global update and global fix

apps/frontend/hooks/use-chat-typing.ts

@@ -0,0 +1,44 @@
+'use client';
+
+import { useCallback, useEffect, useRef, useState } from 'react';
+
+type Typer = { userId: string; userName: string; expiresAt: number };
+
+export function useChatTyping(currentUserId?: string) {
+  const [typers, setTypers] = useState<Typer[]>([]);
+  const timerRef = useRef<number | null>(null);
+
+  const pruneTypers = useCallback(() => {
+    const now = Date.now();
+    setTypers((current) => current.filter((item) => item.expiresAt > now));
+  }, []);
+
+  const registerTyper = useCallback(
+    (userId: string, userName: string) => {
+      if (!userId || userId === currentUserId) return;
+      const expiresAt = Date.now() + 3000;
+      setTypers((current) => {
+        const without = current.filter((item) => item.userId !== userId);
+        return [...without, { userId, userName, expiresAt }];
+      });
+    },
+    [currentUserId]
+  );
+
+  const clearTypers = useCallback(() => {
+    setTypers([]);
+  }, []);
+
+  useEffect(() => {
+    timerRef.current = window.setInterval(pruneTypers, 500);
+    return () => {
+      if (timerRef.current) window.clearInterval(timerRef.current);
+    };
+  }, [pruneTypers]);
+
+  return {
+    typers: typers.map(({ userId, userName }) => ({ userId, userName })),
+    registerTyper,
+    clearTypers
+  };
+}