feat: 生产级 API 错误处理 — 重试拦截器、友好错误提示、网络监测、WebSocket 退避

## 问题
用户看到原始 DioException 堆栈（如 "DioException [unknown]: null Error:
HttpException: Connection reset by peer"），且无重试机制，网络抖动即报错。

## 变更

### 1. RetryInterceptor（指数退避自动重试）
- 新增 `core/network/retry_interceptor.dart`
- 自动重试：连接超时、发送超时、Connection reset、502/503/504/429
- 指数退避（800ms → 1.6s → 3.2s）+ 随机抖动防雪崩
- 最多 3 次重试，非瞬态错误（401/403/404）不重试
- 集成到 dio_client，优化超时：connect 8s、send 15s、receive 20s

### 2. ErrorHandler 全面升级（友好中文错误提示）
- 重写 `core/errors/error_handler.dart`，新增 `friendlyMessage()` 静态方法
- 所有 DioExceptionType 映射为具体中文：
  - Connection reset → "连接被服务器重置，请稍后重试"
  - Connection refused → "服务器拒绝连接，请确认服务是否启动"
  - Timeout → "连接超时，服务器无响应"
  - 401 → "登录已过期，请重新登录"
  - 403/404/429/500/502/503 各有独立提示
- 新增 TimeoutFailure 类型
- 所有 Failure.message 默认中文

### 3. 网络连接监测 + 离线 Banner
- 新增 `core/network/connectivity_provider.dart` — 每30秒探测服务器可达性
- 新增 `core/widgets/offline_banner.dart` — 黄色警告横幅 "网络连接不可用"
- 集成到 ScaffoldWithNav，所有页面顶部自动显示离线状态

### 4. 统一错误展示（杜绝 e.toString()）
- 新增 `core/widgets/error_view.dart` — 统一错误 UI（图标 + 友好文案 + 重试按钮）
- 替换 6 个页面的内联错误 Column 为 ErrorView:
  tasks_page / servers_page / alerts_page / approvals_page / standing_orders_page
- 替换 dashboard 的 3 处 _SummaryCardError(message: e.toString())
- 替换 4 个 provider 的 e.toString(): chat / auth / settings / approvals
- 全项目零 e.toString() 残留（仅剩 time.minute.toString() 时间格式化）

### 5. WebSocket 重连增强
- 指数退避（1s → 2s → 4s → ... → 60s 上限）+ 随机抖动
- 最多 10 次自动重连，超限后停止
- disconnect() 阻止自动重连
- 新增 reconnect() 手动重连方法

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

it0_app/lib/core/errors/error_handler.dart

@@ -1,38 +1,139 @@
+import 'dart:io';
 import 'package:dio/dio.dart';
 import 'failures.dart';
 
 class ErrorHandler {
+  /// Converts any error into a [Failure] with a user-friendly Chinese message.
   static Failure handle(dynamic error) {
+    if (error is Failure) return error;
+
     if (error is DioException) {
+      return _handleDio(error);
+    }
+
+    if (error is SocketException) {
+      return const NetworkFailure('无法连接到服务器，请检查网络');
+    }
+
+    if (error is FormatException) {
+      return const ServerFailure('数据格式异常', statusCode: null);
+    }
+
+    return ServerFailure('发生未知错误: ${_truncate(error.toString(), 80)}');
+  }
+
+  /// Converts any error into a user-friendly Chinese message string.
+  /// Use this everywhere instead of `e.toString()`.
+  static String friendlyMessage(dynamic error) {
+    return handle(error).message;
+  }
+
+  static Failure _handleDio(DioException error) {
     switch (error.type) {
       case DioExceptionType.connectionTimeout:
+        return const TimeoutFailure('连接超时，服务器无响应');
+
       case DioExceptionType.sendTimeout:
+        return const TimeoutFailure('发送请求超时，请检查网络');
+
       case DioExceptionType.receiveTimeout:
-          return const NetworkFailure('Connection timeout');
+        return const TimeoutFailure('等待响应超时，请稍后重试');
+
       case DioExceptionType.connectionError:
-          return const NetworkFailure('No internet connection');
+        return NetworkFailure(_connectionErrorMessage(error));
+
+      case DioExceptionType.badCertificate:
+        return const NetworkFailure('安全证书验证失败');
+
       case DioExceptionType.badResponse:
         return _handleBadResponse(error.response);
-        default:
+
-          return const NetworkFailure();
+      case DioExceptionType.cancel:
+        return const ServerFailure('请求已取消');
+
+      case DioExceptionType.unknown:
+        return NetworkFailure(_unknownErrorMessage(error));
     }
   }
-    return ServerFailure(error.toString());
-  }
 
