fix(app-expo): 稳定 WS TTS 与「正在回复」状态

- useRealtimeSession：恢复 uiRef 同步与 AppState 后台/前台重连，收窄长连 effect 依赖，修正 send API 类型
- 会话页：用派生条件控制 AssistantTypingBubble，避免缓存已有助手末条仍显示 typing
- RealtimeSession：在 commit 落缓存时统一 clearAssistantPendingUi，避免漏掉流式完成帧

Co-authored-by: Cursor <cursoragent@cursor.com>

app-expo/src/app/(main)/conversation/[id].tsx

@@ -1447,6 +1447,18 @@ export default function ConversationScreen() {
     },
   });
 
+  /**
+   * 列表末条已是助手时不再展示「正在回复」footer，避免 WS 完成回调缺失时状态与缓存不一致。
+   * 用渲染期派生条件代替 effect 回写 state（Vercel：rerender-derived-state-no-effect）。
+   */
+  const showAssistantTypingFooter = useMemo(
+    () =>
+      awaitingAssistantReply &&
+      !streamingMessage &&
+      messages?.at(-1)?.senderType !== 'assistant',
+    [awaitingAssistantReply, streamingMessage, messages],
+  );
+
   const handleInterruptAssistantTts = useCallback(() => {
     sendTtsCancel();
     ttsGate.current.interrupt();
@@ -1864,7 +1876,7 @@ export default function ConversationScreen() {
         }
         ListFooterComponent={
           <>
-            {awaitingAssistantReply && !streamingMessage ? (
+            {showAssistantTypingFooter ? (
               <AssistantTypingBubble
                 agentName={t('agentName')}
                 labelStyle={chatTypingLabelStyle}

app-expo/src/features/conversation/hooks.ts

@@ -199,8 +199,12 @@ interface RealtimeSessionState {
   /** 服务端下发的 quick-start 话题 chips；用户首次发文本/语音后清空 */
   topicSuggestions: TopicSuggestion[];
   dismissTopicSuggestions: () => void;
-  sendText: (text: string) => void;
-  sendVoiceMessage: (uri: string, durationMs: number) => Promise<boolean>;
+  sendText: (text: string, options?: { ttsThisTurn?: boolean }) => void;
+  sendVoiceMessage: (
+    uri: string,
+    durationMs: number,
+    options?: { ttsThisTurn?: boolean },
+  ) => Promise<boolean>;
   sendEndConversation: () => void;
   sendTtsCancel: () => void;
   requestAssistantSegmentTts: (body: {
@@ -283,6 +287,35 @@ export function useRealtimeSession({
     setTopicSuggestions([]);
   }, []);
 
+  /** 每轮 render 写入 ref：`attachUiCallbacks` 的包装函数始终读最新实现（TTS / 流式 / 错误）。 */
+  uiRef.current.handleStreamingText = handleStreamingText;
+  uiRef.current.handleError = handleError;
+  uiRef.current.onTtsSegment = onTtsSegment;
+
+  useEffect(() => {
+    if (!enabled || !conversationId) return;
+
+    const sub = AppState.addEventListener('change', (next: AppStateStatus) => {
+      if (next === 'background') {
+        needsResumeAfterBackgroundRef.current = true;
+        disposeAllBackgroundConversationWs();
+        sessionRef.current = null;
+        setConnectionState('disconnected');
+        setStreamingMessage(null);
+        setAwaitingAssistantReply(false);
+      } else if (next === 'active' && needsResumeAfterBackgroundRef.current) {
+        needsResumeAfterBackgroundRef.current = false;
+        setForegroundResumeGeneration((g) => g + 1);
+      }
+    });
+
+    return () => sub.remove();
+  }, [enabled, conversationId]);
+
+  /**
+   * 依赖保持最小：`handleStreamingText` / `onTtsSegment` 等由上方 `uiRef` 每轮 render 同步，
+   * 避免因父组件 `enqueue` 等导致 identity 变化而反复 teardown WS（短时 noop 回调会丢 TTS）。
+   */
   useEffect(() => {
     if (!enabled || !conversationId) return;
 
@@ -318,15 +351,7 @@ export function useRealtimeSession({
       setAwaitingAssistantReply(false);
       setTopicSuggestions([]);
     };
-  }, [
-    conversationId,
-    enabled,
-    queryClient,
-    handleStreamingText,
-    handleError,
-    handleTopicSuggestions,
-    onTtsSegment,
-  ]);
+  }, [conversationId, enabled, queryClient, foregroundResumeGeneration]);
 
   const sendText = useCallback(
     (text: string, options?: { ttsThisTurn?: boolean }) => {

app-expo/src/features/conversation/realtime-session.ts

@@ -463,7 +463,6 @@ export class RealtimeSession {
         );
         if (bufferedTts) {
           this.commitOneAssistantMessage(event.text, id);
-          this.clearAssistantPendingUi();
           this.onTtsSegment?.(bufferedTts);
           this.finishAssistantTurnIfLastSegment(index, total);
         } else {
@@ -475,7 +474,6 @@ export class RealtimeSession {
           const idCaptured = id;
           this.scheduleDeferredSyncCommit(key, index, total, () => {
             this.commitOneAssistantMessage(textCaptured, idCaptured);
-            this.clearAssistantPendingUi();
           });
         }
       } else {
@@ -557,6 +555,8 @@ export class RealtimeSession {
       return [...(old ?? []), message];
     });
     this.updateConversationListPreview(content);
+    /** 与列表真相对齐：任何助手气泡落缓存都应收起「正在回复」占位（防止漏掉 onStreamingText 完成帧） */
+    this.clearAssistantPendingUi();
   }
 
   private commitStreamingBufferWithId(messageId: string): void {
@@ -585,6 +585,7 @@ export class RealtimeSession {
     });
 
     this.updateConversationListPreview(content);
+    this.clearAssistantPendingUi();
   }
 
   private updateConversationListPreview(latestContent: string): void {