence key, never the key itself', () => {
+    for (const key of [
+      'collaboration.presentUserCount',
+      'collaboration.presentUserCountOne',
+      'collaboration.moreUserCount',
+      'collaboration.moreUserCountOne',
+      'collaboration.userStatusTitle',
+      'collaboration.statusActive',
+      'collaboration.statusIdle',
+      'collaboration.statusAway',
+    ]) {
+      const value = COLLAB_DEFAULT_TRANSLATIONS[key];
+      expect(value, `${key} has no English copy`).toBeTruthy();
+      expect(value, `${key} is just its own key`).not.toBe(key);
+    }
+  });
+
+  it('keeps the count placeholder in both halves of each plural pair', () => {
+    expect(COLLAB_DEFAULT_TRANSLATIONS['collaboration.presentUserCount']).toContain('{{count}}');
+    expect(COLLAB_DEFAULT_TRANSLATIONS['collaboration.presentUserCountOne']).toContain('{{count}}');
+    expect(COLLAB_DEFAULT_TRANSLATIONS['collaboration.moreUserCount']).toContain('{{count}}');
+    expect(COLLAB_DEFAULT_TRANSLATIONS['collaboration.moreUserCountOne']).toContain('{{count}}');
+  });
+
+  it('gives the tooltip both of its placeholders', () => {
+    const title = COLLAB_DEFAULT_TRANSLATIONS['collaboration.userStatusTitle'];
+    expect(title).toContain('{{name}}');
+    expect(title).toContain('{{status}}');
+  });
+});
diff --git a/packages/collaboration/src/useCollaborationTranslation.ts b/packages/collaboration/src/useCollaborationTranslation.ts
index 4201b963be..5afee12e7c 100644
--- a/packages/collaboration/src/useCollaborationTranslation.ts
+++ b/packages/collaboration/src/useCollaborationTranslation.ts
@@ -75,6 +75,22 @@ export const COLLAB_DEFAULT_TRANSLATIONS: Record<string, string> = {
   // Composer
   'collaboration.commentPlaceholder': 'Add a comment... (use @ to mention)',
   'collaboration.send': 'Send',
+  // Presence avatar stack (objectui#3440). The group's `aria-label` IS the
+  // control for a screen reader — the stack itself is images and initials —
+  // so this pair is not decoration.
+  'collaboration.presentUserCount': '{{count}} users present',
+  'collaboration.presentUserCountOne': '{{count}} user present',
+  'collaboration.moreUserCount': '{{count}} more users',
+  'collaboration.moreUserCountOne': '{{count}} more user',
+  // Avatar tooltip. The parentheses belong to the translation so a translator
+  // owns the whole shape rather than inheriting English-shaped glue.
+  'collaboration.userStatusTitle': '{{name}} ({{status}})',
+  // Display copy for the `PresenceUser['status']` enum. The enum VALUE stays
+  // raw data everywhere else — these three exist only for the tooltip above,
+  // and a status outside the union falls back to the raw string.
+  'collaboration.statusActive': 'active',
+  'collaboration.statusIdle': 'idle',
+  'collaboration.statusAway': 'away',
   // Shared action words — see the note above.
   'common.save': 'Save',
   'common.cancel': 'Cancel',
diff --git a/packages/i18n/src/locales/ar.ts b/packages/i18n/src/locales/ar.ts
index 7f25c1776a..d729deedd0 100644
--- a/packages/i18n/src/locales/ar.ts
+++ b/packages/i18n/src/locales/ar.ts
@@ -3073,6 +3073,14 @@ const ar = {
     replyingToComment: "الرد على التعليق…",
     commentPlaceholder: "أضف تعليقًا… (استخدم @ للإشارة)",
     send: "إرسال",
+    presentUserCount: "{{count}} مستخدمين متواجدين",
+    presentUserCountOne: "{{count}} مستخدم متواجد",
+    moreUserCount: "{{count}} مستخدمين آخرين",
+    moreUserCountOne: "{{count}} مستخدم آخر",
+    userStatusTitle: "{{name}} ({{status}})",
+    statusActive: "نشط",
+    statusIdle: "خامل",
+    statusAway: "غائب",
   },
 };
 
