diff --git a/.changeset/collaboration-comment-thread-i18n-5506.md b/.changeset/collaboration-comment-thread-i18n-5506.md
new file mode 100644
index 0000000000..f77b6f1fa7
--- /dev/null
+++ b/.changeset/collaboration-comment-thread-i18n-5506.md
@@ -0,0 +1,66 @@
+---
+'@object-ui/collaboration': patch
+'@object-ui/i18n': patch
+---
+
+Localize `@object-ui/collaboration` — `CommentThread` no longer hardcodes English (objectstack#5506)
+
+`@object-ui/collaboration` depended only on `@object-ui/types` and carried every
+user-visible string as an English literal, so a `zh` console rendered a Chinese
+shell around an English comment thread: "3 comments", "Reply", "Resolve",
+"just now", "Add a comment... (use @ to mention)".
+
+The package now takes `@object-ui/i18n` as a dependency and exposes one
+translation seam, `useCollaborationTranslation` /
+`COLLAB_DEFAULT_TRANSLATIONS`, built on `createSafeTranslation` — the same
+factory `data-table`, `form` and `filter-builder` use. Under an `I18nProvider`
+it resolves the session locale; with no provider it resolves the English
+defaults map, which is what keeps `CommentThread` usable standalone. There is
+deliberately no `formatter`/label prop escape hatch: a host that wants
+different copy overrides the locale keys, so one thread can never end up half
+translated by the bundle and half by props.
+
+The issue listed 13 sites. A site-by-site sweep of the file found **20** — the
+seven the original sweep missed are `{n}h ago`, `{n}d ago`, `(edited)`, the
+thread's own comment count, the `Oldest`/`Newest` sort options,
+`Replying to {name}...`, and the composer's `Send` button. All 20 are keyed
+here; leaving any behind would have shipped a thread that is 90% translated.
+
+Two of them carry a second defect on top of being untranslated: the plural
+**rule** was compiled into the component, not just the words.
+
+- the header read `` `${n} comment${n !== 1 ? 's' : ''}` ``;
+- the reaction chip tooltip read `` n === 1 ? '1 reaction' : `${n} reactions` ``.
+
+Both produced correct *English* — this is not the "1 items" bug objectui#3423
+fixed on the tab badge — but the choice between the two forms was English
+grammar hardwired into the render path. No locale could apply its own: ru needs
+three forms and ja needs none, and neither could ever be expressed no matter
+what the packs said.
+
+Both now use the repo's **two-key** plural convention
+(`collaboration.commentCount`/`commentCountOne`,
+`collaboration.reactionCount`/`reactionCountOne`) rather than an i18next
+`_one`/`_other` pair: zh/ja/ko have no separate singular form, so those packs
+would legitimately omit the `_one` half and `all-locales-key-parity` reads a
+legitimately-absent half as a lost key. Counts are interpolated as strings, so
+i18next skips its own plural resolution and the two-key scheme stays in charge.
+
+The reaction tooltip gets a **dedicated** key pair rather than reusing
+`detail.reactionCount`: that one interpolates `{{emoji}}`, and at this call
+site the emoji is the chip's visible label with nothing to hand the
+placeholder — reuse would have left a literal `{{emoji}}` in the accessible
+name under every locale.
+
+Relative timestamps stayed word-level: the existing minute/hour/day buckets are
+untouched and no date library was introduced. The `>= 7d` branch still uses the
+runtime's own `toLocaleDateString()` — that is not a hardcoded English literal,
+and pinning it to the session language has its own failure mode (an
+unrecognised tag throws into the surrounding `catch`, which would render a raw
+ISO string), so it is tracked separately.
+
+`Save` / `Cancel` / `Edit` / `Delete` read from the shared `common` namespace
+instead of being re-spelled under `collaboration` — they are the generic action
+words, already translated in all ten packs, and a second spelling would only be
+a second thing to keep in sync. The 21 genuinely new keys are added to all ten
+locale packs with real translations.
diff --git a/packages/collaboration/package.json b/packages/collaboration/package.json
index c8b31410fe..ad16a6a29d 100644
--- a/packages/collaboration/package.json
+++ b/packages/collaboration/package.json
@@ -37,6 +37,7 @@
     "react": "^18.0.0 || ^19.0.0"
   },
   "dependencies": {
+    "@object-ui/i18n": "workspace:*",
     "@object-ui/types": "workspace:*"
   },
   "devDependencies": {
diff --git a/packages/collaboration/src/CommentThread.tsx b/packages/collaboration/src/CommentThread.tsx
index 397b7b3b08..b90b555073 100644
--- a/packages/collaboration/src/CommentThread.tsx
+++ b/packages/collaboration/src/CommentThread.tsx
@@ -7,6 +7,10 @@
  */
 
 import React, { useState, useCallback, useMemo, useRef, useEffect } from 'react';
+import {
+  useCollaborationTranslation,
+  type CollaborationTranslate,
+} from './useCollaborationTranslation';
 
 export interface Comment {
   id: string;
@@ -47,18 +51,34 @@ export interface CommentThreadProps {
   className?: string;
 }
 
-function formatTimestamp(iso: string): string {
+/**
+ * Relative age of a comment, in the session language.
+ *
+ * `t` is threaded in as a parameter rather than read from a hook: this runs
+ * once per rendered comment from inside `renderComment`, and the buckets are
+ * unchanged — only the words moved into the locale packs. Counts are
+ * interpolated as STRINGS on purpose, so i18next skips its own plural
+ * resolution (`needsPluralHandling` is false for a string `count`) and cannot
+ * silently start looking for `_one`/`_other` variants this repo does not ship.
+ *
+ * The >= 7d branch still uses the runtime's own `toLocaleDateString()`. That is
+ * not a hardcoded English literal — it already follows the environment locale —
+ * and pinning it to the session language is a separate change with its own
+ * failure mode (an unrecognised tag throws `RangeError` straight into the
+ * `catch` below, which would render the raw ISO string). Tracked separately.
+ */
+function formatTimestamp(iso: string, t: CollaborationTranslate): string {
   try {
     const date = new Date(iso);
     const now = new Date();
     const diff = now.getTime() - date.getTime();
     const minutes = Math.floor(diff / 60000);
-    if (minutes < 1) return 'just now';
-    if (minutes < 60) return `${minutes}m ago`;
+    if (minutes < 1) return t('collaboration.justNow');
+    if (minutes < 60) return t('collaboration.minutesAgo', { count: String(minutes) });
     const hours = Math.floor(minutes / 60);
-    if (hours < 24) return `${hours}h ago`;
+    if (hours < 24) return t('collaboration.hoursAgo', { count: String(hours) });
     const days = Math.floor(hours / 24);
-    if (days < 7) return `${days}d ago`;
+    if (days < 7) return t('collaboration.daysAgo', { count: String(days) });
     return date.toLocaleDateString();
   } catch {
     return iso;
@@ -317,6 +337,13 @@ function renderContent(content: string): React.ReactNode {
  *
  * Renders a list of comments with author avatars, timestamps,
  * reply functionality, and an @mention suggestions popup.
+ *
+ * Every user-visible string resolves through `useCollaborationTranslation`
+ * (objectstack#5506): the session locale under an `I18nProvider`, and the
+ * English `COLLAB_DEFAULT_TRANSLATIONS` map with no provider mounted. There is
+ * deliberately no `formatter`/label prop escape hatch — a host that wants
+ * different copy overrides the locale keys, so one thread cannot end up half
+ * translated by the bundle and half by props.
  */
 export function CommentThread({
   threadId,
@@ -340,6 +367,7 @@ export function CommentThread({
   const [mentionIndex, setMentionIndex] = useState(0);
   const [sortOrder, setSortOrder] = useState<'newest' | 'oldest'>('oldest');
   const inputRef = useRef<HTMLTextAreaElement>(null);
+  const { t } = useCollaborationTranslation();
 
