fix(chat): add history loading skeletons

src/components/chat/hooks/useAgentChatSession.ts

@@ -27,6 +27,7 @@ export const useAgentChatSession = ({
   const [chatSessions, setChatSessions] = useState<ChatSessionSummary[]>([]);
   const [isStreaming, setIsStreaming] = useState(false);
   const [isHydrating, setIsHydrating] = useState(true);
+  const [loadingSessionId, setLoadingSessionId] = useState<string | undefined>(undefined);
   const abortRef = useRef<AbortController | null>(null);
   const sessionIdRef = useRef<string | undefined>(undefined);
   const messagesRef = useRef<Message[]>([]);
@@ -756,12 +757,17 @@ export const useAgentChatSession = ({
   }, [isHydrating, isStreaming]);
 
   const switchSession = useCallback(
-    async (nextSessionId: string) => {
+    async (nextSessionId: string, optimisticTitle?: string) => {
       if (isHydrating || isStreaming || sessionIdRef.current === nextSessionId) {
         return;
       }
 
       setIsHydrating(true);
+      setLoadingSessionId(nextSessionId);
+      const nextTitle = optimisticTitle?.trim();
+      if (nextTitle) {
+        setSessionTitle(nextTitle);
+      }
       try {
         const [nextState, sessions] = await Promise.all([
           loadChatSessionById(nextSessionId),
@@ -785,6 +791,7 @@ export const useAgentChatSession = ({
       } catch (error) {
         console.error("[GlobalChatbox] Failed to switch chat session:", error);
       } finally {
+        setLoadingSessionId(undefined);
         setIsHydrating(false);
       }
     },
@@ -932,6 +939,7 @@ export const useAgentChatSession = ({
     chatSessions,
     activeSessionId: sessionIdRef.current,
     isHydrating,
+    loadingSessionId,
     isStreaming,
     sessionTitle,
     sessionId,