diff --git a/packages/i18n/src/locales/de.ts b/packages/i18n/src/locales/de.ts
index 45149a2b4b..d68b6799ab 100644
--- a/packages/i18n/src/locales/de.ts
+++ b/packages/i18n/src/locales/de.ts
@@ -3073,6 +3073,14 @@ const de = {
     replyingToComment: "Antwort auf Kommentar …",
     commentPlaceholder: "Kommentar hinzufügen … (@ für Erwähnungen)",
     send: "Senden",
+    presentUserCount: "{{count}} anwesende Benutzer",
+    presentUserCountOne: "{{count}} anwesender Benutzer",
+    moreUserCount: "{{count}} weitere Benutzer",
+    moreUserCountOne: "{{count}} weiterer Benutzer",
+    userStatusTitle: "{{name}} ({{status}})",
+    statusActive: "aktiv",
+    statusIdle: "inaktiv",
+    statusAway: "abwesend",
   },
 };
 
diff --git a/packages/i18n/src/locales/en.ts b/packages/i18n/src/locales/en.ts
index ed13aa6ff5..6b93dee9db 100644
--- a/packages/i18n/src/locales/en.ts
+++ b/packages/i18n/src/locales/en.ts
@@ -3209,6 +3209,23 @@ const en = {
     replyingToComment: 'Replying to comment...',
     commentPlaceholder: 'Add a comment... (use @ to mention)',
     send: 'Send',
+    // Presence avatar stack (objectui#3440). `presentUserCount*` is the avatar
+    // group's `aria-label` — with only images and initials inside, that label
+    // IS the control for a screen reader. Two keys, same reason as
+    // `commentCount` above.
+    presentUserCount: '{{count}} users present',
+    presentUserCountOne: '{{count}} user present',
+    moreUserCount: '{{count}} more users',
+    moreUserCountOne: '{{count}} more user',
+    // Avatar tooltip. The parentheses are part of the translation, spacing
+    // included, so the CJK packs can drop the space English puts before `(`.
+    userStatusTitle: '{{name}} ({{status}})',
+    // Display copy for the `PresenceUser['status']` enum. The enum value
+    // itself stays raw data — it is translated at the render exit only, and a
+    // status outside the union falls back to the raw string.
+    statusActive: 'active',
+    statusIdle: 'idle',
+    statusAway: 'away',
   },
 } as const;
 
diff --git a/packages/i18n/src/locales/es.ts b/packages/i18n/src/locales/es.ts
index 5e8fa8b278..ca6154ac01 100644
--- a/packages/i18n/src/locales/es.ts
+++ b/packages/i18n/src/locales/es.ts
@@ -3078,6 +3078,14 @@ const es = {
     replyingToComment: "Respondiendo al comentario…",
     commentPlaceholder: "Agregar un comentario… (usa @ para mencionar)",
     send: "Enviar",
+    presentUserCount: "{{count}} usuarios presentes",
+    presentUserCountOne: "{{count}} usuario presente",
+    moreUserCount: "{{count}} usuarios más",
+    moreUserCountOne: "{{count}} usuario más",
+    userStatusTitle: "{{name}} ({{status}})",
+    statusActive: "activo",
+    statusIdle: "inactivo",
+    statusAway: "ausente",
   },
 };
 
diff --git a/packages/i18n/src/locales/fr.ts b/packages/i18n/src/locales/fr.ts
index 3f8a8dccc5..b0142252b9 100644
--- a/packages/i18n/src/locales/fr.ts
+++ b/packages/i18n/src/locales/fr.ts
@@ -3073,6 +3073,14 @@ const fr = {
     replyingToComment: "Réponse au commentaire…",
     commentPlaceholder: "Ajouter un commentaire… (utilisez @ pour mentionner)",
     send: "Envoyer",
+    presentUserCount: "{{count}} utilisateurs présents",
+    presentUserCountOne: "{{count}} utilisateur présent",
+    moreUserCount: "{{count}} autres utilisateurs",
+    moreUserCountOne: "{{count}} autre utilisateur",
+    userStatusTitle: "{{name}} ({{status}})",
+    statusActive: "actif",
+    statusIdle: "inactif",
+    statusAway: "absent",
   },
 };
 
