Refactor USB screen, add debug logging, fix UI issues

- Rewrite UsbScreen to mirror ScannerScreen patterns (status bar,
  tap-to-connect port list, bottom FABs, SnackBar errors)
- Extract MeshCoreUsbManager from MeshCoreConnector for cleaner
  USB transport ownership
- Add debug logging throughout USB connection flow (connector,
  manager, web/native services)
- Print debug logs to console in debug mode even when app debug
  log setting is disabled
- Localize remaining hardcoded strings (Web Serial Device fallback
  label, USB status bar keys, companion firmware timeout hint)
- Fix Swedish misspelling in translations (stöderliga → stödda)
- Guard Linux notification init against missing D-Bus session bus
- Fix SNRIndicator hit-test error by adding minimum size constraints
- Update USB flow tests for new UI patterns

android/app/src/main/kotlin/com/meshcore/meshcore_open/MeshcoreUsbFunctions.kt

@@ -40,15 +40,15 @@ class MeshcoreUsbFunctions(
     private val mainHandler = Handler(Looper.getMainLooper())
     private val usbIoExecutor: ExecutorService = Executors.newSingleThreadExecutor()
 
-    private var eventSink: EventChannel.EventSink? = null
+    @Volatile private var eventSink: EventChannel.EventSink? = null
-    private var usbConnection: UsbDeviceConnection? = null
+    @Volatile private var usbConnection: UsbDeviceConnection? = null
-    private var usbInEndpoint: UsbEndpoint? = null
+    @Volatile private var usbInEndpoint: UsbEndpoint? = null
-    private var usbOutEndpoint: UsbEndpoint? = null
+    @Volatile private var usbOutEndpoint: UsbEndpoint? = null
-    private var controlInterface: UsbInterface? = null
+    @Volatile private var controlInterface: UsbInterface? = null
-    private var dataInterface: UsbInterface? = null
+    @Volatile private var dataInterface: UsbInterface? = null
     private var readThread: Thread? = null
     @Volatile private var isReading = false
-    private var connectedDeviceName: String? = null
+    @Volatile private var connectedDeviceName: String? = null
 
     private var pendingConnectResult: MethodChannel.Result? = null
     private var pendingConnectPortName: String? = null
@@ -86,7 +86,7 @@ class MeshcoreUsbFunctions(
                 if (device == null) {
                     result.error(
                         "usb_device_missing",
-                        "USB device no longer available for $portName",
+                        null,
                         null,
                     )
                     return
@@ -95,7 +95,7 @@ class MeshcoreUsbFunctions(
                 val granted =
                     intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)
                 if (!granted || !usbManager.hasPermission(device)) {
-                    result.error("usb_permission_denied", "USB permission denied", null)
+                    result.error("usb_permission_denied", null, null)
                     return
                 }
 
@@ -176,13 +176,13 @@ class MeshcoreUsbFunctions(
         val portName = call.argument<String>("portName")
         val baudRate = call.argument<Int>("baudRate") ?: 115200
         if (portName.isNullOrBlank()) {
-            result.error("usb_invalid_port", "Port name is required", null)
+            result.error("usb_invalid_port", null, null)
             return
         }
 
         val device = findUsbDevice(portName)
         if (device == null) {
-            result.error("usb_device_missing", "USB device not found for $portName", null)
+            result.error("usb_device_missing", null, null)
             return
         }
 
@@ -192,7 +192,7 @@ class MeshcoreUsbFunctions(
         }
 
         if (pendingConnectResult != null) {
-            result.error("usb_busy", "Another USB permission request is already pending", null)
+            result.error("usb_busy", null, null)
             return
         }
 
@@ -214,11 +214,11 @@ class MeshcoreUsbFunctions(
         val connection = usbConnection
         val endpoint = usbOutEndpoint
         if (data == null) {
-            result.error("usb_invalid_data", "Data is required", null)
+            result.error("usb_invalid_data", null, null)
             return
         }
         if (connection == null || endpoint == null) {
-            result.error("usb_not_connected", "USB serial port is not connected", null)
+            result.error("usb_not_connected", null, null)
             return
         }
 
@@ -259,7 +259,7 @@ class MeshcoreUsbFunctions(
                     mainHandler.post {
                         result.error(
                             "usb_driver_missing",
-                            "No compatible USB serial interface for ${device.deviceName}",
+                            null,
                             null,
                         )
                     }
@@ -271,7 +271,7 @@ class MeshcoreUsbFunctions(
                     mainHandler.post {
                         result.error(
                             "usb_open_failed",
-                            "UsbManager could not open ${device.deviceName}",
+                            null,
                             null,
                         )
                     }
@@ -283,7 +283,7 @@ class MeshcoreUsbFunctions(
                     mainHandler.post {
                         result.error(
                             "usb_open_failed",
-                            "Could not claim USB data interface for ${device.deviceName}",
+                            null,
                             null,
                         )
                     }
@@ -299,20 +299,21 @@ class MeshcoreUsbFunctions(
                     mainHandler.post {
                         result.error(
                             "usb_open_failed",
-                            "Could not claim USB control interface for ${device.deviceName}",
+                            null,
                             null,
                         )
                     }
                     return@execute
                 }
 
-                configureDevice(connection, config, baudRate)
-
                 usbConnection = connection
                 usbInEndpoint = config.inEndpoint
                 usbOutEndpoint = config.outEndpoint
                 controlInterface = config.controlInterface
                 dataInterface = config.dataInterface
+
+                configureDevice(connection, config, baudRate)
+
                 connectedDeviceName = device.deviceName
                 startReadLoop()
 

lib/connector/meshcore_connector.dart

@@ -21,7 +21,7 @@ import '../services/path_history_service.dart';
 import '../services/app_settings_service.dart';
 import '../services/background_service.dart';
 import '../services/notification_service.dart';
-import '../services/usb_serial_service.dart';
+import 'meshcore_connector_usb.dart';
 import '../storage/channel_message_store.dart';
 import '../storage/channel_order_store.dart';
 import '../storage/channel_settings_store.dart';
@@ -114,11 +114,9 @@ class MeshCoreConnector extends ChangeNotifier {
   String? _lastDeviceId;
   String? _lastDeviceDisplayName;
   bool _manualDisconnect = false;
-  final UsbSerialService _usbSerialService = UsbSerialService();
+  final MeshCoreUsbManager _usbManager = MeshCoreUsbManager();
   StreamSubscription<Uint8List>? _usbFrameSubscription;
   MeshCoreTransportType _activeTransport = MeshCoreTransportType.bluetooth;
-  String? _activeUsbPortKey;
-  String? _activeUsbPortLabel;
 
   final List<ScanResult> _scanResults = [];
   final List<Contact> _contacts = [];
@@ -252,9 +250,8 @@ class MeshCoreConnector extends ChangeNotifier {
   String get deviceIdLabel => _deviceId ?? 'Unknown';
 
   MeshCoreTransportType get activeTransport => _activeTransport;
-  String? get activeUsbPort => _activeUsbPortKey;
+  String? get activeUsbPort => _usbManager.activePortKey;
-  String? get activeUsbPortDisplayLabel =>
+  String? get activeUsbPortDisplayLabel => _usbManager.activePortDisplayLabel;
-      _activeUsbPortLabel ?? _activeUsbPortKey;
   bool get isUsbTransportConnected =>
       _state == MeshCoreConnectionState.connected &&
       _activeTransport == MeshCoreTransportType.usb;
@@ -661,7 +658,7 @@ class MeshCoreConnector extends ChangeNotifier {
     _bleDebugLogService = bleDebugLogService;
     _appDebugLogService = appDebugLogService;
     _backgroundService = backgroundService;
-    _usbSerialService.setDebugLogService(_appDebugLogService);
+    _usbManager.setDebugLogService(_appDebugLogService);
 
     // Initialize notification service
     _notificationService.initialize();
@@ -871,10 +868,14 @@ class MeshCoreConnector extends ChangeNotifier {
     }
   }
 
-  Future<List<String>> listUsbPorts() => _usbSerialService.listPorts();
+  Future<List<String>> listUsbPorts() => _usbManager.listPorts();
 
   void setUsbRequestPortLabel(String label) {
-    _usbSerialService.setRequestPortLabel(label);
+    _usbManager.setRequestPortLabel(label);
+  }
+
+  void setUsbFallbackDeviceName(String label) {
+    _usbManager.setFallbackDeviceName(label);
   }
 
   Future<void> connectUsb({
@@ -883,53 +884,70 @@ class MeshCoreConnector extends ChangeNotifier {
   }) async {
     if (_state == MeshCoreConnectionState.connecting ||
         _state == MeshCoreConnectionState.connected) {
+      _appDebugLogService?.warn(
+        'connectUsb ignored: already $_state',
+        tag: 'USB',
+      );
       return;
     }
 
-    _activeTransport = MeshCoreTransportType.bluetooth;
+    _appDebugLogService?.info(
-    _activeUsbPortKey = null;
+      'connectUsb: port=$portName baud=$baudRate',
-    _activeUsbPortLabel = null;
+      tag: 'USB',
+    );
 
     await stopScan();
     _cancelReconnectTimer();
     _manualDisconnect = false;
     _resetConnectionHandshakeState();
     _activeTransport = MeshCoreTransportType.usb;
-    _activeUsbPortKey = portName;
-    _activeUsbPortLabel = portName;
     _setState(MeshCoreConnectionState.connecting);
 
     try {
       await _usbFrameSubscription?.cancel();
       _usbFrameSubscription = null;
-      await _usbSerialService.connect(portName: portName, baudRate: baudRate);
+      _appDebugLogService?.info(
-      _activeUsbPortKey = _usbSerialService.activePortKey ?? _activeUsbPortKey;
+        'connectUsb: opening serial port…',
-      _activeUsbPortLabel =
+        tag: 'USB',
-          _usbSerialService.activePortDisplayLabel ?? _activeUsbPortLabel;
+      );
+      await _usbManager.connect(portName: portName, baudRate: baudRate);
+      _appDebugLogService?.info(
+        'connectUsb: serial port opened, label=${_usbManager.activePortDisplayLabel}',
+        tag: 'USB',
+      );
       notifyListeners();
       if (PlatformInfo.isWeb) {
         await stopScan();
       }
       await Future<void>.delayed(const Duration(milliseconds: 200));
-      _usbFrameSubscription = _usbSerialService.frameStream.listen(
+      _usbFrameSubscription = _usbManager.frameStream.listen(
         _handleFrame,
         onError: (error, stackTrace) {
           _appDebugLogService?.error('USB transport error: $error', tag: 'USB');
           unawaited(disconnect(manual: false));
         },
         onDone: () {
+          _appDebugLogService?.warn('USB frame stream ended', tag: 'USB');
           unawaited(disconnect(manual: false));
         },
       );
 
       _setState(MeshCoreConnectionState.connected);
       _pendingInitialChannelSync = true;
+      _appDebugLogService?.info(
+        'connectUsb: requesting device info…',
+        tag: 'USB',
+      );
       await _requestDeviceInfo();
       _startBatteryPolling();
       var gotSelfInfo = await _waitForSelfInfo(
         timeout: const Duration(seconds: 3),
       );
       if (!gotSelfInfo) {
+        _appDebugLogService?.warn(
+          'connectUsb: SELF_INFO timeout, retrying…',
+          tag: 'USB',
+        );
         await refreshDeviceInfo();
         gotSelfInfo = await _waitForSelfInfo(
           timeout: const Duration(seconds: 3),
@@ -939,7 +957,9 @@ class MeshCoreConnector extends ChangeNotifier {
         throw StateError('Timed out waiting for SELF_INFO during connect');
       }
 
