fix: 蓝牙连接优化

lib/utils/bluetooth/bluetooth_manager.dart

@@ -256,7 +256,10 @@ class BleBluetoothManager<T> {
     return connectToDeviceId(device.remoteId);
   }
 
-  Future<void> connectToDeviceId(String deviceId) {
+  Future<void> connectToDeviceId(
+    String deviceId, {
+    bool prescan = false,
+  }) {
     final pending = _connectInProgress;
     if (pending != null) {
       debugPrint(
@@ -265,14 +268,17 @@ class BleBluetoothManager<T> {
       return pending;
     }
 
-    final task = _connectToDeviceIdLocked(deviceId);
+    final task = _connectToDeviceIdLocked(deviceId, prescan: prescan);
     _connectInProgress = task.whenComplete(() {
       _connectInProgress = null;
     });
     return _connectInProgress!;
   }
 
-  Future<void> _connectToDeviceIdLocked(String deviceId) async {
+  Future<void> _connectToDeviceIdLocked(
+    String deviceId, {
+    required bool prescan,
+  }) async {
     debugPrint(
         '🔥🔥🔥 BLE_CONNECT_DEBUG connect_to_device_id start deviceId=$deviceId');
     if (deviceId.isEmpty) {
@@ -308,14 +314,24 @@ class BleBluetoothManager<T> {
     debugPrint('🔥🔥🔥 BLE_CONNECT_DEBUG connecting deviceId=$deviceId');
 
     final completer = Completer<void>();
-    _connectionSubscription = _ble
-        .connectToDevice(
-      id: deviceId,
-      servicesWithCharacteristicsToDiscover: {
-        serviceUuid: [notifyCharacteristicUuid, writeCharacteristicUuid],
-      },
-      connectionTimeout: connectionTimeout,
-    )
+    final connectionStream = prescan
+        ? _ble.connectToAdvertisingDevice(
+            id: deviceId,
+            withServices: const [],
+            prescanDuration: const Duration(seconds: 5),
+            servicesWithCharacteristicsToDiscover: {
+              serviceUuid: [notifyCharacteristicUuid, writeCharacteristicUuid],
+            },
+            connectionTimeout: connectionTimeout,
+          )
+        : _ble.connectToDevice(
+            id: deviceId,
+            servicesWithCharacteristicsToDiscover: {
+              serviceUuid: [notifyCharacteristicUuid, writeCharacteristicUuid],
+            },
+            connectionTimeout: connectionTimeout,
+          );
+    _connectionSubscription = connectionStream
         .listen(
       (update) async {
         switch (update.connectionState) {
@@ -333,6 +349,7 @@ class BleBluetoothManager<T> {
               if (enableCharacteristicDiscovery) {
                 await _discoverServicesAndResolveWriteCharacteristic(deviceId);
               }
+              await Future<void>.delayed(const Duration(milliseconds: 500));
               final notifyReady = await _enableNotifications(deviceId);
               if (notifyReady) {
                 activateDataSource();
@@ -370,8 +387,10 @@ class BleBluetoothManager<T> {
               'failure=${update.failure}',
             );
             _clearCharacteristics();
-            if (!completer.isCompleted && update.failure != null) {
-              completer.completeError(update.failure!);
+            if (!completer.isCompleted) {
+              completer.completeError(
+                update.failure ?? StateError('蓝牙连接已断开'),
+              );
             }
             break;
         }

lib/views/monitoring/index/cubit/monitoring_index_cubit.dart

@@ -587,7 +587,7 @@ class MonitoringIndexCubit extends Cubit<MonitoringIndexState> {
       return;
     }
 
-    final delaySeconds = ((_bluetoothReconnectAttempts + 1) * 5).clamp(5, 30);
+    final delaySeconds = ((_bluetoothReconnectAttempts + 1) * 8).clamp(8, 40);
     debugPrint(
       '🔥🔥🔥 BLE_CONNECT_DEBUG auto_reconnect_scheduled '
       'delay=${delaySeconds}s attempts=$_bluetoothReconnectAttempts',
@@ -623,7 +623,7 @@ class MonitoringIndexCubit extends Cubit<MonitoringIndexState> {
     );
 
     try {
-      await _bluetoothManager.connectToDeviceId(deviceId);
+      await _bluetoothManager.connectToDeviceId(deviceId, prescan: true);
       debugPrint(
         '🔥🔥🔥 BLE_CONNECT_DEBUG auto_connect_success '
         'deviceId=$deviceId isConnected=${_bluetoothManager.isConnected}',