diff --git a/packages/i18n/src/locales/ja.ts b/packages/i18n/src/locales/ja.ts
index e704091428..d153cab1ae 100644
--- a/packages/i18n/src/locales/ja.ts
+++ b/packages/i18n/src/locales/ja.ts
@@ -3073,6 +3073,14 @@ const ja = {
     replyingToComment: "このコメントに返信中…",
     commentPlaceholder: "コメントを追加…(@ でメンション)",
     send: "送信",
+    presentUserCount: "オンライン {{count}} 人",
+    presentUserCountOne: "オンライン {{count}} 人",
+    moreUserCount: "他 {{count}} 人",
+    moreUserCountOne: "他 {{count}} 人",
+    userStatusTitle: "{{name}}({{status}})",
+    statusActive: "アクティブ",
+    statusIdle: "アイドル",
+    statusAway: "離席中",
   },
 };
 
diff --git a/packages/i18n/src/locales/ko.ts b/packages/i18n/src/locales/ko.ts
index 3cf5f1f6a2..535a80445d 100644
--- a/packages/i18n/src/locales/ko.ts
+++ b/packages/i18n/src/locales/ko.ts
@@ -3073,6 +3073,14 @@ const ko = {
     replyingToComment: "이 댓글에 답글 작성 중…",
     commentPlaceholder: "댓글 추가…(@로 멘션)",
     send: "보내기",
+    presentUserCount: "{{count}}명 접속 중",
+    presentUserCountOne: "{{count}}명 접속 중",
+    moreUserCount: "외 {{count}}명",
+    moreUserCountOne: "외 {{count}}명",
+    userStatusTitle: "{{name}}({{status}})",
+    statusActive: "활성",
+    statusIdle: "유휴",
+    statusAway: "자리 비움",
   },
 };
 
diff --git a/packages/i18n/src/locales/pt.ts b/packages/i18n/src/locales/pt.ts
index cd0cd1b04a..479bf55ab1 100644
--- a/packages/i18n/src/locales/pt.ts
+++ b/packages/i18n/src/locales/pt.ts
@@ -3073,6 +3073,14 @@ const pt = {
     replyingToComment: "Respondendo ao comentário…",
     commentPlaceholder: "Adicionar um comentário… (use @ para mencionar)",
     send: "Enviar",
+    presentUserCount: "{{count}} usuários presentes",
+    presentUserCountOne: "{{count}} usuário presente",
+    moreUserCount: "mais {{count}} usuários",
+    moreUserCountOne: "mais {{count}} usuário",
+    userStatusTitle: "{{name}} ({{status}})",
+    statusActive: "ativo",
+    statusIdle: "inativo",
+    statusAway: "ausente",
   },
 };
 
diff --git a/packages/i18n/src/locales/ru.ts b/packages/i18n/src/locales/ru.ts
index 5357da2c1d..6741737c13 100644
--- a/packages/i18n/src/locales/ru.ts
+++ b/packages/i18n/src/locales/ru.ts
@@ -3073,6 +3073,14 @@ const ru = {
     replyingToComment: "Ответ на комментарий…",
     commentPlaceholder: "Добавьте комментарий… (@ — упоминание)",
     send: "Отправить",
+    presentUserCount: "Присутствует пользователей: {{count}}",
+    presentUserCountOne: "Присутствует {{count}} пользователь",
+    moreUserCount: "Ещё пользователей: {{count}}",
+    moreUserCountOne: "Ещё {{count}} пользователь",
+    userStatusTitle: "{{name}} ({{status}})",
+    statusActive: "активен",
+    statusIdle: "бездействует",
+    statusAway: "отошёл",
   },
 };
 
diff --git a/packages/i18n/src/locales/zh.ts b/packages/i18n/src/locales/zh.ts
index 4a5b5c7db2..8f82d7c7f4 100644
--- a/packages/i18n/src/locales/zh.ts
+++ b/packages/i18n/src/locales/zh.ts
@@ -3127,6 +3127,14 @@ const zh = {
     replyingToComment: '正在回复该评论…',
     commentPlaceholder: '添加评论…(输入 @ 提及他人)',
     send: '发送',
+    presentUserCount: '{{count}} 人在线',
+    presentUserCountOne: '{{count}} 人在线',
+    moreUserCount: '另有 {{count}} 人',
+    moreUserCountOne: '另有 {{count}} 人',
+    userStatusTitle: '{{name}}({{status}})',
+    statusActive: '活跃',
+    statusIdle: '空闲',
+    statusAway: '离开',
   },
 } as const;