fix: simplify method call for writing data in UsbSerialService

- Fix operator precedence bug in _handleAutoAddConfig where `flags &
  flag != 0` was parsed as `flags & (flag != 0)`, always checking bit 0
  instead of the correct flag bit
- Populate _contacts from cache in loadContactCache() so contacts
  persist across app restarts
- Toggle DTR low→high on USB connect to force device to see a fresh
  connection
- Add 10ms inter-frame delay for USB sends to prevent missed responses
- Deassert DTR before closing USB port on disconnect/dispose

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lib/connector/meshcore_connector.dart

@@ -19,7 +19,6 @@ import '../services/message_retry_service.dart';
 import '../services/path_history_service.dart';
 import '../services/app_settings_service.dart';
 import '../services/background_service.dart';
-import '../services/timeout_prediction_service.dart';
 import '../services/notification_service.dart';
 import 'meshcore_connector_usb.dart';
 import 'meshcore_connector_tcp.dart';
@@ -167,10 +166,6 @@ class MeshCoreConnector extends ChangeNotifier {
   bool _isLoadingContacts = false;
   bool _isLoadingChannels = false;
   bool _hasLoadedChannels = false;
-  TimeoutPredictionService? _timeoutPredictionService;
-  // Intentionally global (not per-contact): tracks overall network activity.
-  // Frequent RX from any source indicates a busy network with more collisions.
-  DateTime _lastRxTime = DateTime.now();
   bool _batteryRequested = false;
   bool _awaitingSelfInfo = false;
   bool _hasReceivedDeviceInfo = false;
@@ -294,6 +289,10 @@ class MeshCoreConnector extends ChangeNotifier {
     );
   }
 
+  List<Contact> get allContacts => List.unmodifiable([
+    ..._contacts,
+    ..._discoveredContacts.where((c) => !c.isActive),
+  ]);
   List<Contact> get discoveredContacts {
     return List.unmodifiable(_discoveredContacts);
   }
@@ -673,7 +672,6 @@ class MeshCoreConnector extends ChangeNotifier {
     BleDebugLogService? bleDebugLogService,
     AppDebugLogService? appDebugLogService,
     BackgroundService? backgroundService,
-    TimeoutPredictionService? timeoutPredictionService,
   }) {
     _retryService = retryService;
     _pathHistoryService = pathHistoryService;
@@ -681,7 +679,6 @@ class MeshCoreConnector extends ChangeNotifier {
     _bleDebugLogService = bleDebugLogService;
     _appDebugLogService = appDebugLogService;
     _backgroundService = backgroundService;
-    _timeoutPredictionService = timeoutPredictionService;
     _usbManager.setDebugLogService(_appDebugLogService);
     _tcpConnector.setDebugLogService(_appDebugLogService);
 
@@ -696,28 +693,13 @@ class MeshCoreConnector extends ChangeNotifier {
       updateMessageCallback: _updateMessage,
       clearContactPathCallback: clearContactPath,
       setContactPathCallback: setContactPath,
-      calculateTimeoutCallback:
-          (pathLength, messageBytes, {String? contactKey}) => calculateTimeout(
-            pathLength: pathLength,
-            messageBytes: messageBytes,
-            contactKey: contactKey,
-          ),
+      calculateTimeoutCallback: (pathLength, messageBytes) =>
+          calculateTimeout(pathLength: pathLength, messageBytes: messageBytes),
       getSelfPublicKeyCallback: () => _selfPublicKey,
       prepareContactOutboundTextCallback: prepareContactOutboundText,
       appSettingsService: appSettingsService,
       debugLogService: _appDebugLogService,
       recordPathResultCallback: _recordPathResult,
-      onDeliveryObservedCallback:
-          (contactKey, pathLength, messageBytes, tripTimeMs) {
-            final secSinceRx = DateTime.now().difference(_lastRxTime).inSeconds;
-            _timeoutPredictionService?.recordObservation(
-              contactKey: contactKey,
-              pathLength: pathLength,
-              messageBytes: messageBytes,
-              tripTimeMs: tripTimeMs,
-              secondsSinceLastRx: secSinceRx,
-            );
-          },
     );
   }
 
@@ -726,6 +708,9 @@ class MeshCoreConnector extends ChangeNotifier {
     _knownContactKeys
       ..clear()
       ..addAll(cached.map((c) => c.publicKeyHex));
+    _contacts
+      ..clear()
+      ..addAll(cached);
     for (final contact in cached) {
       _ensureContactSmazSettingLoaded(contact.publicKeyHex);
     }
@@ -1558,6 +1543,10 @@ class MeshCoreConnector extends ChangeNotifier {
 
     if (_activeTransport == MeshCoreTransportType.usb) {
       await _usbManager.write(data);
+      // Brief pause so the device firmware can process each frame before the
+      // next arrives. Without this, rapid-fire frames over USB can cause the
+      // device to miss responses (especially on reconnect).
+      await Future<void>.delayed(const Duration(milliseconds: 10));
     } else if (_activeTransport == MeshCoreTransportType.tcp) {
       await _tcpConnector.write(data);
     } else {
@@ -2520,7 +2509,6 @@ class MeshCoreConnector extends ChangeNotifier {
 
   void _handleFrame(List<int> data) {
     if (data.isEmpty) return;
-    _lastRxTime = DateTime.now();
 
     final frame = Uint8List.fromList(data);
     _receivedFramesController.add(frame);
@@ -2897,71 +2885,43 @@ class MeshCoreConnector extends ChangeNotifier {
     }
   }
 
-  /// Estimate single-packet airtime in ms from radio settings, or a fallback.
-  int _estimateAirtimeMs(int messageBytes) {
+  /// Calculate timeout for a message based on radio settings and path length
+  /// Returns timeout in milliseconds, considering number of hops
+  int calculateTimeout({required int pathLength, int messageBytes = 100}) {
+    // If we have radio settings, use them for accurate calculation
     if (_currentFreqHz != null &&
         _currentBwHz != null &&
         _currentSf != null &&
         _currentCr != null) {
       final cr = _currentCr! <= 4 ? _currentCr! : _currentCr! - 4;
-      return calculateLoRaAirtime(
-        payloadBytes: messageBytes,
-        spreadingFactor: _currentSf!,
-        bandwidthHz: _currentBwHz!,
-        codingRate: cr,
-        lowDataRateOptimize: _currentSf! >= 11,
+      return calculateMessageTimeout(
+        freqHz: _currentFreqHz!,
+        bwHz: _currentBwHz!,
+        sf: _currentSf!,
+        cr: cr,
+        pathLength: pathLength,
+        messageBytes: messageBytes,
       );
     }
-    return 50; // fallback: ~SF7/BW125 for 100 bytes
-  }
 
-  /// Physics-based worst-case timeout (ceiling).
-  int _physicsMaxTimeout(int pathLength, int airtime) {
+    // Fallback: Conservative estimates based on typical settings
+    // Assume SF7, BW125, which gives ~50ms airtime for 100 bytes
+    const estimatedAirtime = 50;
+
     if (pathLength < 0) {
-      return 500 + (16 * airtime);
+      // Flood mode: Base delay + 16× airtime
+      return 500 + (16 * estimatedAirtime);
     } else {
-      return 500 + ((airtime * 6 + 250) * (pathLength + 1));
+      // Direct path: Base delay + ((airtime×6 + 250ms)×(hops+1))
+      return 500 + ((estimatedAirtime * 6 + 250) * (pathLength + 1));
     }
   }
 
-  /// Physics-based minimum timeout (floor): raw traversal time.
-  int _physicsMinTimeout(int pathLength, int airtime) {
-    if (pathLength < 0) {
-      return airtime;
-    } else {
-      return airtime * (pathLength + 1);
-    }
-  }
-
-  /// Calculate timeout for a message based on radio settings and path length.
-  /// Returns timeout in milliseconds, considering number of hops.
-  int calculateTimeout({
-    required int pathLength,
-    int messageBytes = 100,
-    String? contactKey,
-  }) {
-    final airtime = _estimateAirtimeMs(messageBytes);
-    final physicsMin = _physicsMinTimeout(pathLength, airtime);
-    final physicsMax = _physicsMaxTimeout(pathLength, airtime);
-
-    // Try ML-based prediction, clamped between physics bounds
-    final secSinceRx = DateTime.now().difference(_lastRxTime).inSeconds;
-    final mlTimeout = _timeoutPredictionService?.predictTimeout(
-      contactKey: contactKey,
-      pathLength: pathLength,
-      messageBytes: messageBytes,
-      secondsSinceLastRx: secSinceRx,
-    );
-    if (mlTimeout != null) {
-      return mlTimeout.clamp(physicsMin, physicsMax);
-    }
-
-    return physicsMax;
-  }
-
   void _handleContact(Uint8List frame, {bool isContact = true}) {
     final contact = Contact.fromFrame(frame);
     if (contact != null) {
+      _handleDiscovery(contact, frame, noNotify: true, addActive: true);
+
       if (contact.type == advTypeRepeater) {
         _contactUnreadCount.remove(contact.publicKeyHex);
         _unreadStore.saveContactUnreadCount(
@@ -4770,6 +4730,12 @@ class MeshCoreConnector extends ChangeNotifier {
           (_autoAddRoomServers && type == advTypeRoom) ||
           (_autoAddSensors && type == advTypeSensor)) {
         _handleContactAdvert(newContact);
+        _handleDiscovery(
+          newContact,
+          rawPacket,
+          noNotify: true,
+          addActive: true,
+        );
       } else {
         _handleDiscovery(newContact, rawPacket);
       }
@@ -4794,8 +4760,20 @@ class MeshCoreConnector extends ChangeNotifier {
 
