fix: API interceptor 增加 token 刷新单飞机制防止并发刷新

apps/lib/core/api/api_interceptor.dart

@@ -4,11 +4,18 @@ import '../storage/token_storage.dart';
 class ApiInterceptor extends Interceptor {
   final TokenStorage tokenStorage;
   final Dio dio;
+  final Duration refreshFailureCooldown;
   Future<bool> Function()? onTokenRefresh;
+  Future<bool>? _refreshFuture;
+  DateTime? _refreshBlockedUntil;
+
+  static const _retriedRequestKey = '_auth_retry_once';
+  static const _refreshPathSuffix = '/api/v1/auth/sessions/refresh';
 
   ApiInterceptor({
     required this.tokenStorage,
     required this.dio,
+    this.refreshFailureCooldown = const Duration(seconds: 5),
     this.onTokenRefresh,
   });
 
@@ -26,22 +33,69 @@ class ApiInterceptor extends Interceptor {
 
   @override
   void onError(DioException err, ErrorInterceptorHandler handler) async {
-    if (err.response?.statusCode == 401 && onTokenRefresh != null) {
-      final refreshed = await onTokenRefresh!();
+    final requestOptions = err.requestOptions;
+    if (err.response?.statusCode == 401 &&
+        onTokenRefresh != null &&
+        !_shouldSkipRefresh(requestOptions)) {
+      final refreshed = await _refreshTokenSingleflight();
       if (refreshed) {
         final token = await tokenStorage.getAccessToken();
         if (token != null) {
-          err.requestOptions.headers['Authorization'] = 'Bearer $token';
+          final retryHeaders = Map<String, dynamic>.from(requestOptions.headers)
+            ..['Authorization'] = 'Bearer $token';
+          final retryExtra = Map<String, dynamic>.from(requestOptions.extra)
+            ..[_retriedRequestKey] = true;
+          final retryOptions = requestOptions.copyWith(
+            headers: retryHeaders,
+            extra: retryExtra,
+          );
           try {
-            final response = await dio.fetch(err.requestOptions);
+            final response = await dio.fetch(retryOptions);
             handler.resolve(response);
             return;
           } on DioException {
-            // Retry failed, proceed with original error
+            // Retry failed, proceed with original error.
           }
         }
       }
     }
     handler.next(err);
   }
+
+  bool _shouldSkipRefresh(RequestOptions options) {
+    final blockedUntil = _refreshBlockedUntil;
+    if (blockedUntil != null && DateTime.now().isBefore(blockedUntil)) {
+      return true;
+    }
+    return _normalizePath(options.path) == _refreshPathSuffix ||
+        options.extra[_retriedRequestKey] == true;
+  }
+
+  String _normalizePath(String rawPath) {
+    final parsed = Uri.tryParse(rawPath);
+    if (parsed == null) {
+      return rawPath.replaceFirst(RegExp(r'/+$'), '');
+    }
+    final normalized = parsed.path.replaceFirst(RegExp(r'/+$'), '');
+    return normalized.isEmpty ? '/' : normalized;
+  }
+
+  Future<bool> _refreshTokenSingleflight() {
+    final inflight = _refreshFuture;
+    if (inflight != null) {
+      return inflight;
+    }
+    final future = onTokenRefresh!().catchError((_) => false).whenComplete(() {
+      _refreshFuture = null;
+    });
+    _refreshFuture = future;
+    return future.then((refreshed) {
+      if (refreshed) {
+        _refreshBlockedUntil = null;
+      } else {
+        _refreshBlockedUntil = DateTime.now().add(refreshFailureCooldown);
+      }
+      return refreshed;
+    });
+  }
 }