[web] update comment placeholder for mentions (#36167)

GitOrigin-RevId: c702e00004d8dfcf243425503459f558973a657b

services/web/frontend/extracted-translations.json

@@ -344,6 +344,7 @@
   "comment_only": "",
   "comment_only_upgrade_for_track_changes": "",
   "comment_only_upgrade_to_enable_track_changes": "",
+  "comment_or_mention_someone": "",
   "common": "",
   "commons": "",
   "commons_ai": "",

services/web/frontend/js/features/review-panel/components/review-panel-add-comment.tsx

@@ -16,6 +16,7 @@ import {
   MentionsInput,
   MentionsInputHandle,
 } from '@/shared/components/mentions-input'
+import { useFeatureFlag } from '@/shared/context/split-test-context'
 
 export const ReviewPanelAddComment = memo<{
   docId: string
@@ -25,6 +26,7 @@ export const ReviewPanelAddComment = memo<{
   top: number | undefined
 }>(function ReviewPanelAddComment({ from, to, threadId, top, docId }) {
   const { t } = useTranslation()
+  const commentMentionsEnabled = useFeatureFlag('comment-mentions')
   const view = useCodeMirrorViewContext()
   const state = useCodeMirrorStateContext()
   const { addComment } = useThreadsActionsContext()
@@ -154,7 +156,11 @@ export const ReviewPanelAddComment = memo<{
           className="review-panel-add-comment-editor"
           onChange={setContent}
           onSubmit={submitForm}
-          placeholder={t('add_your_comment_here')}
+          placeholder={
+            commentMentionsEnabled
+              ? t('comment_or_mention_someone')
+              : t('add_your_comment_here')
+          }
           disabled={submitting}
         />
         <div className="review-panel-add-comment-buttons">

services/web/locales/en.json

@@ -442,6 +442,7 @@
   "comment_only": "Comment only",
   "comment_only_upgrade_for_track_changes": "Comment only. Upgrade for track changes.",
   "comment_only_upgrade_to_enable_track_changes": "Comment only. <0>Upgrade</0> to enable track changes.",
+  "comment_or_mention_someone": "Comment or @ mention someone",
   "common": "Common",
   "commons": "Commons",
   "commons_ai": "Commons AI",