   static Failure _handleBadResponse(Response? response) {
-    switch (response?.statusCode) {
+    final statusCode = response?.statusCode;
+    // Try to extract server-side error message
+    final serverMsg = _extractServerMessage(response);
+
+    switch (statusCode) {
+      case 400:
+        return ServerFailure(serverMsg ?? '请求参数错误', statusCode: 400);
       case 401:
         return const AuthFailure();
+      case 403:
+        return const ServerFailure('没有权限执行此操作', statusCode: 403);
       case 404:
-        return ServerFailure('Resource not found', statusCode: 404);
+        return ServerFailure(serverMsg ?? '请求的资源不存在', statusCode: 404);
+      case 409:
+        return ServerFailure(serverMsg ?? '数据冲突，请刷新后重试', statusCode: 409);
+      case 422:
+        return ServerFailure(serverMsg ?? '提交的数据不合法', statusCode: 422);
+      case 429:
+        return const ServerFailure('请求过于频繁，请稍后重试', statusCode: 429);
       case 500:
-        return ServerFailure('Internal server error', statusCode: 500);
+        return const ServerFailure('服务器内部错误，请稍后重试', statusCode: 500);
+      case 502:
+        return const ServerFailure('服务器网关错误，请稍后重试', statusCode: 502);
+      case 503:
+        return const ServerFailure('服务器暂时不可用，请稍后重试', statusCode: 503);
       default:
         return ServerFailure(
-          response?.data?['message'] ?? 'Unknown error',
+          serverMsg ?? '服务器错误 ($statusCode)',
-          statusCode: response?.statusCode,
+          statusCode: statusCode,
         );
     }
   }
+
+  static String? _extractServerMessage(Response? response) {
+    try {
+      final data = response?.data;
+      if (data is Map) {
+        return data['message'] as String? ?? data['error'] as String?;
+      }
+    } catch (_) {}
+    return null;
+  }
+
+  static String _connectionErrorMessage(DioException error) {
+    final innerError = error.error;
+    if (innerError is SocketException) {
+      if (innerError.osError?.errorCode == 111 ||
+          innerError.osError?.errorCode == 10061) {
+        return '服务器拒绝连接，请确认服务是否启动';
+      }
+      return '无法连接到服务器，请检查网络';
+    }
+    return '网络连接失败，请检查网络设置';
+  }
+
+  static String _unknownErrorMessage(DioException error) {
+    final errorStr = error.error?.toString() ?? '';
+    if (errorStr.contains('Connection reset')) {
+      return '连接被服务器重置，请稍后重试';
+    }
+    if (errorStr.contains('Connection refused')) {
+      return '服务器拒绝连接，请确认服务是否启动';
+    }
+    if (errorStr.contains('Connection closed')) {
+      return '连接已关闭，请稍后重试';
+    }
+    if (errorStr.contains('SocketException')) {
+      return '网络连接异常，请检查网络设置';
+    }
+    if (errorStr.contains('HandshakeException') ||
+        errorStr.contains('TlsException')) {
+      return '安全连接失败，请检查网络环境';
+    }
+    return '网络请求失败，请检查网络后重试';
+  }
+
+  static String _truncate(String s, int maxLen) {
+    return s.length > maxLen ? '${s.substring(0, maxLen)}...' : s;
+  }
 }

it0_app/lib/core/errors/failures.dart

@@ -1,6 +1,9 @@
 abstract class Failure {
   final String message;
   const Failure(this.message);
+
+  @override
+  String toString() => message;
 }
 
 class ServerFailure extends Failure {
@@ -9,13 +12,17 @@ class ServerFailure extends Failure {
 }
 
 class NetworkFailure extends Failure {
-  const NetworkFailure([super.message = 'Network connection failed']);
+  const NetworkFailure([super.message = '网络连接失败，请检查网络设置']);
+}
+
+class TimeoutFailure extends Failure {
+  const TimeoutFailure([super.message = '连接超时，请稍后重试']);
 }
 
 class CacheFailure extends Failure {
-  const CacheFailure([super.message = 'Cache read/write failed']);
+  const CacheFailure([super.message = '本地缓存读写失败']);
 }
 
 class AuthFailure extends Failure {
-  const AuthFailure([super.message = 'Authentication failed']);
+  const AuthFailure([super.message = '登录已过期，请重新登录']);
 }

