Add initial contacts sync handling for web Bluetooth transport

lib/connector/meshcore_connector.dart

@@ -164,6 +164,7 @@ class MeshCoreConnector extends ChangeNotifier {
   bool _awaitingSelfInfo = false;
   bool _hasReceivedDeviceInfo = false;
   bool _pendingInitialChannelSync = false;
+  bool _pendingInitialContactsSync = false;
   bool _preserveContactsOnRefresh = false;
   static const int _defaultMaxContacts = 32;
   static const int _defaultMaxChannels = 8;
@@ -783,6 +784,9 @@ class MeshCoreConnector extends ChangeNotifier {
     _lastDeviceDisplayName = _deviceDisplayName;
     _manualDisconnect = false;
     _cancelReconnectTimer();
+    if (PlatformInfo.isWeb) {
+      _resetConnectionHandshakeState();
+    }
     unawaited(_backgroundService?.start());
     notifyListeners();
 
@@ -799,13 +803,15 @@ class MeshCoreConnector extends ChangeNotifier {
         license: License.free,
       );
 
-      // Request larger MTU for sending larger frames
+      // Request larger MTU only on native platforms; web does not support it.
+      if (!PlatformInfo.isWeb) {
         try {
           final mtu = await device.requestMtu(185);
           debugPrint('MTU set to: $mtu');
         } catch (e) {
           debugPrint('MTU request failed: $e, using default');
         }
+      }
 
       List<BluetoothService> services = await device.discoverServices();
 
@@ -834,6 +840,18 @@ class MeshCoreConnector extends ChangeNotifier {
         throw Exception("MeshCore characteristics not found");
       }
 
+      if (PlatformInfo.isWeb) {
+        debugPrint('Starting setNotifyValue(true)');
+        debugPrint('Web: Calling setNotifyValue(true) without awaiting');
+        unawaited(() async {
+          try {
+            await _txCharacteristic!.setNotifyValue(true);
+          } catch (error) {
+            debugPrint('Web setNotifyValue error (ignoring): $error');
+          }
+        }());
+        debugPrint('setNotifyValue(true) configuration completed');
+      } else {
         bool notifySet = false;
         for (int attempt = 0; attempt < 3 && !notifySet; attempt++) {
           try {
@@ -847,14 +865,25 @@ class MeshCoreConnector extends ChangeNotifier {
             if (attempt == 2) rethrow;
           }
         }
+      }
       _notifySubscription = _txCharacteristic!.onValueReceived.listen(
         _handleFrame,
       );
 
       _setState(MeshCoreConnectionState.connected);
+      if (_shouldGateInitialChannelSync) {
+        _hasReceivedDeviceInfo = false;
+        _pendingInitialChannelSync = true;
+      }
 
       await _requestDeviceInfo();
       _startBatteryPolling();
+      if (PlatformInfo.isWeb &&
+          _activeTransport == MeshCoreTransportType.bluetooth) {
+        // Chrome's Web Bluetooth stack commonly delays incoming notifications
+        // until the non-blocking notify setup settles. Avoid stacking extra
+        // startup writes while that is happening.
+      } else {
         final gotSelfInfo = await _waitForSelfInfo(
           timeout: const Duration(seconds: 3),
         );
@@ -863,11 +892,13 @@ class MeshCoreConnector extends ChangeNotifier {
           await _waitForSelfInfo(timeout: const Duration(seconds: 3));
         }
 
-      // Keep device clock aligned on every connection.
+        unawaited(syncTime());
-      await syncTime();
+      }
 
       // Fetch channels so we can track unread counts for incoming messages
+      if (!_shouldGateInitialChannelSync) {
         unawaited(getChannels());
+      }
     } catch (e) {
       debugPrint("Connection error: $e");
       await disconnect(manual: false);
@@ -981,6 +1012,7 @@ class MeshCoreConnector extends ChangeNotifier {
     _selfInfoRetryTimer = null;
     _hasReceivedDeviceInfo = false;
     _pendingInitialChannelSync = false;
+    _pendingInitialContactsSync = false;
   }
 
   bool get _shouldAutoReconnect =>
@@ -988,6 +1020,11 @@ class MeshCoreConnector extends ChangeNotifier {
       _lastDeviceId != null &&
       _activeTransport == MeshCoreTransportType.bluetooth;
 
