diff --git a/lib/features/device/providers/device_info_provider.dart b/lib/features/device/providers/device_info_provider.dart
index cc7550a..d1994d4 100644
--- a/lib/features/device/providers/device_info_provider.dart
+++ b/lib/features/device/providers/device_info_provider.dart
@@ -1,6 +1,7 @@
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../models/device_state.dart';
+import '../services/device_log.dart';
 import '../services/device_message.dart';
 import '../services/device_message_service.dart';
 import 'serial_provider.dart';
@@ -27,18 +28,30 @@ class DeviceInfoNotifier extends StateNotifier<DeviceState> {
     final light = _parseLight(data['light_status']);
     final door = _parseDoor(data['door_status']);
     final task = _parseTask(data['task_status']);
+    final prev = state;
+    final changed = prev.lightStatus != light ||
+        prev.doorStatus != door ||
+        prev.taskStatus != task;
     state = state.copyWith(
       lightStatus: light,
       doorStatus: door,
       taskStatus: task,
       lastInfoAt: DateTime.now(),
     );
+    if (changed) {
+      DeviceLog.info(
+        'device_info updated: light=${light.name} door=${door.name} task=${task.name}',
+      );
+    }
   }
 
   /// 主动查询设备信息（发送 need_ack=true 的 create_task 之外的 device_info 请求，
   /// 具体取决于下位机协议约定；目前仅作占位）。
   Future<void> queryDeviceInfo() async {
-    if (!_msgService.canSend) return;
+    if (!_msgService.canSend) {
+      DeviceLog.warn('queryDeviceInfo skipped: serial disconnected');
+      return;
+    }
     final id = _msgService.nextId();
     await _msgService.send(DeviceMessage.request(
       messageId: id,
@@ -53,7 +66,10 @@ class DeviceInfoNotifier extends StateNotifier<DeviceState> {
   /// 主动切换后，下位机通常会通过 device_info 上报新的 light_status
   /// 覆盖本地状态。
   Future<bool> toggleLight() async {
-    if (!_msgService.canSend) return false;
+    if (!_msgService.canSend) {
+      DeviceLog.warn('toggleLight skipped: serial disconnected');
+      return false;
+    }
     final next = state.lightStatus == DeviceLightStatus.on ? 'off' : 'on';
     final id = _msgService.nextId();
     final ok = await _msgService.send(DeviceMessage.request(
@@ -67,13 +83,17 @@ class DeviceInfoNotifier extends StateNotifier<DeviceState> {
       state = state.copyWith(
         lightStatus: next == 'on' ? DeviceLightStatus.on : DeviceLightStatus.off,
       );
+      DeviceLog.info('toggleLight optimistic: -> $next');
     }
     return ok;
   }
 