it0_app/lib/core/network/connectivity_provider.dart

@@ -0,0 +1,65 @@
+import 'dart:async';
+import 'dart:io';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import '../config/app_config.dart';
+
+/// Tracks network connectivity by periodically pinging the API gateway.
+/// More reliable than connectivity_plus (which only checks if Wi-Fi/data is on,
+/// not if the server is actually reachable).
+class ConnectivityNotifier extends StateNotifier<ConnectivityState> {
+  final String _apiBaseUrl;
+  Timer? _timer;
+
+  ConnectivityNotifier(this._apiBaseUrl) : super(const ConnectivityState()) {
+    check();
+    _timer = Timer.periodic(const Duration(seconds: 30), (_) => check());
+  }
+
+  Future<void> check() async {
+    try {
+      final uri = Uri.parse(_apiBaseUrl);
+      final socket = await Socket.connect(
+        uri.host,
+        uri.port,
+        timeout: const Duration(seconds: 5),
+      );
+      socket.destroy();
+      if (mounted) {
+        state = const ConnectivityState(isOnline: true);
+      }
+    } catch (_) {
+      if (mounted) {
+        state = ConnectivityState(
+          isOnline: false,
+          lastOfflineAt: DateTime.now(),
+        );
+      }
+    }
+  }
+
+  @override
+  void dispose() {
+    _timer?.cancel();
+    super.dispose();
+  }
+}
+
+class ConnectivityState {
+  final bool isOnline;
+  final DateTime? lastOfflineAt;
+
+  const ConnectivityState({
+    this.isOnline = true,
+    this.lastOfflineAt,
+  });
+}
+
+final connectivityProvider =
+    StateNotifierProvider<ConnectivityNotifier, ConnectivityState>((ref) {
+  final config = ref.watch(appConfigProvider);
+  return ConnectivityNotifier(config.apiBaseUrl);
+});
+
+final isOnlineProvider = Provider<bool>((ref) {
+  return ref.watch(connectivityProvider).isOnline;
+});

it0_app/lib/core/network/dio_client.dart

@@ -1,6 +1,7 @@
 import 'package:dio/dio.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import '../config/app_config.dart';
+import 'retry_interceptor.dart';
 import '../../features/auth/data/providers/auth_provider.dart';
 import '../../features/auth/data/providers/tenant_provider.dart';
 
@@ -8,8 +9,9 @@ final dioClientProvider = Provider<Dio>((ref) {
   final config = ref.watch(appConfigProvider);
   final dio = Dio(BaseOptions(
     baseUrl: config.apiBaseUrl,
-    connectTimeout: const Duration(seconds: 10),
+    connectTimeout: const Duration(seconds: 8),
-    receiveTimeout: const Duration(seconds: 30),
+    sendTimeout: const Duration(seconds: 15),
+    receiveTimeout: const Duration(seconds: 20),
     headers: {
       'Content-Type': 'application/json',
     },
@@ -55,6 +57,9 @@ final dioClientProvider = Provider<Dio>((ref) {
     },
   ));
 
+  // Retry interceptor (exponential backoff for transient errors)
+  dio.interceptors.add(RetryInterceptor(dio: dio));
+
   // Logging interceptor
   dio.interceptors.add(LogInterceptor(
     requestBody: true,

it0_app/lib/core/network/retry_interceptor.dart

@@ -0,0 +1,69 @@
+import 'dart:math';
+import 'package:dio/dio.dart';
+
+/// Dio interceptor that automatically retries failed requests with
+/// exponential backoff for transient/recoverable errors.
+class RetryInterceptor extends Interceptor {
+  final Dio dio;
+  final int maxRetries;
+  final Duration baseDelay;
+
+  RetryInterceptor({
+    required this.dio,
+    this.maxRetries = 3,
+    this.baseDelay = const Duration(milliseconds: 800),
+  });
+
+  @override
+  void onError(DioException err, ErrorInterceptorHandler handler) async {
+    if (!_shouldRetry(err)) {
+      return handler.next(err);
+    }
+
+    final retryCount = err.requestOptions.extra['_retryCount'] as int? ?? 0;
+    if (retryCount >= maxRetries) {
+      return handler.next(err);
+    }
+
+    // Exponential backoff with jitter
+    final delay = baseDelay * pow(2, retryCount).toInt();
+    final jitter = Duration(milliseconds: Random().nextInt(500));
+    await Future.delayed(delay + jitter);
+
+    // Increment retry count
+    err.requestOptions.extra['_retryCount'] = retryCount + 1;
+
+    try {
+      final response = await dio.fetch(err.requestOptions);
+      return handler.resolve(response);
+    } on DioException catch (e) {
+      return handler.next(e);
+    }
+  }
+
+  bool _shouldRetry(DioException err) {
+    // Network-level errors (connection reset, timeout, DNS failure)
+    if (err.type == DioExceptionType.connectionError ||
+        err.type == DioExceptionType.connectionTimeout ||
+        err.type == DioExceptionType.sendTimeout ||
+        err.type == DioExceptionType.receiveTimeout) {
+      return true;
+    }
+
+    // Unknown errors (e.g. "Connection reset by peer")
+    if (err.type == DioExceptionType.unknown && err.error != null) {
+      return true;
+    }
+
+    // Server errors that are typically transient
+    final statusCode = err.response?.statusCode;
+    if (statusCode != null) {
+      return statusCode == 429 || // Too Many Requests
+          statusCode == 502 || // Bad Gateway
+          statusCode == 503 || // Service Unavailable
+          statusCode == 504; // Gateway Timeout
+    }
+
+    return false;
+  }
+}