       // CRITICAL: Preserve user's path override when contact is refreshed from device
       _contacts[existingIndex] = existing.copyWith(
-        latitude: hasLocation ? latitude : existing.latitude,
-        longitude: hasLocation ? longitude : existing.longitude,
+        latitude:
+            hasLocation &&
+                latitude != null &&
+                latitude.abs() <= 90 &&
+                (latitude != 0 || longitude != 0)
+            ? latitude
+            : existing.latitude,
+        longitude:
+            hasLocation &&
+                longitude != null &&
+                longitude.abs() <= 180 &&
+                (latitude != 0 || longitude != 0)
+            ? longitude
+            : existing.longitude,
         name: hasName ? name : existing.name,
         path: Uint8List.fromList(path.reversed.toList()),
         pathLength: path.length,
@@ -4866,11 +4844,11 @@ class MeshCoreConnector extends ChangeNotifier {
     try {
       reader.skipBytes(1); // Skip the response code byte
       final flags = reader.readByte();
-      _autoAddUsers = flags & autoAddChatFlag != 0;
-      _autoAddRepeaters = flags & autoAddRepeaterFlag != 0;
-      _autoAddRoomServers = flags & autoAddRoomServerFlag != 0;
-      _autoAddSensors = flags & autoAddSensorFlag != 0;
-      _overwriteOldest = flags & autoAddOverwriteOldestFlag != 0;
+      _autoAddUsers = (flags & autoAddChatFlag) != 0;
+      _autoAddRepeaters = (flags & autoAddRepeaterFlag) != 0;
+      _autoAddRoomServers = (flags & autoAddRoomServerFlag) != 0;
+      _autoAddSensors = (flags & autoAddSensorFlag) != 0;
+      _overwriteOldest = (flags & autoAddOverwriteOldestFlag) != 0;
     } catch (e) {
       appLogger.error('Failed to parse auto-add config: $e', tag: 'Connector');
     }
@@ -4880,6 +4858,7 @@ class MeshCoreConnector extends ChangeNotifier {
     Contact contact,
     Uint8List rawPacket, {
     bool noNotify = false,
+    bool addActive = false,
   }) {
     appLogger.info('Discovered new contact: ${contact.name}', tag: 'Connector');
 
@@ -4900,7 +4879,7 @@ class MeshCoreConnector extends ChangeNotifier {
             longitude: contact.longitude,
             lastSeen: contact.lastSeen,
             flags: 0,
-            isActive: false,
+            isActive: addActive,
           );
       notifyListeners();
       unawaited(_persistDiscoveredContacts());
@@ -4918,7 +4897,7 @@ class MeshCoreConnector extends ChangeNotifier {
       longitude: contact.longitude,
       lastSeen: contact.lastSeen,
       lastMessageAt: contact.lastMessageAt,
-      isActive: false,
+      isActive: addActive,
       flags: 0,
     );
     _discoveredContacts.add(disContact);

lib/connector/meshcore_connector_usb.dart

@@ -64,6 +64,8 @@ class MeshCoreUsbManager {
 
   Future<void> write(Uint8List data) => _service.write(data);
 
+  Future<void> writeRaw(Uint8List data) => _service.writeRaw(data);
+
   // --- Label management ---
   void updateConnectedLabel(String selfName) {
     _service.updateConnectedLabel(selfName);

lib/main.dart

@@ -19,7 +19,6 @@ import 'services/app_debug_log_service.dart';
 import 'services/background_service.dart';
 import 'services/map_tile_cache_service.dart';
 import 'services/chat_text_scale_service.dart';
-import 'services/timeout_prediction_service.dart';
 import 'storage/prefs_manager.dart';
 import 'utils/app_logger.dart';
 
@@ -40,7 +39,6 @@ void main() async {
   final backgroundService = BackgroundService();
   final mapTileCacheService = MapTileCacheService();
   final chatTextScaleService = ChatTextScaleService();
-  final timeoutPredictionService = TimeoutPredictionService(storage);
 
   // Load settings
   await appSettingsService.loadSettings();
@@ -58,7 +56,6 @@ void main() async {
   _registerThirdPartyLicenses();
 
   await chatTextScaleService.initialize();
-  await timeoutPredictionService.initialize();
 
   // Wire up connector with services
   connector.initialize(
@@ -68,7 +65,6 @@ void main() async {
     bleDebugLogService: bleDebugLogService,
     appDebugLogService: appDebugLogService,
     backgroundService: backgroundService,
-    timeoutPredictionService: timeoutPredictionService,
   );
 
   await connector.loadContactCache();
@@ -90,7 +86,6 @@ void main() async {
       appDebugLogService: appDebugLogService,
       mapTileCacheService: mapTileCacheService,
       chatTextScaleService: chatTextScaleService,
-      timeoutPredictionService: timeoutPredictionService,
     ),
   );
 }
@@ -126,7 +121,6 @@ class MeshCoreApp extends StatelessWidget {
   final AppDebugLogService appDebugLogService;
   final MapTileCacheService mapTileCacheService;
   final ChatTextScaleService chatTextScaleService;
-  final TimeoutPredictionService timeoutPredictionService;
 
   const MeshCoreApp({
     super.key,
@@ -139,7 +133,6 @@ class MeshCoreApp extends StatelessWidget {
     required this.appDebugLogService,
     required this.mapTileCacheService,
     required this.chatTextScaleService,
-    required this.timeoutPredictionService,
   });
 
   @override
@@ -155,7 +148,6 @@ class MeshCoreApp extends StatelessWidget {
         ChangeNotifierProvider.value(value: chatTextScaleService),
         Provider.value(value: storage),
         Provider.value(value: mapTileCacheService),
-        ChangeNotifierProvider.value(value: timeoutPredictionService),
       ],
       child: Consumer<AppSettingsService>(
         builder: (context, settingsService, child) {

lib/models/app_settings.dart

@@ -40,6 +40,8 @@ class AppSettings {
   final UnitSystem unitSystem;
   final Set<String> mutedChannels;
   final bool mapShowDiscoveryContacts;
+  final String tcpServerAddress;
+  final int tcpServerPort;
 
   AppSettings({
     this.clearPathOnMaxRetry = false,
@@ -68,6 +70,8 @@ class AppSettings {
     this.unitSystem = UnitSystem.metric,
     Set<String>? mutedChannels,
     this.mapShowDiscoveryContacts = true,
+    this.tcpServerAddress = '',
+    this.tcpServerPort = 0,
   }) : batteryChemistryByDeviceId = batteryChemistryByDeviceId ?? {},
        batteryChemistryByRepeaterId = batteryChemistryByRepeaterId ?? {},
        mutedChannels = mutedChannels ?? {};
@@ -100,6 +104,8 @@ class AppSettings {
       'unit_system': unitSystem.value,
       'muted_channels': mutedChannels.toList(),
       'map_show_discovery_contacts': mapShowDiscoveryContacts,
+      'tcp_server_address': tcpServerAddress,
+      'tcp_server_port': tcpServerPort,
     };
   }
 
@@ -157,6 +163,8 @@ class AppSettings {
           {},
       mapShowDiscoveryContacts:
           json['map_show_discovery_contacts'] as bool? ?? true,
+      tcpServerAddress: json['tcp_server_address'] as String? ?? '',
+      tcpServerPort: json['tcp_server_port'] as int? ?? 0,
     );
   }
 
@@ -187,6 +195,8 @@ class AppSettings {
     UnitSystem? unitSystem,
     Set<String>? mutedChannels,
     bool? mapShowDiscoveryContacts,
+    String? tcpServerAddress,
+    int? tcpServerPort,
   }) {
     return AppSettings(
       clearPathOnMaxRetry: clearPathOnMaxRetry ?? this.clearPathOnMaxRetry,
@@ -225,6 +235,8 @@ class AppSettings {
       mutedChannels: mutedChannels ?? this.mutedChannels,
       mapShowDiscoveryContacts:
           mapShowDiscoveryContacts ?? this.mapShowDiscoveryContacts,
+      tcpServerAddress: tcpServerAddress ?? this.tcpServerAddress,
+      tcpServerPort: tcpServerPort ?? this.tcpServerPort,
     );
   }
 }

lib/models/contact.dart

@@ -65,7 +65,17 @@ class Contact {
     return '$pathLength hops';
   }
 
-  bool get hasLocation => latitude != null && longitude != null;
+  bool get hasLocation {
+    const double epsilon = 1e-6;
+    final lat = latitude ?? 0.0;
+    final lon = longitude ?? 0.0;
+    return (lat.abs() > epsilon || lon.abs() > epsilon) &&
+        lat >= -90.0 &&
+        lat <= 90.0 &&
+        lon >= -180.0 &&
+        lon <= 180.0;
+  }
+
   bool get isFavorite => (flags & contactFlagFavorite) != 0;
 