   /// 显式设定灯光
   Future<bool> setLight(bool on) async {
-    if (!_msgService.canSend) return false;
+    if (!_msgService.canSend) {
+      DeviceLog.warn('setLight skipped: serial disconnected');
+      return false;
+    }
     if (on && state.lightStatus == DeviceLightStatus.on) return true;
     if (!on && state.lightStatus == DeviceLightStatus.off) return true;
     final id = _msgService.nextId();
@@ -87,6 +107,7 @@ class DeviceInfoNotifier extends StateNotifier<DeviceState> {
       state = state.copyWith(
         lightStatus: on ? DeviceLightStatus.on : DeviceLightStatus.off,
       );
+      DeviceLog.info('setLight optimistic: -> ${on ? "on" : "off"}');
     }
     return ok;
   }
diff --git a/lib/features/device/services/device_log.dart b/lib/features/device/services/device_log.dart
new file mode 100644
index 0000000..3e4ca04
--- /dev/null
+++ b/lib/features/device/services/device_log.dart
@@ -0,0 +1,49 @@
+import 'dart:developer' as developer;
+
+/// 串口/协议层统一日志入口
+///
+/// 使用 `dart:developer.log` 便于 Dart DevTools 抓取与分级。
+/// 所有日志统一以 `kuaishai.device` 为 name 前缀，方便在 DevTools 中过滤。
+class DeviceLog {
+  static const String _name = 'kuaishai.device';
+
+  /// 信息级别：正常收发与状态变化
+  static void info(String message, {Object? error, Map<String, Object?>? context}) {
+    developer.log(message, name: _name, level: 800, error: error);
+  }
+
+  /// 警告级别：可恢复的异常（解析错误、写入失败等）
+  static void warn(String message, {Object? error, Map<String, Object?>? context}) {
+    developer.log(
+      message,
+      name: _name,
+      level: 900,
+      error: error,
+      // dart:developer 当前不支持直接附带 context；调用方可在 message 中拼接
+    );
+  }
+
+  /// 严重级别：连接断开、协议级不可恢复错误
+  static void severe(String message, {Object? error, Map<String, Object?>? context}) {
+    developer.log(message, name: _name, level: 1000, error: error);
+  }
+
+  /// 将 Map 数据截断为可读摘要，避免在日志中泄露超长负载
+  static String summarizeData(Map<String, dynamic>? data, {int maxKeys = 8}) {
+    if (data == null || data.isEmpty) return '{}';
+    final keys = data.keys.take(maxKeys).toList();
+    final shown = keys.map((k) {
+      final v = data[k];
+      if (v is String) return '$k="${_truncate(v, 32)}"';
+      if (v is List) return '$k=[${v.length}]';
+      return '$k=$v';
+    }).join(', ');
+    final suffix = data.length > maxKeys ? ', ...' : '';
+    return '{$shown$suffix}';
+  }
+
+  static String _truncate(String s, int max) {
+    if (s.length <= max) return s;
+    return '${s.substring(0, max)}…';
+  }
+}
diff --git a/lib/features/device/services/device_message_service.dart b/lib/features/device/services/device_message_service.dart
index b696b02..f3e3016 100644
--- a/lib/features/device/services/device_message_service.dart
+++ b/lib/features/device/services/device_message_service.dart
@@ -2,6 +2,7 @@ import 'dart:async';
 import 'dart:typed_data';
 
 import 'serial_port_service.dart';
+import 'device_log.dart';
 import 'device_message.dart';
 import 'json_protocol.dart';
 
@@ -77,10 +78,18 @@ class DeviceMessageService {
         _emitError('写入失败：${message.type.wireName}');
         return false;
       }
+      DeviceLog.info(
+        'TX ${message.type.wireName} '
+        'id=${message.messageId} '
+        'ack=${message.ack ?? "-"} '
+        'needAck=${message.needAck} '
+        'data=${DeviceLog.summarizeData(message.data)}\n'
+        '   json=${message.encode()}',
+      );
       _messageCtrl.add(message);
       return true;
     } catch (e) {
-      _emitError('编码异常: $e');
+      _emitError('编码异常: $e', error: e);
       return false;
     }
   }
@@ -104,7 +113,7 @@ class DeviceMessageService {
     _stateSub?.cancel();
 
     _rxSub = _serial.onData.listen(_onData);
-    _errorSub = _serial.onError.listen(_emitError);
+    _errorSub = _serial.onError.listen((msg) => _emitError(msg));
     _stateSub = _serial.connectionStateChanges.listen((s) {
       if (s == SerialConnectionState.disconnected) {
         _protocol.reset();
@@ -129,6 +138,13 @@ class DeviceMessageService {
   }
 
   void _dispatch(DeviceMessage msg) {
+    DeviceLog.info(
+      'RX ${msg.type.wireName} '
+      'id=${msg.messageId} '
+      'ack=${msg.ack ?? "-"} '
+      'data=${DeviceLog.summarizeData(msg.data)}\n'
+      '   json=${msg.encode()}',
+    );
     _messageCtrl.add(msg);
     final list = _handlers[msg.type];
     if (list == null) return;
@@ -136,12 +152,18 @@ class DeviceMessageService {
       try {
         handler(msg);
       } catch (e) {
-        _emitError('消息处理异常 (${msg.type.wireName}): $e');
+        _emitError('消息处理异常 (${msg.type.wireName}): $e', error: e);
+        DeviceLog.severe('消息处理异常 (${msg.type.wireName})', error: e);
       }
     }
   }
 
