diff --git a/frontend/src/app/workspace/chats/[thread_id]/page.tsx b/frontend/src/app/workspace/chats/[thread_id]/page.tsx
index c812ffb1..d1011764 100644
--- a/frontend/src/app/workspace/chats/[thread_id]/page.tsx
+++ b/frontend/src/app/workspace/chats/[thread_id]/page.tsx
@@ -66,9 +66,6 @@ export default function ChatPage() {
     !isNewThread ||
     searchParams.get("xclaw_used")?.trim().toLowerCase() === "true";
 
-  // Submission strategy: always reuse the thread id from query; never create new.
-  const createNewSession = false;
-  /*
   // Original strategy:
   // - isnew=false + thread_id: reuse existing thread (explicit request from URL)
   // - xclaw_used=true: follow `isnew` (isnew=false => reuse existing thread)
@@ -87,9 +84,13 @@ export default function ChatPage() {
     if (searchParams.get("xclaw_used")?.trim().toLowerCase() !== "true") {
       return true;
     }
-    return searchParams.get("isnew")?.trim().toLowerCase() !== "false";
+    return searchParams.get("isnew")?.trim().toLowerCase() === "true";
   }, [isNewThread, searchParams]);
-  */
+  console.log(createNewSession, "createNewSession");
+  const shouldStayOnNewRoute = useMemo(
+    () => searchParams.get("isnew")?.trim().toLowerCase() === "true",
+    [searchParams],
+  );
   const streamThreadId = useMemo(() => {
     return isNewThread && createNewSession ? undefined : threadId;
   }, [createNewSession, isNewThread, threadId]);
@@ -105,11 +106,14 @@ export default function ChatPage() {
   const [thread, sendMessage, isUploading] = useThreadStream({
     threadId: streamThreadId,
     context: settings.context,
+    createNewSession,
     isMock,
     onStart: (currentThreadId) => {
       setIsNewThread(false);
-      // Keep /new in history so router.back() can return to it.
-      router.replace(`/workspace/chats/${currentThreadId}`);
+      if (!shouldStayOnNewRoute) {
+        // Keep /new in history so router.back() can return to it.
+        router.replace(`/workspace/chats/${currentThreadId}`);
+      }
       // history.pushState(null, "", pathOfThread(currentThreadId));
     },
     onFinish: (state) => {
diff --git a/frontend/src/components/workspace/chats/use-thread-chat.ts b/frontend/src/components/workspace/chats/use-thread-chat.ts
index c4f68868..8ac0761c 100644
--- a/frontend/src/components/workspace/chats/use-thread-chat.ts
+++ b/frontend/src/components/workspace/chats/use-thread-chat.ts
@@ -60,9 +60,8 @@ export function useThreadChat() {
     }
     return value === "new" ? queryThreadIdFromParams : value;
   };
-  const xClawUsedFromQuery = searchParams.get("xclaw_used");
-  const isNewFromQuery =
-    searchParams.get("isnew")?.trim().toLowerCase() === "false";
+  const isNewRequested =
+    searchParams.get("isnew")?.trim().toLowerCase() === "true";
   const effectiveThreadIdFromPath =
     normalizeThreadId(threadIdFromPath) ?? readStoredThreadId();
   // console.log("[useThreadChat] effectiveThreadIdFromPath", effectiveThreadIdFromPath);
@@ -71,28 +70,18 @@ export function useThreadChat() {
     return effectiveThreadIdFromPath ?? undefined;
   });
 
-  // /new 或缺少 query 的 thread_id 时，视为新会话状态。 但是这个并不是新会话的意思，而是说当前处在对话状态。
-  const [isNewThread, setIsNewThread] = useState(
-    () => threadIdFromPath === "new" || !queryThreadIdFromParams,
-  );
+  // New session is only controlled by `isnew=true`.
+  const [isNewThread, setIsNewThread] = useState(() => isNewRequested);
 
