chore: update version to 7.0.0+8 in pubspec.yaml

Improvements to path tracing and location handling

lib/connector/meshcore_connector.dart

@@ -19,6 +19,7 @@ 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';
@@ -166,6 +167,10 @@ 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;
@@ -672,6 +677,7 @@ class MeshCoreConnector extends ChangeNotifier {
     BleDebugLogService? bleDebugLogService,
     AppDebugLogService? appDebugLogService,
     BackgroundService? backgroundService,
+    TimeoutPredictionService? timeoutPredictionService,
   }) {
     _retryService = retryService;
     _pathHistoryService = pathHistoryService;
@@ -679,6 +685,7 @@ class MeshCoreConnector extends ChangeNotifier {
     _bleDebugLogService = bleDebugLogService;
     _appDebugLogService = appDebugLogService;
     _backgroundService = backgroundService;
+    _timeoutPredictionService = timeoutPredictionService;
     _usbManager.setDebugLogService(_appDebugLogService);
     _tcpConnector.setDebugLogService(_appDebugLogService);
 
@@ -693,13 +700,28 @@ class MeshCoreConnector extends ChangeNotifier {
       updateMessageCallback: _updateMessage,
       clearContactPathCallback: clearContactPath,
       setContactPathCallback: setContactPath,
-      calculateTimeoutCallback: (pathLength, messageBytes) =>
+      calculateTimeoutCallback:
-          calculateTimeout(pathLength: pathLength, messageBytes: messageBytes),
+          (pathLength, messageBytes, {String? contactKey}) => calculateTimeout(
+            pathLength: pathLength,
+            messageBytes: messageBytes,
+            contactKey: contactKey,
+          ),
       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,
+            );
+          },
     );
   }
 
@@ -2509,6 +2531,7 @@ class MeshCoreConnector extends ChangeNotifier {
 
   void _handleFrame(List<int> data) {
     if (data.isEmpty) return;
+    _lastRxTime = DateTime.now();
 
     final frame = Uint8List.fromList(data);
     _receivedFramesController.add(frame);
@@ -2885,36 +2908,66 @@ class MeshCoreConnector extends ChangeNotifier {
     }
   }
 
-  /// Calculate timeout for a message based on radio settings and path length
+  /// Estimate single-packet airtime in ms from radio settings, or a fallback.
-  /// Returns timeout in milliseconds, considering number of hops
+  int _estimateAirtimeMs(int messageBytes) {
-  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 calculateMessageTimeout(
+      return calculateLoRaAirtime(
-        freqHz: _currentFreqHz!,
+        payloadBytes: messageBytes,
-        bwHz: _currentBwHz!,
+        spreadingFactor: _currentSf!,
-        sf: _currentSf!,
+        bandwidthHz: _currentBwHz!,
-        cr: cr,
+        codingRate: cr,
-        pathLength: pathLength,
+        lowDataRateOptimize: _currentSf! >= 11,
-        messageBytes: messageBytes,
       );
     }
-
+    return 50; // fallback: ~SF7/BW125 for 100 bytes
-    // Fallback: Conservative estimates based on typical settings
-    // Assume SF7, BW125, which gives ~50ms airtime for 100 bytes
-    const estimatedAirtime = 50;
-
-    if (pathLength < 0) {
-      // Flood mode: Base delay + 16× airtime
-      return 500 + (16 * estimatedAirtime);
-    } else {
-      // Direct path: Base delay + ((airtime×6 + 250ms)×(hops+1))
-      return 500 + ((estimatedAirtime * 6 + 250) * (pathLength + 1));
   }
+
+  /// Physics-based worst-case timeout (ceiling).
+  int _physicsMaxTimeout(int pathLength, int airtime) {
+    if (pathLength < 0) {
+      return 500 + (16 * airtime);
+    } else {
+      return 500 + ((airtime * 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}) {

lib/l10n/app_bg.arb

@@ -285,6 +285,7 @@
   "contacts_newGroup": "Нова група",
   "contacts_groupName": "Група",
   "contacts_groupNameRequired": "Името на групата е задължително.",
+  "contacts_groupNameReserved": "Това име на група е запазено",
   "contacts_groupAlreadyExists": "Групата \"{name}\" вече съществува.",
   "@contacts_groupAlreadyExists": {
     "placeholders": {

lib/l10n/app_de.arb

@@ -285,6 +285,7 @@
   "contacts_newGroup": "Neue Gruppe",
   "contacts_groupName": "Gruppenname",
   "contacts_groupNameRequired": "Der Gruppennamen ist erforderlich.",
+  "contacts_groupNameReserved": "Dieser Gruppenname ist reserviert",
   "contacts_groupAlreadyExists": "Die Gruppe \"{name}\" existiert bereits.",
   "@contacts_groupAlreadyExists": {
     "placeholders": {

