feat:重启tag的删除功能

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

@@ -135,10 +135,16 @@ export default function ChatPage() {
       setHistoryCutoff(null);
       return;
     }
-    if (historyCutoff === null && !thread.isThreadLoading) {
-      setHistoryCutoff(thread.messages.length);
-    }
+    if (hasSubmitted) return;
+    // Welcome 态下、未提交前，把当前已有消息都当作“历史”切掉。
+    // 这样即使历史消息是后续异步补齐，也不会重新露出。
+    setHistoryCutoff((prev) => {
+      const next = thread.messages.length;
+      if (prev === null) return next;
+      return next > prev ? next : prev;
+    });
   }, [
+    hasSubmitted,
     historyCutoff,
     shouldRenderHistory,
     thread.isThreadLoading,
@@ -200,9 +206,9 @@ export default function ChatPage() {
         return;
       }
       setHasSubmitted(true);
-      void sendMessage(threadId, message);
+      void sendMessage(safeThreadId, message);
     },
-    [isSelectedSkillBootstrapping, sendMessage, threadId],
+    [isSelectedSkillBootstrapping, safeThreadId, sendMessage],
   );
   const handleStop = useCallback(async () => {
     await thread.stop();
@@ -331,9 +337,11 @@ export default function ChatPage() {
                     threadId={threadId}
                     thread={thread}
                     messagesOverride={
-                      shouldRenderHistory || historyCutoff === null
+                      shouldRenderHistory
                         ? undefined
-                        : thread.messages.slice(historyCutoff)
+                        : historyCutoff === null
+                          ? []
+                          : thread.messages.slice(historyCutoff)
                     }
                     paddingBottom={todoListCollapsed ? 160 : 280}
                     showScrollToBottomButton={!showWelcomeStyle}

frontend/src/components/workspace/input-box.tsx

@@ -691,13 +691,13 @@ function IframeSkillDialogButton({
             <Tag key={`${skill.skill_id}-${skill.title}-${index}`} className="shrink-0">
               {skill.title}
               {/* TODO: 因为后端接口不支持取消选择skill，所以暂时禁用取消选择按钮 */}
-              {/* <button
+              <button
                 onClick={() => clearSkill(skill.skill_id)}
                 className="hover:bg-muted-foreground/20 ml-1 rounded-full"
                 type="button"
               >
                 <XIcon className="size-3" />
-              </button> */}
+              </button>
             </Tag>
           ))}
         </div>

frontend/src/core/threads/hooks.ts

@@ -69,6 +69,15 @@ function getStreamErrorMessage(error: unknown): string {
   return "Request failed.";
 }
 
+function normalizeThreadId(
+  value: string | null | undefined,
+): string | undefined {
+  if (!value) return undefined;
+  const normalized = value.trim();
+  if (!normalized || normalized === "new") return undefined;
+  return normalized;
+}
+
 export function useThreadStreamLegacy({
   threadId,
   isNewThread,
@@ -155,12 +164,14 @@ export function useThreadStream({
   }, [onStart, onFinish, onToolEnd]);
 
   useEffect(() => {
-    const normalizedThreadId = threadId ?? null;
+    const normalizedThreadId = normalizeThreadId(threadId) ?? null;
     if (!normalizedThreadId) {
       // Just reset for new thread creation when threadId becomes null/undefined
       startedRef.current = false;
-      setOnStreamThreadId(normalizedThreadId);
     }
+    setOnStreamThreadId((prev) =>
+      prev === normalizedThreadId ? prev : normalizedThreadId,
+    );
     threadIdRef.current = normalizedThreadId;
   }, [threadId]);
 
@@ -288,7 +299,9 @@ export function useThreadStream({
 
       const text = message.text.trim();
       const resolvedThreadId =
-        threadId ?? threadIdRef.current ?? undefined;
+        normalizeThreadId(threadId) ??
+        normalizeThreadId(threadIdRef.current) ??
+        undefined;
       if (resolvedThreadId === "new") {
         toast.error("Invalid thread id 'new'. Please refresh and retry.");
         sendInFlightRef.current = false;