   Contact copyWith({
@@ -108,7 +118,7 @@ class Contact {
   }
 
   String get pathIdList {
-    final pathBytes = _pathBytesForDisplay;
+    final pathBytes = pathBytesForDisplay;
     if (pathBytes.isEmpty) return '';
     final parts = <String>[];
     final groupSize = pathHashSize;
@@ -130,43 +140,7 @@ class Contact {
     return "<${publicKeyHex.substring(0, 8)}...${publicKeyHex.substring(publicKeyHex.length - 8)}>";
   }
 
-  Uint8List? get traceRouteBytes {
-    final pathBytes = _pathBytesForDisplay;
-    Uint8List? traceBytes;
-
-    if (pathBytes.isEmpty) {
-      traceBytes = Uint8List(1);
-      traceBytes[0] = publicKey[0];
-      return traceBytes;
-    }
-
-    if (type == advTypeRepeater || type == advTypeRoom) {
-      final len = (pathBytes.length + pathBytes.length + 1);
-      traceBytes = Uint8List(len);
-      traceBytes[pathBytes.length] = publicKey[0];
-      for (int i = 0; i < pathBytes.length; i++) {
-        traceBytes[i] = pathBytes[i];
-        if (i < pathBytes.length) {
-          traceBytes[len - 1 - i] = pathBytes[i];
-        }
-      }
-    } else {
-      if (pathBytes.length < 2) {
-        return pathBytes[0] == 0 ? null : pathBytes;
-      }
-      final len = (pathBytes.length + pathBytes.length - 1);
-      traceBytes = Uint8List(len);
-      for (int i = 0; i < pathBytes.length; i++) {
-        traceBytes[i] = pathBytes[i];
-        if (i < pathBytes.length - 1) {
-          traceBytes[len - 1 - i] = pathBytes[i];
-        }
-      }
-    }
-    return traceBytes;
-  }
-
-  Uint8List get _pathBytesForDisplay {
+  Uint8List get pathBytesForDisplay {
     if (pathOverride != null) {
       if (pathOverride! < 0) return Uint8List(0);
       return pathOverrideBytes ?? Uint8List(0);
@@ -197,6 +171,7 @@ class Contact {
       double? lat, lon;
       final latRaw = reader.readInt32LE();
       final lonRaw = reader.readInt32LE();
+
       if (latRaw != 0 || lonRaw != 0) {
         lat = latRaw / 1e6;
         lon = lonRaw / 1e6;

lib/models/delivery_observation.dart

@@ -1,43 +0,0 @@
-class DeliveryObservation {
-  final String contactKey;
-  final int pathLength;
-  final int messageBytes;
-  final int secondsSinceLastRx;
-  final bool isFlood;
-  final int deliveryMs;
-  final DateTime timestamp;
-
-  DeliveryObservation({
-    required this.contactKey,
-    required this.pathLength,
-    required this.messageBytes,
-    required this.secondsSinceLastRx,
-    required this.isFlood,
-    required this.deliveryMs,
-    required this.timestamp,
-  });
-
-  Map<String, dynamic> toJson() {
-    return {
-      'contact_key': contactKey,
-      'path_length': pathLength,
-      'message_bytes': messageBytes,
-      'seconds_since_last_rx': secondsSinceLastRx,
-      'is_flood': isFlood,
-      'delivery_ms': deliveryMs,
-      'timestamp': timestamp.toIso8601String(),
-    };
-  }
-
-  factory DeliveryObservation.fromJson(Map<String, dynamic> json) {
-    return DeliveryObservation(
-      contactKey: json['contact_key'] as String,
-      pathLength: json['path_length'] as int,
-      messageBytes: json['message_bytes'] as int,
-      secondsSinceLastRx: json['seconds_since_last_rx'] as int? ?? 0,
-      isFlood: json['is_flood'] as bool,
-      deliveryMs: json['delivery_ms'] as int,
-      timestamp: DateTime.parse(json['timestamp'] as String),
-    );
-  }
-}

lib/screens/channel_message_path_screen.dart

@@ -40,10 +40,7 @@ class ChannelMessagePathScreen extends StatelessWidget {
         final primaryPath = !channelMessage && !message.isOutgoing
             ? Uint8List.fromList(primaryPathTmp.reversed.toList())
             : primaryPathTmp;
-        final contacts = <Contact>[
-          ...connector.contacts,
-          ...connector.discoveredContacts,
-        ];
+        final contacts = connector.allContacts;
         final hops = _buildPathHops(primaryPath, contacts, l10n);
         final hasHopDetails = primaryPath.isNotEmpty;
         final observedLabel = _formatObservedHops(
@@ -65,8 +62,9 @@ class ChannelMessagePathScreen extends StatelessWidget {
                     builder: (context) => PathTraceMapScreen(
                       title: context.l10n.contacts_repeaterPathTrace,
                       path: primaryPath,
-                      flipPathRound: true,
-                      reversePathRound: !message.isOutgoing && !channelMessage,
+                      flipPathAround: true,
+                      reversePathAround:
+                          !(!channelMessage && !message.isOutgoing),
                     ),
                   ),
                 ),
@@ -367,10 +365,7 @@ class _ChannelMessagePathMapScreenState
             : selectedPathTmp;
 
         final selectedIndex = _indexForPath(selectedPath, observedPaths);
-        final contacts = <Contact>[
-          ...connector.contacts,
-          ...connector.discoveredContacts,
-        ];
+        final contacts = connector.allContacts;
         final hops = _buildPathHops(selectedPath, contacts, context.l10n);
 
         final points = <LatLng>[];

lib/screens/chat_screen.dart

@@ -858,7 +858,7 @@ class _ChatScreenState extends State<ChatScreen> {
                 builder: (context) => PathTraceMapScreen(
                   title: context.l10n.contacts_repeaterPathTrace,
                   path: Uint8List.fromList(pathBytes),
-                  flipPathRound: true,
+                  flipPathAround: true,
                   targetContact: widget.contact,
                 ),
               ),
@@ -1027,7 +1027,7 @@ class _ChatScreenState extends State<ChatScreen> {
     final currentPathLabel = _currentPathLabel(currentContact);
 
     // Filter out the current contact from available contacts
-    final availableContacts = connector.contacts
+    final availableContacts = connector.allContacts
         .where((c) => c != widget.contact)
         .toList();
 

lib/screens/contacts_screen.dart

@@ -1064,7 +1064,7 @@ class _ContactsScreenState extends State<ContactsScreen>
             if (isRepeater) ...[
               ListTile(
                 leading: const Icon(Icons.radar, color: Colors.green),
-                title: contact.pathLength > 0
+                title: contact.pathBytesForDisplay.isNotEmpty
                     ? Text(context.l10n.contacts_pathTrace)
                     : Text(context.l10n.contacts_ping),
                 onTap: () {
@@ -1072,10 +1072,12 @@ class _ContactsScreenState extends State<ContactsScreen>
                     context,
                     MaterialPageRoute(
                       builder: (context) => PathTraceMapScreen(
-                        title: contact.pathLength > 0
+                        title: contact.pathBytesForDisplay.isNotEmpty
                             ? context.l10n.contacts_repeaterPathTrace
                             : context.l10n.contacts_repeaterPing,
-                        path: contact.traceRouteBytes ?? Uint8List(0),
+                        path: contact.pathBytesForDisplay,
+                        flipPathAround: true,
+                        targetContact: contact,
                       ),
                     ),
                   );
@@ -1100,10 +1102,12 @@ class _ContactsScreenState extends State<ContactsScreen>
                     context,
                     MaterialPageRoute(
                       builder: (context) => PathTraceMapScreen(
-                        title: contact.pathLength > 0
+                        title: contact.pathBytesForDisplay.isNotEmpty
                             ? context.l10n.contacts_roomPathTrace
                             : context.l10n.contacts_roomPing,
-                        path: contact.traceRouteBytes ?? Uint8List(0),
+                        path: contact.pathBytesForDisplay,
+                        flipPathAround: contact.pathBytesForDisplay.isNotEmpty,
+                        targetContact: contact,
                       ),
                     ),
                   );
@@ -1145,7 +1149,8 @@ class _ContactsScreenState extends State<ContactsScreen>
                           title: context.l10n.contacts_pathTraceTo(
                             contact.name,
                           ),
-                          path: contact.traceRouteBytes ?? Uint8List(0),
+                          path: contact.pathBytesForDisplay,
+                          flipPathAround: true,
                           targetContact: contact,
                         ),
                       ),

lib/screens/map_screen.dart

@@ -137,10 +137,7 @@ class _MapScreenState extends State<MapScreen> {
       builder: (context, connector, settingsService, pathHistory, child) {
         final tileCache = context.read<MapTileCacheService>();
         final settings = settingsService.settings;
-        final allContacts = <Contact>[
-          ...connector.contacts,
-          ...connector.discoveredContacts.where((c) => !c.isActive),
-        ];
+        final allContacts = connector.allContacts;
 
         final contacts = settings.mapShowDiscoveryContacts
             ? allContacts
@@ -179,20 +176,13 @@ class _MapScreenState extends State<MapScreen> {
 
         // Filter by location
         final contactsWithLocation = filteredByKeyPrefix.where((c) {
-          if (!c.hasLocation) {
-            return false;
-          }
-          return _checkLocationPlausibility(c.latitude!, c.longitude!);
+          return c.hasLocation;
         }).toList();
 
