feat(device): 启动自动连接 USB 串口 + 隐藏设置页配置项 + 标题栏连接状态

- 新增 AutoSerialConnect 服务：启动后自动连接第一个 USB 串口设备，
  固定 115200/8/N/1，连接失败时每 3s 重试，断开后重新进入重试循环
- main.dart 通过 ProviderContainer 在 runApp 之前触发 autoSerialConnectProvider
- 移除设置页「串口配置」菜单项及对应面板分支
- StatusBar 在「设备运行状态」前增加串口连接状态指示（已连接/连接中/未连接）

lib/features/device/providers/serial_provider.dart

@@ -2,6 +2,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../../../core/database/database_service.dart';
 import '../models/serial_config.dart';
+import '../services/auto_serial_connect.dart';
 import '../services/device_message_service.dart';
 import '../services/json_protocol.dart';
 import '../services/runner_interface.dart';
@@ -15,6 +16,18 @@ final serialPortServiceProvider = Provider<SerialPortService>((ref) {
   return service;
 });
 
+/// 启动自动连接服务
+///
+/// 通过 [main] 中的 ProviderContainer 在 runApp 之前触发一次，
+/// 服务内部立即尝试连接第一个 USB 串口设备，失败时按 3s 间隔重试。
+final autoSerialConnectProvider = Provider<AutoSerialConnect>((ref) {
+  final service = ref.watch(serialPortServiceProvider);
+  final auto = AutoSerialConnect(service);
+  auto.start();
+  ref.onDispose(auto.dispose);
+  return auto;
+});
+
 /// JSON 协议编解码器（可在调试/真机协议不一致时整体替换）
 final jsonProtocolProvider = Provider<JsonProtocolService>((ref) {
   return JsonProtocolService();

lib/features/device/services/auto_serial_connect.dart

@@ -0,0 +1,109 @@
+import 'dart:async';
+
+import 'package:usb_serial/usb_serial.dart';
+
+import '../models/serial_config.dart';
+import 'device_log.dart';
+import 'serial_port_service.dart';
+
+/// 启动自动连接服务
+///
+/// App 启动时调用 [start]，自动连接第一个可用的 USB 串口设备：
+/// - 固定 115200 波特率 / 8 数据位 / 1 停止位 / 默认其它
+/// - 连接失败时每 3 秒重试一次
+/// - 连接成功后停止重试；连接断开后重新进入重试循环
+class AutoSerialConnect {
+  /// 重试间隔
+  static const Duration retryInterval = Duration(seconds: 3);
+
+  /// 自动连接使用的固定参数
+  static const SerialConfig autoConfig = SerialConfig(
+    baudRate: 115200,
+    dataBits: 8,
+    stopBits: 1,
+  );
+
+  final SerialPortService _service;
+  Timer? _retryTimer;
+  StreamSubscription<SerialConnectionState>? _stateSub;
+  bool _disposed = false;
+
+  AutoSerialConnect(this._service);
+
+  /// 启动自动连接：立即尝试一次，失败则按 [retryInterval] 周期重试
+  void start() {
+    if (_stateSub != null) return;
+    _stateSub = _service.connectionStateChanges.listen(_onStateChange);
+    unawaited(_tryConnect());
+  }
+
+  void _onStateChange(SerialConnectionState s) {
+    if (_disposed) return;
+    switch (s) {
+      case SerialConnectionState.connected:
+        // 连接成功：停止重试
+        _cancelRetry();
+      case SerialConnectionState.disconnected:
+      case SerialConnectionState.error:
+        // 设备断开或出错：进入重试
+        _scheduleRetry();
+      case SerialConnectionState.connecting:
+        // 正在连接中，忽略
+        break;
+    }
+  }
+
+  Future<void> _tryConnect() async {
+    if (_disposed) return;
+    if (_service.isConnected ||
+        _service.state == SerialConnectionState.connecting) {
+      return;
+    }
+
+    final List<UsbDevice> devices;
+    try {
+      devices = await _service.listDevices();
+    } catch (e) {
+      DeviceLog.warn('列出 USB 设备失败: $e，${retryInterval.inSeconds}s 后重试');
+      _scheduleRetry();
+      return;
+    }
+
+    if (devices.isEmpty) {
+      DeviceLog.info('未检测到 USB 串口设备，${retryInterval.inSeconds}s 后重试');
+      _scheduleRetry();
+      return;
+    }
+
+    final device = devices.first;
+    final ok = await _service.connect(device, autoConfig);
+    if (!ok) {
+      DeviceLog.warn('串口自动连接失败: '
+          '${_service.lastError ?? "未知错误"}，${retryInterval.inSeconds}s 后重试');
+      _scheduleRetry();
+    }
+  }
+
+  void _scheduleRetry() {
+    if (_disposed) return;
+    if (_retryTimer != null) return;
+    _retryTimer = Timer(retryInterval, () {
+      _retryTimer = null;
+      unawaited(_tryConnect());
+    });
+  }
+
+  void _cancelRetry() {
+    _retryTimer?.cancel();
+    _retryTimer = null;
+  }
+
+  /// 释放资源
+  Future<void> dispose() async {
+    if (_disposed) return;
+    _disposed = true;
+    _cancelRetry();
+    await _stateSub?.cancel();
+    _stateSub = null;
+  }
+}

lib/features/home/widgets/status_bar.dart

@@ -5,6 +5,8 @@ import '../../../core/localization/app_localizations.dart';
 import '../../../core/theme/app_theme.dart';
 import '../../../shared/widgets/status_indicator.dart';
 import '../../device/providers/device_info_provider.dart';
+import '../../device/providers/serial_provider.dart';
+import '../../device/services/serial_port_service.dart';
 