-  void _emitError(String message) {
+  void _emitError(String message, {Object? error}) {
+    if (error != null) {
+      DeviceLog.warn(message, error: error);
+    } else {
+      DeviceLog.warn(message);
+    }
     if (!_errorCtrl.isClosed) _errorCtrl.add(message);
   }
 }
diff --git a/lib/features/device/services/serial_port_service.dart b/lib/features/device/services/serial_port_service.dart
new file mode 100644
index 0000000..2aaa4c9
--- /dev/null
+++ b/lib/features/device/services/serial_port_service.dart
@@ -0,0 +1,225 @@
+import 'dart:async';
+import 'dart:typed_data';
+
+import 'package:usb_serial/usb_serial.dart';
+
+import '../models/serial_config.dart';
+import 'device_log.dart';
+
+/// 串口连接状态
+enum SerialConnectionState { disconnected, connecting, connected, error }
+
+/// 串口服务
+///
+/// 封装 [UsbSerial] 库，对外暴露稳定的连接/读写接口，
+/// 屏蔽底层 USB 设备的插拔、权限请求、参数配置等细节。
+class SerialPortService {
+  UsbPort? _port;
+  UsbDevice? _device;
+  StreamSubscription<Uint8List>? _readSub;
+  final _connectionCtrl = StreamController<SerialConnectionState>.broadcast();
+  final _dataCtrl = StreamController<Uint8List>.broadcast();
+  final _errorCtrl = StreamController<String>.broadcast();
+  SerialConnectionState _state = SerialConnectionState.disconnected;
+  String? _lastError;
+
+  /// 当前连接状态
+  SerialConnectionState get state => _state;
+
+  /// 最后一次错误信息
+  String? get lastError => _lastError;
+
+  /// 是否已连接
+  bool get isConnected => _state == SerialConnectionState.connected;
+
+  /// 当前连接设备（仅在已连接时可用）
+  UsbDevice? get currentDevice => _device;
+
+  /// 连接状态变更流
+  Stream<SerialConnectionState> get connectionStateChanges =>
+      _connectionCtrl.stream;
+
+  /// 接收到的数据流
+  Stream<Uint8List> get onData => _dataCtrl.stream;
+
+  /// 错误信息流
+  Stream<String> get onError => _errorCtrl.stream;
+
+  /// 列出当前连接的 USB 串口设备
+  Future<List<UsbDevice>> listDevices() async {
+    return await UsbSerial.listDevices();
+  }
+
+  /// 设备名（vendor/product 拼接）
+  static String deviceLabel(UsbDevice d) {
+    final v = _hex(d.vid);
+    final p = _hex(d.pid);
+    final name = d.productName ?? d.manufacturerName ?? 'USB Serial';
+    return '$name [$v:$p]';
+  }
+
+  static String _hex(int? v) =>
+      (v ?? 0).toRadixString(16).padLeft(4, '0').toUpperCase();
+
+  /// 打开指定设备并按 [config] 配置参数
+  Future<bool> connect(UsbDevice device, SerialConfig config) async {
+    if (_state == SerialConnectionState.connected ||
+        _state == SerialConnectionState.connecting) {
+      await disconnect();
+    }
+
+    DeviceLog.info('连接串口设备: ${deviceLabel(device)}, '
+        'baud=${config.baudRate} dataBits=${config.dataBits} '
+        'stopBits=${config.stopBits} parity=${config.parity.name}');
+    _setState(SerialConnectionState.connecting);
+    try {
+      // UsbSerial.create 内部会触发 Android USB 权限弹窗
+      final port = await device.create();
+      if (port == null) {
+        _fail('创建设备端口失败（可能未授予 USB 权限）');
+        return false;
+      }
+
+      final opened = await port.open();
+      if (!opened) {
+        await port.close();
+        _fail('打开端口失败');
+        return false;
+      }
+
+      await _applyConfig(port, config);
+
+      _port = port;
+      _device = device;
+      _subscribeStream(port);
+      _setState(SerialConnectionState.connected);
+      DeviceLog.info('串口已连接: ${deviceLabel(device)}');
+      return true;
+    } catch (e) {
+      _fail('连接异常: $e');
+      return false;
+    }
+  }
+
+  /// 应用串口参数
+  Future<void> _applyConfig(UsbPort port, SerialConfig config) async {
+    await port.setPortParameters(
+      config.baudRate,
+      config.dataBits,
+      config.stopBits,
+      _parityToCode(config.parity),
+    );
+    await port.setFlowControl(_flowControlToCode(config.flowControl));
+  }
+
+  /// 断开当前连接
+  Future<void> disconnect() async {
+    if (_state == SerialConnectionState.disconnected) return;
+    await _readSub?.cancel();
+    _readSub = null;
+    try {
+      await _port?.close();
+    } catch (_) {}
+    _port = null;
+    _device = null;
+    _setState(SerialConnectionState.disconnected);
+    DeviceLog.info('串口已断开');
+  }
+
+  /// 写入数据，返回成功写入的字节数（设备库本身不返回字节数，连接失败时返回 0）
+  Future<int> write(Uint8List data) async {
+    final port = _port;
+    if (port == null || !isConnected) {
+      _emitError('串口未连接，写入失败');
+      return 0;
+    }
+    try {
+      await port.write(data);
+      DeviceLog.info('串口 TX: ${data.length} 字节');
+      return data.length;
+    } catch (e) {
+      _emitError('写入异常: $e', error: e);
+      return 0;
+    }
+  }
+
+  /// 释放资源（应用退出时调用）
+  Future<void> dispose() async {
+    await disconnect();
+    await _connectionCtrl.close();
+    await _dataCtrl.close();
+    await _errorCtrl.close();
+  }
+
+  void _subscribeStream(UsbPort port) {
+    _readSub?.cancel();
+    final stream = port.inputStream;
+    if (stream == null) {
+      _emitError('当前端口无输入流');
+      return;
+    }
+    _readSub = stream.listen(
+      (data) {
+        if (data.isNotEmpty) {
+          DeviceLog.info('串口 RX: ${data.length} 字节');
+          _dataCtrl.add(data);
+        }
+      },
+      onError: (Object e) {
+        _emitError('读取异常: $e', error: e);
+      },
+      onDone: () {
+        DeviceLog.info('串口输入流关闭');
+        _setState(SerialConnectionState.disconnected);
+      },
+      cancelOnError: false,
+    );
+  }
+
+  void _setState(SerialConnectionState s) {
+    _state = s;
+    if (s != SerialConnectionState.error) {
+      _lastError = null;
+    }
+    if (!_connectionCtrl.isClosed) {
+      _connectionCtrl.add(s);
+    }
+  }
+
+  void _fail(String message) {
+    _lastError = message;
+    _setState(SerialConnectionState.error);
+    _emitError(message);
+  }
+
+  void _emitError(String message, {Object? error}) {
+    _lastError = message;
+    if (error != null) {
+      DeviceLog.severe(message, error: error);
+    } else {
+      DeviceLog.warn(message);
+    }
+    if (!_errorCtrl.isClosed) {
+      _errorCtrl.add(message);
+    }
+  }
+
+  static int _parityToCode(SerialParity p) {
+    return switch (p) {
+      SerialParity.none => UsbPort.PARITY_NONE,
+      SerialParity.odd => UsbPort.PARITY_ODD,
+      SerialParity.even => UsbPort.PARITY_EVEN,
+      SerialParity.mark => UsbPort.PARITY_MARK,
+      SerialParity.space => UsbPort.PARITY_SPACE,
+    };
+  }
+
+  static int _flowControlToCode(SerialFlowControl f) {
+    return switch (f) {
+      SerialFlowControl.none => UsbPort.FLOW_CONTROL_OFF,
+      SerialFlowControl.rtsCts => UsbPort.FLOW_CONTROL_RTS_CTS,
+      SerialFlowControl.xonXoff => UsbPort.FLOW_CONTROL_XON_XOFF,
+      SerialFlowControl.dtrDsr => UsbPort.FLOW_CONTROL_DSR_DTR,
+    };
+  }
+}
diff --git a/lib/features/device/services/serial_runner.dart b/lib/features/device/services/serial_runner.dart
index c1d76a6..9687c8f 100644
--- a/lib/features/device/services/serial_runner.dart
+++ b/lib/features/device/services/serial_runner.dart
@@ -2,6 +2,7 @@ import 'dart:async';
 
