1.广角/主摄切换按钮已上移：

2.新增 isSwitchingLens 状态、避免切换镜头    stop 按钮禁用，不会触发 stopRecording
倍距按钮禁用，避免连续切换
ViewModel 层也兜底：isSwitchingLens=true 时直接拒绝 stop
3.合并失败兜底提示

lib/features/recording/view-model/view_model_recording.dart

@@ -349,10 +349,14 @@ class RecordingViewModel extends Notifier<RecordingModel> {
   /// 设置相机倍距，原生层会返回设备实际应用后的倍距范围与当前值。
   Future<void> setZoomRatio(double ratio) async {
     final session = state.session;
+    if (session.isSwitchingLens) {
+      return;
+    }
     final clamped = ratio
         .clamp(session.minZoomRatio, session.maxZoomRatio)
         .toDouble();
 
+    _updateSession((s) => s.copyWith(isSwitchingLens: true));
     try {
       final zoom = await RecordingPlatform.setZoomRatio(clamped);
       _updateSession(
@@ -368,13 +372,19 @@ class RecordingViewModel extends Notifier<RecordingModel> {
           ? '切换镜头失败，请重试'
           : (error.message ?? '相机倍距设置失败');
       _updateSession((s) => s.copyWith(errorMessage: message));
+    } finally {
+      _updateSession(
+        (s) => s.copyWith(isSwitchingLens: false, errorMessage: s.errorMessage),
+      );
     }
   }
 
   /// 开始录制，可选开启勿扰模式。
   Future<void> startRecording({bool enableDoNotDisturb = true}) async {
     final session = state.session;
-    if (session.isRecording || session.isStartingRecording) {
+    if (session.isRecording ||
+        session.isStartingRecording ||
+        session.isSwitchingLens) {
       return;
     }
     if (!session.isPreviewReady) {
@@ -401,6 +411,7 @@ class RecordingViewModel extends Notifier<RecordingModel> {
           isTouchLocked: true,
           errorMessage: null,
           fileSaveFailed: false,
+          segmentOutputPaths: const [],
           clearLastSaved: true,
         ),
       );
@@ -415,7 +426,7 @@ class RecordingViewModel extends Notifier<RecordingModel> {
 
   /// 停止录制、保存到文件夹，并恢复相机预览。
   Future<void> stopRecording() async {
-    if (!state.session.isRecording) return;
+    if (!state.session.isRecording || state.session.isSwitchingLens) return;
 
     try {
       final result = await RecordingPlatform.stopRecording();
@@ -432,6 +443,7 @@ class RecordingViewModel extends Notifier<RecordingModel> {
               ? (result.fileErrorMessage ?? '保存到文件夹失败，请检查文件保存权限')
               : null,
           fileSaveFailed: fileFailed,
+          segmentOutputPaths: result.segmentOutputPaths,
         ),
       );
     } on PlatformException catch (error) {