feat: 目标不在线时进行提示和更新UI

webrtc_controller_flutter/lib/controller/remote_controller.dart

@@ -30,6 +30,9 @@ class RemoteController {
   /// ICE 连接断开（用于提示用户并返回连接设置）。
   void Function(String message)? onIceDisconnected;
 
+  /// 目标被控端不在线（服务器回送 TARGET_OFFLINE，用于提示用户并复位 UI）。
+  void Function(String message)? onTargetOffline;
+
   /// 远端视频渲染器就绪。
   void Function(RTCVideoRenderer renderer)? onRemoteStream;
 
@@ -92,6 +95,11 @@ class RemoteController {
         final payload = jsonDecode(message.payload!) as Map<String, dynamic>;
         _webRtc?.handleIceCandidate(payload);
         break;
+      case 'TARGET_OFFLINE':
+        final text = message.payload ?? '目标被控端不在线，请确认设备已开启并连接服务器';
+        onStatusChanged?.call('状态: $text');
+        onTargetOffline?.call(text);
+        break;
     }
   }
 

webrtc_controller_flutter/lib/main.dart

@@ -99,6 +99,9 @@ class _ControllerHomeState extends State<ControllerHome> {
     _controller!.onIceDisconnected = (message) {
       _onIceDisconnected(message);
     };
+    _controller!.onTargetOffline = (message) {
+      _onTargetOffline(message);
+    };
     _controller!.onRemoteStream = (renderer) {
       setState(() => _renderer = renderer);
       renderer.addListener(_onRendererUpdate);
@@ -130,6 +133,20 @@ class _ControllerHomeState extends State<ControllerHome> {
     await _disconnect();
   }
 
+  /// 目标被控端不在线：提示用户并复位到连接设置面板。
+  Future<void> _onTargetOffline(String message) async {
+    final scaffoldCtx = _scaffoldKey.currentState?.context;
+    if (mounted && scaffoldCtx != null) {
+      ScaffoldMessenger.of(scaffoldCtx).showSnackBar(
+        SnackBar(
+          content: Text(message),
+          duration: const Duration(seconds: 3),
+        ),
+      );
+    }
+    setState(() => _connected = false);
+  }
+
   Future<void> _disconnect() async {
     await _controller?.disconnect();
     _controller = null;