+      _appDebugLogService?.info('connectUsb: syncing time…', tag: 'USB');
       await syncTime();
+      _appDebugLogService?.info('connectUsb: complete', tag: 'USB');
     } catch (error) {
       _appDebugLogService?.error('USB connection error: $error', tag: 'USB');
       await disconnect(manual: false);
@@ -954,8 +974,6 @@ class MeshCoreConnector extends ChangeNotifier {
     }
 
     _activeTransport = MeshCoreTransportType.bluetooth;
-    _activeUsbPortKey = null;
-    _activeUsbPortLabel = null;
 
     await stopScan();
     _setState(MeshCoreConnectionState.connecting);
@@ -1282,7 +1300,7 @@ class MeshCoreConnector extends ChangeNotifier {
 
     await _usbFrameSubscription?.cancel();
     _usbFrameSubscription = null;
-    await _usbSerialService.disconnect();
+    await _usbManager.disconnect();
 
     await _notifySubscription?.cancel();
     _notifySubscription = null;
@@ -1341,8 +1359,6 @@ class MeshCoreConnector extends ChangeNotifier {
     _reactionSendQueueSequence = 0;
 
     _activeTransport = MeshCoreTransportType.bluetooth;
-    _activeUsbPortKey = null;
-    _activeUsbPortLabel = null;
 
     _setState(MeshCoreConnectionState.disconnected);
     _appDebugLogService?.info(
@@ -1365,7 +1381,7 @@ class MeshCoreConnector extends ChangeNotifier {
     _bleDebugLogService?.logFrame(data, outgoing: true);
 
     if (_activeTransport == MeshCoreTransportType.usb) {
-      await _usbSerialService.write(data);
+      await _usbManager.write(data);
     } else {
       if (_rxCharacteristic == null) {
         throw Exception("MeshCore RX characteristic not available");
@@ -2464,9 +2480,7 @@ class MeshCoreConnector extends ChangeNotifier {
     if (_activeTransport == MeshCoreTransportType.usb &&
         selfName != null &&
         selfName.isNotEmpty) {
-      _usbSerialService.updateConnectedLabel(selfName);
+      _usbManager.updateConnectedLabel(selfName);
-      _activeUsbPortLabel =
-          _usbSerialService.activePortDisplayLabel ?? _activeUsbPortLabel;
     }
     _awaitingSelfInfo = false;
     _selfInfoRetryTimer?.cancel();
@@ -4246,7 +4260,7 @@ class MeshCoreConnector extends ChangeNotifier {
     _reconnectTimer?.cancel();
     _batteryPollTimer?.cancel();
     _receivedFramesController.close();
-    _usbSerialService.dispose();
+    _usbManager.dispose();
 
     // Flush pending unread writes before disposal
     _unreadStore.flush();
@@ -4269,6 +4283,10 @@ class MeshCoreConnector extends ChangeNotifier {
       final header = packet.readByte();
       routeType = header & 0x03;
       payloadType = (header >> 2) & 0x0F;
+      if (routeType == _routeTransportFlood ||
+          routeType == _routeTransportDirect) {
+        packet.skipBytes(4); // Skip transport-specific bytes
+      }
       //final payloadVer = (header >> 6) & 0x03;
       final pathLen = packet.readByte();
       pathBytes = packet.readBytes(pathLen);
@@ -4301,7 +4319,12 @@ class MeshCoreConnector extends ChangeNotifier {
       packet.skipBytes(1); // Skip SNR byte
       packet.skipBytes(1); // Skip RSSI byte
       final header = packet.readByte();
+      final routeType = header & 0x03;
       payloadType = (header >> 2) & 0x0F;
+      if (routeType == _routeTransportFlood ||
+          routeType == _routeTransportDirect) {
+        packet.skipBytes(4); // Skip transport-specific bytes
+      }
       //final payloadVer = (header >> 6) & 0x03;
       final pathLen = packet.readByte();
       pathBytes = packet.readBytes(pathLen);

lib/connector/meshcore_connector_usb.dart

@@ -1,32 +1,71 @@
-import 'package:flutter/foundation.dart';
+import 'dart:typed_data';
 
-import 'meshcore_connector.dart';
+import '../services/app_debug_log_service.dart';
+import '../services/usb_serial_service.dart';
 
-class MeshCoreConnectorUsb {
+/// Manages USB serial transport for MeshCore devices.
-  const MeshCoreConnectorUsb(this.connector);
+///
+/// Owns the [UsbSerialService] and USB-specific connection state.
+/// The main [MeshCoreConnector] delegates all USB operations here.
+class MeshCoreUsbManager {
+  MeshCoreUsbManager();
 
-  final MeshCoreConnector connector;
+  final UsbSerialService _service = UsbSerialService();
+  AppDebugLogService? _debugLog;
+  String? _activePortKey;
+  String? _activePortLabel;
 
-  MeshCoreConnectionState get state => connector.state;
+  // --- Getters ---
-  MeshCoreTransportType get activeTransport => connector.activeTransport;
+  String? get activePortKey => _activePortKey;
-  String? get activeUsbPortDisplayLabel => connector.activeUsbPortDisplayLabel;
+  String? get activePortDisplayLabel => _activePortLabel ?? _activePortKey;
-  bool get isUsbTransportConnected => connector.isUsbTransportConnected;
+  bool get isConnected => _service.isConnected;
+  Stream<Uint8List> get frameStream => _service.frameStream;
 
-  void addListener(VoidCallback listener) => connector.addListener(listener);
+  // --- Configuration ---
-  void removeListener(VoidCallback listener) =>
+  Future<List<String>> listPorts() => _service.listPorts();
-      connector.removeListener(listener);
 
-  Future<List<String>> listPorts() => connector.listUsbPorts();
+  void setRequestPortLabel(String label) =>
+      _service.setRequestPortLabel(label);
 
-  void setRequestPortLabel(String label) {
+  void setFallbackDeviceName(String label) =>
-    connector.setUsbRequestPortLabel(label);
+      _service.setFallbackDeviceName(label);
+
+  void setDebugLogService(AppDebugLogService? service) {
+    _debugLog = service;
+    _service.setDebugLogService(service);
   }
 
-  Future<void> connect({required String portName, int baudRate = 115200}) {
+  // --- Connection lifecycle ---
-    return connector.connectUsb(portName: portName, baudRate: baudRate);
+  Future<void> connect({required String portName, int baudRate = 115200}) async {
+    _debugLog?.info(
+      'UsbManager.connect: portName=$portName baud=$baudRate',
+      tag: 'USB',
+    );
+    await _service.connect(portName: portName, baudRate: baudRate);
+    _activePortKey = _service.activePortKey ?? portName;
+    _activePortLabel = _service.activePortDisplayLabel ?? portName;
+    _debugLog?.info(
+      'UsbManager.connect: done, key=$_activePortKey label=$_activePortLabel',
+      tag: 'USB',
+    );
   }
 
-  Future<void> disconnect({bool manual = true}) {
+  Future<void> disconnect() async {
-    return connector.disconnect(manual: manual);
+    _debugLog?.info('UsbManager.disconnect', tag: 'USB');
+    await _service.disconnect();
+    _activePortKey = null;
+    _activePortLabel = null;
+  }
+
+  Future<void> write(Uint8List data) => _service.write(data);
+
+  // --- Label management ---
+  void updateConnectedLabel(String selfName) {
+    _service.updateConnectedLabel(selfName);
+    _activePortLabel = _service.activePortDisplayLabel ?? _activePortLabel;
+  }
+
+  void dispose() {
+    _service.dispose();
   }
 }

lib/l10n/app_bg.arb

@@ -1847,5 +1847,17 @@
   "usbErrorAlreadyActive": "USB връзката вече е активирана.",
   "usbErrorNoDeviceSelected": "Няма избран USB устройство.",
   "usbErrorPortClosed": "USB връзката не е активна.",
-  "usbErrorConnectTimedOut": "Изчаква се, но устройството не отговаря в рамките на зададения време."
+  "usbFallbackDeviceName": "Устройство за четене на уеб серийни данни",
+  "@usbConnectionFailed": {
+    "placeholders": {
+      "error": {
+        "type": "String"
+      }
+    }
+  },
+  "usbStatus_connecting": "Свързване към USB устройство...",
+  "usbConnectionFailed": "Неуспешно свързване през USB: {error}",
+  "usbStatus_notConnected": "Изберете USB устройство",
+  "usbStatus_searching": "Търсене на USB устройства...",
+  "usbErrorConnectTimedOut": "Връзката прекъсна. Уверете се, че устройството има софтуер за USB връзка."
 }

lib/l10n/app_de.arb

@@ -1875,5 +1875,17 @@
   "usbErrorAlreadyActive": "Eine USB-Verbindung ist bereits hergestellt.",
   "usbErrorNoDeviceSelected": "Kein USB-Gerät wurde ausgewählt.",
   "usbErrorPortClosed": "Die USB-Verbindung ist nicht aktiv.",
-  "usbErrorConnectTimedOut": "Wartezeit abgelaufen, da keine Antwort vom Gerät empfangen wurde."
+  "usbFallbackDeviceName": "Web-Serielle Geräte",
+  "@usbConnectionFailed": {
+    "placeholders": {
+      "error": {
+        "type": "String"
+      }
+    }
+  },
+  "usbStatus_searching": "Suche nach USB-Geräten...",
+  "usbStatus_notConnected": "Wählen Sie ein USB-Gerät aus",
+  "usbStatus_connecting": "Verbindung zum USB-Gerät...",
+  "usbConnectionFailed": "Fehler beim USB-Verbindungsaufbau: {error}",
+  "usbErrorConnectTimedOut": "Verbindung konnte nicht hergestellt werden. Stellen Sie sicher, dass das Gerät die entsprechende USB-Firmware enthält."
 }

lib/l10n/app_en.arb

@@ -65,7 +65,19 @@
   "usbErrorAlreadyActive": "A USB connection is already active.",
   "usbErrorNoDeviceSelected": "No USB device was selected.",
   "usbErrorPortClosed": "The USB connection is not open.",
-  "usbErrorConnectTimedOut": "Timed out waiting for the device to respond.",
+  "usbErrorConnectTimedOut": "Connection timed out. Make sure the device has USB Companion firmware.",
+  "usbFallbackDeviceName": "Web Serial Device",
+  "usbStatus_notConnected": "Select a USB device",
+  "usbStatus_connecting": "Connecting to USB device...",
+  "usbStatus_searching": "Searching for USB devices...",
+  "usbConnectionFailed": "USB connection failed: {error}",
+  "@usbConnectionFailed": {
+    "placeholders": {
+      "error": {
+        "type": "String"
+      }
+    }
+  },
   "scanner_scanning": "Scanning for devices...",
   "scanner_connecting": "Connecting...",
   "scanner_disconnecting": "Disconnecting...",

lib/l10n/app_es.arb

@@ -1875,5 +1875,17 @@
   "usbErrorAlreadyActive": "La conexión USB ya está activa.",
   "usbErrorNoDeviceSelected": "No se ha seleccionado ningún dispositivo USB.",
   "usbErrorPortClosed": "La conexión USB no está activa.",
-  "usbErrorConnectTimedOut": "Se ha agotado el tiempo de espera mientras se esperaba la respuesta del dispositivo."
+  "usbFallbackDeviceName": "Dispositivo de serie web",
+  "@usbConnectionFailed": {
+    "placeholders": {
+      "error": {
+        "type": "String"
+      }
+    }
+  },
+  "usbStatus_connecting": "Conectándose al dispositivo USB...",
+  "usbStatus_searching": "Buscando dispositivos USB...",
+  "usbStatus_notConnected": "Seleccione un dispositivo USB",
+  "usbConnectionFailed": "Error al conectar mediante USB: {error}",
+  "usbErrorConnectTimedOut": "La conexión ha caducado. Asegúrese de que el dispositivo tenga el firmware USB Companion."
 }