   const filteredMentions = useMemo(() => {
     if (mentionQuery === null) return [];
@@ -483,9 +511,9 @@ export function CommentThread({
         // Header
         React.createElement('div', { style: styles.commentHeader },
           React.createElement('span', { style: styles.authorName }, comment.author.name),
-          React.createElement('span', { style: styles.timestamp }, formatTimestamp(comment.createdAt)),
+          React.createElement('span', { style: styles.timestamp }, formatTimestamp(comment.createdAt, t)),
           comment.updatedAt
-            ? React.createElement('span', { style: styles.timestamp }, '(edited)')
+            ? React.createElement('span', { style: styles.timestamp }, t('collaboration.edited'))
             : null,
         ),
         // Content or edit input
@@ -500,11 +528,11 @@ export function CommentThread({
               React.createElement('button', {
                 onClick: handleEditSave,
                 style: { ...styles.submitBtn, padding: '4px 10px', fontSize: '12px' },
-              }, 'Save'),
+              }, t('common.save')),
               React.createElement('button', {
                 onClick: () => { setEditingId(null); setEditValue(''); },
                 style: { ...styles.actionBtn },
-              }, 'Cancel'),
+              }, t('common.cancel')),
             )
           : React.createElement('div', { style: styles.content }, renderContent(comment.content)),
         // Reactions display
@@ -517,13 +545,22 @@ export function CommentThread({
                 ...(userIds.includes(currentUser.id) ? styles.reactionBtnActive : {}),
               },
               onClick: () => onReaction?.(comment.id, emoji),
-              title: userIds.length === 1 ? '1 reaction' : `${userIds.length} reactions`,
+              // Dedicated key pair — `detail.reactionCount` interpolates an
+              // `{{emoji}}` this tooltip has no value for (the emoji is the
+              // button's visible label), so reusing it would leave a literal
+              // `{{emoji}}` in the accessible name under every locale.
+              title: t(
+                userIds.length === 1
+                  ? 'collaboration.reactionCountOne'
+                  : 'collaboration.reactionCount',
+                { count: String(userIds.length) },
+              ),
             }, `${emoji} ${userIds.length}`),
           ),
           onReaction && React.createElement('button', {
             style: styles.reactionPicker,
             onClick: () => onReaction(comment.id, '👍'),
-            title: 'Add thumbs up',
+            title: t('collaboration.addThumbsUp'),
           }, '+'),
         ),
         // Actions
@@ -531,7 +568,7 @@ export function CommentThread({
           React.createElement('button', {
             style: styles.actionBtn,
             onClick: () => setReplyTo(comment.id),
-          }, 'Reply'),
+          }, t('collaboration.reply')),
           onReaction && React.createElement('button', {
             style: styles.actionBtn,
             onClick: () => onReaction(comment.id, '👍'),
@@ -543,11 +580,11 @@ export function CommentThread({
           isOwner && onEditComment && React.createElement('button', {
             style: styles.actionBtn,
             onClick: () => handleEdit(comment.id),
-          }, 'Edit'),
+          }, t('common.edit')),
           isOwner && onDeleteComment && React.createElement('button', {
             style: styles.actionBtn,
             onClick: () => onDeleteComment(comment.id),
-          }, 'Delete'),
+          }, t('common.delete')),
         ),
       ),
     );
@@ -561,23 +598,33 @@ export function CommentThread({
     // Header
     React.createElement('div', { style: styles.header },
       React.createElement('span', null,
-        `${comments.length} comment${comments.length !== 1 ? 's' : ''}`,
-        resolved ? ' · Resolved' : '',
+        // Two keys instead of an English `s` glued on at render time. The old
+        // `` `${n} comment${n !== 1 ? 's' : ''}` `` produced correct *English*
+        // — the bug 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).
+        t(
+          comments.length === 1
+            ? 'collaboration.commentCountOne'
+            : 'collaboration.commentCount',
+          { count: String(comments.length) },
+        ),
+        resolved ? t('collaboration.resolvedSuffix') : '',
       ),
       React.createElement('div', { style: { display: 'flex', gap: '6px', alignItems: 'center' } },
         React.createElement('select', {
           value: sortOrder,
           onChange: (e: React.ChangeEvent<HTMLSelectElement>) => setSortOrder(e.target.value as 'newest' | 'oldest'),
           style: styles.sortSelect,
-          'aria-label': 'Sort comments',
+          'aria-label': t('collaboration.sortComments'),
         },
-          React.createElement('option', { value: 'oldest' }, 'Oldest'),
-          React.createElement('option', { value: 'newest' }, 'Newest'),
+          React.createElement('option', { value: 'oldest' }, t('collaboration.sortOldest')),
+          React.createElement('option', { value: 'newest' }, t('collaboration.sortNewest')),
         ),
         onResolve && React.createElement('button', {
           style: styles.resolveBtn,
           onClick: () => onResolve(!resolved),
-        }, resolved ? 'Reopen' : 'Resolve'),
+        }, resolved ? t('collaboration.reopen') : t('collaboration.resolve')),
       ),
     ),
     // Comments list
@@ -593,7 +640,15 @@ export function CommentThread({
     replyTo && React.createElement('div', {
       style: { padding: '4px 12px', fontSize: '12px', color: '#64748b', backgroundColor: '#f8fafc', display: 'flex', justifyContent: 'space-between' },
     },
-      React.createElement('span', null, `Replying to ${comments.find(c => c.id === replyTo)?.author.name ?? 'comment'}...`),
+      // Two whole sentences rather than one sentence plus a translatable word
+      // standing in for a name: languages that inflect around the addressee
+      // cannot build the no-author case out of the `{{name}}` form.
+      React.createElement('span', null, (() => {
+        const replyToName = comments.find(c => c.id === replyTo)?.author.name;
+        return replyToName
+          ? t('collaboration.replyingTo', { name: replyToName })
+          : t('collaboration.replyingToComment');
+      })()),
       React.createElement('button', {
         style: styles.actionBtn,
         onClick: () => setReplyTo(null),
@@ -631,7 +686,7 @@ export function CommentThread({
         value: inputValue,
         onChange: handleInputChange,
         onKeyDown: handleKeyDown,
-        placeholder: 'Add a comment... (use @ to mention)',
+        placeholder: t('collaboration.commentPlaceholder'),
         style: styles.textarea,
         rows: 1,
       }),
@@ -642,7 +697,7 @@ export function CommentThread({
           ...styles.submitBtn,
           ...(!inputValue.trim() ? styles.submitBtnDisabled : {}),
         },
-      }, 'Send'),
+      }, t('collaboration.send')),
     ),
   );
 }
diff --git a/packages/collaboration/src/__tests__/comment-thread-i18n.test.tsx b/packages/collaboration/src/__tests__/comment-thread-i18n.test.tsx
new file mode 100644
index 0000000000..82908ae6f1
--- /dev/null
+++ b/packages/collaboration/src/__tests__/comment-thread-i18n.test.tsx
@@ -0,0 +1,318 @@
+/**
+ * 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.
+ */
+
+/**
+ * `CommentThread` speaks the session language — objectstack#5506 / objectui#3424.
+ *
+ * The whole package shipped its copy as English literals, so a `zh` console
+ * rendered a Chinese shell around an English comment thread: "3 comments",
+ * "Reply", "Resolve", "just now", "Add a comment... (use @ to mention)".
+ *
+ * ── Directions: predicted first, then corrected by the run ────────────────
+ * Reverting `CommentThread.tsx` to `origin/main` and keeping this file turns
+ * all 13 `zh` / `de` / `ja` cases RED and leaves all 4 `en` cases GREEN.
+ *
+ * The `en` cases being green on BOTH sides is the point, not a gap: the
+ * English copy must survive the move into the locale packs, and a case that
+ * flipped would mean the copy changed under us.
+ *
+ * One prediction was WRONG and is recorded here rather than quietly dropped.
+ * The `en` singular case (`1 comment`) was expected to be red-before, on the
+ * assumption that the header glued a bare `s` on with no singular branch —
+ * the way `page:tabs`' count badge did in objectstack#5506's earlier half
+ * (objectui#3423), where a one-row list announced "1 items". It does not:
+ * `origin/main` reads `` `${n} comment${n !== 1 ? 's' : ''}` `` and the
+ * reaction tooltip reads `n === 1 ? '1 reaction' : …`, so both already
+ * produced correct English. The defect they carry is different — the plural
+ * RULE is compiled into the component, so no locale can apply its own (ru
+ * needs three forms, ja needs none, and neither could ever be expressed).
+ * The `de` case above is what actually pins that, and the `en` singular cases
+ * stay as green-both-sides copy pins.
+ *
+ * The provider-less English fallback is asserted in
+ * `comment-thread-no-provider-fallback.test.tsx` and cannot live here — see
+ * that file's header for the react-i18next global-instance reason.
+ */
+
+import type { ComponentProps } from 'react';
+import { describe, it, expect, afterEach } from 'vitest';
+import { render, screen, cleanup, fireEvent } from '@testing-library/react';
+import { I18nProvider } from '@object-ui/i18n';
+import { CommentThread, type Comment } from '../CommentThread';
+
+const alice = { id: 'u_alice', name: 'Alice Chen' };
+const bob = { id: 'u_bob', name: 'Bob Ito' };
+
+/** Ages chosen to land squarely inside each bucket, never on a boundary. */
+const minutesAgo = (n: number) => new Date(Date.now() - n * 60_000).toISOString();
+
+const baseComments: Comment[] = [
+  {
+    id: 'c1',
+    author: alice,
+    content: 'First pass looks good.',
+    mentions: [],
+    createdAt: minutesAgo(0),
+  },
+  {
+    id: 'c2',
+    author: bob,
+    content: 'Agreed.',
+    mentions: [],
+    createdAt: minutesAgo(5),
+    updatedAt: minutesAgo(4),
+    reactions: { '👍': [alice.id, bob.id], '❤️': [alice.id] },
+  },
+];
+
+function renderThread(
+  language: string,
+  overrides: Partial<ComponentProps<typeof CommentThread>> = {},
+) {
+  return render(
+    <I18nProvider config={{ defaultLanguage: language, detectBrowserLanguage: false }}>
+      <CommentThread
+        threadId="t_1"
+        comments={baseComments}
+        currentUser={alice}
+        onAddComment={() => {}}
+        onEditComment={() => {}}
+        onDeleteComment={() => {}}
+        onResolve={() => {}}
+        onReaction={() => {}}
+        {...overrides}
+      />
+    </I18nProvider>,
+  );
+}
+
+afterEach(() => cleanup());
+
+describe('CommentThread header (objectstack#5506)', () => {
+  it('counts, sorts and resolves in English under an en session', () => {
+    renderThread('en');
+
+    expect(screen.getByText('2 comments')).toBeTruthy();
+    expect(screen.getByLabelText('Sort comments')).toBeTruthy();
+    expect(screen.getByText('Oldest')).toBeTruthy();
+    expect(screen.getByText('Newest')).toBeTruthy();
+    expect(screen.getByText('Resolve')).toBeTruthy();
+  });
+
+  it('counts, sorts and resolves in Chinese under a zh session', () => {
+    renderThread('zh');
+
+    expect(screen.getByText('2 条评论')).toBeTruthy();
+    expect(screen.getByLabelText('评论排序')).toBeTruthy();
+    expect(screen.getByText('最早优先')).toBeTruthy();
+    expect(screen.getByText('最新优先')).toBeTruthy();
+    expect(screen.getByText('标记已解决')).toBeTruthy();
+    // The English literals are gone, not merely shadowed.
+    expect(screen.queryByText('2 comments')).toBeNull();
+    expect(screen.queryByLabelText('Sort comments')).toBeNull();
+  });
+
+  it('appends the resolved marker in the session language', () => {
+    renderThread('zh', { resolved: true });
+
+    expect(screen.getByText('2 条评论 · 已解决')).toBeTruthy();
+    // Resolved threads offer "reopen", not "resolve".
+    expect(screen.getByText('重新打开')).toBeTruthy();
+  });
+
+  /**
+   * German is the load-bearing plural case: unlike zh it HAS a distinct
+   * singular, so a collapsed one-key scheme would show up right here.
+   */
+  it('splits singular and plural under a de session', () => {
+    renderThread('de', { comments: [baseComments[0]] });
+    expect(screen.getByText('1 Kommentar')).toBeTruthy();
+    cleanup();
+
+    renderThread('de');
+    expect(screen.getByText('2 Kommentare')).toBeTruthy();
+  });
+
+  /**
+   * Green on both sides — a copy pin, not a demonstration of the bug. See the
+   * file header: `origin/main` did have a singular branch here, contrary to
+   * the prediction this test was first written under.
+   */
+  it('has a real English singular for a one-comment thread', () => {
+    renderThread('en', { comments: [baseComments[0]] });
+
+    expect(screen.getByText('1 comment')).toBeTruthy();
+    expect(screen.queryByText('1 comments')).toBeNull();
+  });
+});
+
+describe('CommentThread relative timestamps (objectstack#5506)', () => {
+  it('reads English relative ages under an en session', () => {
+    renderThread('en', {
+      comments: [
+        { ...baseComments[0], id: 'a', createdAt: minutesAgo(0) },
+        { ...baseComments[0], id: 'b', createdAt: minutesAgo(7) },
+        { ...baseComments[0], id: 'c', createdAt: minutesAgo(3 * 60) },
+        { ...baseComments[0], id: 'd', createdAt: minutesAgo(2 * 24 * 60) },
+      ],
+    });
+
+    expect(screen.getByText('just now')).toBeTruthy();
+    expect(screen.getByText('7m ago')).toBeTruthy();
+    expect(screen.getByText('3h ago')).toBeTruthy();
+    expect(screen.getByText('2d ago')).toBeTruthy();
+  });
+
+  it('reads Chinese relative ages under a zh session', () => {
+    renderThread('zh', {
+      comments: [
+        { ...baseComments[0], id: 'a', createdAt: minutesAgo(0) },
+        { ...baseComments[0], id: 'b', createdAt: minutesAgo(7) },
+        { ...baseComments[0], id: 'c', createdAt: minutesAgo(3 * 60) },
+        { ...baseComments[0], id: 'd', createdAt: minutesAgo(2 * 24 * 60) },
+      ],
+    });
+
+    expect(screen.getByText('刚刚')).toBeTruthy();
+    expect(screen.getByText('7 分钟前')).toBeTruthy();
+    expect(screen.getByText('3 小时前')).toBeTruthy();
+    expect(screen.getByText('2 天前')).toBeTruthy();
+    expect(screen.queryByText('just now')).toBeNull();
+    expect(screen.queryByText('7m ago')).toBeNull();
+  });
+
+  it('marks an edited comment in the session language', () => {
+    renderThread('ja');
+    expect(screen.getByText('(編集済み)')).toBeTruthy();
+    expect(screen.queryByText('(edited)')).toBeNull();
+  });
+});
+
+describe('CommentThread reaction tooltip (objectstack#5506)', () => {
+  /**
+   * The tooltip gets its OWN key pair. `detail.reactionCount` interpolates an
+   * `{{emoji}}`, and here the emoji is the chip's visible label with nothing to
+   * hand that placeholder — reuse would leave a literal `{{emoji}}` in the
+   * accessible name. These assertions are what pins that.
+   */
+  it('names reaction chips in English, with singular and plural', () => {
+    renderThread('en');
+
+    expect(screen.getByTitle('2 reactions')).toBeTruthy();
+    expect(screen.getByTitle('1 reaction')).toBeTruthy();
+    expect(screen.getByTitle('Add thumbs up')).toBeTruthy();
+  });
+
+  it('names reaction chips in the session language', () => {
+    renderThread('zh');
+
+    expect(screen.getByTitle('2 个回应')).toBeTruthy();
+    expect(screen.getByTitle('点赞')).toBeTruthy();
+    expect(screen.queryByTitle('2 reactions')).toBeNull();
+    expect(screen.queryByTitle('Add thumbs up')).toBeNull();
+  });
+
+  it('never leaks an unresolved placeholder into the tooltip', () => {
+    renderThread('de');
+
+    const tooltips = Array.from(document.querySelectorAll('[title]')).map((n) =>
+      n.getAttribute('title'),
+    );
+    expect(tooltips).toContain('2 Reaktionen');
+    expect(tooltips).toContain('1 Reaktion');
+    // The bug reuse of `detail.reactionCount` would have produced.
+    expect(tooltips.some((v) => v?.includes('{{'))).toBe(false);
+  });
+});
+
+describe('CommentThread per-comment actions (objectstack#5506)', () => {
+  it('labels reply / edit / delete in the session language', () => {
+    renderThread('zh');
+
+    expect(screen.getAllByText('回复').length).toBeGreaterThan(0);
+    expect(screen.getAllByText('编辑').length).toBeGreaterThan(0);
+    expect(screen.getAllByText('删除').length).toBeGreaterThan(0);
+    expect(screen.queryByText('Reply')).toBeNull();
+    expect(screen.queryByText('Delete')).toBeNull();
+  });
+
+  it('labels the inline editor save / cancel in the session language', () => {
+    renderThread('zh');
+
+    // Only the current user's own comment offers Edit; c1 is Alice's.
+    fireEvent.click(screen.getAllByText('编辑')[0]);
+
+    expect(screen.getByText('保存')).toBeTruthy();
+    expect(screen.getByText('取消')).toBeTruthy();
+    expect(screen.queryByText('Save')).toBeNull();
+    expect(screen.queryByText('Cancel')).toBeNull();
+  });
+
+  it('translates the reply banner, interpolating the author name', () => {
+    renderThread('zh');
+
+    fireEvent.click(screen.getAllByText('回复')[0]);
+
+    expect(screen.getByText('正在回复 Alice Chen…')).toBeTruthy();
+    expect(screen.queryByText('Replying to Alice Chen...')).toBeNull();
+  });
+
+  /**
+   * The no-author half of the banner: the comment being replied to is gone
+   * (deleted by someone else mid-reply — the collaboration case this package
+   * exists for), so there is no `{{name}}` to interpolate and a separate whole
+   * sentence is used instead of substituting a noun.
+   */
+  it('translates the reply banner when the target comment vanished', () => {
+    const { rerender } = renderThread('zh');
+
+    fireEvent.click(screen.getAllByText('回复')[0]);
+    rerender(
+      <I18nProvider config={{ defaultLanguage: 'zh', detectBrowserLanguage: false }}>
+        <CommentThread
+          threadId="t_1"
+          comments={[]}
+          currentUser={alice}
+          onAddComment={() => {}}
+          onEditComment={() => {}}
+          onDeleteComment={() => {}}
+          onResolve={() => {}}
+          onReaction={() => {}}
+        />
+      </I18nProvider>,
+    );
+
+    expect(screen.getByText('正在回复该评论…')).toBeTruthy();
+    expect(screen.queryByText('Replying to comment...')).toBeNull();
+  });
+});
+
+describe('CommentThread composer (objectstack#5506)', () => {
+  it('translates the placeholder and the send button', () => {
+    renderThread('zh');
+
+    expect(screen.getByPlaceholderText('添加评论…(输入 @ 提及他人)')).toBeTruthy();
+    expect(screen.getByText('发送')).toBeTruthy();
+    expect(screen.queryByPlaceholderText('Add a comment... (use @ to mention)')).toBeNull();
+    expect(screen.queryByText('Send')).toBeNull();
+  });
+
+  it('keeps the English copy under an en session', () => {
+    renderThread('en');
+
+    expect(screen.getByPlaceholderText('Add a comment... (use @ to mention)')).toBeTruthy();
+    expect(screen.getByText('Send')).toBeTruthy();
+  });
+
+  it('translates the placeholder for ja too', () => {
+    renderThread('ja');
+
+    expect(screen.getByPlaceholderText('コメントを追加…(@ でメンション)')).toBeTruthy();
+    expect(screen.getByText('送信')).toBeTruthy();
+  });
+});
diff --git a/packages/collaboration/src/__tests__/comment-thread-no-provider-fallback.test.tsx b/packages/collaboration/src/__tests__/comment-thread-no-provider-fallback.test.tsx
new file mode 100644
index 0000000000..5823e2dc96
--- /dev/null
+++ b/packages/collaboration/src/__tests__/comment-thread-no-provider-fallback.test.tsx
@@ -0,0 +1,205 @@
+/**
+ * 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 objectstack#5506 / objectui#3424 moved into the locale packs
+ * still resolves to ENGLISH when no `I18nProvider` is mounted.
+ *
+ * `CommentThread` is exported for standalone use and its host may mount no
+ * ObjectUI shell at all. Routing a literal through `t()` without a working
+ * default is exactly how a label turns into a raw dotted key
+ * (`collaboration.reply`) in someone else's app — and it would do so silently,
+ * because `fallbackLng: 'en'` never fires when there is no i18next instance to
+ * fall back inside of. `COLLAB_DEFAULT_TRANSLATIONS` is the thing that has to
+ * hold, and this file is what holds it.
+ *
+ * ── Directions: predicted first, then corrected by the run ────────────────
+ * **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 supposed to
+ * be byte-identical before and after, so a flip 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 mis-spelled) in
+ * `COLLAB_DEFAULT_TRANSLATIONS` goes red here and nowhere else.
+ *
+ * One prediction was wrong and is recorded rather than dropped: the singular
+ * comment count was expected to be red-before, on the assumption that the
+ * header glued a bare `s` on with no singular branch — the way `page:tabs`'
+ * badge did in objectui#3423 ("1 items"). `origin/main` in fact reads
+ * `` `${n} comment${n !== 1 ? 's' : ''}` `` and already produced correct
+ * English, so that case is green on both sides like the rest. The real defect
+ * in those two sites is that the plural RULE was compiled into the component
+ * and no locale could apply its own; the `de` cases in
+ * `comment-thread-i18n.test.tsx` are what pin that.
+ *
+ * ── Why this is its own FILE, not a describe block ────────────────────────
+ * `createI18n` calls `instance.use(initReactI18next)`, and `initReactI18next`
+ * 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 about the
+ * fallback, or a baffling red where a provider-less thread 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.** (Importing `@object-ui/i18n` for a pure
+ * helper would be safe — nothing calls `createI18n` at module scope — but the
+ * cheapest way to keep that true is to not import it at all.)
+ */
+
+import { describe, it, expect, afterEach } from 'vitest';
+import { render, screen, cleanup, fireEvent } from '@testing-library/react';
+import { CommentThread, type Comment } from '../CommentThread';
+import { COLLAB_DEFAULT_TRANSLATIONS } from '../useCollaborationTranslation';
+
+const alice = { id: 'u_alice', name: 'Alice Chen' };
+const bob = { id: 'u_bob', name: 'Bob Ito' };
+
+const minutesAgo = (n: number) => new Date(Date.now() - n * 60_000).toISOString();
+
+const comments: Comment[] = [
+  { id: 'c1', author: alice, content: 'First pass looks good.', mentions: [], createdAt: minutesAgo(0) },
+  {
+    id: 'c2',
+    author: bob,
+    content: 'Agreed.',
+    mentions: [],
+    createdAt: minutesAgo(7),
+    updatedAt: minutesAgo(6),
+    reactions: { '👍': [alice.id, bob.id], '❤️': [alice.id] },
+  },
+];
+
+function renderBare(overrides: Record<string, unknown> = {}) {
+  return render(
+    <CommentThread
+      threadId="t_1"
+      comments={comments}
+      currentUser={alice}
+      onAddComment={() => {}}
+      onEditComment={() => {}}
+      onDeleteComment={() => {}}
+      onResolve={() => {}}
+      onReaction={() => {}}
+      {...overrides}
+    />,
+  );
+}
+
+afterEach(() => cleanup());
+
+describe('CommentThread with no I18nProvider — English fallback (objectstack#5506)', () => {
+  it('renders the header, sort control and resolve button in English', () => {
+    renderBare();
+
+    expect(screen.getByText('2 comments')).toBeTruthy();
+    expect(screen.getByLabelText('Sort comments')).toBeTruthy();
+    expect(screen.getByText('Oldest')).toBeTruthy();
+    expect(screen.getByText('Newest')).toBeTruthy();
+    expect(screen.getByText('Resolve')).toBeTruthy();
+  });
+
+  it('renders relative timestamps and the edited marker in English', () => {
+    renderBare();
+
+    expect(screen.getByText('just now')).toBeTruthy();
+    expect(screen.getByText('7m ago')).toBeTruthy();
+    expect(screen.getByText('(edited)')).toBeTruthy();
+  });
+
+  it('renders reaction tooltips and per-comment actions in English', () => {
+    renderBare();
+
+    expect(screen.getByTitle('2 reactions')).toBeTruthy();
+    expect(screen.getByTitle('1 reaction')).toBeTruthy();
+    expect(screen.getByTitle('Add thumbs up')).toBeTruthy();
+    expect(screen.getAllByText('Reply').length).toBeGreaterThan(0);
+    expect(screen.getByText('Edit')).toBeTruthy();
+    expect(screen.getByText('Delete')).toBeTruthy();
+  });
+
+  it('renders the inline editor and reply banner in English', () => {
+    renderBare();
+
+    fireEvent.click(screen.getByText('Edit'));
+    expect(screen.getByText('Save')).toBeTruthy();
+    expect(screen.getByText('Cancel')).toBeTruthy();
+
+    fireEvent.click(screen.getAllByText('Reply')[0]);
+    expect(screen.getByText('Replying to Bob Ito...')).toBeTruthy();
+  });
+
+  it('renders the composer in English', () => {
+    renderBare();
+
+    expect(screen.getByPlaceholderText('Add a comment... (use @ to mention)')).toBeTruthy();
+    expect(screen.getByText('Send')).toBeTruthy();
+  });
+
+  it('appends the resolved marker in English', () => {
+    renderBare({ resolved: true });
+
+    expect(screen.getByText('2 comments · Resolved')).toBeTruthy();
+    expect(screen.getByText('Reopen')).toBeTruthy();
+  });
+
+  /**
+   * A copy pin, green on both sides — see the file header for why this was
+   * expected to be the one red-before case and is not.
+   */
+  it('has a real English singular for a one-comment thread', () => {
+    renderBare({ comments: [comments[0]] });
+
+    expect(screen.getByText('1 comment')).toBeTruthy();
+    expect(screen.queryByText('1 comments')).toBeNull();
+  });
+
+  /**
+   * 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.
+   */
+  it('never renders a raw i18n key', () => {
+    const { container } = renderBare({ resolved: true });
+
+    expect(container.textContent).not.toMatch(/collaboration\.\w+/);
+    expect(container.textContent).not.toMatch(/common\.\w+/);
+    expect(container.innerHTML).not.toMatch(/\{\{\w+\}\}/);
+  });
+});
+
+describe('COLLAB_DEFAULT_TRANSLATIONS is the package-wide English source', () => {
+  /**
+   * The defaults map is the *only* English copy left in the package, so an
+   * empty or half-populated map would make every assertion above pass for the
+   * wrong reason (a key that resolves to itself still "renders").
+   */
+  it('covers every key the thread asks for, with no placeholder-only values', () => {
+    const keys = Object.keys(COLLAB_DEFAULT_TRANSLATIONS);
+
+    expect(keys.length).toBeGreaterThanOrEqual(25);
+    expect(keys).toContain('collaboration.reactionCount');
+    expect(keys).toContain('collaboration.reactionCountOne');
+    // The shared action words are borrowed from `common`, not re-spelled.
+    expect(keys).toContain('common.save');
+    expect(keys.some((k) => k.startsWith('collaboration.save'))).toBe(false);
+
+    for (const [key, value] of Object.entries(COLLAB_DEFAULT_TRANSLATIONS)) {
+      expect(value, `${key} has no English copy`).toBeTruthy();
+      expect(value, `${key} is just its own key`).not.toBe(key);
+    }
+  });
+
+  /**
+   * The reaction tooltip must NOT be `detail.reactionCount`, which carries an
+   * `{{emoji}}` this call site has no value for.
+   */
+  it('keeps the reaction tooltip free of an {{emoji}} placeholder', () => {
+    expect(COLLAB_DEFAULT_TRANSLATIONS['collaboration.reactionCount']).toBe('{{count}} reactions');
+    expect(COLLAB_DEFAULT_TRANSLATIONS['collaboration.reactionCountOne']).toBe('{{count}} reaction');
+  });
+});
diff --git a/packages/collaboration/src/index.ts b/packages/collaboration/src/index.ts
index a92fb6396d..667f42a4ba 100644
--- a/packages/collaboration/src/index.ts
+++ b/packages/collaboration/src/index.ts
@@ -49,6 +49,16 @@ export {
   type CommentThreadProps,
 } from './CommentThread';
 
