rollback fix

management/src/components/ExamGridProctor.tsx

@@ -31,9 +31,13 @@ export const ExamGridProctor: React.FC<ExamGridProctorProps> = ({
   );
   const onlineKey = useMemo(() => onlineIds.join(','), [onlineIds]);
 
+  const onlineIdsRef = useRef<number[]>(onlineIds);
+  onlineIdsRef.current = onlineIds;
+
   const syncSubscriptions = (ws: WebSocket) => {
     if (ws.readyState !== WebSocket.OPEN) return;
-    const target = new Set(onlineIds);
+    const currentOnlineIds = onlineIdsRef.current;
+    const target = new Set(currentOnlineIds);
     const prev = subscribedRef.current;
 
     prev.forEach((id) => {
@@ -42,7 +46,7 @@ export const ExamGridProctor: React.FC<ExamGridProctorProps> = ({
         prev.delete(id);
       }
     });
-    onlineIds.forEach((id) => {
+    currentOnlineIds.forEach((id) => {
       if (!prev.has(id)) {
         ws.send(JSON.stringify({ event: 'teacher:subscribe', data: { studentId: id } }));
         prev.add(id);