 /// 状态栏标签项数据
 class StatusBarTab {
@@ -76,6 +78,7 @@ class _StatusBarState extends ConsumerState<StatusBar> {
   Widget build(BuildContext context) {
     final l10n = AppLocalizations.of(context);
     final deviceInfo = ref.watch(deviceInfoProvider);
+    final serialState = ref.watch(serialPortServiceProvider).state;
 
     return Container(
       height: 56,
@@ -117,6 +120,8 @@ class _StatusBarState extends ConsumerState<StatusBar> {
             onTap: _onLightTap,
           ),
           const SizedBox(width: 20),
+          _SerialConnectionIndicator(state: serialState),
+          const SizedBox(width: 20),
           StatusIndicator(
             text: widget.isRunning
                 ? (l10n?.running ?? '运行中')
@@ -262,3 +267,49 @@ class _LightToggleButton extends StatelessWidget {
     );
   }
 }
+
+/// 串口连接状态指示器
+///
+/// 位于「设备运行状态」之前，反映当前 USB 串口的连接情况。
+class _SerialConnectionIndicator extends StatelessWidget {
+  final SerialConnectionState state;
+  const _SerialConnectionIndicator({required this.state});
+
+  @override
+  Widget build(BuildContext context) {
+    final connected = state == SerialConnectionState.connected;
+    final connecting = state == SerialConnectionState.connecting;
+    final text = connected
+        ? '已连接'
+        : connecting
+            ? '连接中'
+            : '未连接';
+    final color = connected
+        ? AppTheme.statusRunning
+        : connecting
+            ? AppTheme.statusPaused
+            : AppTheme.statusStopped;
+    return Row(
+      mainAxisSize: MainAxisSize.min,
+      children: [
+        Container(
+          width: 10,
+          height: 10,
+          decoration: BoxDecoration(
+            shape: BoxShape.circle,
+            color: color,
+          ),
+        ),
+        const SizedBox(width: 6),
+        Text(
+          text,
+          style: TextStyle(
+            color: Colors.white,
+            fontWeight: FontWeight.w600,
+            fontSize: 13,
+          ),
+        ),
+      ],
+    );
+  }
+}

lib/features/settings/pages/settings_page.dart

@@ -5,11 +5,10 @@ import '../../../core/theme/app_theme.dart';
 import '../../../shared/widgets/common_button.dart';
 import '../widgets/language_panel.dart';
 import '../widgets/password_panel.dart';
-import '../widgets/serial_config_panel.dart';
 import '../widgets/usb_import_panel.dart';
 
 /// 设置页菜单
-enum _SettingsMenu { upgrade, language, password, usbImport, serialConfig }
+enum _SettingsMenu { upgrade, language, password, usbImport }
 
 /// 系统设置页面
 class SettingsPage extends ConsumerStatefulWidget {
@@ -70,14 +69,6 @@ class _SettingsPageState extends ConsumerState<SettingsPage> {
                       onTap: () => setState(
                           () => _currentMenu = _SettingsMenu.upgrade),
                     ),
-                    // 串口配置
-                    _buildMenuItem(
-                      icon: Icons.settings_input_hdmi,
-                      title: '串口配置',
-                      selected: _currentMenu == _SettingsMenu.serialConfig,
-                      onTap: () => setState(
-                          () => _currentMenu = _SettingsMenu.serialConfig),
-                    ),
                     // 语言设置
                     _buildMenuItem(
                       icon: Icons.language,
@@ -127,7 +118,6 @@ class _SettingsPageState extends ConsumerState<SettingsPage> {
 
   Widget _buildContent() {
     return switch (_currentMenu) {
-      _SettingsMenu.serialConfig => const SerialConfigPanel(),
       _SettingsMenu.language => const LanguagePanel(),
       _SettingsMenu.password => const PasswordPanel(),
       _SettingsMenu.usbImport => const UsbImportPanel(),

lib/main.dart

@@ -8,6 +8,7 @@ import 'core/theme/app_theme.dart';
 import 'core/localization/app_localizations.dart';
 import 'core/localization/locale_provider.dart';
 import 'core/database/database_service.dart';
+import 'features/device/providers/serial_provider.dart';
 
 /// 应用入口
 void main() async {
@@ -22,7 +23,17 @@ void main() async {
   final db = DatabaseService.instance;
   await db.database;
   await db.initTestData();
-  runApp(const ProviderScope(child: KuaishaiApp()));
+
+  // 使用 ProviderContainer 在 runApp 之前触发启动自动连接
+  final container = ProviderContainer();
+  container.read(autoSerialConnectProvider);
+
+  runApp(
+    UncontrolledProviderScope(
+      container: container,
+      child: const KuaishaiApp(),
+    ),
+  );
 }
 
 /// 应用主体