lib/l10n/app_en.arb

@@ -416,6 +416,7 @@
   "contacts_newGroup": "New Group",
   "contacts_groupName": "Group name",
   "contacts_groupNameRequired": "Group name is required",
+  "contacts_groupNameReserved": "This group name is reserved",
   "contacts_groupAlreadyExists": "Group \"{name}\" already exists",
   "@contacts_groupAlreadyExists": {
     "placeholders": {

lib/l10n/app_es.arb

@@ -285,6 +285,7 @@
   "contacts_newGroup": "Nuevo Grupo",
   "contacts_groupName": "Nombre del grupo",
   "contacts_groupNameRequired": "El nombre del grupo es obligatorio",
+  "contacts_groupNameReserved": "Este nombre de grupo está reservado",
   "contacts_groupAlreadyExists": "El grupo \"{name}\" ya existe",
   "@contacts_groupAlreadyExists": {
     "placeholders": {

lib/l10n/app_fr.arb

@@ -285,6 +285,7 @@
   "contacts_newGroup": "Nouveau Groupe",
   "contacts_groupName": "Nom du groupe",
   "contacts_groupNameRequired": "Le nom du groupe est obligatoire.",
+  "contacts_groupNameReserved": "Ce nom de groupe est réservé",
   "contacts_groupAlreadyExists": "Le groupe \"{name}\" existe déjà.",
   "@contacts_groupAlreadyExists": {
     "placeholders": {

lib/l10n/app_it.arb

@@ -285,6 +285,7 @@
   "contacts_newGroup": "Nuovo Gruppo",
   "contacts_groupName": "Nome gruppo",
   "contacts_groupNameRequired": "Il nome del gruppo è obbligatorio.",
+  "contacts_groupNameReserved": "Questo nome del gruppo è riservato",
   "contacts_groupAlreadyExists": "Il gruppo \"{name}\" esiste già.",
   "@contacts_groupAlreadyExists": {
     "placeholders": {

lib/l10n/app_localizations.dart

@@ -1714,6 +1714,12 @@ abstract class AppLocalizations {
   /// **'Group name is required'**
   String get contacts_groupNameRequired;
 
+  /// No description provided for @contacts_groupNameReserved.
+  ///
+  /// In en, this message translates to:
+  /// **'This group name is reserved'**
+  String get contacts_groupNameReserved;
+
   /// No description provided for @contacts_groupAlreadyExists.
   ///
   /// In en, this message translates to:

lib/l10n/app_localizations_bg.dart

@@ -902,6 +902,9 @@ class AppLocalizationsBg extends AppLocalizations {
   @override
   String get contacts_groupNameRequired => 'Името на групата е задължително.';
 
+  @override
+  String get contacts_groupNameReserved => 'Това име на група е запазено';
+
   @override
   String contacts_groupAlreadyExists(String name) {
     return 'Групата \"$name\" вече съществува.';

lib/l10n/app_localizations_de.dart

@@ -902,6 +902,9 @@ class AppLocalizationsDe extends AppLocalizations {
   @override
   String get contacts_groupNameRequired => 'Der Gruppennamen ist erforderlich.';
 
+  @override
+  String get contacts_groupNameReserved => 'Dieser Gruppenname ist reserviert';
+
   @override
   String contacts_groupAlreadyExists(String name) {
     return 'Die Gruppe \"$name\" existiert bereits.';

lib/l10n/app_localizations_en.dart

@@ -889,6 +889,9 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get contacts_groupNameRequired => 'Group name is required';
 
+  @override
+  String get contacts_groupNameReserved => 'This group name is reserved';
+
   @override
   String contacts_groupAlreadyExists(String name) {
     return 'Group \"$name\" already exists';

lib/l10n/app_localizations_es.dart

@@ -901,6 +901,10 @@ class AppLocalizationsEs extends AppLocalizations {
   @override
   String get contacts_groupNameRequired => 'El nombre del grupo es obligatorio';
 
+  @override
+  String get contacts_groupNameReserved =>
+      'Este nombre de grupo está reservado';
+
   @override
   String contacts_groupAlreadyExists(String name) {
     return 'El grupo \"$name\" ya existe';

lib/l10n/app_localizations_fr.dart

@@ -905,6 +905,9 @@ class AppLocalizationsFr extends AppLocalizations {
   @override
   String get contacts_groupNameRequired => 'Le nom du groupe est obligatoire.';
 
