feat: Implement client-side caching for conversations in useMessaging to reduce re-fetching and improve performance.

src/hooks/useMessaging.ts

@@ -49,16 +49,22 @@ interface UseMessagingReturn {
   hasMoreMessages: boolean;
 }
 
+// Module-level cache to avoid re-fetching on tab switch
+let _cachedConversations: Conversation[] | null = null;
+let _cachedTimestamp = 0;
+const CACHE_TTL = 30000; // 30 seconds
+
 export function useMessaging(options: UseMessagingOptions = {}): UseMessagingReturn {
   const { autoConnect = true } = options;
   const { data: session } = useSession();
 
-  // State
-  const [conversations, setConversations] = useState<Conversation[]>([]);
+  // State — initialize from cache if available and fresh
+  const hasFreshCache = _cachedConversations && (Date.now() - _cachedTimestamp < CACHE_TTL);
+  const [conversations, setConversations] = useState<Conversation[]>(hasFreshCache ? _cachedConversations! : []);
   const [currentConversation, setCurrentConversation] = useState<Conversation | null>(null);
   const [messages, setMessages] = useState<Message[]>([]);
   const [isConnected, setIsConnected] = useState(false);
-  const [isLoading, setIsLoading] = useState(false);
+  const [isLoading, setIsLoading] = useState(!hasFreshCache);
   const [isLoadingMessages, setIsLoadingMessages] = useState(false);
   const [typingUsers, setTypingUsers] = useState<Set<string>>(new Set());
   const [unreadCount, setUnreadCount] = useState(0);
@@ -109,6 +115,9 @@ export function useMessaging(options: UseMessagingOptions = {}): UseMessagingRet
     try {
       const data = await messagesService.getConversations();
       setConversations(data);
+      // Update module-level cache
+      _cachedConversations = data;
+      _cachedTimestamp = Date.now();
     } catch (error) {
       console.error('Failed to load conversations:', error);
     } finally {
@@ -557,7 +566,13 @@ export function useMessaging(options: UseMessagingOptions = {}): UseMessagingRet
     if (autoConnect && isAuthenticated && !isInitializedRef.current) {
       isInitializedRef.current = true;
       connect();
-      loadConversations();
+
+      // Only fetch conversations if cache is stale or empty
+      if (!_cachedConversations || Date.now() - _cachedTimestamp >= CACHE_TTL) {
+        loadConversations();
+      } else {
+        setIsLoading(false);
+      }
 
       // Get initial unread count
       messagesService.getUnreadCount().then(setUnreadCount).catch(console.error);