 import '../../programs/models/program.dart';
 import '../../programs/models/step.dart';
+import 'device_log.dart';
 import 'device_message.dart';
 import 'device_message_service.dart';
 import 'runner_interface.dart';
@@ -65,6 +66,8 @@ class JsonSerialRunner implements Runner {
     final messageId = _msg.nextId();
     _pendingCreateTaskId = messageId;
     final msg = payload.toMessage(messageId, needAck: true);
+    DeviceLog.info('Runner.start: program="${program.name}" steps=${steps.length} '
+        'temperature=${program.temperature} airflow=${program.airflowTime}');
     _msg.send(msg).then((ok) {
       if (!ok) {
         _pendingCreateTaskId = null;
@@ -77,6 +80,7 @@ class JsonSerialRunner implements Runner {
   @override
   void pause() {
     if (status != RunnerStatus.running) return;
+    DeviceLog.info('Runner.pause');
     _sendControl('pause');
     _stopLocalTicker();
     status = RunnerStatus.paused;
@@ -85,6 +89,7 @@ class JsonSerialRunner implements Runner {
   @override
   void resume() {
     if (status != RunnerStatus.paused) return;
+    DeviceLog.info('Runner.resume');
     _sendControl('continue');
     status = RunnerStatus.running;
     _startLocalTicker();
@@ -93,6 +98,7 @@ class JsonSerialRunner implements Runner {
   @override
   void stop() {
     if (status == RunnerStatus.idle) return;
+    DeviceLog.info('Runner.stop');
     _sendControl('stop');
     _teardown();
     status = RunnerStatus.idle;
@@ -125,6 +131,7 @@ class JsonSerialRunner implements Runner {
   void _onCreateTaskAck(DeviceMessage ack) {
     if (ack.ack != _pendingCreateTaskId) return;
     _pendingCreateTaskId = null;
+    DeviceLog.info('Runner received create_task ack: id=${ack.messageId}');
     // ack 即视为下位机已接受任务，进入 running 状态
     if (status == RunnerStatus.idle || status == RunnerStatus.error) {
       status = RunnerStatus.running;
@@ -135,6 +142,7 @@ class JsonSerialRunner implements Runner {
   void _onControlAck(DeviceMessage ack) {
     if (ack.ack != _pendingControlId) return;
     _pendingControlId = null;
+    DeviceLog.info('Runner received control ack: id=${ack.messageId}');
     // control ack 不修改状态，状态机在调用 pause/resume/stop 时已切过
   }
 