+// This package's i18n seam. Exported like `plugin-detail`'s
+// `useDetailTranslation` / `DETAIL_DEFAULT_TRANSLATIONS` so a host can read the
+// English defaults (e.g. to seed its own bundle) and so anything added to this
+// package later translates through the same map instead of a second one.
+export {
+  useCollaborationTranslation,
+  COLLAB_DEFAULT_TRANSLATIONS,
+  type CollaborationTranslate,
+} from './useCollaborationTranslation';
+
 export {
   useMentionNotifications,
   type MentionNotificationsConfig,
diff --git a/packages/collaboration/src/useCollaborationTranslation.ts b/packages/collaboration/src/useCollaborationTranslation.ts
new file mode 100644
index 0000000000..4201b963be
--- /dev/null
+++ b/packages/collaboration/src/useCollaborationTranslation.ts
@@ -0,0 +1,105 @@
+/**
+ * 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.
+ */
+
+/**
+ * i18n entry point for `@object-ui/collaboration` (objectstack#5506, objectui#3424).
+ *
+ * The package shipped every user-visible string as an English literal, so a
+ * `zh` session read a Chinese console with an English comment thread inside it.
+ * This is the package's single translation seam: components call
+ * {@link useCollaborationTranslation} and never hold a literal.
+ *
+ * `createSafeTranslation` (the same factory `data-table`, `form` and
+ * `filter-builder` use) does two things at once:
+ *
+ *  1. under an `I18nProvider` it resolves against the session locale, and
+ *  2. with **no** provider it resolves against {@link COLLAB_DEFAULT_TRANSLATIONS}.
+ *
+ * (2) is not a nicety — it is the contract. `CommentThread` is exported for
+ * standalone use with no ObjectUI shell around it, and its host may mount no
+ * provider at all. Routing a literal through `t()` without a working default
+ * would turn every label into a raw dotted key on that path. The defaults map
+ * below is therefore the authoritative English copy of this package, and it
+ * must stay byte-identical to the `en` locale pack's `collaboration` namespace.
+ *
+ * Plural keys come in PAIRS (`…Count` / `…CountOne`) rather than i18next
+ * `_one`/`_other` suffixes: zh/ja/ko have no separate singular form, so those
+ * packs would legitimately omit the `_one` half and `all-locales-key-parity`
+ * reads a legitimately-absent half as a lost key. Same convention as
+ * `detail.reactionCount` / `common.itemCount`.
+ */
+import { createSafeTranslation } from '@object-ui/i18n';
+
+/**
+ * English fallback copy for everything this package renders.
+ *
+ * Four entries are borrowed from the shared `common` namespace rather than
+ * duplicated under `collaboration`: `Save` / `Cancel` / `Edit` / `Delete` are
+ * the generic action words, already translated in all ten packs, and a second
+ * spelling of them would only be a second thing to keep in sync.
+ */
+export const COLLAB_DEFAULT_TRANSLATIONS: Record<string, string> = {
+  // Thread header
+  'collaboration.commentCount': '{{count}} comments',
+  'collaboration.commentCountOne': '{{count}} comment',
+  'collaboration.resolvedSuffix': ' · Resolved',
+  'collaboration.sortComments': 'Sort comments',
+  'collaboration.sortOldest': 'Oldest',
+  'collaboration.sortNewest': 'Newest',
+  'collaboration.resolve': 'Resolve',
+  'collaboration.reopen': 'Reopen',
+  // Relative timestamps. Word-level entries, not a date-formatting layer — the
+  // buckets stay exactly where the component already put them and no date
+  // library is introduced.
+  'collaboration.justNow': 'just now',
+  'collaboration.minutesAgo': '{{count}}m ago',
+  'collaboration.hoursAgo': '{{count}}h ago',
+  'collaboration.daysAgo': '{{count}}d ago',
+  'collaboration.edited': '(edited)',
+  // Reactions. A DEDICATED pair, deliberately not `detail.reactionCount` —
+  // that one interpolates `{{emoji}}` and this tooltip has no emoji to hand it
+  // (the emoji is the button's visible content), so reuse would render a
+  // stray `{{emoji}}` under every locale.
+  'collaboration.reactionCount': '{{count}} reactions',
+  'collaboration.reactionCountOne': '{{count}} reaction',
+  'collaboration.addThumbsUp': 'Add thumbs up',
+  // Per-comment actions and the reply banner
+  'collaboration.reply': 'Reply',
+  'collaboration.replyingTo': 'Replying to {{name}}...',
+  'collaboration.replyingToComment': 'Replying to comment...',
+  // Composer
+  'collaboration.commentPlaceholder': 'Add a comment... (use @ to mention)',
+  'collaboration.send': 'Send',
+  // Shared action words — see the note above.
+  'common.save': 'Save',
+  'common.cancel': 'Cancel',
+  'common.edit': 'Edit',
+  'common.delete': 'Delete',
+};
+
+/**
+ * Session-locale translation for this package, with the English map above as
+ * the no-provider fallback.
+ *
+ * The probe key must be one this package owns: a shared `common.*` key would
+ * also resolve under an unrelated bundle and report "i18n is configured" for a
+ * host that never loaded the collaboration namespace.
+ */
+export const useCollaborationTranslation = createSafeTranslation(
+  COLLAB_DEFAULT_TRANSLATIONS,
+  'collaboration.commentPlaceholder',
+);
+
+/**
+ * The translate function `useCollaborationTranslation` hands back.
+ *
+ * Derived from the hook rather than hand-written so module-level helpers that
+ * take `t` as a parameter (see `formatTimestamp`) cannot drift from whichever
+ * half of the union — real i18next `t` or the English fallback — is live.
+ */
+export type CollaborationTranslate = ReturnType<typeof useCollaborationTranslation>['t'];
diff --git a/packages/i18n/src/locales/ar.ts b/packages/i18n/src/locales/ar.ts
index dff27533c9..7f25c1776a 100644
--- a/packages/i18n/src/locales/ar.ts
+++ b/packages/i18n/src/locales/ar.ts
@@ -3051,6 +3051,29 @@ const ar = {
     addSort: "إضافة ترتيب",
     removeSort: "إزالة الترتيب",
   },
+  collaboration: {
+    commentCount: "{{count}} تعليقات",
+    commentCountOne: "{{count}} تعليق",
+    resolvedSuffix: " · تم الحل",
+    sortComments: "ترتيب التعليقات",
+    sortOldest: "الأقدم أولاً",
+    sortNewest: "الأحدث أولاً",
+    resolve: "وضع علامة كمحلول",
+    reopen: "إعادة الفتح",
+    justNow: "الآن",
+    minutesAgo: "قبل {{count}} دقيقة",
+    hoursAgo: "قبل {{count}} ساعة",
+    daysAgo: "قبل {{count}} يوم",
+    edited: "(تم التعديل)",
+    reactionCount: "{{count}} تفاعلات",
+    reactionCountOne: "{{count}} تفاعل",
+    addThumbsUp: "إضافة إعجاب",
+    reply: "رد",
+    replyingTo: "الرد على {{name}}…",
+    replyingToComment: "الرد على التعليق…",
+    commentPlaceholder: "أضف تعليقًا… (استخدم @ للإشارة)",
+    send: "إرسال",
+  },
 };
 