   useEffect(() => {
     // 记住最近一次有效的 thread_id，供下次加载兜底使用。
     if (threadId && threadId !== "new" && typeof window !== "undefined") {
       window.sessionStorage.setItem("workspace.thread_id", threadId);
     }
-    if (pathname.endsWith("/new")) {
-      setIsNewThread(true);
-      const nextQueryThreadId = readQueryThreadId();
-      const nextIsNewFromQuery =
-        searchParams.get("isnew")?.trim().toLowerCase() === "false";
-      const nextXClawUsed = searchParams.get("xclaw_used");
-      setThreadId(nextQueryThreadId ?? undefined);
-      return;
-    }
-    setIsNewThread(false);
-    // console.log("threadIdFromPath", threadIdFromPath, "normalized", normalizeThreadId(threadIdFromPath));
-    
+    setIsNewThread(
+      searchParams.get("isnew")?.trim().toLowerCase() === "true",
+    );
+    // Prefer path thread id, fall back to query thread_id when path is /new.
     setThreadId(normalizeThreadId(threadIdFromPath));
   }, [pathname, router, searchParams, threadIdFromPath]);
   const isMock = searchParams.get("mock") === "true";
diff --git a/frontend/src/core/threads/hooks.ts b/frontend/src/core/threads/hooks.ts
index e96696a8..a55b1c5b 100644
--- a/frontend/src/core/threads/hooks.ts
+++ b/frontend/src/core/threads/hooks.ts
@@ -31,6 +31,7 @@ export type ToolEndEvent = {
 export type ThreadStreamOptions = {
   threadId?: string | null | undefined;
   context: LocalSettings["context"];
+  createNewSession?: boolean;
   isMock?: boolean;
   onStart?: (threadId: string) => void;
   onFinish?: (state: AgentThreadState) => void;
@@ -128,6 +129,7 @@ export function useThreadStreamLegacy({
 export function useThreadStream({
   threadId,
   context,
+  createNewSession = false,
   isMock,
   onStart,
   onFinish,
@@ -179,9 +181,10 @@ export function useThreadStream({
 
   const queryClient = useQueryClient();
   const updateSubtask = useUpdateSubtask();
+  const apiClient = getAPIClient(isMock);
 
   const thread = useStream<AgentThreadState>({
-    client: getAPIClient(isMock),
+    client: apiClient,
     assistantId: "lead_agent",
     threadId: onStreamThreadId,
     reconnectOnMount: true,
@@ -329,6 +332,11 @@ export function useThreadStream({
       let uploadedFileInfo: UploadedFileInfo[] = [];
 
       try {
+        // isnew 为 true 时，删除旧线程并创建同名新线程
+        if (createNewSession && resolvedThreadId) {
+          await apiClient.threads.delete(resolvedThreadId).catch(() => undefined);
+        }
+
         // Upload files first if any
         if (message.files && message.files.length > 0) {
           setIsUploading(true);
@@ -474,7 +482,15 @@ export function useThreadStream({
         sendInFlightRef.current = false;
       }
     },
-    [thread, _handleOnStart, t.uploads.uploadingFiles, context, queryClient],
+    [
+      thread,
+      _handleOnStart,
+      t.uploads.uploadingFiles,
+      context,
+      queryClient,
+      apiClient,
+      createNewSession,
+    ],
   );
 
   // Merge thread with optimistic messages for display
@@ -524,11 +540,11 @@ export function useSubmitThread({
       }
 
       if (createNewSession && threadId) {
-        try {
-          await apiClient.threads.delete(threadId);
-        } catch {
-          // Ignore delete errors
-        }
+        await apiClient.threads.delete(threadId).catch(() => undefined);
+        await apiClient.threads.create({
+          threadId,
+          ifExists: "do_nothing",
+        });
       }
 
       if (message.files && message.files.length > 0) {
diff --git a/frontend/src/hooks/use-iframe-skill.ts b/frontend/src/hooks/use-iframe-skill.ts
index f33bdabb..bb491ba7 100644
--- a/frontend/src/hooks/use-iframe-skill.ts
+++ b/frontend/src/hooks/use-iframe-skill.ts
@@ -29,6 +29,7 @@ export function useIframeSkill(): UseIframeSkillReturn {
   const titleFromQuery = searchParams.get("title");
   const threadIdFromQuery = searchParams.get("thread_id");
   const xClawUsedFromQuery = searchParams.get("xclaw_used");
+  const isNewFromQuery = searchParams.get("isnew")?.trim().toLowerCase() === "true";
   const lastThreadIdRef = useRef<string | null>(null);
 
   const [selectedSkill, setSelectedSkill] = useState<SkillData | null>(null);
@@ -45,10 +46,11 @@ export function useIframeSkill(): UseIframeSkillReturn {
     
     if (!threadIdFromQuery) return;
     if (xClawUsedFromQuery !== "true") return;
+    if (isNewFromQuery) return;
     if (lastThreadIdRef.current === threadIdFromQuery) return;
     lastThreadIdRef.current = threadIdFromQuery;
     router.replace(`/workspace/chats/${threadIdFromQuery}`);
-  }, [router, threadIdFromQuery, xClawUsedFromQuery]);
+  }, [isNewFromQuery, router, threadIdFromQuery, xClawUsedFromQuery]);
 
   // 2. 监听宿主页 postMessage
   useEffect(() => {