lib/l10n/app_fr.arb

@@ -1847,5 +1847,17 @@
   "usbErrorAlreadyActive": "Une connexion USB est déjà établie.",
   "usbErrorNoDeviceSelected": "Aucun appareil USB n'a été sélectionné.",
   "usbErrorPortClosed": "La connexion USB n'est pas établie.",
-  "usbErrorConnectTimedOut": "Attente avec délai, en attendant une réponse de l'appareil."
+  "usbFallbackDeviceName": "Dispositif de communication série sur le Web",
+  "@usbConnectionFailed": {
+    "placeholders": {
+      "error": {
+        "type": "String"
+      }
+    }
+  },
+  "usbStatus_notConnected": "Sélectionnez un périphérique USB",
+  "usbConnectionFailed": "Échec de la connexion USB : {error}",
+  "usbStatus_connecting": "Connexion au périphérique USB...",
+  "usbStatus_searching": "Recherche de périphériques USB...",
+  "usbErrorConnectTimedOut": "La connexion a expiré. Assurez-vous que l'appareil dispose du firmware USB Companion."
 }

lib/l10n/app_it.arb

@@ -1847,5 +1847,17 @@
   "usbErrorAlreadyActive": "La connessione USB è già attiva.",
   "usbErrorNoDeviceSelected": "Non è stato selezionato alcun dispositivo USB.",
   "usbErrorPortClosed": "La connessione USB non è attiva.",
-  "usbErrorConnectTimedOut": "Attesa superata, in attesa di una risposta dal dispositivo."
+  "usbFallbackDeviceName": "Dispositivo per comunicazione seriale su rete",
+  "@usbConnectionFailed": {
+    "placeholders": {
+      "error": {
+        "type": "String"
+      }
+    }
+  },
+  "usbStatus_searching": "Ricerca di dispositivi USB...",
+  "usbConnectionFailed": "Errore nella connessione USB: {error}",
+  "usbStatus_notConnected": "Seleziona un dispositivo USB",
+  "usbStatus_connecting": "Connessione al dispositivo USB...",
+  "usbErrorConnectTimedOut": "La connessione è scaduta. Assicurarsi che il dispositivo abbia il firmware USB Companion."
 }

lib/l10n/app_localizations.dart

@@ -433,9 +433,39 @@ abstract class AppLocalizations {
   /// No description provided for @usbErrorConnectTimedOut.
   ///
   /// In en, this message translates to:
-  /// **'Timed out waiting for the device to respond.'**
+  /// **'Connection timed out. Make sure the device has USB Companion firmware.'**
   String get usbErrorConnectTimedOut;
 
+  /// No description provided for @usbFallbackDeviceName.
+  ///
+  /// In en, this message translates to:
+  /// **'Web Serial Device'**
+  String get usbFallbackDeviceName;
+
+  /// No description provided for @usbStatus_notConnected.
+  ///
+  /// In en, this message translates to:
+  /// **'Select a USB device'**
+  String get usbStatus_notConnected;
+
+  /// No description provided for @usbStatus_connecting.
+  ///
+  /// In en, this message translates to:
+  /// **'Connecting to USB device...'**
+  String get usbStatus_connecting;
+
+  /// No description provided for @usbStatus_searching.
+  ///
+  /// In en, this message translates to:
+  /// **'Searching for USB devices...'**
+  String get usbStatus_searching;
+
+  /// No description provided for @usbConnectionFailed.
+  ///
+  /// In en, this message translates to:
+  /// **'USB connection failed: {error}'**
+  String usbConnectionFailed(String error);
+
   /// No description provided for @scanner_scanning.
   ///
   /// In en, this message translates to:

lib/l10n/app_localizations_bg.dart

@@ -175,7 +175,25 @@ class AppLocalizationsBg extends AppLocalizations {
 
   @override
   String get usbErrorConnectTimedOut =>
-      'Изчаква се, но устройството не отговаря в рамките на зададения време.';
+      'Връзката прекъсна. Уверете се, че устройството има софтуер за USB връзка.';
+
+  @override
+  String get usbFallbackDeviceName =>
+      'Устройство за четене на уеб серийни данни';
+
+  @override
+  String get usbStatus_notConnected => 'Изберете USB устройство';
+
+  @override
+  String get usbStatus_connecting => 'Свързване към USB устройство...';
+
+  @override
+  String get usbStatus_searching => 'Търсене на USB устройства...';
+
+  @override
+  String usbConnectionFailed(String error) {
+    return 'Неуспешно свързване през USB: $error';
+  }
 
   @override
   String get scanner_scanning => 'Сканиране за устройства...';

lib/l10n/app_localizations_de.dart

@@ -177,7 +177,24 @@ class AppLocalizationsDe extends AppLocalizations {
 
   @override
   String get usbErrorConnectTimedOut =>
-      'Wartezeit abgelaufen, da keine Antwort vom Gerät empfangen wurde.';
+      'Verbindung konnte nicht hergestellt werden. Stellen Sie sicher, dass das Gerät die entsprechende USB-Firmware enthält.';
+
+  @override
+  String get usbFallbackDeviceName => 'Web-Serielle Geräte';
+
+  @override
+  String get usbStatus_notConnected => 'Wählen Sie ein USB-Gerät aus';
+
+  @override
+  String get usbStatus_connecting => 'Verbindung zum USB-Gerät...';
+
+  @override
+  String get usbStatus_searching => 'Suche nach USB-Geräten...';
+
+  @override
+  String usbConnectionFailed(String error) {
+    return 'Fehler beim USB-Verbindungsaufbau: $error';
+  }
 
   @override
   String get scanner_scanning => 'Scannen nach Geräten...';

lib/l10n/app_localizations_en.dart

@@ -174,7 +174,24 @@ class AppLocalizationsEn extends AppLocalizations {
 
   @override
   String get usbErrorConnectTimedOut =>
-      'Timed out waiting for the device to respond.';
+      'Connection timed out. Make sure the device has USB Companion firmware.';
+
+  @override
+  String get usbFallbackDeviceName => 'Web Serial Device';
+
+  @override
+  String get usbStatus_notConnected => 'Select a USB device';
+
+  @override
+  String get usbStatus_connecting => 'Connecting to USB device...';
+
+  @override
+  String get usbStatus_searching => 'Searching for USB devices...';
+
+  @override
+  String usbConnectionFailed(String error) {
+    return 'USB connection failed: $error';
+  }
 
   @override
   String get scanner_scanning => 'Scanning for devices...';

lib/l10n/app_localizations_es.dart

@@ -177,7 +177,24 @@ class AppLocalizationsEs extends AppLocalizations {
 
   @override
   String get usbErrorConnectTimedOut =>
-      'Se ha agotado el tiempo de espera mientras se esperaba la respuesta del dispositivo.';
+      'La conexión ha caducado. Asegúrese de que el dispositivo tenga el firmware USB Companion.';
+
+  @override
+  String get usbFallbackDeviceName => 'Dispositivo de serie web';
+
+  @override
+  String get usbStatus_notConnected => 'Seleccione un dispositivo USB';
+
+  @override
+  String get usbStatus_connecting => 'Conectándose al dispositivo USB...';
+
+  @override
+  String get usbStatus_searching => 'Buscando dispositivos USB...';
+
+  @override
+  String usbConnectionFailed(String error) {
+    return 'Error al conectar mediante USB: $error';
+  }
 
   @override
   String get scanner_scanning => 'Escaneando dispositivos...';

lib/l10n/app_localizations_fr.dart

@@ -176,7 +176,25 @@ class AppLocalizationsFr extends AppLocalizations {
 
   @override
   String get usbErrorConnectTimedOut =>
-      'Attente avec délai, en attendant une réponse de l\'appareil.';
+      'La connexion a expiré. Assurez-vous que l\'appareil dispose du firmware USB Companion.';
+
+  @override
+  String get usbFallbackDeviceName =>
+      'Dispositif de communication série sur le Web';
+
+  @override
+  String get usbStatus_notConnected => 'Sélectionnez un périphérique USB';
+
+  @override
+  String get usbStatus_connecting => 'Connexion au périphérique USB...';
+
+  @override
+  String get usbStatus_searching => 'Recherche de périphériques USB...';
+
+  @override
+  String usbConnectionFailed(String error) {
+    return 'Échec de la connexion USB : $error';
+  }
 
   @override
   String get scanner_scanning => 'Recherche de périphériques...';

lib/l10n/app_localizations_it.dart

@@ -177,7 +177,25 @@ class AppLocalizationsIt extends AppLocalizations {
 
   @override
   String get usbErrorConnectTimedOut =>
-      'Attesa superata, in attesa di una risposta dal dispositivo.';
+      'La connessione è scaduta. Assicurarsi che il dispositivo abbia il firmware USB Companion.';
+
+  @override
+  String get usbFallbackDeviceName =>
+      'Dispositivo per comunicazione seriale su rete';
+
+  @override
+  String get usbStatus_notConnected => 'Seleziona un dispositivo USB';
+
+  @override
+  String get usbStatus_connecting => 'Connessione al dispositivo USB...';
+
+  @override
+  String get usbStatus_searching => 'Ricerca di dispositivi USB...';
+
+  @override
+  String usbConnectionFailed(String error) {
+    return 'Errore nella connessione USB: $error';
+  }
 
   @override
   String get scanner_scanning => 'Scansione in corso per i dispositivi...';

lib/l10n/app_localizations_nl.dart

@@ -175,7 +175,24 @@ class AppLocalizationsNl extends AppLocalizations {
 
   @override
   String get usbErrorConnectTimedOut =>
-      'Wachtperiode is verlopen, aangezien het apparaat niet reageerde.';
+      'Verbinding is verbroken. Zorg ervoor dat het apparaat de juiste USB-firmware heeft.';
+
+  @override
+  String get usbFallbackDeviceName => 'Web-serieapparaat';
+
+  @override
+  String get usbStatus_notConnected => 'Selecteer een USB-apparaat';
+
+  @override
+  String get usbStatus_connecting => 'Verbinding maken met USB-apparaat...';
+
+  @override
+  String get usbStatus_searching => 'Zoeken naar USB-apparaten...';
+
+  @override
+  String usbConnectionFailed(String error) {
+    return 'Fout bij de USB-verbinding: $error';
+  }
 
   @override
   String get scanner_scanning => 'Scannen naar apparaten...';

lib/l10n/app_localizations_pl.dart

@@ -177,7 +177,25 @@ class AppLocalizationsPl extends AppLocalizations {
 
   @override
   String get usbErrorConnectTimedOut =>
-      'Czekanie na odpowiedź urządzenia zakończyło się z powodu braku reakcji.';
+      'Połączenie nie zostało nawiązane. Upewnij się, że urządzenie posiada oprogramowanie \"USB Companion\".';
+
+  @override
+  String get usbFallbackDeviceName =>
+      'Urządzenie do komunikacji przez sieć (seria)';
+
+  @override
+  String get usbStatus_notConnected => 'Wybierz urządzenie USB';
+
+  @override
+  String get usbStatus_connecting => 'Połączenie z urządzeniem USB...';
+
+  @override
+  String get usbStatus_searching => 'Wyszukiwanie urządzeń USB...';
+
+  @override
+  String usbConnectionFailed(String error) {
+    return 'Błąd połączenia USB: $error';
+  }
 
