fix(room): make handleSelect read DOM directly instead of stale props

Root cause: MentionPopover's native keydown listener fires before React
state updates, so handleSelect read stale inputValue/cursorPosition props
and silently returned early.

Fix: handleSelect now reads textarea.value/selectionStart directly from
the DOM, matching the approach already used in ChatInputArea's
handleMentionSelect. No more stale closure.

src/components/room/MentionPopover.tsx

@@ -62,10 +62,6 @@ interface MentionPopoverProps {
   onSelect: (newValue: string, newCursorPosition: number) => void;
   textareaRef: React.RefObject<HTMLTextAreaElement | null>;
   onOpenChange: (open: boolean) => void;
-  /** Mutable ref: write the confirm fn here so ChatInputArea can call it on Enter */
-  onMentionConfirmRef?: React.MutableRefObject<() => void>;
-  /** Simpler alternative to onMentionConfirmRef — parent provides a callback directly */
-  onMentionConfirm?: () => void;
 }
 
 // Category configuration with icons and colors
@@ -377,8 +373,6 @@ export function MentionPopover({
   onSelect,
   textareaRef,
   onOpenChange,
-  onMentionConfirmRef,
-  onMentionConfirm,
 }: MentionPopoverProps) {
   const [position, setPosition] = useState<PopoverPosition>({ top: 0, left: 0 });
   const [selectedIndex, setSelectedIndex] = useState(0);
@@ -509,11 +503,20 @@ export function MentionPopover({
 
   const handleSelect = useCallback(
     (suggestion: MentionSuggestion) => {
-      const ms = mentionStateRef.current;
-      if (!ms || suggestion.type !== 'item') return;
+      if (!textareaRef.current || suggestion.type !== 'item') return;
+
+      const textarea = textareaRef.current;
+      const cursorPos = textarea.selectionStart;
+      const textBefore = textarea.value.substring(0, cursorPos);
+      const atMatch = textBefore.match(/@([^:@\s<]*)(:([^\s<]*))?$/);
+      if (!atMatch) return;
+
+      const [fullMatch] = atMatch;
+      const startPos = cursorPos - fullMatch.length;
+
+      const before = textarea.value.substring(0, startPos);
+      const after = textarea.value.substring(cursorPos);
 
-      const before = inputValue.slice(0, ms.startPos);
-      const after = inputValue.slice(cursorPosition);
       const html = buildMentionHtml(
         suggestion.category!,
         suggestion.mentionId!,
@@ -521,23 +524,17 @@ export function MentionPopover({
       );
       const spacer = ' ';
       const newValue = before + html + spacer + after;
-      const newCursorPos = ms.startPos + html.length + spacer.length;
+      const newCursorPos = startPos + html.length + spacer.length;
+
       onSelect(newValue, newCursorPos);
       closePopover();
     },
-    [inputValue, cursorPosition, onSelect, closePopover],
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+    [onSelect, closePopover],
   );
 
   handleSelectRef.current = handleSelect;
 
-  // Register confirm fn so ChatInputArea can call it on Enter
-  if (onMentionConfirmRef) {
-    onMentionConfirmRef.current = () => {
-      const item = visibleSuggestionsRef.current[selectedIndexRef.current];
-      if (item) handleSelectRef.current(item);
-    };
-  }
-
   // Position calculation
   useEffect(() => {
     if (!mentionState || !textareaRef.current) return;

src/components/room/RoomChatPanel.tsx

@@ -31,7 +31,6 @@ import { RoomThreadPanel } from './RoomThreadPanel';
 
 const MENTION_PATTERN = /@([^:@\s]*)(:([^\s]*))?$/;
 const MENTION_POPOVER_KEYS = ['Enter', 'Tab', 'ArrowUp', 'ArrowDown'];
-export const mentionConfirmRef = { current: (() => {}) as () => void };
 
 
 export interface ChatInputAreaHandle {
@@ -52,8 +51,6 @@ interface ChatInputAreaProps {
   draft: string;
   onDraftChange: (content: string) => void;
   onClearDraft: () => void;
-  /** Called when Enter is pressed with mention popover open — parent triggers mention selection */
-  onMentionConfirm?: () => void;
   ref?: React.Ref<ChatInputAreaHandle>;
 }
 
@@ -71,7 +68,6 @@ const ChatInputArea = memo(function ChatInputArea({
   draft,
   onDraftChange,
   onClearDraft,
-  onMentionConfirm,
   ref,
 }: ChatInputAreaProps) {
   const textareaRef = useRef<HTMLTextAreaElement>(null);
@@ -161,9 +157,7 @@ const ChatInputArea = memo(function ChatInputArea({
 
     if (hasMention && MENTION_POPOVER_KEYS.includes(e.key) && !e.ctrlKey && !e.shiftKey) {
       e.preventDefault();
-      if ((e.key === 'Enter' || e.key === 'Tab') && onMentionConfirm) {
-        onMentionConfirm();
-      }
+      // Enter/Tab is handled by MentionPopover's native keydown listener
       return;
     }
 
@@ -609,7 +603,6 @@ export function RoomChatPanel({ room, isAdmin, onClose, onDelete }: RoomChatPane
           draft={draft}
           onDraftChange={setDraft}
           onClearDraft={clearDraft}
-          onMentionConfirm={() => { console.log('[RoomChatPanel] onMentionConfirm called'); mentionConfirmRef.current(); }}
         />
       </div>