it0_app/lib/core/network/websocket_client.dart

@@ -1,5 +1,6 @@
 import 'dart:async';
 import 'dart:convert';
+import 'dart:math';
 import 'package:web_socket_channel/web_socket_channel.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import '../config/app_config.dart';
@@ -10,18 +11,29 @@ class WebSocketClient {
   Timer? _heartbeatTimer;
   Timer? _reconnectTimer;
   bool _isConnected = false;
+  int _reconnectAttempts = 0;
+  String? _lastPath;
+  String? _lastToken;
   final _messageController = StreamController<Map<String, dynamic>>.broadcast();
 
+  static const int _maxReconnectAttempts = 10;
+  static const Duration _baseReconnectDelay = Duration(milliseconds: 1000);
+  static const Duration _maxReconnectDelay = Duration(seconds: 60);
+
   Stream<Map<String, dynamic>> get messages => _messageController.stream;
   bool get isConnected => _isConnected;
 
   WebSocketClient({required this.baseUrl});
 
   Future<void> connect(String path, {String? token}) async {
+    _lastPath = path;
+    _lastToken = token;
+
     final uri = Uri.parse('$baseUrl$path');
     try {
       _channel = WebSocketChannel.connect(uri);
       _isConnected = true;
+      _reconnectAttempts = 0;
 
       _channel!.stream.listen(
         (data) {
@@ -30,18 +42,18 @@ class WebSocketClient {
         },
         onDone: () {
           _isConnected = false;
-          _scheduleReconnect(path, token: token);
+          _scheduleReconnect();
         },
         onError: (error) {
           _isConnected = false;
-          _scheduleReconnect(path, token: token);
+          _scheduleReconnect();
         },
       );
 
       _startHeartbeat();
     } catch (e) {
       _isConnected = false;
-      _scheduleReconnect(path, token: token);
+      _scheduleReconnect();
     }
   }
 
@@ -59,18 +71,44 @@ class WebSocketClient {
     );
   }
 
-  void _scheduleReconnect(String path, {String? token}) {
+  /// Reconnects with exponential backoff + jitter, up to [_maxReconnectAttempts].
+  void _scheduleReconnect() {
+    _heartbeatTimer?.cancel();
     _reconnectTimer?.cancel();
-    _reconnectTimer = Timer(
+
-      const Duration(seconds: 5),
+    if (_reconnectAttempts >= _maxReconnectAttempts) return;
-      () => connect(path, token: token),
+
+    // Exponential backoff: 1s, 2s, 4s, 8s, ... capped at 60s
+    final delayMs = min(
+      _baseReconnectDelay.inMilliseconds * pow(2, _reconnectAttempts).toInt(),
+      _maxReconnectDelay.inMilliseconds,
     );
+    final jitter = Random().nextInt(500);
+
+    _reconnectAttempts++;
+    _reconnectTimer = Timer(
+      Duration(milliseconds: delayMs + jitter),
+      () {
+        if (_lastPath != null) {
+          connect(_lastPath!, token: _lastToken);
+        }
+      },
+    );
+  }
+
+  /// Resets reconnect counter and forces an immediate reconnect attempt.
+  Future<void> reconnect() async {
+    _reconnectAttempts = 0;
+    if (_lastPath != null) {
+      await connect(_lastPath!, token: _lastToken);
+    }
   }
 
   Future<void> disconnect() async {
     _heartbeatTimer?.cancel();
     _reconnectTimer?.cancel();
     _isConnected = false;
+    _reconnectAttempts = _maxReconnectAttempts; // Prevent auto-reconnect
     await _channel?.sink.close();
   }
 

it0_app/lib/core/router/app_router.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:go_router/go_router.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import '../widgets/offline_banner.dart';
 import '../../features/auth/data/providers/auth_provider.dart';
 import '../../features/auth/presentation/pages/login_page.dart';
 import '../../features/dashboard/presentation/pages/dashboard_page.dart';
@@ -97,7 +98,12 @@ class ScaffoldWithNav extends ConsumerWidget {
     final currentIndex = _selectedIndex(context);
 
     return Scaffold(
-      body: child,
+      body: Column(
+        children: [
+          const OfflineBanner(),
+          Expanded(child: child),
+        ],
+      ),
       bottomNavigationBar: NavigationBar(
         selectedIndex: currentIndex,
         destinations: [