   @override
   String get scanner_scanning => 'Skanowanie urządzeń...';

lib/l10n/app_localizations_pt.dart

@@ -177,7 +177,24 @@ class AppLocalizationsPt extends AppLocalizations {
 
   @override
   String get usbErrorConnectTimedOut =>
-      'Tempo limite aguardando a resposta do dispositivo.';
+      'A conexão expirou. Verifique se o dispositivo possui o firmware USB Companion.';
+
+  @override
+  String get usbFallbackDeviceName => 'Dispositivo de Serial para a Web';
+
+  @override
+  String get usbStatus_notConnected => 'Selecione um dispositivo USB';
+
+  @override
+  String get usbStatus_connecting => 'Conectando ao dispositivo USB...';
+
+  @override
+  String get usbStatus_searching => 'Procurando por dispositivos USB...';
+
+  @override
+  String usbConnectionFailed(String error) {
+    return 'Falha na conexão USB: $error';
+  }
 
   @override
   String get scanner_scanning => 'Procurando por dispositivos...';

lib/l10n/app_localizations_ru.dart

@@ -177,7 +177,25 @@ class AppLocalizationsRu extends AppLocalizations {
 
   @override
   String get usbErrorConnectTimedOut =>
-      'Ожидание ответа от устройства превысило установленное время.';
+      'Соединение не установлено. Убедитесь, что устройство имеет установленное программное обеспечение USB Companion.';
+
+  @override
+  String get usbFallbackDeviceName =>
+      'Устройство для последовательного подключения к сети';
+
+  @override
+  String get usbStatus_notConnected => 'Выберите USB-устройство';
+
+  @override
+  String get usbStatus_connecting => 'Подключение к USB-устройству...';
+
+  @override
+  String get usbStatus_searching => 'Поиск USB-устройств...';
+
+  @override
+  String usbConnectionFailed(String error) {
+    return 'Не удалось установить соединение через USB: $error';
+  }
 
   @override
   String get scanner_scanning => 'Поиск устройств...';

lib/l10n/app_localizations_sk.dart

@@ -177,7 +177,24 @@ class AppLocalizationsSk extends AppLocalizations {
 
   @override
   String get usbErrorConnectTimedOut =>
-      'Čakal som, kým sa zariadenie neozvými, ale časový limit sa dobehol.';
+      'Pripojenie nebolo úspešné. Uistite sa, že zariadenie má nainštalovaný firmware USB Companion.';
+
+  @override
+  String get usbFallbackDeviceName => 'Webový sériový zariadenie';
+
+  @override
+  String get usbStatus_notConnected => 'Vyberte USB zariadenie';
+
+  @override
+  String get usbStatus_connecting => 'Pripojenie k USB zariadeniu...';
+
+  @override
+  String get usbStatus_searching => 'Hľadanie USB zariadení...';
+
+  @override
+  String usbConnectionFailed(String error) {
+    return 'Neúspešné pripojenie cez USB: $error';
+  }
 
   @override
   String get scanner_scanning => 'Skrívania zariadení...';

lib/l10n/app_localizations_sl.dart

@@ -174,7 +174,25 @@ class AppLocalizationsSl extends AppLocalizations {
 
   @override
   String get usbErrorConnectTimedOut =>
-      'Čakanje je preseglo določeno časovno obdobo, ker se naprave ni odzval.';
+      'Vzpostavitve ni bilo mogo. Prosimo, da se prepričate, da ima naprave trenutno nameštan firmware USB Companion.';
+
+  @override
+  String get usbFallbackDeviceName =>
+      'Naprave za serijsko komunikacijo preko spleta';
+
+  @override
+  String get usbStatus_notConnected => 'Izberite USB naprave.';
+
+  @override
+  String get usbStatus_connecting => 'Povezava z USB napravo...';
+
+  @override
+  String get usbStatus_searching => 'Iskanje USB naprav...';
+
+  @override
+  String usbConnectionFailed(String error) {
+    return 'Napaka pri povezavi preko USB: $error';
+  }
 
   @override
   String get scanner_scanning => 'Skeniram za naprave...';

lib/l10n/app_localizations_sv.dart

@@ -129,7 +129,7 @@ class AppLocalizationsSv extends AppLocalizations {
 
   @override
   String get usbScreenNote =>
-      'USB-seriell kommunikation är aktiv på stöderliga Android-enheter och på skrivbordsplattformar.';
+      'USB-seriell kommunikation är aktiv på stödda Android-enheter och på skrivbordsplattformar.';
 
   @override
   String get usbScreenEmptyState =>
@@ -175,7 +175,24 @@ class AppLocalizationsSv extends AppLocalizations {
 
   @override
   String get usbErrorConnectTimedOut =>
-      'Tiden har löpt ut medan vi väntade på att enheten skulle svara.';
+      'Anslutningen har tidsutgått. Se till att enheten har rätt USB-firmware.';
+
+  @override
+  String get usbFallbackDeviceName => 'Web-serieenhet';
+
+  @override
+  String get usbStatus_notConnected => 'Välj en USB-enhet';
+
+  @override
+  String get usbStatus_connecting => 'Anslutning till USB-enhet...';
+
+  @override
+  String get usbStatus_searching => 'Söker efter USB-enheter...';
+
+  @override
+  String usbConnectionFailed(String error) {
+    return 'Fel vid USB-anslutning: $error';
+  }
 
   @override
   String get scanner_scanning => 'Söker efter enheter...';

lib/l10n/app_localizations_uk.dart

@@ -175,7 +175,25 @@ class AppLocalizationsUk extends AppLocalizations {
 
   @override
   String get usbErrorConnectTimedOut =>
-      'Час очікування закінчився, оскільки пристрій не відповів.';
+      'З\'єднання не вдалося встановити. Переконайтеся, що пристрій має встановлене програмне забезпечення USB Companion.';
+
+  @override
+  String get usbFallbackDeviceName =>
+      'Пристрій для передачі даних по веб-серіалах';
+
+  @override
+  String get usbStatus_notConnected => 'Виберіть пристрій USB';
+
+  @override
+  String get usbStatus_connecting => 'Підключення до USB-пристрою...';
+
+  @override
+  String get usbStatus_searching => 'Пошук пристроїв USB...';
+
+  @override
+  String usbConnectionFailed(String error) {
+    return 'Не вдалося встановити з\'єднання через USB: $error';
+  }
 
   @override
   String get scanner_scanning => 'Пошук пристроїв...';

lib/l10n/app_localizations_zh.dart

@@ -166,7 +166,24 @@ class AppLocalizationsZh extends AppLocalizations {
   String get usbErrorPortClosed => 'USB 连接未建立。';
 
   @override
-  String get usbErrorConnectTimedOut => '等待设备响应超时。';
+  String get usbErrorConnectTimedOut => '连接超时。请确保设备已安装 USB 伴侣固件。';
+
+  @override
+  String get usbFallbackDeviceName => 'Web 串流设备';
+
+  @override
+  String get usbStatus_notConnected => '选择一个 USB 设备';
+
+  @override
+  String get usbStatus_connecting => '连接USB设备...';
+
+  @override
+  String get usbStatus_searching => '正在搜索 USB 设备...';
+
+  @override
+  String usbConnectionFailed(String error) {
+    return 'USB 连接失败：$error';
+  }
 
   @override
   String get scanner_scanning => '正在搜索设备...';

lib/l10n/app_nl.arb

@@ -1847,5 +1847,17 @@
   "usbErrorAlreadyActive": "Een USB-verbinding is al actief.",
   "usbErrorNoDeviceSelected": "Geen USB-apparaat is geselecteerd.",
   "usbErrorPortClosed": "De USB-verbinding is niet actief.",
-  "usbErrorConnectTimedOut": "Wachtperiode is verlopen, aangezien het apparaat niet reageerde."
+  "usbFallbackDeviceName": "Web-serieapparaat",
+  "@usbConnectionFailed": {
+    "placeholders": {
+      "error": {
+        "type": "String"
+      }
+    }
+  },
+  "usbConnectionFailed": "Fout bij de USB-verbinding: {error}",
+  "usbStatus_notConnected": "Selecteer een USB-apparaat",
+  "usbStatus_connecting": "Verbinding maken met USB-apparaat...",
+  "usbStatus_searching": "Zoeken naar USB-apparaten...",
+  "usbErrorConnectTimedOut": "Verbinding is verbroken. Zorg ervoor dat het apparaat de juiste USB-firmware heeft."
 }

lib/l10n/app_pl.arb

@@ -1847,5 +1847,17 @@
   "usbErrorAlreadyActive": "Połączenie USB jest już aktywne.",
   "usbErrorNoDeviceSelected": "Nie został wybrany żaden urządzenie USB.",
   "usbErrorPortClosed": "Połączenie USB nie jest aktywne.",
-  "usbErrorConnectTimedOut": "Czekanie na odpowiedź urządzenia zakończyło się z powodu braku reakcji."
+  "usbFallbackDeviceName": "Urządzenie do komunikacji przez sieć (seria)",
+  "@usbConnectionFailed": {
+    "placeholders": {
+      "error": {
+        "type": "String"
+      }
+    }
+  },
+  "usbStatus_searching": "Wyszukiwanie urządzeń USB...",
+  "usbStatus_connecting": "Połączenie z urządzeniem USB...",
+  "usbStatus_notConnected": "Wybierz urządzenie USB",
+  "usbConnectionFailed": "Błąd połączenia USB: {error}",
+  "usbErrorConnectTimedOut": "Połączenie nie zostało nawiązane. Upewnij się, że urządzenie posiada oprogramowanie \"USB Companion\"."
 }

lib/l10n/app_pt.arb

@@ -1847,5 +1847,17 @@
   "usbErrorAlreadyActive": "A conexão USB já está ativa.",
   "usbErrorNoDeviceSelected": "Nenhum dispositivo USB foi selecionado.",
   "usbErrorPortClosed": "A conexão USB não está ativa.",
-  "usbErrorConnectTimedOut": "Tempo limite aguardando a resposta do dispositivo."
+  "usbFallbackDeviceName": "Dispositivo de Serial para a Web",
+  "@usbConnectionFailed": {
+    "placeholders": {
+      "error": {
+        "type": "String"
+      }
+    }
+  },
+  "usbStatus_searching": "Procurando por dispositivos USB...",
+  "usbStatus_notConnected": "Selecione um dispositivo USB",
+  "usbConnectionFailed": "Falha na conexão USB: {error}",
+  "usbStatus_connecting": "Conectando ao dispositivo USB...",
+  "usbErrorConnectTimedOut": "A conexão expirou. Verifique se o dispositivo possui o firmware USB Companion."
 }

lib/l10n/app_ru.arb

@@ -1087,5 +1087,17 @@
   "usbErrorAlreadyActive": "USB-соединение уже установлено.",
   "usbErrorNoDeviceSelected": "Не было выбрано ни одно устройство USB.",
   "usbErrorPortClosed": "USB-соединение не установлено.",
-  "usbErrorConnectTimedOut": "Ожидание ответа от устройства превысило установленное время."
+  "usbFallbackDeviceName": "Устройство для последовательного подключения к сети",
+  "@usbConnectionFailed": {
+    "placeholders": {
+      "error": {
+        "type": "String"
+      }
+    }
+  },
+  "usbStatus_searching": "Поиск USB-устройств...",
+  "usbStatus_connecting": "Подключение к USB-устройству...",
+  "usbConnectionFailed": "Не удалось установить соединение через USB: {error}",
+  "usbStatus_notConnected": "Выберите USB-устройство",
+  "usbErrorConnectTimedOut": "Соединение не установлено. Убедитесь, что устройство имеет установленное программное обеспечение USB Companion."
 }