 export default ar;
diff --git a/packages/i18n/src/locales/de.ts b/packages/i18n/src/locales/de.ts
index 7f73eb02b1..45149a2b4b 100644
--- a/packages/i18n/src/locales/de.ts
+++ b/packages/i18n/src/locales/de.ts
@@ -3051,6 +3051,29 @@ const de = {
     addSort: "Sortierung hinzufügen",
     removeSort: "Sortierung entfernen",
   },
+  collaboration: {
+    commentCount: "{{count}} Kommentare",
+    commentCountOne: "{{count}} Kommentar",
+    resolvedSuffix: " · Gelöst",
+    sortComments: "Kommentare sortieren",
+    sortOldest: "Älteste zuerst",
+    sortNewest: "Neueste zuerst",
+    resolve: "Lösen",
+    reopen: "Erneut öffnen",
+    justNow: "gerade eben",
+    minutesAgo: "vor {{count}} Min.",
+    hoursAgo: "vor {{count}} Std.",
+    daysAgo: "vor {{count}} T.",
+    edited: "(bearbeitet)",
+    reactionCount: "{{count}} Reaktionen",
+    reactionCountOne: "{{count}} Reaktion",
+    addThumbsUp: "Daumen hoch hinzufügen",
+    reply: "Antworten",
+    replyingTo: "Antwort an {{name}} …",
+    replyingToComment: "Antwort auf Kommentar …",
+    commentPlaceholder: "Kommentar hinzufügen … (@ für Erwähnungen)",
+    send: "Senden",
+  },
 };
 