it0_app/lib/core/widgets/error_view.dart

@@ -0,0 +1,50 @@
+import 'package:flutter/material.dart';
+import '../errors/error_handler.dart';
+import '../theme/app_colors.dart';
+
+/// Unified error display widget used across all pages.
+/// Converts any error into a user-friendly Chinese message via [ErrorHandler].
+class ErrorView extends StatelessWidget {
+  final dynamic error;
+  final VoidCallback? onRetry;
+
+  const ErrorView({
+    super.key,
+    required this.error,
+    this.onRetry,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    final message = ErrorHandler.friendlyMessage(error);
+
+    return Center(
+      child: Padding(
+        padding: const EdgeInsets.all(32),
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: [
+            const Icon(Icons.error_outline, color: AppColors.error, size: 48),
+            const SizedBox(height: 16),
+            Text(
+              message,
+              style: const TextStyle(
+                fontSize: 15,
+                color: AppColors.textSecondary,
+              ),
+              textAlign: TextAlign.center,
+            ),
+            if (onRetry != null) ...[
+              const SizedBox(height: 20),
+              OutlinedButton.icon(
+                onPressed: onRetry,
+                icon: const Icon(Icons.refresh, size: 18),
+                label: const Text('重试'),
+              ),
+            ],
+          ],
+        ),
+      ),
+    );
+  }
+}

it0_app/lib/core/widgets/offline_banner.dart

@@ -0,0 +1,51 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import '../network/connectivity_provider.dart';
+import '../theme/app_colors.dart';
+
+/// Banner displayed at the top of the app when the device is offline.
+/// Auto-hides when connectivity is restored.
+class OfflineBanner extends ConsumerWidget {
+  const OfflineBanner({super.key});
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final isOnline = ref.watch(isOnlineProvider);
+
+    if (isOnline) return const SizedBox.shrink();
+
+    return Container(
+      width: double.infinity,
+      padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
+      color: AppColors.warning,
+      child: Row(
+        children: [
+          const Icon(Icons.wifi_off, size: 16, color: Colors.black87),
+          const SizedBox(width: 8),
+          const Expanded(
+            child: Text(
+              '网络连接不可用',
+              style: TextStyle(
+                color: Colors.black87,
+                fontSize: 13,
+                fontWeight: FontWeight.w500,
+              ),
+            ),
+          ),
+          GestureDetector(
+            onTap: () => ref.read(connectivityProvider.notifier).check(),
+            child: const Text(
+              '重试',
+              style: TextStyle(
+                color: Colors.black87,
+                fontSize: 13,
+                fontWeight: FontWeight.w600,
+                decoration: TextDecoration.underline,
+              ),
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+}

it0_app/lib/features/alerts/presentation/pages/alerts_page.dart

@@ -5,6 +5,7 @@ import '../../../../core/network/dio_client.dart';
 import '../../../../core/theme/app_colors.dart';
 import '../../../../core/utils/date_formatter.dart';
 import '../../../../core/widgets/empty_state.dart';
+import '../../../../core/widgets/error_view.dart';
 import '../../../../core/widgets/status_badge.dart';
 
 // ---------------------------------------------------------------------------
@@ -100,37 +101,9 @@ class _AlertsPageState extends ConsumerState<AlertsPage> {
                 },
                 loading: () =>
                     const Center(child: CircularProgressIndicator()),
-                error: (e, _) => Center(
+                error: (e, _) => ErrorView(
-                  child: Padding(
+                  error: e,
-                    padding: const EdgeInsets.all(32),
+                  onRetry: () => ref.invalidate(alertEventsProvider),
-                    child: Column(
-                      mainAxisAlignment: MainAxisAlignment.center,
-                      children: [
-                        const Icon(Icons.error_outline,
-                            color: AppColors.error, size: 48),
-                        const SizedBox(height: 12),
-                        const Text(
-                          '加载告警失败',
-                          style: TextStyle(
-                              fontSize: 16, fontWeight: FontWeight.w600),
-                        ),
-                        const SizedBox(height: 6),
-                        Text(
-                          e.toString(),
-                          style: const TextStyle(
-                              color: AppColors.textSecondary, fontSize: 13),
-                          textAlign: TextAlign.center,
-                        ),
-                        const SizedBox(height: 16),
-                        OutlinedButton.icon(
-                          onPressed: () =>
-                              ref.invalidate(alertEventsProvider),
-                          icon: const Icon(Icons.refresh),
-                          label: const Text('重试'),
-                        ),
-                      ],
-                    ),
-                  ),
                 ),
               ),
             ),

it0_app/lib/features/approvals/presentation/pages/approvals_page.dart

@@ -5,7 +5,9 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import '../../../../core/config/api_endpoints.dart';
 import '../../../../core/network/dio_client.dart';
 import '../../../../core/theme/app_colors.dart';
+import '../../../../core/errors/error_handler.dart';
 import '../../../../core/widgets/empty_state.dart';
+import '../../../../core/widgets/error_view.dart';
 