lib/l10n/app_sk.arb

@@ -1847,5 +1847,17 @@
   "usbErrorAlreadyActive": "Pripojenie cez USB je už aktivované.",
   "usbErrorNoDeviceSelected": "Nebolo vybrané žiadne USB zariadenie.",
   "usbErrorPortClosed": "Pripojenie cez USB nie je aktivované.",
-  "usbErrorConnectTimedOut": "Čakal som, kým sa zariadenie neozvými, ale časový limit sa dobehol."
+  "usbFallbackDeviceName": "Webový sériový zariadenie",
+  "@usbConnectionFailed": {
+    "placeholders": {
+      "error": {
+        "type": "String"
+      }
+    }
+  },
+  "usbStatus_searching": "Hľadanie USB zariadení...",
+  "usbConnectionFailed": "Neúspešné pripojenie cez USB: {error}",
+  "usbStatus_notConnected": "Vyberte USB zariadenie",
+  "usbStatus_connecting": "Pripojenie k USB zariadeniu...",
+  "usbErrorConnectTimedOut": "Pripojenie nebolo úspešné. Uistite sa, že zariadenie má nainštalovaný firmware USB Companion."
 }

lib/l10n/app_sl.arb

@@ -1847,5 +1847,17 @@
   "usbErrorAlreadyActive": "USB povezava je že aktivirana.",
   "usbErrorNoDeviceSelected": "Ni bilo izbranega USB naprave.",
   "usbErrorPortClosed": "USB povezava ni aktivirana.",
-  "usbErrorConnectTimedOut": "Čakanje je preseglo določeno časovno obdobo, ker se naprave ni odzval."
+  "usbFallbackDeviceName": "Naprave za serijsko komunikacijo preko spleta",
+  "@usbConnectionFailed": {
+    "placeholders": {
+      "error": {
+        "type": "String"
+      }
+    }
+  },
+  "usbStatus_notConnected": "Izberite USB naprave.",
+  "usbStatus_connecting": "Povezava z USB napravo...",
+  "usbStatus_searching": "Iskanje USB naprav...",
+  "usbConnectionFailed": "Napaka pri povezavi preko USB: {error}",
+  "usbErrorConnectTimedOut": "Vzpostavitve ni bilo mogo. Prosimo, da se prepričate, da ima naprave trenutno nameštan firmware USB Companion."
 }

lib/l10n/app_sv.arb

@@ -1834,7 +1834,7 @@
   "usbScreenSubtitle": "Välj en detekterad seriell enhet och anslut direkt till din MeshCore-nod.",
   "usbScreenTitle": "Anslut via USB",
   "usbScreenStatus": "Välj en USB-enhet",
-  "usbScreenNote": "USB-seriell kommunikation är aktiv på stöderliga Android-enheter och på skrivbordsplattformar.",
+  "usbScreenNote": "USB-seriell kommunikation är aktiv på stödda Android-enheter och på skrivbordsplattformar.",
   "usbScreenEmptyState": "Inga USB-enheter hittades. Anslut en och uppdatera.",
   "usbErrorPermissionDenied": "Tillgången via USB nekas.",
   "usbErrorDeviceMissing": "Den valda USB-enheten är inte längre tillgänglig.",
@@ -1847,5 +1847,17 @@
   "usbErrorAlreadyActive": "En USB-anslutning är redan aktiv.",
   "usbErrorNoDeviceSelected": "Ingen USB-enhet valdes.",
   "usbErrorPortClosed": "USB-anslutningen är inte aktiv.",
-  "usbErrorConnectTimedOut": "Tiden har löpt ut medan vi väntade på att enheten skulle svara."
+  "usbFallbackDeviceName": "Web-serieenhet",
+  "@usbConnectionFailed": {
+    "placeholders": {
+      "error": {
+        "type": "String"
+      }
+    }
+  },
+  "usbStatus_connecting": "Anslutning till USB-enhet...",
+  "usbStatus_notConnected": "Välj en USB-enhet",
+  "usbConnectionFailed": "Fel vid USB-anslutning: {error}",
+  "usbStatus_searching": "Söker efter USB-enheter...",
+  "usbErrorConnectTimedOut": "Anslutningen har tidsutgått. Se till att enheten har rätt USB-firmware."
 }

lib/l10n/app_uk.arb

@@ -1847,5 +1847,17 @@
   "usbErrorAlreadyActive": "USB-з'єднання вже встановлено.",
   "usbErrorNoDeviceSelected": "Не було вибрано жодного пристрою USB.",
   "usbErrorPortClosed": "З'єднання USB не встановлено.",
-  "usbErrorConnectTimedOut": "Час очікування закінчився, оскільки пристрій не відповів."
+  "usbFallbackDeviceName": "Пристрій для передачі даних по веб-серіалах",
+  "@usbConnectionFailed": {
+    "placeholders": {
+      "error": {
+        "type": "String"
+      }
+    }
+  },
+  "usbStatus_searching": "Пошук пристроїв USB...",
+  "usbStatus_notConnected": "Виберіть пристрій USB",
+  "usbConnectionFailed": "Не вдалося встановити з'єднання через USB: {error}",
+  "usbStatus_connecting": "Підключення до USB-пристрою...",
+  "usbErrorConnectTimedOut": "З'єднання не вдалося встановити. Переконайтеся, що пристрій має встановлене програмне забезпечення USB Companion."
 }

lib/l10n/app_zh.arb

@@ -1852,5 +1852,17 @@
   "usbErrorAlreadyActive": "USB 连接已建立。",
   "usbErrorNoDeviceSelected": "未选择任何 USB 设备。",
   "usbErrorPortClosed": "USB 连接未建立。",
-  "usbErrorConnectTimedOut": "等待设备响应超时。"
+  "usbFallbackDeviceName": "Web 串流设备",
+  "@usbConnectionFailed": {
+    "placeholders": {
+      "error": {
+        "type": "String"
+      }
+    }
+  },
+  "usbStatus_searching": "正在搜索 USB 设备...",
+  "usbStatus_connecting": "连接USB设备...",
+  "usbStatus_notConnected": "选择一个 USB 设备",
+  "usbConnectionFailed": "USB 连接失败：{error}",
+  "usbErrorConnectTimedOut": "连接超时。请确保设备已安装 USB 伴侣固件。"
 }

lib/screens/usb_screen.dart

@@ -1,16 +1,15 @@
 import 'dart:async';
-import 'dart:math' as math;
 
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:provider/provider.dart';
 
 import '../connector/meshcore_connector.dart';
-import '../connector/meshcore_connector_usb.dart';
 import '../l10n/l10n.dart';
 import '../utils/app_logger.dart';
 import '../utils/platform_info.dart';
 import '../utils/usb_port_labels.dart';
+import '../widgets/adaptive_app_bar_title.dart';
 import 'contacts_screen.dart';
 import 'scanner_screen.dart';
 
@@ -24,20 +23,12 @@ class UsbScreen extends StatefulWidget {
 class _UsbScreenState extends State<UsbScreen> {
   final List<String> _ports = <String>[];
   bool _isLoadingPorts = true;
-  bool _isConnecting = false;
   bool _navigatedToContacts = false;
   bool _didScheduleInitialLoad = false;
-  String? _selectedPort;
-  String? _connectedPortDisplayLabel;
-  String? _errorText;
   Timer? _hotPlugTimer;
   late final MeshCoreConnector _connector;
-  late final MeshCoreConnectorUsb _usbConnector;
   late final VoidCallback _connectionListener;
 
-  /// Whether the current platform supports dynamic hot-plug polling.
-  /// On desktop (macOS, Windows, Linux) we poll continuously so the user
-  /// never needs to hit Refresh manually.
   bool get _supportsHotPlug =>
       PlatformInfo.isWindows || PlatformInfo.isLinux || PlatformInfo.isMacOS;
 
@@ -45,25 +36,13 @@ class _UsbScreenState extends State<UsbScreen> {
   void initState() {
     super.initState();
     _connector = context.read<MeshCoreConnector>();
-    _usbConnector = MeshCoreConnectorUsb(_connector);
     _connectionListener = () {
       if (!mounted) return;
-      final activeUsbPortDisplayLabel = _usbConnector.activeUsbPortDisplayLabel;
+      if (_connector.state == MeshCoreConnectionState.disconnected) {
-      final shouldUpdateDisplayLabel =
-          activeUsbPortDisplayLabel != _connectedPortDisplayLabel;
-      if (_usbConnector.state == MeshCoreConnectionState.disconnected) {
         _navigatedToContacts = false;
-        setState(() {
-          _isConnecting = false;
-          _connectedPortDisplayLabel = activeUsbPortDisplayLabel;
-        });
-      } else if (shouldUpdateDisplayLabel) {
-        setState(() {
-          _connectedPortDisplayLabel = activeUsbPortDisplayLabel;
-        });
       }
-      if (_usbConnector.state == MeshCoreConnectionState.connected &&
+      if (_connector.state == MeshCoreConnectionState.connected &&
-          _usbConnector.isUsbTransportConnected &&
+          _connector.isUsbTransportConnected &&
           !_navigatedToContacts) {
         _navigatedToContacts = true;
         Navigator.of(context).pushReplacement(
@@ -71,14 +50,15 @@ class _UsbScreenState extends State<UsbScreen> {
         );
       }
     };
-    _usbConnector.addListener(_connectionListener);
+    _connector.addListener(_connectionListener);
     _startHotPlugTimer();
   }
 
   @override
   void didChangeDependencies() {
     super.didChangeDependencies();
-    _usbConnector.setRequestPortLabel(context.l10n.usbScreenStatus);
+    _connector.setUsbRequestPortLabel(context.l10n.usbScreenStatus);
+    _connector.setUsbFallbackDeviceName(context.l10n.usbFallbackDeviceName);
     if (!_didScheduleInitialLoad) {
       _didScheduleInitialLoad = true;
       unawaited(_loadPorts());
@@ -89,12 +69,12 @@ class _UsbScreenState extends State<UsbScreen> {
   void dispose() {
     _hotPlugTimer?.cancel();
     _hotPlugTimer = null;
-    _usbConnector.removeListener(_connectionListener);
+    _connector.removeListener(_connectionListener);
     if (!_navigatedToContacts &&
-        _usbConnector.activeTransport == MeshCoreTransportType.usb &&
+        _connector.activeTransport == MeshCoreTransportType.usb &&
-        _usbConnector.state != MeshCoreConnectionState.disconnected) {
+        _connector.state != MeshCoreConnectionState.disconnected) {
       WidgetsBinding.instance.addPostFrameCallback((_) {
-        unawaited(_usbConnector.disconnect(manual: true));
+        unawaited(_connector.disconnect(manual: true));
       });
     }
     super.dispose();
@@ -102,234 +82,192 @@ class _UsbScreenState extends State<UsbScreen> {
 