 export default de;
diff --git a/packages/i18n/src/locales/en.ts b/packages/i18n/src/locales/en.ts
index 2bf1e43f8d..ed13aa6ff5 100644
--- a/packages/i18n/src/locales/en.ts
+++ b/packages/i18n/src/locales/en.ts
@@ -3164,6 +3164,52 @@ const en = {
     addSort: 'Add sort',
     removeSort: 'Remove sort',
   },
+  // `@object-ui/collaboration` — the comment thread's copy (objectstack#5506,
+  // objectui#3424). The package used to carry every one of these as an English
+  // literal, so a zh session read a Chinese console with an English comment
+  // thread inside it. `COLLAB_DEFAULT_TRANSLATIONS` in that package mirrors
+  // this namespace verbatim as its no-provider fallback; keep the two in step.
+  //
+  // The generic action words (Save / Cancel / Edit / Delete) are NOT repeated
+  // here — the thread reads them from `common`.
+  collaboration: {
+    // Thread header. `commentCount`/`commentCountOne` are two keys, NOT an
+    // i18next `_one`/`_other` pair — see the `reactionCount` note under
+    // `detail`: zh/ja/ko have no separate singular form, so those packs would
+    // legitimately omit the `_one` half and `all-locales-key-parity` reads a
+    // legitimately-absent half as a lost key.
+    commentCount: '{{count}} comments',
+    commentCountOne: '{{count}} comment',
+    // Appended to the count, separator included, so a translator owns the
+    // whole phrase rather than inheriting an English-shaped ` · ` glue.
+    resolvedSuffix: ' · Resolved',
+    sortComments: 'Sort comments',
+    sortOldest: 'Oldest',
+    sortNewest: 'Newest',
+    resolve: 'Resolve',
+    reopen: 'Reopen',
+    // Relative comment age. Word-level entries only — the component keeps its
+    // existing minute/hour/day buckets and no date library was introduced.
+    justNow: 'just now',
+    minutesAgo: '{{count}}m ago',
+    hoursAgo: '{{count}}h ago',
+    daysAgo: '{{count}}d ago',
+    edited: '(edited)',
+    // Reaction-chip tooltip. A DEDICATED pair rather than `detail.reactionCount`:
+    // that one interpolates `{{emoji}}`, and here the emoji is the chip's
+    // visible label with nothing to hand the placeholder.
+    reactionCount: '{{count}} reactions',
+    reactionCountOne: '{{count}} reaction',
+    addThumbsUp: 'Add thumbs up',
+    reply: 'Reply',
+    replyingTo: 'Replying to {{name}}...',
+    // The no-author-found half of the reply banner, as a whole sentence:
+    // languages that inflect around the addressee cannot build it by
+    // substituting a noun into the `{{name}}` form.
+    replyingToComment: 'Replying to comment...',
+    commentPlaceholder: 'Add a comment... (use @ to mention)',
+    send: 'Send',
+  },
 } as const;
 