 // ---------------------------------------------------------------------------
 // Approvals provider
@@ -161,36 +163,9 @@ class _ApprovalsPageState extends ConsumerState<ApprovalsPage> {
                 },
                 loading: () =>
                     const Center(child: CircularProgressIndicator()),
-                error: (e, _) => Center(
+                error: (e, _) => ErrorView(
-                  child: Padding(
+                  error: e,
-                    padding: const EdgeInsets.all(32),
+                  onRetry: () => ref.invalidate(approvalsProvider),
-                    child: Column(
-                      mainAxisAlignment: MainAxisAlignment.center,
-                      children: [
-                        const Icon(Icons.error_outline,
-                            color: AppColors.error, size: 48),
-                        const SizedBox(height: 12),
-                        const Text(
-                          '加载审批失败',
-                          style: TextStyle(
-                              fontSize: 16, fontWeight: FontWeight.w600),
-                        ),
-                        const SizedBox(height: 6),
-                        Text(
-                          e.toString(),
-                          style: const TextStyle(
-                              color: AppColors.textSecondary, fontSize: 13),
-                          textAlign: TextAlign.center,
-                        ),
-                        const SizedBox(height: 16),
-                        OutlinedButton.icon(
-                          onPressed: () => ref.invalidate(approvalsProvider),
-                          icon: const Icon(Icons.refresh),
-                          label: const Text('重试'),
-                        ),
-                      ],
-                    ),
-                  ),
                 ),
               ),
             ),
@@ -332,7 +307,7 @@ class _ApprovalCardState extends State<_ApprovalCard> {
       if (mounted) {
         ScaffoldMessenger.of(context).showSnackBar(
           SnackBar(
-            content: Text('操作失败: $e'),
+            content: Text('操作失败: ${ErrorHandler.friendlyMessage(e)}'),
             backgroundColor: AppColors.error,
           ),
         );

it0_app/lib/features/auth/data/providers/auth_provider.dart

@@ -5,6 +5,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:flutter_secure_storage/flutter_secure_storage.dart';
 import '../../../../core/config/api_endpoints.dart';
 import '../../../../core/config/app_config.dart';
+import '../../../../core/errors/error_handler.dart';
 import '../../../notifications/presentation/providers/notification_providers.dart';
 import '../models/auth_response.dart';
 import 'tenant_provider.dart';
@@ -184,7 +185,7 @@ class AuthNotifier extends StateNotifier<AuthState> {
     } catch (e) {
       state = state.copyWith(
         isLoading: false,
-        error: e.toString(),
+        error: ErrorHandler.friendlyMessage(e),
       );
       return false;
     }

it0_app/lib/features/chat/presentation/providers/chat_providers.dart

@@ -7,6 +7,7 @@ import '../../data/datasources/chat_local_datasource.dart';
 import '../../data/datasources/chat_remote_datasource.dart';
 import '../../data/models/chat_message_model.dart';
 import '../../data/repositories/chat_repository_impl.dart';
+import '../../../../core/errors/error_handler.dart';
 import '../../domain/entities/chat_message.dart';
 import '../../domain/entities/stream_event.dart';
 import '../../domain/repositories/chat_repository.dart';
@@ -143,7 +144,7 @@ class ChatNotifier extends StateNotifier<ChatState> {
         onError: (error) {
           state = state.copyWith(
             agentStatus: AgentStatus.error,
-            error: error.toString(),
+            error: ErrorHandler.friendlyMessage(error),
           );
         },
         onDone: () {
@@ -155,7 +156,7 @@ class ChatNotifier extends StateNotifier<ChatState> {
     } catch (e) {
       state = state.copyWith(
         agentStatus: AgentStatus.error,
-        error: e.toString(),
+        error: ErrorHandler.friendlyMessage(e),
       );
     }
   }

it0_app/lib/features/dashboard/presentation/pages/dashboard_page.dart

@@ -6,6 +6,7 @@ import '../../../../core/theme/app_colors.dart';
 import '../../../../core/utils/date_formatter.dart';
 import '../../../../core/widgets/empty_state.dart';
 import '../../../../core/widgets/status_badge.dart';
+import '../../../../core/errors/error_handler.dart';
 