   @override
   Widget build(BuildContext context) {
-    final theme = Theme.of(context);
-    final l10n = context.l10n;
-
     return Scaffold(
       appBar: AppBar(
         leading: IconButton(
           icon: const Icon(Icons.arrow_back),
-          onPressed: () {
+          onPressed: () => Navigator.of(context).maybePop(),
-            appLogger.info('Back button pressed', tag: 'UsbScreen');
-            Navigator.of(context).maybePop();
-          },
-        ),
-        title: Text(
-          l10n.connectionChoiceUsbLabel,
-          style: theme.textTheme.titleLarge,
         ),
+        title: AdaptiveAppBarTitle(context.l10n.usbScreenTitle),
         centerTitle: true,
-        actions: [
-          if (PlatformInfo.isWeb ||
-              PlatformInfo.isAndroid ||
-              PlatformInfo.isIOS)
-            TextButton.icon(
-              onPressed: () {
-                appLogger.info(
-                  'Bluetooth selected, opening ScannerScreen',
-                  tag: 'UsbScreen',
-                );
-                Navigator.of(context).pushReplacement(
-                  MaterialPageRoute(builder: (_) => const ScannerScreen()),
-                );
-              },
-              icon: const Icon(Icons.bluetooth),
-              label: Text(l10n.connectionChoiceBluetoothLabel),
-            ),
-        ],
       ),
       body: SafeArea(
-        child: LayoutBuilder(
+        top: false,
-          builder: (context, constraints) {
+        child: Consumer<MeshCoreConnector>(
-            final availableHeight = constraints.maxHeight.isFinite
+          builder: (context, connector, child) {
-                ? constraints.maxHeight
+            return Column(
-                : 600.0;
+              children: [
-            final availableWidth = constraints.maxWidth.isFinite
+                _buildStatusBar(context, connector),
-                ? constraints.maxWidth
+                Expanded(child: _buildPortList(context, connector)),
-                : 800.0;
+              ],
-            final gap = math.max(8.0, math.min(16.0, availableHeight * 0.025));
-            final iconSize = math.max(
-              28.0,
-              math.min(72.0, availableHeight * 0.12),
-            );
-            final isNarrow = availableWidth < 460.0;
-
-            return Padding(
-              padding: const EdgeInsets.symmetric(horizontal: 24, vertical: 20),
-              child: Column(
-                crossAxisAlignment: CrossAxisAlignment.stretch,
-                children: [
-                  // ── Compact header ──────────────────────────────────────
-                  Row(
-                    children: [
-                      Icon(
-                        Icons.usb,
-                        size: iconSize.clamp(24.0, 40.0),
-                        color: theme.colorScheme.primary,
-                      ),
-                      SizedBox(width: gap),
-                      Expanded(
-                        child: Column(
-                          crossAxisAlignment: CrossAxisAlignment.start,
-                          mainAxisSize: MainAxisSize.min,
-                          children: [
-                            Text(
-                              l10n.usbScreenTitle,
-                              maxLines: 1,
-                              overflow: TextOverflow.ellipsis,
-                              style: theme.textTheme.titleLarge?.copyWith(
-                                fontWeight: FontWeight.w600,
-                              ),
-                            ),
-                            Text(
-                              l10n.usbScreenSubtitle,
-                              maxLines: 2,
-                              overflow: TextOverflow.ellipsis,
-                              style: theme.textTheme.bodySmall?.copyWith(
-                                color: theme.colorScheme.onSurfaceVariant,
-                              ),
-                            ),
-                          ],
-                        ),
-                      ),
-                    ],
-                  ),
-                  SizedBox(height: gap),
-                  // ── Port list takes all remaining space ─────────────────
-                  Expanded(child: _buildPortList(context)),
-                  if (_errorText != null) ...[
-                    SizedBox(height: gap * 0.5),
-                    Text(
-                      _errorText!,
-                      textAlign: TextAlign.center,
-                      maxLines: 3,
-                      overflow: TextOverflow.ellipsis,
-                      style: theme.textTheme.bodySmall?.copyWith(
-                        color: theme.colorScheme.error,
-                      ),
-                    ),
-                  ],
-                  SizedBox(height: gap),
-                  // ── Action buttons ──────────────────────────────────────
-                  if (isNarrow)
-                    Column(
-                      crossAxisAlignment: CrossAxisAlignment.stretch,
-                      children: [
-                        if (!_supportsHotPlug) ...[
-                          OutlinedButton.icon(
-                            onPressed: _isLoadingPorts || _isConnecting
-                                ? null
-                                : () {
-                                    appLogger.info(
-                                      'Refresh ports pressed',
-                                      tag: 'UsbScreen',
-                                    );
-                                    _loadPorts();
-                                  },
-                            icon: const Icon(Icons.refresh),
-                            label: Text(l10n.repeater_refresh),
-                          ),
-                          SizedBox(height: gap),
-                        ],
-                        FilledButton.icon(
-                          onPressed: _canConnect
-                              ? () {
-                                  final rawPortName = normalizeUsbPortName(
-                                    _selectedPort!,
-                                  );
-                                  appLogger.info(
-                                    'Connect pressed for $_selectedPort (raw: $rawPortName)',
-                                    tag: 'UsbScreen',
-                                  );
-                                  _connectSelectedPort();
-                                }
-                              : null,
-                          icon: _isConnecting
-                              ? const SizedBox(
-                                  width: 18,
-                                  height: 18,
-                                  child: CircularProgressIndicator(
-                                    strokeWidth: 2,
-                                  ),
-                                )
-                              : const Icon(Icons.usb),
-                          label: Text(l10n.common_connect),
-                        ),
-                      ],
-                    )
-                  else
-                    Row(
-                      children: [
-                        if (!_supportsHotPlug) ...[
-                          Expanded(
-                            child: OutlinedButton.icon(
-                              onPressed: _isLoadingPorts || _isConnecting
-                                  ? null
-                                  : () {
-                                      appLogger.info(
-                                        'Refresh ports pressed',
-                                        tag: 'UsbScreen',
-                                      );
-                                      _loadPorts();
-                                    },
-                              icon: const Icon(Icons.refresh),
-                              label: Text(l10n.repeater_refresh),
-                            ),
-                          ),
-                          SizedBox(width: gap),
-                        ],
-                        Expanded(
-                          child: FilledButton.icon(
-                            onPressed: _canConnect
-                                ? () {
-                                    final rawPortName = normalizeUsbPortName(
-                                      _selectedPort!,
-                                    );
-                                    appLogger.info(
-                                      'Connect pressed for $_selectedPort (raw: $rawPortName)',
-                                      tag: 'UsbScreen',
-                                    );
-                                    _connectSelectedPort();
-                                  }
-                                : null,
-                            icon: _isConnecting
-                                ? const SizedBox(
-                                    width: 18,
-                                    height: 18,
-                                    child: CircularProgressIndicator(
-                                      strokeWidth: 2,
-                                    ),
-                                  )
-                                : const Icon(Icons.usb),
-                            label: Text(l10n.common_connect),
-                          ),
-                        ),
-                      ],
-                    ),
-                  SizedBox(height: math.max(4.0, gap * 0.5)),
-                  Text(
-                    l10n.usbScreenNote,
-                    textAlign: TextAlign.center,
-                    maxLines: 2,
-                    overflow: TextOverflow.ellipsis,
-                    style: theme.textTheme.bodySmall?.copyWith(
-                      color: theme.colorScheme.onSurfaceVariant,
-                    ),
-                  ),
-                ],
-              ),
             );
           },
         ),
       ),
+      bottomNavigationBar: Consumer<MeshCoreConnector>(
+        builder: (context, connector, child) {
+          final isLoading = _isLoadingPorts;
+          final showBle = PlatformInfo.isWeb ||
+              PlatformInfo.isAndroid ||
+              PlatformInfo.isIOS;
+
+          return SafeArea(
+            top: false,
+            minimum: const EdgeInsets.fromLTRB(16, 8, 16, 16),
+            child: Row(
+              mainAxisAlignment: MainAxisAlignment.end,
+              children: [
+                if (showBle)
+                  FloatingActionButton.extended(
+                    onPressed: () {
+                      Navigator.of(context).pushReplacement(
+                        MaterialPageRoute(
+                          builder: (_) => const ScannerScreen(),
+                        ),
+                      );
+                    },
+                    heroTag: 'usb_ble_action',
+                    icon: const Icon(Icons.bluetooth),
+                    label: Text(context.l10n.connectionChoiceBluetoothLabel),
+                  ),
+                if (showBle) const SizedBox(width: 12),
+                if (!_supportsHotPlug)
+                  FloatingActionButton.extended(
+                    onPressed: isLoading ? null : _loadPorts,
+                    heroTag: 'usb_refresh_action',
+                    icon: isLoading
+                        ? const SizedBox(
+                            width: 20,
+                            height: 20,
+                            child: CircularProgressIndicator(strokeWidth: 2),
+                          )
+                        : const Icon(Icons.refresh),
+                    label: Text(context.l10n.repeater_refresh),
+                  ),
+              ],
+            ),
+          );
+        },
+      ),
     );
   }
 
-  bool get _canConnect =>
+  Widget _buildStatusBar(BuildContext context, MeshCoreConnector connector) {
-      !_isLoadingPorts &&
+    final l10n = context.l10n;
-      !_isConnecting &&
+    String statusText;
-      _selectedPort != null &&
+    Color statusColor;
-      _selectedPort!.isNotEmpty;
+
+    if (_isLoadingPorts) {
+      statusText = l10n.usbStatus_searching;
+      statusColor = Colors.blue;
+    } else if (connector.isUsbTransportConnected) {
+      switch (connector.state) {
+        case MeshCoreConnectionState.connected:
+          statusText = l10n.scanner_connectedTo(
+            connector.activeUsbPortDisplayLabel ?? 'USB',
+          );
+          statusColor = Colors.green;
+        case MeshCoreConnectionState.disconnecting:
+          statusText = l10n.scanner_disconnecting;
+          statusColor = Colors.orange;
+        default:
+          statusText = l10n.usbStatus_notConnected;
+          statusColor = Colors.grey;
+      }
+    } else if (connector.state == MeshCoreConnectionState.connecting &&
+        connector.activeTransport == MeshCoreTransportType.usb) {
+      statusText = l10n.usbStatus_connecting;
+      statusColor = Colors.orange;
+    } else {
+      statusText = l10n.usbStatus_notConnected;
+      statusColor = Colors.grey;
+    }
+
+    return Container(
+      width: double.infinity,
+      padding: const EdgeInsets.symmetric(vertical: 8, horizontal: 16),
+      color: statusColor.withValues(alpha: 0.1),
+      child: Row(
+        children: [
+          Icon(Icons.circle, size: 12, color: statusColor),
+          const SizedBox(width: 8),
+          Text(
+            statusText,
+            style: TextStyle(color: statusColor, fontWeight: FontWeight.w500),
+          ),
+        ],
+      ),
+    );
+  }
+
+  Widget _buildPortList(BuildContext context, MeshCoreConnector connector) {
+    final l10n = context.l10n;
+
+    if (_isLoadingPorts) {
+      return Center(
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: [
+            Icon(Icons.usb, size: 64, color: Colors.grey[400]),
+            const SizedBox(height: 16),
+            Text(
+              l10n.usbStatus_searching,
+              style: TextStyle(fontSize: 16, color: Colors.grey[600]),
+            ),
+          ],
+        ),
+      );
+    }
+
+    if (_ports.isEmpty) {
+      return Center(
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: [
+            Icon(Icons.usb, size: 64, color: Colors.grey[400]),
+            const SizedBox(height: 16),
+            Text(
+              l10n.usbScreenEmptyState,
+              textAlign: TextAlign.center,
+              style: TextStyle(fontSize: 16, color: Colors.grey[600]),
+            ),
+          ],
+        ),
+      );
+    }
+
+    final isConnecting =
+        connector.state == MeshCoreConnectionState.connecting &&
+            connector.activeTransport == MeshCoreTransportType.usb;
+
+    return ListView.separated(
+      padding: const EdgeInsets.all(8),
+      itemCount: _ports.length,
+      separatorBuilder: (context, index) => const Divider(),
+      itemBuilder: (context, index) {
+        final port = _ports[index];
+        final displayName = friendlyUsbPortName(port);
+        final rawName = normalizeUsbPortName(port);
+        final showRawName =
+            rawName != displayName && !rawName.startsWith('web:');
+
+        return ListTile(
+          leading: const Icon(Icons.usb),
+          title: Text(
+            displayName,
+            style: const TextStyle(fontWeight: FontWeight.w500),
+          ),
+          subtitle: showRawName ? Text(rawName) : null,
+          trailing: ElevatedButton(
+            onPressed:
+                isConnecting ? null : () => _connectPort(port),
+            child: Text(l10n.common_connect),
+          ),
+          onTap: isConnecting ? null : () => _connectPort(port),
+        );
+      },
+    );
+  }
 
   void _startHotPlugTimer() {
     if (!_supportsHotPlug) return;
@@ -340,9 +278,10 @@ class _UsbScreenState extends State<UsbScreen> {
   }
 