 export default en;
diff --git a/packages/i18n/src/locales/es.ts b/packages/i18n/src/locales/es.ts
index c4e317c3c2..5e8fa8b278 100644
--- a/packages/i18n/src/locales/es.ts
+++ b/packages/i18n/src/locales/es.ts
@@ -3056,6 +3056,29 @@ const es = {
     addSort: "Agregar orden",
     removeSort: "Quitar orden",
   },
+  collaboration: {
+    commentCount: "{{count}} comentarios",
+    commentCountOne: "{{count}} comentario",
+    resolvedSuffix: " · Resuelto",
+    sortComments: "Ordenar comentarios",
+    sortOldest: "Más antiguos",
+    sortNewest: "Más recientes",
+    resolve: "Resolver",
+    reopen: "Reabrir",
+    justNow: "ahora mismo",
+    minutesAgo: "hace {{count}} min",
+    hoursAgo: "hace {{count}} h",
+    daysAgo: "hace {{count}} d",
+    edited: "(editado)",
+    reactionCount: "{{count}} reacciones",
+    reactionCountOne: "{{count}} reacción",
+    addThumbsUp: "Agregar me gusta",
+    reply: "Responder",
+    replyingTo: "Respondiendo a {{name}}…",
+    replyingToComment: "Respondiendo al comentario…",
+    commentPlaceholder: "Agregar un comentario… (usa @ para mencionar)",
+    send: "Enviar",
+  },
 };
 
