1

flutter_app/lib/models/model_manager.dart

@@ -81,6 +81,7 @@ class ModelManager extends ChangeNotifier {
   final Set<int> _downloadedIds = {};
   final Map<int, double> _progress = {};
   final Map<int, String> _errors = {};
+  final Set<int> _cancelRequested = {};
   bool _activeLoaded = false;
   bool _ready = false;
   bool _refreshing = false;
@@ -104,6 +105,12 @@ class ModelManager extends ChangeNotifier {
   /// 下载失败原因（失败后可重试）
   String? errorOf(int datasetId) => _errors[datasetId];
 
+  /// 中断进行中的下载：下一个数据块到达时终止（丢弃 .part），卡片恢复「使用」。
+  /// 取消不记错误，可再次下载。
+  void cancelDownload(int datasetId) {
+    _cancelRequested.add(datasetId);
+  }
+
   ModelManager._({String? baseUrl, http.Client? client})
       : this(baseUrl: baseUrl, client: client);
 
@@ -209,11 +216,13 @@ class ModelManager extends ChangeNotifier {
     // 并发保护：同一数据集已有进行中的下载则直接短路（预置 0 先占位，
     // 使 onProgress 首次回调前的双击/refresh 交错也被 containsKey 拦下）
     if (_progress.containsKey(item.datasetId)) return false;
+    _cancelRequested.remove(item.datasetId);
     _progress[item.datasetId] = 0;
     final dir = await _modelDir(item.datasetId);
     final file = File('${dir.path}/model.tflite');
     try {
       for (var attempt = 0; attempt < 2; attempt++) {
+        if (_cancelRequested.contains(item.datasetId)) break;
         final ok = await _downloadAndVerify(item, dir, file,
             onProgress: (r, t) {
           _progress[item.datasetId] = t == 0 ? 0 : r / t;
@@ -227,17 +236,39 @@ class ModelManager extends ChangeNotifier {
           await setActive(item.datasetId, true);
           return true;
         }
+        if (_cancelRequested.contains(item.datasetId)) break;
         await file.delete().catchError((_) => file);
         await File('${dir.path}/model.tflite.part')
             .delete()
             .catchError((_) => file);
       }
+      if (_cancelRequested.contains(item.datasetId)) {
+        // 用户取消：清理残留，不记错误
+        await file.delete().catchError((_) => file);
+        await File('${dir.path}/model.tflite.part')
+            .delete()
+            .catchError((_) => file);
+        _progress.remove(item.datasetId);
+        notifyListeners();
+        debugPrint('[ModelManager] 下载已取消: ${item.datasetName}');
+        return false;
+      }
       _progress.remove(item.datasetId);
       _errors[item.datasetId] = '下载失败，请重试';
       notifyListeners();
       debugPrint('[ModelManager] 下载失败: ${item.datasetName} ${item.version}');
       return false;
     } catch (e) {
+      if (_cancelRequested.contains(item.datasetId)) {
+        await file.delete().catchError((_) => file);
+        await File('${dir.path}/model.tflite.part')
+            .delete()
+            .catchError((_) => file);
+        _progress.remove(item.datasetId);
+        notifyListeners();
+        debugPrint('[ModelManager] 下载已取消: ${item.datasetName}');
+        return false;
+      }
       _progress.remove(item.datasetId);
       _errors[item.datasetId] = '下载异常:$e';
       notifyListeners();
@@ -262,10 +293,15 @@ class ModelManager extends ChangeNotifier {
       }
       final total = res.contentLength ?? item.sizeBytes;
       await for (final chunk in res.stream) {
+        if (_cancelRequested.contains(item.datasetId)) break; // 用户取消
         sink.add(chunk);
         received += chunk.length;
         onProgress?.call(received, total);
       }
+      if (_cancelRequested.contains(item.datasetId)) {
+        await sink.close();
+        return false;
+      }
       await sink.close();
       final bytes = await part.readAsBytes();
       final hex = sha256.convert(bytes).toString();