   Future<void> _pollHotPlug() async {
-    // Don't interfere with an active connection attempt or initial load.
+    if (_isLoadingPorts) return;
-    if (_isConnecting || _isLoadingPorts) return;
     if (!mounted) return;
+    // Don't poll while connecting or connected.
+    if (_connector.state != MeshCoreConnectionState.disconnected) return;
     try {
       final ports = await _connector.listUsbPorts();
       if (!mounted) return;
@@ -353,186 +292,72 @@ class _UsbScreenState extends State<UsbScreen> {
         _ports
           ..clear()
           ..addAll(ports);
-        if (_ports.isEmpty) {
-          _selectedPort = null;
-        } else if (added.isNotEmpty) {
-          // Auto-select the newly-connected device.
-          _selectedPort = added.first;
-        } else if (_selectedPort != null && !_ports.contains(_selectedPort)) {
-          // Previously-selected device was unplugged.
-          _selectedPort = _ports.isNotEmpty ? _ports.first : null;
-        }
       });
     } catch (_) {
       // Silent — hot-plug failures are non-critical.
     }
   }
 
-  Widget _buildPortList(BuildContext context) {
-    final theme = Theme.of(context);
-    final l10n = context.l10n;
-
-    if (_isLoadingPorts) {
-      return Center(
-        child: Column(
-          mainAxisSize: MainAxisSize.min,
-          children: [
-            const CircularProgressIndicator(),
-            const SizedBox(height: 12),
-            Text(l10n.common_loading),
-          ],
-        ),
-      );
-    }
-
-    if (_ports.isEmpty) {
-      return Center(
-        child: Text(
-          l10n.usbScreenEmptyState,
-          textAlign: TextAlign.center,
-          style: theme.textTheme.bodyMedium?.copyWith(
-            color: theme.colorScheme.onSurfaceVariant,
-          ),
-        ),
-      );
-    }
-
-    return ListView.separated(
-      itemCount: _ports.length,
-      itemBuilder: (context, index) {
-        final port = _ports[index];
-        final isSelected = port == _selectedPort;
-        final displayName = _friendlyPortName(port);
-        final rawName = normalizeUsbPortName(port);
-        final showRawName =
-            rawName != displayName && !rawName.startsWith('web:');
-        return Material(
-          color: isSelected
-              ? theme.colorScheme.primaryContainer
-              : theme.colorScheme.surfaceContainerLow,
-          borderRadius: BorderRadius.circular(16),
-          child: ListTile(
-            onTap: _isConnecting
-                ? null
-                : () {
-                    setState(() {
-                      _selectedPort = port;
-                      _errorText = null;
-                    });
-                    appLogger.info('Selected port $port', tag: 'UsbScreen');
-                  },
-            leading: Icon(
-              Icons.usb,
-              color: isSelected
-                  ? theme.colorScheme.onPrimaryContainer
-                  : theme.colorScheme.onSurfaceVariant,
-            ),
-            title: Text(
-              displayName,
-              maxLines: 1,
-              overflow: TextOverflow.ellipsis,
-              style: theme.textTheme.titleMedium?.copyWith(
-                color: isSelected ? theme.colorScheme.onPrimaryContainer : null,
-              ),
-            ),
-            subtitle: showRawName
-                ? Text(
-                    rawName,
-                    maxLines: 1,
-                    overflow: TextOverflow.ellipsis,
-                    style: theme.textTheme.bodySmall?.copyWith(
-                      color: isSelected
-                          ? theme.colorScheme.onPrimaryContainer
-                          : theme.colorScheme.onSurfaceVariant,
-                    ),
-                  )
-                : null,
-            trailing: isSelected
-                ? Icon(
-                    Icons.check_circle,
-                    color: theme.colorScheme.onPrimaryContainer,
-                  )
-                : null,
-          ),
-        );
-      },
-      separatorBuilder: (context, index) => const SizedBox(height: 10),
-    );
-  }
-
   Future<void> _loadPorts() async {
     if (!mounted) return;
-    _usbConnector.setRequestPortLabel(context.l10n.usbScreenStatus);
+    _connector.setUsbRequestPortLabel(context.l10n.usbScreenStatus);
 
     setState(() {
       _isLoadingPorts = true;
-      _errorText = null;
     });
 
     try {
-      final ports = await _usbConnector.listPorts();
+      final ports = await _connector.listUsbPorts();
       if (!mounted) return;
       setState(() {
         _ports
           ..clear()
           ..addAll(ports);
-        if (_ports.isEmpty) {
-          _selectedPort = null;
-        } else if (!_ports.contains(_selectedPort)) {
-          _selectedPort = _ports.first;
-        }
         _isLoadingPorts = false;
       });
     } catch (error) {
       if (!mounted) return;
       setState(() {
         _ports.clear();
-        _selectedPort = null;
-        _errorText = _friendlyErrorMessage(error);
         _isLoadingPorts = false;
       });
+      _showError(error);
     }
   }
 
-  Future<void> _connectSelectedPort() async {
+  Future<void> _connectPort(String port) async {
-    final selectedPort = _selectedPort;
+    if (_connector.state != MeshCoreConnectionState.disconnected) return;
-    if (selectedPort == null || selectedPort.isEmpty) {
-      return;
-    }
-    _usbConnector.setRequestPortLabel(context.l10n.usbScreenStatus);
-    if (_usbConnector.state != MeshCoreConnectionState.disconnected) {
-      setState(() {
-        _isConnecting = false;
-        _errorText = null;
-      });
-      return;
-    }
-    final rawPortName = normalizeUsbPortName(selectedPort);
 
-    setState(() {
+    final rawPortName = normalizeUsbPortName(port);
-      _isConnecting = true;
+    appLogger.info('Connect tapped for $port (raw: $rawPortName)',
-      _errorText = null;
+        tag: 'UsbScreen');
-    });
 
     try {
-      await _usbConnector.connect(portName: rawPortName);
+      await _connector.connectUsb(portName: rawPortName);
     } catch (error, stackTrace) {
       appLogger.error(
         'Connect failed for $rawPortName: $error\n$stackTrace',
         tag: 'UsbScreen',
       );
       if (!mounted) return;
-      setState(() {
+      _showError(error);
-        _isConnecting = false;
-        _errorText = _friendlyErrorMessage(error);
-      });
-      // Re-scan so stale or renamed port entries are cleared from the list.
       unawaited(_loadPorts());
     }
   }
 
+  void _showError(Object error) {
+    if (!mounted) return;
+    ScaffoldMessenger.of(context).showSnackBar(
+      SnackBar(
+        content: Text(_friendlyErrorMessage(error)),
+        backgroundColor: Colors.red,
+      ),
+    );
+  }
+
   String _friendlyErrorMessage(Object error) {
     final l10n = context.l10n;
+
     if (error is PlatformException) {
       switch (error.code) {
         case 'usb_permission_denied':
@@ -546,43 +371,35 @@ class _UsbScreenState extends State<UsbScreen> {
           return l10n.usbErrorBusy;
         case 'usb_not_connected':
           return l10n.usbErrorNotConnected;
-        case 'usb_driver_missing':
         case 'usb_open_failed':
+        case 'usb_driver_missing':
           return l10n.usbErrorOpenFailed;
         case 'usb_connect_failed':
-        case 'usb_write_failed':
-        case 'usb_io_error':
           return l10n.usbErrorConnectFailed;
       }
     }
 
-    var msg = error.toString();
+    if (error is UnsupportedError) {
-    if (msg.startsWith('Bad state: ')) {
+      return l10n.usbErrorUnsupported;
-      msg = msg.substring('Bad state: '.length);
-    } else if (msg.startsWith('Exception: ')) {
-      msg = msg.substring('Exception: '.length);
     }
 
-    switch (msg) {
+    if (error is StateError) {
-      case 'USB serial transport is already active':
+      final msg = error.message;
-        return l10n.usbErrorAlreadyActive;
+      if (msg.contains('already active')) return l10n.usbErrorAlreadyActive;
-      case 'No USB serial device selected':
+      if (msg.contains('No USB serial device selected')) {
         return l10n.usbErrorNoDeviceSelected;
-      case 'USB serial port is not open':
+      }
+      if (msg.contains('not open') || msg.contains('closed')) {
         return l10n.usbErrorPortClosed;
-      case 'USB serial is not supported on this platform.':
+      }
-      case 'Web Serial is not supported by this browser.':
+      if (msg.contains('Timed out')) return l10n.usbErrorConnectTimedOut;
-        return l10n.usbErrorUnsupported;
+      if (msg.contains('Failed to open')) return l10n.usbErrorOpenFailed;
-      case 'Timed out waiting for SELF_INFO during connect':
-        return l10n.usbErrorConnectTimedOut;
     }
 
-    if (msg.startsWith('Failed to open USB port ')) {
+    if (error is TimeoutException) {
-      return l10n.usbErrorOpenFailed;
+      return l10n.usbErrorConnectTimedOut;
     }
 
-    return msg;
+    return error.toString();
   }
-
-  String _friendlyPortName(String portLabel) => friendlyUsbPortName(portLabel);
 }

lib/services/app_debug_log_service.dart

@@ -52,7 +52,12 @@ class AppDebugLogService extends ChangeNotifier {
     String tag = 'App',
     AppDebugLogLevel level = AppDebugLogLevel.info,
   }) {
-    if (!_enabled) return;
+    if (!_enabled && !kDebugMode) return;
+    if (!_enabled) {
+      // In debug mode, still print to console but don't store entries.
+      debugPrint('[$tag] $message');
+      return;
+    }
 
     _entries.add(
       AppDebugLogEntry(

lib/services/notification_service.dart

@@ -1,9 +1,11 @@
+import 'dart:io' show Platform, File;
 import 'dart:ui';
 
 import 'package:flutter_local_notifications/flutter_local_notifications.dart';
 import 'package:flutter/foundation.dart';
 
 import '../l10n/app_localizations.dart';
+import '../utils/platform_info.dart';
 
 class NotificationService {
   static final NotificationService _instance = NotificationService._internal();
@@ -75,6 +77,15 @@ class NotificationService {
       linux: linuxSettings,
     );
 
+    // On Linux, the notifications plugin opens a D-Bus session bus
+    // connection whose async subscription can throw an unhandled
+    // SocketException when the bus socket is missing (e.g. running as
+    // root or inside a container without a session bus).
+    if (PlatformInfo.isLinux && !_isDbusSessionAvailable()) {
+      debugPrint('Skipping notification init: D-Bus session bus unavailable');
+      return;
+    }
+
     try {
       await _notifications.initialize(
         settings: initSettings,
@@ -86,6 +97,16 @@ class NotificationService {
     }
   }
 