         // All contacts with a known location — used as anchors regardless of
         // time/key-prefix filters so that repeaters are always available.
         final allContactsWithLocation = allContacts
-            .where(
-              (c) =>
-                  c.hasLocation &&
-                  _checkLocationPlausibility(c.latitude!, c.longitude!),
-            )
+            .where((c) => c.hasLocation)
             .toList();
 
         // Compute guessed locations with caching

lib/screens/neighbors_screen.dart

@@ -124,10 +124,7 @@ class _NeighborsScreenState extends State<NeighborsScreen> {
 
   void _handleNeighborsResponse(MeshCoreConnector connector, Uint8List frame) {
     final buffer = BufferReader(frame);
-    final contacts = <Contact>[
-      ...connector.contacts,
-      ...connector.discoveredContacts,
-    ];
+    final contacts = connector.allContacts;
     try {
       final neighborCount = buffer.readUInt16LE();
       final parsedNeighbors = parseNeighborsData(buffer, buffer.readUInt16LE());

lib/screens/path_trace_map.dart

@@ -52,8 +52,8 @@ class PathTraceMapScreen extends StatefulWidget {
   final String title;
   final Uint8List path;
   final int? repeaterId;
-  final bool flipPathRound;
-  final bool reversePathRound;
+  final bool flipPathAround;
+  final bool reversePathAround;
   final Contact? targetContact;
 
   const PathTraceMapScreen({
@@ -61,8 +61,8 @@ class PathTraceMapScreen extends StatefulWidget {
     required this.title,
     required this.path,
     this.repeaterId,
-    this.flipPathRound = false,
-    this.reversePathRound = false,
+    this.flipPathAround = false,
+    this.reversePathAround = false,
     this.targetContact,
   });
 
@@ -93,6 +93,7 @@ class _PathTraceMapScreenState extends State<PathTraceMapScreen> {
   ValueKey<String> _mapKey = const ValueKey('initial');
   double _pathDistanceMeters = 0.0;
   bool _showNodeLabels = true;
+  Contact? _targetContact;
 
   String _formatPathPrefixes(Uint8List pathBytes) {
     return pathBytes
@@ -158,21 +159,16 @@ class _PathTraceMapScreenState extends State<PathTraceMapScreen> {
       });
     }
 
-    final Uint8List path;
-
-    Uint8List pathTmp = widget.reversePathRound
+    final pathTmp = widget.reversePathAround
         ? Uint8List.fromList(widget.path.reversed.toList())
         : widget.path;
 
-    if (widget.flipPathRound) {
-      path = buildPath(pathTmp);
-    } else {
-      path = pathTmp;
-    }
+    final path = widget.flipPathAround ? buildPath(pathTmp) : pathTmp;
 
     appLogger.info(
       'Initiating path trace with path: ${_formatPathPrefixes(path)}',
       tag: 'PathTraceMapScreen',
+      noNotify: !mounted,
     );
 
     final connector = Provider.of<MeshCoreConnector>(context, listen: false);
@@ -263,10 +259,7 @@ class _PathTraceMapScreenState extends State<PathTraceMapScreen> {
           .toList();
 
       Map<int, Contact> pathContacts = {};
-      final contacts = <Contact>[
-        ...connector.contacts,
-        ...connector.discoveredContacts,
-      ];
+      final contacts = connector.allContacts;
       contacts.where((c) => c.type != advTypeChat).forEach((repeater) {
         for (var repeaterData in pathData) {
           if (listEquals(
@@ -312,18 +305,21 @@ class _PathTraceMapScreenState extends State<PathTraceMapScreen> {
         // Compute endpoint position for the target contact.
         LatLng? targetPos;
         bool targetGuessed = false;
-        final target = widget.targetContact;
-        if (target != null) {
-          if (target.hasLocation) {
-            targetPos = LatLng(target.latitude!, target.longitude!);
-          } else if (pathData.isNotEmpty) {
+        _targetContact = widget.targetContact;
+
+        if (_targetContact != null) {
+          final tc = _targetContact!;
+          if (tc.hasLocation) {
+            targetPos = LatLng(tc.latitude!, tc.longitude!);
+          } else if (widget.path.length > 1) {
             // Infer from the last hop: average GPS contacts sharing that hop.
-            // For a round-trip path (flipPathRound), the target-side hop sits
-            // in the middle of the symmetric sequence; .last is the local side.
-            final lastHop = (widget.flipPathRound && pathData.length > 1)
-                ? pathData[(pathData.length - 1) ~/ 2]
-                : pathData.last;
-            final peers = connector.contacts
+            // For a round-trip path (flipPathAround/reversePathAround), the target-side hop
+            // sits in the middle of the symmetric sequence; .last is the local side.
+            final lastHop = widget.reversePathAround
+                ? widget.path.first
+                : widget.path.last;
+
+            final peers = connector.allContacts
                 .where(
                   (c) =>
                       c.hasLocation &&
@@ -339,12 +335,34 @@ class _PathTraceMapScreenState extends State<PathTraceMapScreen> {
                   peers.map((c) => c.longitude!).reduce((a, b) => a + b) /
                   peers.length;
               const offsetDeg = 0.003;
-              final angle = (target.publicKey[1] / 255.0) * 2 * pi;
+              final angle = (tc.publicKey[1] / 255.0) * 2 * pi;
               targetPos = LatLng(
                 lat + offsetDeg * cos(angle),
                 lon + offsetDeg * sin(angle),
               );
               targetGuessed = true;
+            } else if (inferredPositions.containsKey(lastHop)) {
+              final lat = inferredPositions[lastHop]!.latitude;
+              final lon = inferredPositions[lastHop]!.longitude;
+              const offsetDeg = 0.003;
+              final angle = (tc.publicKey[1] / 255.0) * 2 * pi;
+              targetPos = LatLng(
+                lat + offsetDeg * cos(angle),
+                lon + offsetDeg * sin(angle),
+              );
+              targetGuessed = true;
+            } else {
+              // As a last resort, just place it at the same position as the last hop.
+              final contact = pathContacts[lastHop];
+              if (contact != null && contact.hasLocation) {
+                const offsetDeg = 0.003;
+                final angle = (tc.publicKey[1] / 255.0) * 2 * pi;
+                targetPos = LatLng(
+                  contact.latitude! + offsetDeg * cos(angle),
+                  contact.longitude! + offsetDeg * sin(angle),
+                );
+                targetGuessed = true;
+              }
             }
           }
         }
@@ -353,7 +371,12 @@ class _PathTraceMapScreenState extends State<PathTraceMapScreen> {
 
         _points = <LatLng>[];
         _points.add(LatLng(connector.selfLatitude!, connector.selfLongitude!));
+        int hopLast = 0;
+        int hopLastLast = 0;
         for (final hop in _traceData!.pathData) {
+          if (hop == hopLastLast && widget.flipPathAround) {
+            break; //skip duplicate hops in round-trip paths
+          }
           final contact = _traceData!.pathContacts[hop];
           if (contact != null && contact.hasLocation) {
             _points.add(LatLng(contact.latitude!, contact.longitude!));
@@ -361,8 +384,14 @@ class _PathTraceMapScreenState extends State<PathTraceMapScreen> {
             final inferred = inferredPositions[hop];
             if (inferred != null) _points.add(inferred);
           }
+          hopLastLast = hopLast;
+          hopLast = hop;
+        }
+        if (targetPos != null) {
+          if (_targetContact != null && _targetContact!.type == advTypeChat) {
+            _points.add(targetPos);
+          }
         }
-        if (targetPos != null) _points.add(targetPos);
         _polylines = _points.length > 1
             ? [
                 Polyline(
@@ -451,7 +480,8 @@ class _PathTraceMapScreenState extends State<PathTraceMapScreen> {
                       ],
                     ),
                   ),
-                if (_hasData) _buildMapPathTrace(context, tileCache),
+                if (_hasData)
+                  _buildMapPathTrace(context, tileCache, _targetContact),
                 if (_points.isEmpty &&
                     !_hasData &&
                     !_isLoading &&
@@ -480,17 +510,28 @@ class _PathTraceMapScreenState extends State<PathTraceMapScreen> {
   List<Marker> _buildHopMarkers(
     List<int> pathData, {
     required bool showLabels,
+    required Contact? target,
   }) {
     final markers = <Marker>[];
+    int hopLast = 0;
+    int hopLastLast = 0;
     for (final hop in pathData) {
       final contact = _traceData!.pathContacts[hop];
       final inferred = _inferredHopPositions[hop];
       final hasGps = contact != null && contact.hasLocation;
-      if (!hasGps && inferred == null) continue;
+      if (hop == hopLastLast && widget.flipPathAround) {
+        continue; //skip duplicate hops in round-trip paths
+      }
+      if (!hasGps && inferred == null) {
+        hopLastLast = hopLast;
+        hopLast = hop;
+        continue; //skip hops with no GPS and no inferred position
+      }
       final point = hasGps
           ? LatLng(contact.latitude!, contact.longitude!)
           : inferred!;
       final label = hop.toRadixString(16).padLeft(2, '0').toUpperCase();
+
       markers.add(
         Marker(
           point: point,
@@ -532,6 +573,8 @@ class _PathTraceMapScreenState extends State<PathTraceMapScreen> {
           ),
         );
       }
+      hopLastLast = hopLast;
+      hopLast = hop;
     }
 
     final selfLat = context.read<MeshCoreConnector>().selfLatitude;
@@ -581,9 +624,9 @@ class _PathTraceMapScreenState extends State<PathTraceMapScreen> {
 