@@ -149,6 +157,7 @@ class JsonSerialRunner implements Runner {
       if (_remainingSeconds <= 0) {
         _currentStepIndex++;
         if (_currentStepIndex >= _steps.length) {
+          DeviceLog.info('Runner 本地倒计时完成 (timeout fallback)');
           _stopLocalTicker();
           status = RunnerStatus.completed;
           _callbacks?.onComplete?.call();
diff --git a/test/device_protocol_test.dart b/test/device_protocol_test.dart
index 5aa81c7..8b012ae 100644
--- a/test/device_protocol_test.dart
+++ b/test/device_protocol_test.dart
@@ -3,6 +3,7 @@ import 'dart:typed_data';
 
 import 'package:flutter_test/flutter_test.dart';
 import 'package:kuaishai2/features/device/models/device_state.dart';
+import 'package:kuaishai2/features/device/services/device_log.dart';
 import 'package:kuaishai2/features/device/services/device_message.dart';
 import 'package:kuaishai2/features/device/services/json_protocol.dart';
 import 'package:kuaishai2/features/device/services/task_payload.dart';
@@ -218,4 +219,38 @@ void main() {
       expect(s.infoStale, isTrue);
     });
   });
+
+  group('DeviceLog', () {
+    test('summarizeData 截断长字符串与多余键', () {
+      final data = {
+        'a': 1,
+        'b': 'short',
+        'c': 'x' * 200,
+        'd': [1, 2, 3],
+        'e': true,
+        'f': null,
+        'g': 'extra',
+        'h': 'extra2',
+        'i': 'extra3',
+      };
+      final summary = DeviceLog.summarizeData(data, maxKeys: 4);
+      expect(summary.contains('a=1'), isTrue);
+      expect(summary.contains('b="short"'), isTrue);
+      expect(summary.contains('…'), isTrue); // 长字符串被截断
+      expect(summary.contains('…'), isTrue);
+      expect(summary.contains(', ...'), isTrue); // 多余键被截断
+    });
+
+    test('summarizeData 空 Map / null 友好处理', () {
+      expect(DeviceLog.summarizeData(null), '{}');
+      expect(DeviceLog.summarizeData({}), '{}');
+    });
+
+    test('info / warn / severe 不抛异常', () {
+      // 仅验证调用不抛异常；dart:developer.log 在测试环境无可见输出
+      DeviceLog.info('hello');
+      DeviceLog.warn('warn', error: StateError('x'));
+      DeviceLog.severe('severe', error: 'err');
+    });
+  });
 }