+  static bool _isDbusSessionAvailable() {
+    final addr = Platform.environment['DBUS_SESSION_BUS_ADDRESS'];
+    if (addr != null && addr.isNotEmpty) return true;
+    // Fallback: check the default socket for the current user.
+    final uid = Platform.environment['UID'] ??
+        Platform.environment['EUID'];
+    final path = '/run/user/${uid ?? '1000'}/bus';
+    return File(path).existsSync();
+  }
+
   Future<bool> _ensureInitialized() async {
     if (!_isInitialized) {
       await initialize();

lib/services/usb_serial_service_native.dart

@@ -325,6 +325,10 @@ class UsbSerialService {
     // Native implementations do not use a synthetic chooser row.
   }
 
+  void setFallbackDeviceName(String label) {
+    // Native implementations use OS-provided device names.
+  }
+
   void updateConnectedLabel(String label) {
     final trimmed = label.trim();
     if (trimmed.isEmpty) {

lib/services/usb_serial_service_web.dart

@@ -32,6 +32,7 @@ class UsbSerialService {
   String? _connectedPortName;
   String? _connectedPortKey;
   String _requestPortLabel = 'Choose USB Device';
+  String _fallbackDeviceName = 'Web Serial Device';
   AppDebugLogService? _debugLogService;
 
   UsbSerialStatus get status => _status;
@@ -77,11 +78,19 @@ class UsbSerialService {
 
     try {
       final requestedPortName = normalizeUsbPortName(portName);
+      _debugLogService?.info(
+        'Web connect: requested=$requestedPortName baud=$baudRate',
+        tag: 'USB Serial',
+      );
       final selectedPortKey = requestedPortName.startsWith('web:port:')
           ? requestedPortName
           : null;
       _port = _authorizedPortsByKey[requestedPortName];
       final authorizedPorts = await _getAuthorizedPorts();
+      _debugLogService?.info(
+        'Web connect: ${authorizedPorts.length} authorized port(s), cached=${_port != null}',
+        tag: 'USB Serial',
+      );
       _port ??= _selectPort(authorizedPorts, requestedPortName);
 
       _port ??= await _requestPort();
@@ -89,6 +98,10 @@ class UsbSerialService {
         throw StateError('No USB serial device selected');
       }
 
+      _debugLogService?.info(
+        'Web connect: opening port at $baudRate baud…',
+        tag: 'USB Serial',
+      );
       await _openPort(_port!, baudRate);
       _connectedPortKey = _cachePort(_port!, preferredKey: selectedPortKey);
       _connectedPortName = _displayLabelForPort(
@@ -105,6 +118,10 @@ class UsbSerialService {
         tag: 'USB Serial',
       );
     } catch (error) {
+      _debugLogService?.error(
+        'Web connect failed: $error',
+        tag: 'USB Serial',
+      );
       await _cleanupFailedConnect();
       _status = UsbSerialStatus.disconnected;
       _connectedPortName = null;
@@ -194,6 +211,14 @@ class UsbSerialService {
     _requestPortLabel = trimmed;
   }
 
+  void setFallbackDeviceName(String label) {
+    final trimmed = label.trim();
+    if (trimmed.isEmpty) {
+      return;
+    }
+    _fallbackDeviceName = trimmed;
+  }
+
   void setDebugLogService(AppDebugLogService? service) {
     _debugLogService = service;
   }
@@ -403,6 +428,7 @@ class UsbSerialService {
       vendorId: hasVendor ? vendorId : null,
       productId: hasProduct ? productId : null,
       requestPortLabel: _requestPortLabel,
+      fallbackDeviceName: _fallbackDeviceName,
       knownUsbNames: _knownUsbNames,
     );
   }

lib/utils/usb_port_labels.dart

@@ -31,6 +31,7 @@ String describeWebUsbPort({
   required int? vendorId,
   required int? productId,
   String requestPortLabel = 'Choose USB Device',
+  String fallbackDeviceName = 'Web Serial Device',
   Map<String, String> knownUsbNames = const <String, String>{},
 }) {
   if (vendorId == null && productId == null) {
@@ -43,7 +44,7 @@ String describeWebUsbPort({
       ? knownUsbNames['${vendorHex.toLowerCase()}:${productHex.toLowerCase()}']
       : null;
 
-  final parts = <String>[knownName ?? 'Web Serial Device'];
+  final parts = <String>[knownName ?? fallbackDeviceName];
   if (vendorHex != null) {
     parts.add('VID:$vendorHex');
   }

lib/widgets/snr_indicator.dart

@@ -78,40 +78,36 @@ class _SNRIndicatorState extends State<SNRIndicator> {
       widget.connector.currentSf,
     );
 
-    return InkWell(
+    return ConstrainedBox(
-      onTap: () {
+      constraints: const BoxConstraints(minWidth: 40, minHeight: 40),
-        if (directRepeater != null) {
+      child: InkWell(
-          _showFullPathDialog(context, directBestRepeaters);
+        onTap: directRepeater != null
-        }
+            ? () => _showFullPathDialog(context, directBestRepeaters)
-      },
+            : null,
-      borderRadius: BorderRadius.circular(8),
+        borderRadius: BorderRadius.circular(8),
-      child: Padding(
+        child: Padding(
-        padding: const EdgeInsets.symmetric(horizontal: 4, vertical: 8),
+          padding: const EdgeInsets.symmetric(horizontal: 4, vertical: 8),
-        child: Column(
+          child: Column(
-          mainAxisSize: MainAxisSize.min,
+            mainAxisSize: MainAxisSize.min,
-          children: [
+            children: [
-            Column(
+              Icon(snrUi.icon, size: 18, color: snrUi.color),
-              mainAxisSize: MainAxisSize.min,
-              children: [
-                Icon(snrUi.icon, size: 18, color: snrUi.color),
-                Text(
-                  snrUi.text,
-                  style: TextStyle(fontSize: 12, color: snrUi.color),
-                ),
-              ],
-            ),
-            if (directRepeater != null)
               Text(
-                '${directRepeaters.length}: ${directRepeater.pubkeyFirstByte.toRadixString(16).padLeft(2, '0')}: ${_formatLastUpdated(directRepeater.lastUpdated)}',
+                snrUi.text,
-                style: TextStyle(
+                style: TextStyle(fontSize: 12, color: snrUi.color),
-                  fontSize: 12,
-                  fontWeight: FontWeight.w500,
-                  color: Colors.grey,
-                ),
-                maxLines: 1,
-                overflow: TextOverflow.ellipsis,
               ),
-          ],
+              if (directRepeater != null)
+                Text(
+                  '${directRepeaters.length}: ${directRepeater.pubkeyFirstByte.toRadixString(16).padLeft(2, '0')}: ${_formatLastUpdated(directRepeater.lastUpdated)}',
+                  style: TextStyle(
+                    fontSize: 12,
+                    fontWeight: FontWeight.w500,
+                    color: Colors.grey,
+                  ),
+                  maxLines: 1,
+                  overflow: TextOverflow.ellipsis,
+                ),
+            ],
+          ),
         ),
       ),
     );
@@ -148,8 +144,10 @@ class _SNRIndicatorState extends State<SNRIndicator> {
       builder: (context) => AlertDialog(
         title: Text(l10n.snrIndicator_nearByRepeaters),
         content: SizedBox(
+          width: double.maxFinite,
           child: Scrollbar(
             child: ListView.separated(
+              shrinkWrap: true,
               padding: const EdgeInsets.symmetric(vertical: 4),
               itemCount: directBestRepeaters.length,
               separatorBuilder: (_, _) => const Divider(height: 1),

test/screens/usb_flow_test.dart

@@ -19,6 +19,7 @@ class _FakeMeshCoreConnector extends MeshCoreConnector {
   final List<String> _ports;
 
   String? requestPortLabel;
+  String? fallbackDeviceName;
   int connectUsbCalls = 0;
   String? lastConnectPortName;
   String? fakeActiveUsbPort;
@@ -30,6 +31,9 @@ class _FakeMeshCoreConnector extends MeshCoreConnector {
   @override
   MeshCoreConnectionState get state => initialState;
 
+  @override
+  MeshCoreTransportType get activeTransport => MeshCoreTransportType.usb;
+
   @override
   String? get activeUsbPort => fakeActiveUsbPort;
 
@@ -64,6 +68,11 @@ class _FakeMeshCoreConnector extends MeshCoreConnector {
   void setUsbRequestPortLabel(String label) {
     requestPortLabel = label;
   }
+
+  @override
+  void setUsbFallbackDeviceName(String label) {
+    fallbackDeviceName = label;
+  }
 }
 
 Widget _buildTestApp({
@@ -107,16 +116,23 @@ void main() {
       );
       await tester.pumpAndSettle();
 
-      await tester.tap(find.widgetWithText(FilledButton, 'Connect'));
+      await tester.tap(find.ancestor(
+            of: find.text('Connect'),
+            matching: find.bySubtype<ElevatedButton>(),
+          ));
       await tester.pump();
 
       expect(connector.connectUsbCalls, 0);
-      expect(find.byType(CircularProgressIndicator), findsNothing);
+
+      // UsbScreen.dispose() schedules disconnect work that debounces notify.
+      // Drain that debounce timer before test teardown.
+      await tester.pumpWidget(const SizedBox.shrink());
+      await tester.pump(const Duration(milliseconds: 60));
     },
   );
 
   testWidgets(
-    'UsbScreen keeps raw selection when connector USB display label changes',
+    'UsbScreen sends raw port name when tapping Connect',
     (tester) async {
       final connector = _FakeMeshCoreConnector(
         ports: <String>['COM6 - USB Serial Device (COM6)'],
@@ -127,12 +143,10 @@ void main() {
       );
       await tester.pumpAndSettle();
 
-      connector.fakeActiveUsbPortDisplayLabel =
+      await tester.tap(find.ancestor(
-          'COM6 - KD3CGK mesh-utility.org';
+            of: find.text('Connect'),
-      connector.notifyListeners();
+            matching: find.bySubtype<ElevatedButton>(),
-      await tester.pump(const Duration(milliseconds: 60));
+          ));
-
-      await tester.tap(find.widgetWithText(FilledButton, 'Connect'));
       await tester.pump();
 
       expect(connector.connectUsbCalls, 1);
@@ -163,7 +177,8 @@ void main() {
   });
 
   group('Error Handling', () {
-    testWidgets('shows error message when listing ports fails', (tester) async {
+    testWidgets('shows error SnackBar when listing ports fails',
+        (tester) async {
       final connector = _FakeMeshCoreConnector();
       connector.listUsbPortsImpl = () async {
         throw PlatformException(
@@ -180,7 +195,7 @@ void main() {
       expect(find.text('USB permission was denied.'), findsOneWidget);
     });
 
-    testWidgets('connection failure completes without leaving loading state', (
+    testWidgets('connection failure shows SnackBar error', (
       tester,
     ) async {
       final connector = _FakeMeshCoreConnector(ports: <String>['COM1']);
@@ -195,11 +210,17 @@ void main() {
       );
       await tester.pumpAndSettle();
 
-      await tester.tap(find.widgetWithText(FilledButton, 'Connect'));
+      await tester.tap(find.ancestor(
+            of: find.text('Connect'),
+            matching: find.bySubtype<ElevatedButton>(),
+          ));
       await tester.pumpAndSettle();
 
       expect(connectAttempted, isTrue);
-      expect(find.byType(CircularProgressIndicator), findsNothing);
+      expect(
+        find.text('Another USB connection request is already in progress.'),
+        findsOneWidget,
+      );
     });
   });
 }