     // Add target contact endpoint marker.
     final targetPos = _targetContactPosition;
-    if (targetPos != null) {
+    if (targetPos != null && target != null && target.type == advTypeChat) {
       final isGuessed = _targetContactIsGuessed;
-      final targetName = widget.targetContact?.name ?? '?';
+      final targetName = target.name;
       markers.add(
         Marker(
           point: targetPos,
@@ -719,6 +762,7 @@ class _PathTraceMapScreenState extends State<PathTraceMapScreen> {
   Widget _buildMapPathTrace(
     BuildContext context,
     MapTileCacheService tileCache,
+    Contact? target,
   ) {
     return FlutterMap(
       key: _mapKey,
@@ -757,6 +801,7 @@ class _PathTraceMapScreenState extends State<PathTraceMapScreen> {
             markers: _buildHopMarkers(
               _traceData!.pathData,
               showLabels: _showNodeLabels,
+              target: target,
             ),
           ),
       ],

lib/screens/tcp_screen.dart

@@ -5,6 +5,7 @@ import 'package:provider/provider.dart';
 
 import '../connector/meshcore_connector.dart';
 import '../l10n/l10n.dart';
+import '../services/app_settings_service.dart';
 import '../utils/platform_info.dart';
 import '../widgets/adaptive_app_bar_title.dart';
 import 'contacts_screen.dart';
@@ -27,8 +28,14 @@ class _TcpScreenState extends State<TcpScreen> {
   @override
   void initState() {
     super.initState();
-    _hostController = TextEditingController();
-    _portController = TextEditingController(text: '5000');
+    _hostController = TextEditingController(
+      text: context.read<AppSettingsService>().settings.tcpServerAddress,
+    );
+    _portController = TextEditingController(
+      text: context.read<AppSettingsService>().settings.tcpServerPort > 0
+          ? context.read<AppSettingsService>().settings.tcpServerPort.toString()
+          : '',
+    );
     _connector = context.read<MeshCoreConnector>();
 
     _connectionListener = () {
@@ -39,6 +46,12 @@ class _TcpScreenState extends State<TcpScreen> {
       if (_connector.state == MeshCoreConnectionState.connected &&
           _connector.isTcpTransportConnected &&
           !_navigatedToContacts) {
+        context.read<AppSettingsService>().setTcpServerAddress(
+          _hostController.text,
+        );
+        context.read<AppSettingsService>().setTcpServerPort(
+          int.tryParse(_portController.text) ?? 0,
+        );
         _navigatedToContacts = true;
         Navigator.of(context).pushReplacement(
           MaterialPageRoute(builder: (_) => const ContactsScreen()),

lib/services/app_debug_log_service.dart

@@ -51,6 +51,7 @@ class AppDebugLogService extends ChangeNotifier {
     String message, {
     String tag = 'App',
     AppDebugLogLevel level = AppDebugLogLevel.info,
+    bool noNotify = false,
   }) {
     if (!_enabled && !kDebugMode) return;
     if (!_enabled) {
@@ -72,22 +73,24 @@ class AppDebugLogService extends ChangeNotifier {
       _entries.removeRange(0, _entries.length - maxEntries);
     }
 
-    notifyListeners();
+    if (!noNotify) {
+      notifyListeners();
+    }
 
     // Also print to console for development
     debugPrint('[$tag] $message');
   }
 
-  void info(String message, {String tag = 'App'}) {
-    log(message, tag: tag, level: AppDebugLogLevel.info);
+  void info(String message, {String tag = 'App', bool noNotify = false}) {
+    log(message, tag: tag, level: AppDebugLogLevel.info, noNotify: noNotify);
   }
 
-  void warn(String message, {String tag = 'App'}) {
-    log(message, tag: tag, level: AppDebugLogLevel.warning);
+  void warn(String message, {String tag = 'App', bool noNotify = false}) {
+    log(message, tag: tag, level: AppDebugLogLevel.warning, noNotify: noNotify);
   }
 
-  void error(String message, {String tag = 'App'}) {
-    log(message, tag: tag, level: AppDebugLogLevel.error);
+  void error(String message, {String tag = 'App', bool noNotify = false}) {
+    log(message, tag: tag, level: AppDebugLogLevel.error, noNotify: noNotify);
   }
 
   void clear() {

lib/services/app_settings_service.dart

@@ -182,4 +182,12 @@ class AppSettingsService extends ChangeNotifier {
       ..remove(channelName);
     await updateSettings(_settings.copyWith(mutedChannels: updated));
   }
+
+  Future<void> setTcpServerAddress(String value) async {
+    await updateSettings(_settings.copyWith(tcpServerAddress: value));
+  }
+
+  Future<void> setTcpServerPort(int value) async {
+    await updateSettings(_settings.copyWith(tcpServerPort: value));
+  }
 }

lib/services/message_retry_service.dart

@@ -58,13 +58,12 @@ class MessageRetryService extends ChangeNotifier {
   Function(Message)? _updateMessageCallback;
   Function(Contact)? _clearContactPathCallback;
   Function(Contact, Uint8List, int)? _setContactPathCallback;
-  Function(int, int, {String? contactKey})? _calculateTimeoutCallback;
+  Function(int, int)? _calculateTimeoutCallback;
   Uint8List? Function()? _getSelfPublicKeyCallback;
   String Function(Contact, String)? _prepareContactOutboundTextCallback;
   AppSettingsService? _appSettingsService;
   AppDebugLogService? _debugLogService;
   Function(String, PathSelection, bool, int?)? _recordPathResultCallback;
-  Function(String, int, int, int)? _onDeliveryObservedCallback;
 
   MessageRetryService();
 
@@ -74,20 +73,12 @@ class MessageRetryService extends ChangeNotifier {
     required Function(Message) updateMessageCallback,
     Function(Contact)? clearContactPathCallback,
     Function(Contact, Uint8List, int)? setContactPathCallback,
-    Function(int pathLength, int messageBytes, {String? contactKey})?
-    calculateTimeoutCallback,
+    Function(int pathLength, int messageBytes)? calculateTimeoutCallback,
     Uint8List? Function()? getSelfPublicKeyCallback,
     String Function(Contact, String)? prepareContactOutboundTextCallback,
     AppSettingsService? appSettingsService,
     AppDebugLogService? debugLogService,
     Function(String, PathSelection, bool, int?)? recordPathResultCallback,
-    Function(
-      String contactKey,
-      int pathLength,
-      int messageBytes,
-      int tripTimeMs,
-    )?
-    onDeliveryObservedCallback,
   }) {
     _sendMessageCallback = sendMessageCallback;
     _addMessageCallback = addMessageCallback;
@@ -100,7 +91,6 @@ class MessageRetryService extends ChangeNotifier {
     _appSettingsService = appSettingsService;
     _debugLogService = debugLogService;
     _recordPathResultCallback = recordPathResultCallback;
-    _onDeliveryObservedCallback = onDeliveryObservedCallback;
   }
 
   /// Compute expected ACK hash using same algorithm as firmware:
@@ -433,33 +423,25 @@ class MessageRetryService extends ChangeNotifier {
       );
     }
 
-    // Calculate timeout: prefer ML prediction, then device-provided, then physics fallback
-    int pathLengthValue;
-    if (selection != null) {
-      pathLengthValue = selection.useFlood ? -1 : selection.hopCount;
-      if (pathLengthValue < 0) pathLengthValue = contact.pathLength;
-    } else if (message.pathLength != null) {
-      pathLengthValue = message.pathLength!;
-    } else {
-      pathLengthValue = contact.pathLength;
-    }
-
+    // Use device-provided timeout, or calculate from radio settings if timeout is 0 or invalid
     int actualTimeout = timeoutMs;
-    if (_calculateTimeoutCallback != null) {
-      final calculated = _calculateTimeoutCallback!(
+    if (timeoutMs <= 0 && _calculateTimeoutCallback != null) {
+      int pathLengthValue;
+      if (selection != null) {
+        pathLengthValue = selection.useFlood ? -1 : selection.hopCount;
+        if (pathLengthValue < 0) pathLengthValue = contact.pathLength;
+      } else if (message.pathLength != null) {
+        pathLengthValue = message.pathLength!;
+      } else {
+        pathLengthValue = contact.pathLength;
+      }
+      actualTimeout = _calculateTimeoutCallback!(
         pathLengthValue,
         message.text.length,
-        contactKey: contact.publicKeyHex,
       );
-      // calculateTimeout tries ML first, falls back to physics.
-      // Use calculated value if device didn't provide one, or if ML
-      // produced a tighter prediction than the device's estimate.
-      if (timeoutMs <= 0 || calculated < timeoutMs) {
-        actualTimeout = calculated;
-        debugPrint(
-          'Using calculated timeout: ${actualTimeout}ms for path length $pathLengthValue',
-        );
-      }
+      debugPrint(
+        'Using calculated timeout: ${actualTimeout}ms for path length $pathLengthValue',
+      );
     }
 
     final updatedMessage = message.copyWith(
@@ -756,16 +738,6 @@ class MessageRetryService extends ChangeNotifier {
           true,
           tripTimeMs,
         );
-        if (_onDeliveryObservedCallback != null &&
-            tripTimeMs > 0 &&
-            message.pathLength != null) {
-          _onDeliveryObservedCallback!(
-            contact.publicKeyHex,
-            message.pathLength!,
-            message.text.length,
-            tripTimeMs,
-          );
-        }
         _onMessageResolved(matchedMessageId, contact.publicKeyHex);
       }
 

lib/services/storage_service.dart

@@ -1,5 +1,4 @@
 import 'dart:convert';
-import '../models/delivery_observation.dart';
 import '../models/path_history.dart';
 import '../storage/prefs_manager.dart';
 