 // ---------------------------------------------------------------------------
 // TODO 38 – Dashboard providers & page
@@ -208,7 +209,7 @@ class DashboardPage extends ConsumerWidget {
         ],
       ),
       loading: () => const _SummaryCardLoading(),
-      error: (e, _) => _SummaryCardError(message: e.toString()),
+      error: (e, _) => _SummaryCardError(message: ErrorHandler.friendlyMessage(e)),
     );
   }
 
@@ -230,7 +231,7 @@ class DashboardPage extends ConsumerWidget {
         ],
       ),
       loading: () => const _SummaryCardLoading(),
-      error: (e, _) => _SummaryCardError(message: e.toString()),
+      error: (e, _) => _SummaryCardError(message: ErrorHandler.friendlyMessage(e)),
     );
   }
 
@@ -251,7 +252,7 @@ class DashboardPage extends ConsumerWidget {
         );
       },
       loading: () => const _SummaryCardLoading(),
-      error: (e, _) => _SummaryCardError(message: e.toString()),
+      error: (e, _) => _SummaryCardError(message: ErrorHandler.friendlyMessage(e)),
     );
   }
 
@@ -297,7 +298,7 @@ class DashboardPage extends ConsumerWidget {
       error: (e, _) => Center(
         child: Padding(
           padding: const EdgeInsets.all(32),
-          child: Text('加载失败: $e', style: const TextStyle(color: AppColors.error)),
+          child: Text('加载失败: ${ErrorHandler.friendlyMessage(e)}', style: const TextStyle(color: AppColors.error)),
         ),
       ),
     );

it0_app/lib/features/servers/presentation/pages/servers_page.dart

@@ -4,6 +4,7 @@ import '../../../../core/config/api_endpoints.dart';
 import '../../../../core/network/dio_client.dart';
 import '../../../../core/theme/app_colors.dart';
 import '../../../../core/widgets/empty_state.dart';
+import '../../../../core/widgets/error_view.dart';
 import '../../../../core/widgets/status_badge.dart';
 
 // ---------------------------------------------------------------------------
@@ -87,36 +88,9 @@ class _ServersPageState extends ConsumerState<ServersPage> {
                 },
                 loading: () =>
                     const Center(child: CircularProgressIndicator()),
-                error: (e, _) => Center(
+                error: (e, _) => ErrorView(
-                  child: Padding(
+                  error: e,
-                    padding: const EdgeInsets.all(32),
+                  onRetry: () => ref.invalidate(serversProvider),
-                    child: Column(
-                      mainAxisAlignment: MainAxisAlignment.center,
-                      children: [
-                        const Icon(Icons.error_outline,
-                            color: AppColors.error, size: 48),
-                        const SizedBox(height: 12),
-                        const Text(
-                          '加载服务器失败',
-                          style: TextStyle(
-                              fontSize: 16, fontWeight: FontWeight.w600),
-                        ),
-                        const SizedBox(height: 6),
-                        Text(
-                          e.toString(),
-                          style: const TextStyle(
-                              color: AppColors.textSecondary, fontSize: 13),
-                          textAlign: TextAlign.center,
-                        ),
-                        const SizedBox(height: 16),
-                        OutlinedButton.icon(
-                          onPressed: () => ref.invalidate(serversProvider),
-                          icon: const Icon(Icons.refresh),
-                          label: const Text('重试'),
-                        ),
-                      ],
-                    ),
-                  ),
                 ),
               ),
             ),

it0_app/lib/features/settings/presentation/providers/settings_providers.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:shared_preferences/shared_preferences.dart';
+import '../../../../core/errors/error_handler.dart';
 import '../../../../core/network/dio_client.dart';
 import '../../data/datasources/settings_datasource.dart';
 import '../../data/datasources/settings_remote_datasource.dart';
@@ -148,7 +149,7 @@ class AccountProfileNotifier extends StateNotifier<AccountProfile> {
         isLoading: false,
       );
     } catch (e) {
-      state = state.copyWith(isLoading: false, error: e.toString());
+      state = state.copyWith(isLoading: false, error: ErrorHandler.friendlyMessage(e));
     }
   }
 
@@ -162,7 +163,7 @@ class AccountProfileNotifier extends StateNotifier<AccountProfile> {
       );
       return true;
     } catch (e) {
-      state = state.copyWith(isLoading: false, error: e.toString());
+      state = state.copyWith(isLoading: false, error: ErrorHandler.friendlyMessage(e));
       return false;
     }
   }
@@ -180,7 +181,7 @@ class AccountProfileNotifier extends StateNotifier<AccountProfile> {
       final message = data['message'] as String?;
       return (success: success, message: message);
     } catch (e) {
-      return (success: false, message: e.toString());
+      return (success: false, message: ErrorHandler.friendlyMessage(e));
     }
   }
 }

it0_app/lib/features/standing_orders/presentation/pages/standing_orders_page.dart

