fix(frontend):keep DeerFlow chat thread ids in sync (#1931)

* fix: replay thread sync changes on top of main

* fix: avoid stale thread ids during stream startup

frontend/src/app/workspace/agents/[agent_name]/chats/[thread_id]/page.tsx

@@ -41,20 +41,22 @@ export default function AgentChatPage() {
 
   const { agent } = useAgent(agent_name);
 
-  const { threadId, isNewThread, setIsNewThread } = useThreadChat();
+  const { threadId, setThreadId, isNewThread, setIsNewThread } =
+    useThreadChat();
   const [settings, setSettings] = useThreadSettings(threadId);
 
   const { showNotification } = useNotification();
   const [thread, sendMessage] = useThreadStream({
     threadId: isNewThread ? undefined : threadId,
     context: { ...settings.context, agent_name: agent_name },
-    onStart: () => {
+    onStart: (createdThreadId) => {
+      setThreadId(createdThreadId);
       setIsNewThread(false);
       // ! Important: Never use next.js router for navigation in this case, otherwise it will cause the thread to re-mount and lose all states. Use native history API instead.
       history.replaceState(
         null,
         "",
-        `/workspace/agents/${agent_name}/chats/${threadId}`,
+        `/workspace/agents/${agent_name}/chats/${createdThreadId}`,
       );
     },
     onFinish: (state) => {