@@ -7,7 +6,6 @@ class StorageService {
   static const String _pathHistoryPrefix = 'path_history_';
   static const String _pendingMessagesKey = 'pending_messages';
   static const String _repeaterPasswordsKey = 'repeater_passwords';
-  static const String _deliveryObservationsKey = 'delivery_observations';
 
   Future<void> savePathHistory(
     String contactPubKeyHex,
@@ -124,33 +122,4 @@ class StorageService {
     final prefs = PrefsManager.instance;
     await prefs.remove(_repeaterPasswordsKey);
   }
-
-  Future<void> saveDeliveryObservations(
-    List<DeliveryObservation> observations,
-  ) async {
-    final prefs = PrefsManager.instance;
-    final jsonStr = jsonEncode(observations.map((o) => o.toJson()).toList());
-    await prefs.setString(_deliveryObservationsKey, jsonStr);
-  }
-
-  Future<List<DeliveryObservation>> loadDeliveryObservations() async {
-    final prefs = PrefsManager.instance;
-    final jsonStr = prefs.getString(_deliveryObservationsKey);
-
-    if (jsonStr == null) return [];
-
-    try {
-      final list = jsonDecode(jsonStr) as List;
-      return list
-          .map((e) => DeliveryObservation.fromJson(e as Map<String, dynamic>))
-          .toList();
-    } catch (e) {
-      return [];
-    }
-  }
-
-  Future<void> clearDeliveryObservations() async {
-    final prefs = PrefsManager.instance;
-    await prefs.remove(_deliveryObservationsKey);
-  }
 }

lib/services/timeout_prediction_service.dart

@@ -1,229 +0,0 @@
-import 'dart:async';
-import 'package:flutter/foundation.dart';
-import 'package:ml_algo/ml_algo.dart';
-import 'package:ml_dataframe/ml_dataframe.dart';
-import '../models/delivery_observation.dart';
-import 'storage_service.dart';
-
-class _ContactStats {
-  int count = 0;
-  double _sum = 0;
-
-  void add(double ms) {
-    count++;
-    _sum += ms;
-  }
-
-  double get mean => _sum / count;
-}
-
-class TimeoutPredictionService extends ChangeNotifier {
-  final StorageService? _storage;
-
-  static const int minObservations = 10;
-  static const int maxObservations = 100;
-  static const int _retrainInterval = 5;
-  // 1.5x multiplier on raw prediction to account for variance in delivery
-  // times — tight enough to improve on worst-case physics, loose enough
-  // to avoid premature timeouts from model noise.
-  static const double _safetyMargin = 1.5;
-  static const int _minContactObservations = 10;
-
-  List<DeliveryObservation> _observations = [];
-  LinearRegressor? _model;
-  List<String> _activeFeatures = [];
-  int _observationsSinceLastTrain = 0;
-  final Map<String, _ContactStats> _contactStats = {};
-  Timer? _persistTimer;
-
-  TimeoutPredictionService(StorageService storage) : _storage = storage;
-  TimeoutPredictionService.noStorage() : _storage = null;
-
-  int get observationCount => _observations.length;
-  bool get hasModel => _model != null;
-
-  Future<void> initialize() async {
-    _observations = await _storage?.loadDeliveryObservations() ?? [];
-    _rebuildContactStats();
-
-    if (_observations.length >= minObservations) {
-      _trainModel();
-    }
-
-    debugPrint(
-      'TimeoutPrediction: initialized with ${_observations.length} observations, '
-      'model=${_model != null ? "ready" : "waiting for data"}',
-    );
-  }
-
-  void recordObservation({
-    required String contactKey,
-    required int pathLength,
-    required int messageBytes,
-    required int tripTimeMs,
-    int secondsSinceLastRx = 0,
-  }) {
-    final observation = DeliveryObservation(
-      contactKey: contactKey,
-      pathLength: pathLength,
-      messageBytes: messageBytes,
-      secondsSinceLastRx: secondsSinceLastRx,
-      isFlood: pathLength < 0,
-      deliveryMs: tripTimeMs,
-      timestamp: DateTime.now(),
-    );
-
-    _observations.add(observation);
-    if (_observations.length > maxObservations) {
-      _observations.removeAt(0);
-    }
-
-    _contactStats.putIfAbsent(contactKey, () => _ContactStats());
-    _contactStats[contactKey]!.add(tripTimeMs.toDouble());
-
-    _observationsSinceLastTrain++;
-    if (_observationsSinceLastTrain >= _retrainInterval &&
-        _observations.length >= minObservations) {
-      _trainModel();
-    }
-
-    _persistTimer?.cancel();
-    _persistTimer = Timer(const Duration(seconds: 2), () {
-      _storage?.saveDeliveryObservations(_observations);
-    });
-    debugPrint(
-      'TimeoutPrediction: recorded ${tripTimeMs}ms for $pathLength hops '
-      '(${_observations.length} total)',
-    );
-  }
-
-  int? predictTimeout({
-    String? contactKey,
-    required int pathLength,
-    required int messageBytes,
-    int secondsSinceLastRx = 0,
-  }) {
-    if (_model == null) return null;
-
-    try {
-      if (_activeFeatures.isEmpty) return null;
-
-      final allFeatures = {
-        'pathLength': pathLength.toDouble(),
-        'messageBytes': messageBytes.toDouble(),
-        'secSinceRx': secondsSinceLastRx.toDouble(),
-        'isFlood': pathLength < 0 ? 1.0 : 0.0,
-      };
-      final row = _activeFeatures.map((f) => allFeatures[f]!).toList();
-
-      final features = DataFrame(
-        [row],
-        headerExists: false,
-        header: _activeFeatures,
-      );
-
-      final prediction = _model!.predict(features);
-      final rawValue = prediction.rows.first.first;
-      var predictedMs = (rawValue is double)
-          ? rawValue
-          : (rawValue as num).toDouble();
-
-      debugPrint(
-        'TimeoutPrediction: raw prediction=$predictedMs for '
-        'pathLength=$pathLength, messageBytes=$messageBytes, '
-        'features=$_activeFeatures',
-      );
-
-      // Sanity check: if prediction is negative or zero, fall back
-      if (predictedMs <= 0) return null;
-
-      // Blend with per-contact mean if enough data
-      if (contactKey != null) {
-        final stats = _contactStats[contactKey];
-        if (stats != null && stats.count >= _minContactObservations) {
-          predictedMs = 0.5 * predictedMs + 0.5 * stats.mean;
-        }
-      }
-
-      // Connector clamps this between physics min/max bounds
-      final timeout = (predictedMs * _safetyMargin).ceil();
-      debugPrint(
-        'TimeoutPrediction: ML timeout ${timeout}ms '
-        '(raw: ${predictedMs.round()}ms, contact: $contactKey)',
-      );
-      return timeout;
-    } catch (e) {
-      debugPrint('TimeoutPrediction: prediction failed: $e');
-      return null;
-    }
-  }
-
-  void _trainModel() {
-    try {
-      // Build feature columns, then exclude any with zero variance
-      // (ml_algo's OLS produces all-zero coefficients for singular matrices)
-      final allNames = ['pathLength', 'messageBytes', 'secSinceRx', 'isFlood'];
-      final allExtractors = <double Function(DeliveryObservation)>[
-        (o) => o.pathLength.toDouble(),
-        (o) => o.messageBytes.toDouble(),
-        (o) => o.secondsSinceLastRx.toDouble(),
-        (o) => o.isFlood ? 1.0 : 0.0,
-      ];
-
-      _activeFeatures = [];
-      for (var i = 0; i < allNames.length; i++) {
-        final values = _observations.map(allExtractors[i]).toSet();
-        if (values.length > 1) _activeFeatures.add(allNames[i]);
-      }
-
-      if (_activeFeatures.isEmpty) {
-        debugPrint(
-          'TimeoutPrediction: no features with variance, skipping training',
-        );
-        return;
-      }
-
-      final header = [..._activeFeatures, 'deliveryMs'];
-      final rows = _observations.map((o) {
-        final row = <double>[];
-        for (var i = 0; i < allNames.length; i++) {
-          if (_activeFeatures.contains(allNames[i])) {
-            row.add(allExtractors[i](o));
-          }
-        }
-        row.add(o.deliveryMs.toDouble());
-        return row;
-      });
-
-      final data = DataFrame([header, ...rows], headerExists: true);
-
-      _model = LinearRegressor(data, 'deliveryMs');
-      _observationsSinceLastTrain = 0;
-
-      // Log training summary with sample predictions
-      final avgMs =
-          _observations.map((o) => o.deliveryMs).reduce((a, b) => a + b) /
-          _observations.length;
-      debugPrint(
-        'TimeoutPrediction: trained on ${_observations.length} observations '
-        '(avg: ${avgMs.round()}ms, features: $_activeFeatures)',
-      );
-    } catch (e) {
-      debugPrint('TimeoutPrediction: training failed: $e');
-    }
-  }
-
-  @override
-  void dispose() {
-    _persistTimer?.cancel();
-    super.dispose();
-  }
-
-  void _rebuildContactStats() {
-    _contactStats.clear();
-    for (final obs in _observations) {
-      _contactStats.putIfAbsent(obs.contactKey, () => _ContactStats());
-      _contactStats[obs.contactKey]!.add(obs.deliveryMs.toDouble());
-    }
-  }
-}

lib/services/usb_serial_service_native.dart

@@ -189,6 +189,10 @@ class UsbSerialService {
           serial.setStopBits1();
           serial.setFlowControlNone();
           serial.setRTS(false);
+          // Toggle DTR low→high so the device sees a fresh connection even
+          // if the previous disconnect didn't cleanly signal DTR drop.
+          serial.setDTR(false);
+          await Future<void>.delayed(const Duration(milliseconds: 50));
           serial.setDTR(true);
           _serial = serial;
           // Update the normalized port name to whichever candidate succeeded.
@@ -249,6 +253,21 @@ class UsbSerialService {
     _status = UsbSerialStatus.connected;
   }
 