@@ -4,7 +4,9 @@ import '../../../../core/config/api_endpoints.dart';
 import '../../../../core/network/dio_client.dart';
 import '../../../../core/theme/app_colors.dart';
 import '../../../../core/utils/date_formatter.dart';
+import '../../../../core/errors/error_handler.dart';
 import '../../../../core/widgets/empty_state.dart';
+import '../../../../core/widgets/error_view.dart';
 import '../../../../core/widgets/status_badge.dart';
 
 // ---------------------------------------------------------------------------
@@ -68,37 +70,9 @@ class StandingOrdersPage extends ConsumerWidget {
             );
           },
           loading: () => const Center(child: CircularProgressIndicator()),
-          error: (e, _) => Center(
+          error: (e, _) => ErrorView(
-            child: Padding(
+            error: e,
-              padding: const EdgeInsets.all(32),
+            onRetry: () => ref.invalidate(standingOrdersProvider),
-              child: Column(
-                mainAxisAlignment: MainAxisAlignment.center,
-                children: [
-                  const Icon(Icons.error_outline,
-                      color: AppColors.error, size: 48),
-                  const SizedBox(height: 12),
-                  const Text(
-                    '加载常驻指令失败',
-                    style:
-                        TextStyle(fontSize: 16, fontWeight: FontWeight.w600),
-                  ),
-                  const SizedBox(height: 6),
-                  Text(
-                    e.toString(),
-                    style: const TextStyle(
-                        color: AppColors.textSecondary, fontSize: 13),
-                    textAlign: TextAlign.center,
-                  ),
-                  const SizedBox(height: 16),
-                  OutlinedButton.icon(
-                    onPressed: () =>
-                        ref.invalidate(standingOrdersProvider),
-                    icon: const Icon(Icons.refresh),
-                    label: const Text('重试'),
-                  ),
-                ],
-              ),
-            ),
           ),
         ),
       ),
@@ -264,7 +238,7 @@ class _StandingOrderCardState extends ConsumerState<_StandingOrderCard> {
       if (mounted) {
         ScaffoldMessenger.of(context).showSnackBar(
           SnackBar(
-            content: Text('更新状态失败: $e'),
+            content: Text('更新状态失败: ${ErrorHandler.friendlyMessage(e)}'),
             backgroundColor: AppColors.error,
           ),
         );

it0_app/lib/features/tasks/presentation/pages/tasks_page.dart

@@ -1,10 +1,12 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import '../../../../core/config/api_endpoints.dart';
+import '../../../../core/errors/error_handler.dart';
 import '../../../../core/network/dio_client.dart';
 import '../../../../core/theme/app_colors.dart';
 import '../../../../core/utils/date_formatter.dart';
 import '../../../../core/widgets/empty_state.dart';
+import '../../../../core/widgets/error_view.dart';
 import '../../../../core/widgets/status_badge.dart';
 
 // ---------------------------------------------------------------------------
@@ -81,33 +83,9 @@ class TasksPage extends ConsumerWidget {
             );
           },
           loading: () => const Center(child: CircularProgressIndicator()),
-          error: (e, _) => Center(
+          error: (e, _) => ErrorView(
-            child: Padding(
+            error: e,
-              padding: const EdgeInsets.all(32),
+            onRetry: () => ref.invalidate(tasksProvider),
-              child: Column(
-                mainAxisAlignment: MainAxisAlignment.center,
-                children: [
-                  const Icon(Icons.error_outline, color: AppColors.error, size: 48),
-                  const SizedBox(height: 12),
-                  Text(
-                    '加载任务失败',
-                    style: const TextStyle(fontSize: 16, fontWeight: FontWeight.w600),
-                  ),
-                  const SizedBox(height: 6),
-                  Text(
-                    e.toString(),
-                    style: const TextStyle(color: AppColors.textSecondary, fontSize: 13),
-                    textAlign: TextAlign.center,
-                  ),
-                  const SizedBox(height: 16),
-                  OutlinedButton.icon(
-                    onPressed: () => ref.invalidate(tasksProvider),
-                    icon: const Icon(Icons.refresh),
-                    label: const Text('重试'),
-                  ),
-                ],
-              ),
-            ),
           ),
         ),
       ),
@@ -413,7 +391,7 @@ class _CreateTaskSheetState extends State<_CreateTaskSheet> {
       if (mounted) {
         ScaffoldMessenger.of(context).showSnackBar(
           SnackBar(
-            content: Text('创建任务失败: $e'),
+            content: Text('创建任务失败: ${ErrorHandler.friendlyMessage(e)}'),
             backgroundColor: AppColors.error,
           ),
         );