 export default es;
diff --git a/packages/i18n/src/locales/fr.ts b/packages/i18n/src/locales/fr.ts
index c9e6726a4c..3f8a8dccc5 100644
--- a/packages/i18n/src/locales/fr.ts
+++ b/packages/i18n/src/locales/fr.ts
@@ -3051,6 +3051,29 @@ const fr = {
     addSort: "Ajouter un tri",
     removeSort: "Supprimer le tri",
   },
+  collaboration: {
+    commentCount: "{{count}} commentaires",
+    commentCountOne: "{{count}} commentaire",
+    resolvedSuffix: " · Résolu",
+    sortComments: "Trier les commentaires",
+    sortOldest: "Plus anciens",
+    sortNewest: "Plus récents",
+    resolve: "Résoudre",
+    reopen: "Rouvrir",
+    justNow: "à l'instant",
+    minutesAgo: "il y a {{count}} min",
+    hoursAgo: "il y a {{count}} h",
+    daysAgo: "il y a {{count}} j",
+    edited: "(modifié)",
+    reactionCount: "{{count}} réactions",
+    reactionCountOne: "{{count}} réaction",
+    addThumbsUp: "Ajouter un pouce levé",
+    reply: "Répondre",
+    replyingTo: "Réponse à {{name}}…",
+    replyingToComment: "Réponse au commentaire…",
+    commentPlaceholder: "Ajouter un commentaire… (utilisez @ pour mentionner)",
+    send: "Envoyer",
+  },
 };
 