+  bool get _shouldGateInitialChannelSync =>
+      _activeTransport == MeshCoreTransportType.usb ||
+      (_activeTransport == MeshCoreTransportType.bluetooth &&
+          PlatformInfo.isWeb);
+
   void _cancelReconnectTimer() {
     _reconnectTimer?.cancel();
     _reconnectTimer = null;
@@ -1087,6 +1124,7 @@ class MeshCoreConnector extends ChangeNotifier {
     _awaitingSelfInfo = false;
     _hasReceivedDeviceInfo = false;
     _pendingInitialChannelSync = false;
+    _pendingInitialContactsSync = false;
     _maxContacts = _defaultMaxContacts;
     _maxChannels = _defaultMaxChannels;
     _isSyncingQueuedMessages = false;
@@ -1191,6 +1229,10 @@ class MeshCoreConnector extends ChangeNotifier {
 
   void _scheduleSelfInfoRetry() {
     _selfInfoRetryTimer?.cancel();
+    if (PlatformInfo.isWeb &&
+        _activeTransport == MeshCoreTransportType.bluetooth) {
+      return;
+    }
     _selfInfoRetryTimer = Timer.periodic(const Duration(milliseconds: 3500), (
       timer,
     ) {
@@ -1974,6 +2016,12 @@ class MeshCoreConnector extends ChangeNotifier {
         _preserveContactsOnRefresh = false;
         notifyListeners();
         unawaited(_persistContacts());
+        if (PlatformInfo.isWeb &&
+            _activeTransport == MeshCoreTransportType.bluetooth &&
+            _isSyncingChannels &&
+            !_channelSyncInFlight) {
+          unawaited(_requestNextChannel());
+        }
         if (!_didInitialQueueSync || _pendingQueueSync) {
           _didInitialQueueSync = true;
           _pendingQueueSync = false;
@@ -2120,16 +2168,22 @@ class MeshCoreConnector extends ChangeNotifier {
     _selfInfoRetryTimer = null;
     notifyListeners();
 
-    // Auto-fetch contacts after getting self info
+    // Auto-fetch contacts after getting self info. On web BLE, defer this
+    // until after channel 0 so startup writes stay serialized.
+    if (PlatformInfo.isWeb &&
+        _activeTransport == MeshCoreTransportType.bluetooth) {
+      _pendingInitialContactsSync = true;
+    } else {
       getContacts();
-    if (_activeTransport == MeshCoreTransportType.usb) {
+    }
+    if (_shouldGateInitialChannelSync) {
       _maybeStartInitialChannelSync();
     }
   }
 
   void _handleDeviceInfo(Uint8List frame) {
     if (frame.length < 4) return;
-    if (_activeTransport == MeshCoreTransportType.usb) {
+    if (_shouldGateInitialChannelSync) {
       _hasReceivedDeviceInfo = true;
     }
     _firmwareVerCode = frame[1];
@@ -2156,14 +2210,13 @@ class MeshCoreConnector extends ChangeNotifier {
         unawaited(loadChannelSettings(maxChannels: nextMaxChannels));
         unawaited(loadAllChannelMessages(maxChannels: nextMaxChannels));
         if (isConnected &&
-            (_activeTransport != MeshCoreTransportType.usb ||
+            (!_shouldGateInitialChannelSync || !_pendingInitialChannelSync)) {
-                !_pendingInitialChannelSync)) {
           unawaited(getChannels(maxChannels: nextMaxChannels));
         }
       }
     }
     notifyListeners();
-    if (_activeTransport == MeshCoreTransportType.usb) {
+    if (_shouldGateInitialChannelSync) {
       _maybeStartInitialChannelSync();
     }
   }
@@ -3075,6 +3128,14 @@ class MeshCoreConnector extends ChangeNotifier {
 
         // Move to next channel
         _nextChannelIndexToRequest++;
+        if (PlatformInfo.isWeb &&
+            _activeTransport == MeshCoreTransportType.bluetooth &&
+            channel.index == 0 &&
+            _pendingInitialContactsSync) {
+          _pendingInitialContactsSync = false;
+          unawaited(getContacts());
+          return;
+        }
         unawaited(_requestNextChannel());
         return;
       } else {
@@ -3738,6 +3799,7 @@ class MeshCoreConnector extends ChangeNotifier {
     // They're only cleared on manual disconnect via disconnect() method
     _hasReceivedDeviceInfo = false;
     _pendingInitialChannelSync = false;
+    _pendingInitialContactsSync = false;
     _maxContacts = _defaultMaxContacts;
     _maxChannels = _defaultMaxChannels;
     _isSyncingQueuedMessages = false;