+  Future<void> writeRaw(Uint8List data) async {
+    if (!isConnected) {
+      throw StateError('USB serial port is not open');
+    }
+    if (_useAndroidUsbHost) {
+      try {
+        await _androidMethodChannel.invokeMethod<void>('write', {'data': data});
+      } on PlatformException catch (error) {
+        throw StateError(error.message ?? error.code);
+      }
+    } else {
+      _serial!.write(data);
+    }
+  }
+
   Future<void> write(Uint8List data) async {
     if (!isConnected) {
       throw StateError('USB serial port is not open');
@@ -300,6 +319,7 @@ class UsbSerialService {
       _serial = null;
       try {
         if (serial?.isOpen() == FlOpenStatus.open) {
+          serial?.setDTR(false);
           serial?.closePort();
         }
       } catch (_) {
@@ -350,6 +370,7 @@ class UsbSerialService {
       final serial = _serial;
       try {
         if (serial?.isOpen() == FlOpenStatus.open) {
+          serial?.setDTR(false);
           serial?.closePort(); // synchronous C call — kills the SerialThread
         }
       } catch (_) {}

lib/services/usb_serial_service_web.dart

@@ -127,6 +127,17 @@ class UsbSerialService {
     }
   }
 
+  Future<void> writeRaw(Uint8List data) async {
+    if (!isConnected || _writer == null) {
+      throw StateError('USB serial port is not open');
+    }
+    final promise = _writer!.callMethod<JSPromise<JSAny?>>(
+      'write'.toJS,
+      data.toJS,
+    );
+    await promise.toDart;
+  }
+
   Future<void> write(Uint8List data) async {
     if (!isConnected || _writer == null) {
       throw StateError('USB serial port is not open');

lib/utils/app_logger.dart

@@ -23,23 +23,23 @@ class AppLogger {
   bool get isEnabled => _enabled;
 
   /// Log an info message
-  void info(String message, {String tag = 'App'}) {
+  void info(String message, {String tag = 'App', bool noNotify = false}) {
     if (_enabled && _service != null) {
-      _service!.info(message, tag: tag);
+      _service!.info(message, tag: tag, noNotify: noNotify);
     }
   }
 
   /// Log a warning message
-  void warn(String message, {String tag = 'App'}) {
+  void warn(String message, {String tag = 'App', bool noNotify = false}) {
     if (_enabled && _service != null) {
-      _service!.warn(message, tag: tag);
+      _service!.warn(message, tag: tag, noNotify: noNotify);
     }
   }
 
   /// Log an error message
-  void error(String message, {String tag = 'App'}) {
+  void error(String message, {String tag = 'App', bool noNotify = false}) {
     if (_enabled && _service != null) {
-      _service!.error(message, tag: tag);
+      _service!.error(message, tag: tag, noNotify: noNotify);
     }
   }
 
@@ -48,9 +48,10 @@ class AppLogger {
     String message, {
     String tag = 'App',
     AppDebugLogLevel level = AppDebugLogLevel.info,
+    bool noNotify = false,
   }) {
     if (_enabled && _service != null) {
-      _service!.log(message, tag: tag, level: level);
+      _service!.log(message, tag: tag, level: level, noNotify: noNotify);
     }
   }
 }

lib/widgets/path_management_dialog.dart

@@ -78,7 +78,7 @@ class _PathManagementDialogState extends State<_PathManagementDialog> {
                 builder: (context) => PathTraceMapScreen(
                   title: context.l10n.contacts_repeaterPathTrace,
                   path: Uint8List.fromList(pathBytes),
-                  flipPathRound: true,
+                  flipPathAround: true,
                   targetContact: widget.contact,
                 ),
               ),
@@ -107,7 +107,7 @@ class _PathManagementDialogState extends State<_PathManagementDialog> {
     }
 
     final pathForInput = currentContact.pathIdList;
-    final availableContacts = connector.contacts
+    final availableContacts = connector.allContacts
         .where((c) => c.publicKeyHex != currentContact.publicKeyHex)
         .toList();
 

lib/widgets/path_selection_dialog.dart

@@ -1,5 +1,6 @@
 import 'dart:typed_data';
 import 'package:flutter/material.dart';
+import 'package:meshcore_open/connector/meshcore_protocol.dart';
 import '../l10n/l10n.dart';
 import '../models/contact.dart';
 
@@ -65,7 +66,7 @@ class _PathSelectionDialogState extends State<PathSelectionDialog> {
 
   void _filterValidContacts() {
     _validContacts = widget.availableContacts
-        .where((c) => c.type == 2 || c.type == 3)
+        .where((c) => c.type == advTypeRepeater || c.type == advTypeRoom)
         .toList();
   }
 

lib/widgets/snr_indicator.dart

@@ -157,10 +157,7 @@ class _SNRIndicatorState extends State<SNRIndicator> {
                   repeater.snr,
                   widget.connector.currentSf,
                 );
-                final allContacts = [
-                  ...widget.connector.contacts,
-                  ...widget.connector.discoveredContacts,
-                ];
+                final allContacts = widget.connector.allContacts;
                 final name = allContacts
                     .where((c) => c.publicKey.first == repeater.pubkeyFirstByte)
                     .map((c) => c.name)

pubspec.yaml

@@ -69,8 +69,6 @@ dependencies:
   material_symbols_icons: ^4.2906.0
   web: ^1.1.1
   flutter_svg: ^2.0.10+1
-  ml_algo: ^16.0.0
-  ml_dataframe: ^1.0.0
 
 dev_dependencies:
   flutter_test:

test/services/ml_algo_sanity_test.dart

@@ -1,156 +0,0 @@
-import 'package:flutter/foundation.dart';
-import 'package:flutter_test/flutter_test.dart';
-import 'package:ml_algo/ml_algo.dart';
-import 'package:ml_dataframe/ml_dataframe.dart';
-
-void main() {
-  test('LinearRegressor basic sanity check', () {
-    // Simple: y = 2x + 100
-    final data = DataFrame(
-      [
-        [1.0, 102.0],
-        [2.0, 104.0],
-        [3.0, 106.0],
-        [4.0, 108.0],
-        [5.0, 110.0],
-        [10.0, 120.0],
-        [20.0, 140.0],
-        [50.0, 200.0],
-        [0.0, 100.0],
-        [100.0, 300.0],
-      ],
-      headerExists: false,
-      header: ['x', 'y'],
-    );
-
-    debugPrint('Training data columns: ${data.header}');
-    debugPrint('Training data rows: ${data.rows.length}');
-
-    final model = LinearRegressor(data, 'y');
-
-    final testDf = DataFrame(
-      [
-        [25.0],
-      ],
-      headerExists: false,
-      header: ['x'],
-    );
-
-    final prediction = model.predict(testDf);
-    final value = prediction.rows.first.first;
-    debugPrint('Predict x=25 → y=$value (expected ~150)');
-    expect((value as num).toDouble(), closeTo(150, 5));
-  });
-
-  test('LinearRegressor multi-feature with constant column produces zeros', () {
-    // isFlood=0 for all rows → zero-variance column → singular matrix
-    final data = DataFrame(
-      [
-        [0.0, 50.0, 14.0, 0.0, 1900.0],
-        [0.0, 80.0, 14.0, 0.0, 2200.0],
-        [2.0, 50.0, 14.0, 0.0, 5000.0],
-        [4.0, 50.0, 14.0, 0.0, 9500.0],
-      ],
-      headerExists: false,
-      header: [
-        'pathLength',
-        'messageBytes',
-        'hourOfDay',
-        'isFlood',
-        'deliveryMs',
-      ],
-    );
-
-    final model = LinearRegressor(data, 'deliveryMs');
-    final testDf = DataFrame(
-      [
-        [2.0, 50.0, 14.0, 0.0],
-      ],
-      headerExists: false,
-      header: ['pathLength', 'messageBytes', 'hourOfDay', 'isFlood'],
-    );
-    final pred = model.predict(testDf).rows.first.first;
-    debugPrint(
-      'With constant isFlood column: hops=2 → ${(pred as num).round()}ms (likely 0)',
-    );
-  });
-
-  test('LinearRegressor 2-feature works correctly', () {
-    // Just pathLength + messageBytes → deliveryMs
-    final data = DataFrame(
-      [
-        [0.0, 50.0, 1900.0],
-        [0.0, 80.0, 2200.0],
-        [2.0, 50.0, 5000.0],
-        [2.0, 80.0, 5500.0],
-        [4.0, 50.0, 9500.0],
-        [4.0, 80.0, 10000.0],
-        [0.0, 30.0, 1800.0],
-        [2.0, 30.0, 4800.0],
-        [4.0, 30.0, 9000.0],
-        [0.0, 60.0, 2000.0],
-      ],
-      headerExists: false,
-      header: ['pathLength', 'messageBytes', 'deliveryMs'],
-    );
-
-    final model = LinearRegressor(data, 'deliveryMs');
-
-    for (final hops in [0.0, 2.0, 4.0]) {
-      final testDf = DataFrame(
-        [
-          [hops, 50.0],
-        ],
-        headerExists: false,
-        header: ['pathLength', 'messageBytes'],
-      );
-      final pred = model.predict(testDf).rows.first.first;
-      debugPrint('2-feature: hops=$hops → ${(pred as num).round()}ms');
-    }
-  });
-
-  test('LinearRegressor multi-feature with variance in all columns', () {
-    // Mix flood and direct so isFlood has variance
-    final data = DataFrame(
-      [
-        [0.0, 50.0, 14.0, 0.0, 1900.0],
-        [0.0, 80.0, 10.0, 0.0, 2200.0],
-        [2.0, 50.0, 16.0, 0.0, 5000.0],
-        [2.0, 80.0, 20.0, 0.0, 5500.0],
-        [4.0, 50.0, 8.0, 0.0, 9500.0],
-        [4.0, 80.0, 12.0, 0.0, 10000.0],
-        [-1.0, 40.0, 14.0, 1.0, 5000.0],
-        [-1.0, 60.0, 18.0, 1.0, 6500.0],
-        [-1.0, 30.0, 10.0, 1.0, 4000.0],
-        [-1.0, 80.0, 22.0, 1.0, 7000.0],
-      ],
-      headerExists: false,
-      header: [
-        'pathLength',
-        'messageBytes',
-        'hourOfDay',
-        'isFlood',
-        'deliveryMs',
-      ],
-    );
-
-    final model = LinearRegressor(data, 'deliveryMs');
-
-    for (final tc in [
-      [0.0, 50.0, 14.0, 0.0],
-      [2.0, 50.0, 14.0, 0.0],
-      [4.0, 50.0, 14.0, 0.0],
-      [-1.0, 50.0, 14.0, 1.0],
-    ]) {
-      final testDf = DataFrame(
-        [tc],
-        headerExists: false,
-        header: ['pathLength', 'messageBytes', 'hourOfDay', 'isFlood'],
-      );
-      final pred = model.predict(testDf).rows.first.first;
-      debugPrint(
-        '4-feature: hops=${tc[0]} flood=${tc[3]} → ${(pred as num).round()}ms',
-      );
-    }
-  });
-}

test/services/timeout_prediction_service_test.dart

@@ -1,164 +0,0 @@
-import 'package:flutter/foundation.dart';
-import 'package:flutter_test/flutter_test.dart';
-import 'package:meshcore_open/models/delivery_observation.dart';
-import 'package:meshcore_open/services/timeout_prediction_service.dart';
-
-void main() {
-  late TimeoutPredictionService service;
-
-  setUp(() {
-    service = TimeoutPredictionService.noStorage();
-  });
-
-  test('trains on sample data and predicts sensible timeouts', () {
-    // Simulate realistic delivery data:
-    // Direct 0-hop messages: ~1500-2500ms
-    // 2-hop messages: ~4000-6000ms
-    // 4-hop messages: ~8000-12000ms
-    // Flood messages: ~3000-8000ms
-    final sampleData = [
-      // 0-hop direct
-      _obs(pathLength: 0, messageBytes: 20, deliveryMs: 1800),
-      _obs(pathLength: 0, messageBytes: 50, deliveryMs: 2100),
-      _obs(pathLength: 0, messageBytes: 80, deliveryMs: 2400),
-      _obs(pathLength: 0, messageBytes: 30, deliveryMs: 1925),
-      // 2-hop direct
-      _obs(pathLength: 2, messageBytes: 40, deliveryMs: 4500),
-      _obs(pathLength: 2, messageBytes: 60, deliveryMs: 5200),
-      _obs(pathLength: 2, messageBytes: 25, deliveryMs: 4100),
-      // 4-hop direct
-      _obs(pathLength: 4, messageBytes: 50, deliveryMs: 9800),
-      _obs(pathLength: 4, messageBytes: 30, deliveryMs: 8500),
-      _obs(pathLength: 4, messageBytes: 70, deliveryMs: 10570),
-      // Flood
-      _obs(pathLength: -1, messageBytes: 40, deliveryMs: 5000),
-      _obs(pathLength: -1, messageBytes: 60, deliveryMs: 6500),
-    ];
-
-    // Feed all observations
-    for (final obs in sampleData) {
-      service.recordObservation(
-        contactKey: obs.contactKey,
-        pathLength: obs.pathLength,
-        messageBytes: obs.messageBytes,
-        tripTimeMs: obs.deliveryMs,
-      );
-    }
-
-    expect(service.hasModel, isTrue);
-    expect(service.observationCount, equals(12));
-
-    // Predict for different scenarios
-    final direct0 = service.predictTimeout(pathLength: 0, messageBytes: 50);
-    final direct2 = service.predictTimeout(pathLength: 2, messageBytes: 50);
-    final direct4 = service.predictTimeout(pathLength: 4, messageBytes: 50);
-    final flood = service.predictTimeout(pathLength: -1, messageBytes: 50);
-
-    // All should return non-null (model is trained)
-    expect(direct0, isNotNull);
-    expect(direct2, isNotNull);
-    expect(direct4, isNotNull);
-    expect(flood, isNotNull);
-
-    // More hops should predict longer timeouts
-    expect(direct4!, greaterThan(direct2!));
-    expect(direct2, greaterThan(direct0!));
-
-    // All should be positive
-    expect(direct0, greaterThan(0));
-    expect(direct4, greaterThan(0));
-
-    // Print predictions for visibility
-    debugPrint('Predictions (with 1.5x safety margin):');
-    debugPrint('  0-hop direct: ${direct0}ms');
-    debugPrint('  2-hop direct: ${direct2}ms');
-    debugPrint('  4-hop direct: ${direct4}ms');
-    debugPrint('  flood:        ${flood}ms');
-  });
-
-  test('returns null before minimum observations', () {
-    for (var i = 0; i < TimeoutPredictionService.minObservations - 1; i++) {
-      service.recordObservation(
-        contactKey: 'abc',
-        pathLength: 0,
-        messageBytes: 50,
-        tripTimeMs: 2000,
-      );
-    }
-
-    expect(service.hasModel, isFalse);
-    expect(service.predictTimeout(pathLength: 0, messageBytes: 50), isNull);
-  });
-
-  test('caps observations at maxObservations', () {
-    for (var i = 0; i < TimeoutPredictionService.maxObservations + 20; i++) {
-      service.recordObservation(
-        contactKey: 'abc',
-        pathLength: 0,
-        messageBytes: 50,
-        tripTimeMs: 2000 + i,
-      );
-    }
-
-    expect(
-      service.observationCount,
-      equals(TimeoutPredictionService.maxObservations),
-    );
-  });
-
-  test('blends per-contact stats after enough observations', () {
-    // Train with mixed contacts and varied features:
-    // contactA is fast (0-hop), contactB is slow (2-hop)
-    for (var i = 0; i < 12; i++) {
-      service.recordObservation(
-        contactKey: 'contactA',
-        pathLength: 0,
-        messageBytes: 30 + i,
-        tripTimeMs: 1500,
-      );
-      service.recordObservation(
-        contactKey: 'contactB',
-        pathLength: 2,
-        messageBytes: 30 + i,
-        tripTimeMs: 8000,
-      );
-    }
-
-    final predA = service.predictTimeout(
-      contactKey: 'contactA',
-      pathLength: 0,
-      messageBytes: 50,
-    );
-    final predB = service.predictTimeout(
-      contactKey: 'contactB',
-      pathLength: 0,
-      messageBytes: 50,
-    );
-
-    expect(predA, isNotNull);
-    expect(predB, isNotNull);
-    // Contact B (slow) should have a higher predicted timeout than A (fast)
-    expect(predB!, greaterThan(predA!));
-
-    debugPrint('Per-contact blending:');
-    debugPrint('  contactA (fast): ${predA}ms');
-    debugPrint('  contactB (slow): ${predB}ms');
-  });
-}
-
-DeliveryObservation _obs({
-  required int pathLength,
-  required int messageBytes,
-  required int deliveryMs,
-  String contactKey = 'test_contact',
-}) {
-  return DeliveryObservation(
-    contactKey: contactKey,
-    pathLength: pathLength,
-    messageBytes: messageBytes,
-    secondsSinceLastRx: 5,
-    isFlood: pathLength < 0,
-    deliveryMs: deliveryMs,
-    timestamp: DateTime.now(),
-  );
-}