fix(ux): 用户发送后即时显示 assistant 头部和等待提示

static/src/app/methods/message.ts

@@ -255,6 +255,16 @@ export const messageMethods = {
     // 标记任务进行中，直到任务完成或用户手动停止
     this.taskInProgress = true;
     this.chatAddUserMessage(message, images, videos);
+    // 关键体验修复：用户发送后立刻显示 assistant 头部 + 工作中计时 + 等待提示，
+    // 不等待 createTask / 轮询首事件返回。
+    this.chatStartAssistantMessage();
+    this.stopRequested = false;
+    if (typeof this.monitorShowPendingReply === 'function') {
+      this.monitorShowPendingReply();
+    }
+    if (this.autoScrollEnabled) {
+      this.scrollToBottom();
+    }
 
     // 使用 REST API 创建任务（轮询模式）
     try {
@@ -278,13 +288,17 @@ export const messageMethods = {
         message: error.message || '创建任务失败，请重试',
         type: 'error'
       });
+      this.streamingMessage = false;
       this.taskInProgress = false;
+      if (typeof this.cleanupTrailingEmptyAssistantPlaceholder === 'function') {
+        this.cleanupTrailingEmptyAssistantPlaceholder('create_task_failed');
+      }
+      if (typeof this.forceUnlockMonitor === 'function') {
+        this.forceUnlockMonitor('create_task_failed');
+      }
       return;
     }
 
-    if (typeof this.monitorShowPendingReply === 'function') {
-      this.monitorShowPendingReply();
-    }
     this.inputClearMessage();
     this.inputClearSelectedImages();
     this.inputClearSelectedVideos();
@@ -555,6 +569,11 @@ export const messageMethods = {
     }
     this.taskInProgress = true;
     this.chatAddUserMessage(message, []);
+    this.chatStartAssistantMessage();
+    this.stopRequested = false;
+    if (typeof this.monitorShowPendingReply === 'function') {
+      this.monitorShowPendingReply();
+    }
     try {
       const { useTaskStore } = await import('../../stores/task');
       const taskStore = useTaskStore();
@@ -569,12 +588,16 @@ export const messageMethods = {
         message: error?.message || '创建任务失败，请重试',
         type: 'error'
       });
+      this.streamingMessage = false;
       this.taskInProgress = false;
+      if (typeof this.cleanupTrailingEmptyAssistantPlaceholder === 'function') {
+        this.cleanupTrailingEmptyAssistantPlaceholder('auto_create_task_failed');
+      }
+      if (typeof this.forceUnlockMonitor === 'function') {
+        this.forceUnlockMonitor('auto_create_task_failed');
+      }
       return false;
     }
-    if (typeof this.monitorShowPendingReply === 'function') {
-      this.monitorShowPendingReply();
-    }
     if (this.autoScrollEnabled) {
       this.scrollToBottom();
     }

static/src/app/methods/taskPolling.ts

@@ -83,6 +83,24 @@ function isEmptyAssistantPlaceholderMessage(message: any): boolean {
   return actions.length === 0 && !!message.awaitingFirstContent;
 }
 
+function getOptimisticUserEchoTarget(messages: any[]): any | null {
+  if (!Array.isArray(messages) || messages.length === 0) {
+    return null;
+  }
+  const lastIndex = messages.length - 1;
+  const last = messages[lastIndex];
+  if (last?.role === 'user') {
+    return last;
+  }
+  if (isEmptyAssistantPlaceholderMessage(last) && lastIndex > 0) {
+    const prev = messages[lastIndex - 1];
+    if (prev?.role === 'user') {
+      return prev;
+    }
+  }
+  return null;
+}
+
 /**
  * 任务轮询事件处理器
  * 将从 REST API 轮询获取的事件转换为前端状态更新
@@ -1284,10 +1302,7 @@ export const taskPollingMethods = {
         : Array.isArray(data?.mediaRefs)
           ? data.mediaRefs
           : [];
-      const last =
-        Array.isArray(this.messages) && this.messages.length > 0
-          ? this.messages[this.messages.length - 1]
-          : null;
+      const last = getOptimisticUserEchoTarget(this.messages || []);
       const isLikelyOptimisticEcho = !!(
         last &&
         last.role === 'user' &&