 export default fr;
diff --git a/packages/i18n/src/locales/ja.ts b/packages/i18n/src/locales/ja.ts
index c7afb037d6..e704091428 100644
--- a/packages/i18n/src/locales/ja.ts
+++ b/packages/i18n/src/locales/ja.ts
@@ -3051,6 +3051,29 @@ const ja = {
     addSort: "並べ替えを追加",
     removeSort: "並べ替えを削除",
   },
+  collaboration: {
+    commentCount: "コメント {{count}} 件",
+    commentCountOne: "コメント {{count}} 件",
+    resolvedSuffix: " · 解決済み",
+    sortComments: "コメントの並べ替え",
+    sortOldest: "古い順",
+    sortNewest: "新しい順",
+    resolve: "解決済みにする",
+    reopen: "再オープン",
+    justNow: "たった今",
+    minutesAgo: "{{count}} 分前",
+    hoursAgo: "{{count}} 時間前",
+    daysAgo: "{{count}} 日前",
+    edited: "(編集済み)",
+    reactionCount: "リアクション {{count}} 件",
+    reactionCountOne: "リアクション {{count}} 件",
+    addThumbsUp: "いいねを追加",
+    reply: "返信",
+    replyingTo: "{{name}} に返信中…",
+    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",
+  },
 };
 
 export default ja;
diff --git a/packages/i18n/src/locales/ko.ts b/packages/i18n/src/locales/ko.ts
index 6b334b27a6..3cf5f1f6a2 100644
--- a/packages/i18n/src/locales/ko.ts
+++ b/packages/i18n/src/locales/ko.ts
@@ -3051,6 +3051,29 @@ const ko = {
     addSort: "정렬 추가",
     removeSort: "정렬 삭제",
   },
+  collaboration: {
+    commentCount: "댓글 {{count}}개",
+    commentCountOne: "댓글 {{count}}개",
+    resolvedSuffix: " · 해결됨",
+    sortComments: "댓글 정렬",
+    sortOldest: "오래된 순",
+    sortNewest: "최신 순",
+    resolve: "해결됨으로 표시",
+    reopen: "다시 열기",
+    justNow: "방금",
+    minutesAgo: "{{count}}분 전",
+    hoursAgo: "{{count}}시간 전",
+    daysAgo: "{{count}}일 전",
+    edited: "(수정됨)",
+    reactionCount: "반응 {{count}}개",
+    reactionCountOne: "반응 {{count}}개",
+    addThumbsUp: "좋아요 추가",
+    reply: "답글",
+    replyingTo: "{{name}}님에게 답글 작성 중…",
+    replyingToComment: "이 댓글에 답글 작성 중…",
+    commentPlaceholder: "댓글 추가…(@로 멘션)",
+    send: "보내기",
+  },
 };
 
 export default ko;
diff --git a/packages/i18n/src/locales/pt.ts b/packages/i18n/src/locales/pt.ts
index 250de516b7..cd0cd1b04a 100644
--- a/packages/i18n/src/locales/pt.ts
+++ b/packages/i18n/src/locales/pt.ts
@@ -3051,6 +3051,29 @@ const pt = {
     addSort: "Adicionar ordenação",
     removeSort: "Remover ordenação",
   },
+  collaboration: {
+    commentCount: "{{count}} comentários",
+    commentCountOne: "{{count}} comentário",
+    resolvedSuffix: " · Resolvido",
+    sortComments: "Ordenar comentários",
+    sortOldest: "Mais antigos",
+    sortNewest: "Mais recentes",
+    resolve: "Resolver",
+    reopen: "Reabrir",
+    justNow: "agora mesmo",
+    minutesAgo: "há {{count}} min",
+    hoursAgo: "há {{count}} h",
+    daysAgo: "há {{count}} d",
+    edited: "(editado)",
+    reactionCount: "{{count}} reações",
+    reactionCountOne: "{{count}} reação",
+    addThumbsUp: "Adicionar curtida",
+    reply: "Responder",
+    replyingTo: "Respondendo a {{name}}…",
+    replyingToComment: "Respondendo ao comentário…",
+    commentPlaceholder: "Adicionar um comentário… (use @ para mencionar)",
+    send: "Enviar",
+  },
 };
 
 export default pt;
diff --git a/packages/i18n/src/locales/ru.ts b/packages/i18n/src/locales/ru.ts
index 4a9a161740..5357da2c1d 100644
--- a/packages/i18n/src/locales/ru.ts
+++ b/packages/i18n/src/locales/ru.ts
@@ -3051,6 +3051,29 @@ const ru = {
     addSort: "Добавить сортировку",
     removeSort: "Удалить сортировку",
   },
+  collaboration: {
+    commentCount: "Комментариев: {{count}}",
+    commentCountOne: "{{count}} комментарий",
+    resolvedSuffix: " · Решено",
+    sortComments: "Сортировка комментариев",
+    sortOldest: "Сначала старые",
+    sortNewest: "Сначала новые",
+    resolve: "Решить",
+    reopen: "Открыть заново",
+    justNow: "только что",
+    minutesAgo: "{{count}} мин назад",
+    hoursAgo: "{{count}} ч назад",
+    daysAgo: "{{count}} д назад",
+    edited: "(изменено)",
+    reactionCount: "Реакций: {{count}}",
+    reactionCountOne: "{{count}} реакция",
+    addThumbsUp: "Поставить лайк",
+    reply: "Ответить",
+    replyingTo: "Ответ для {{name}}…",
+    replyingToComment: "Ответ на комментарий…",
+    commentPlaceholder: "Добавьте комментарий… (@ — упоминание)",
+    send: "Отправить",
+  },
 };
 
 export default ru;
diff --git a/packages/i18n/src/locales/zh.ts b/packages/i18n/src/locales/zh.ts
index 45048171f3..4a5b5c7db2 100644
--- a/packages/i18n/src/locales/zh.ts
+++ b/packages/i18n/src/locales/zh.ts
@@ -3105,6 +3105,29 @@ const zh = {
     addSort: '添加排序',
     removeSort: '删除排序',
   },
+  collaboration: {
+    commentCount: '{{count}} 条评论',
+    commentCountOne: '{{count}} 条评论',
+    resolvedSuffix: ' · 已解决',
+    sortComments: '评论排序',
+    sortOldest: '最早优先',
+    sortNewest: '最新优先',
+    resolve: '标记已解决',
+    reopen: '重新打开',
+    justNow: '刚刚',
+    minutesAgo: '{{count}} 分钟前',
+    hoursAgo: '{{count}} 小时前',
+    daysAgo: '{{count}} 天前',
+    edited: '(已编辑)',
+    reactionCount: '{{count}} 个回应',
+    reactionCountOne: '{{count}} 个回应',
+    addThumbsUp: '点赞',
+    reply: '回复',
+    replyingTo: '正在回复 {{name}}…',
+    replyingToComment: '正在回复该评论…',
+    commentPlaceholder: '添加评论…(输入 @ 提及他人)',
+    send: '发送',
+  },
 } as const;
 
 export default zh;
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index c1df4e0081..8ae1e4bb5e 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -870,6 +870,9 @@ importers:
 
   packages/collaboration:
     dependencies:
+      '@object-ui/i18n':
+        specifier: workspace:*
+        version: link:../i18n
       '@object-ui/types':
         specifier: workspace:*
         version: link:../types