+  @override
+  String get contacts_groupNameReserved => 'Ce nom de groupe est réservé';
+
   @override
   String contacts_groupAlreadyExists(String name) {
     return 'Le groupe \"$name\" existe déjà.';

lib/l10n/app_localizations_it.dart

@@ -901,6 +901,9 @@ class AppLocalizationsIt extends AppLocalizations {
   @override
   String get contacts_groupNameRequired => 'Il nome del gruppo è obbligatorio.';
 
+  @override
+  String get contacts_groupNameReserved => 'Questo nome del gruppo è riservato';
+
   @override
   String contacts_groupAlreadyExists(String name) {
     return 'Il gruppo \"$name\" esiste già.';

lib/l10n/app_localizations_nl.dart

@@ -895,6 +895,9 @@ class AppLocalizationsNl extends AppLocalizations {
   @override
   String get contacts_groupNameRequired => 'De groepnaam is verplicht.';
 
+  @override
+  String get contacts_groupNameReserved => 'Deze groepsnaam is gereserveerd';
+
   @override
   String contacts_groupAlreadyExists(String name) {
     return 'De groep \"$name\" bestaat al.';

lib/l10n/app_localizations_pl.dart

@@ -904,6 +904,9 @@ class AppLocalizationsPl extends AppLocalizations {
   @override
   String get contacts_groupNameRequired => 'Nazwa grupy jest wymagana';
 
+  @override
+  String get contacts_groupNameReserved => 'Ta nazwa grupy jest zastrzeżona';
+
   @override
   String contacts_groupAlreadyExists(String name) {
     return 'Grupa \"$name\" już istnieje';

lib/l10n/app_localizations_pt.dart

@@ -903,6 +903,9 @@ class AppLocalizationsPt extends AppLocalizations {
   @override
   String get contacts_groupNameRequired => 'O nome do grupo é obrigatório.';
 
+  @override
+  String get contacts_groupNameReserved => 'Este nome de grupo está reservado';
+
   @override
   String contacts_groupAlreadyExists(String name) {
     return 'O grupo \"$name\" já existe';

lib/l10n/app_localizations_ru.dart

@@ -902,6 +902,9 @@ class AppLocalizationsRu extends AppLocalizations {
   @override
   String get contacts_groupNameRequired => 'Имя группы обязательно';
 
+  @override
+  String get contacts_groupNameReserved => 'Это имя группы зарезервировано';
+
   @override
   String contacts_groupAlreadyExists(String name) {
     return 'Группа \"$name\" уже существует';

lib/l10n/app_localizations_sk.dart

@@ -894,6 +894,9 @@ class AppLocalizationsSk extends AppLocalizations {
   @override
   String get contacts_groupNameRequired => 'Skupina musí mať názov.';
 
+  @override
+  String get contacts_groupNameReserved => 'Tento názov skupiny je rezervovaný';
+
   @override
   String contacts_groupAlreadyExists(String name) {
     return 'Skupina \"$name\" už existuje';

lib/l10n/app_localizations_sl.dart

@@ -892,6 +892,9 @@ class AppLocalizationsSl extends AppLocalizations {
   @override
   String get contacts_groupNameRequired => 'Ime skupine je obvezno.';
 
+  @override
+  String get contacts_groupNameReserved => 'To ime skupine je rezervirano';
+
   @override
   String contacts_groupAlreadyExists(String name) {
     return 'Skupina \"$name\" že obstaja';

lib/l10n/app_localizations_sv.dart

@@ -888,6 +888,9 @@ class AppLocalizationsSv extends AppLocalizations {
   @override
   String get contacts_groupNameRequired => 'Gruppnamnet är obligatoriskt';
 
+  @override
+  String get contacts_groupNameReserved => 'Detta gruppnamn är reserverat';
+
   @override
   String contacts_groupAlreadyExists(String name) {
     return 'Gruppen \"$name\" finns redan.';

lib/l10n/app_localizations_uk.dart

@@ -898,6 +898,9 @@ class AppLocalizationsUk extends AppLocalizations {
   @override
   String get contacts_groupNameRequired => 'Назва групи обов\'язкова.';
 
+  @override
+  String get contacts_groupNameReserved => 'Ця назва групи зарезервована';
+
   @override
   String contacts_groupAlreadyExists(String name) {
     return 'Група «$name» вже існує.';

lib/l10n/app_localizations_zh.dart

@@ -845,6 +845,9 @@ class AppLocalizationsZh extends AppLocalizations {
   @override
   String get contacts_groupNameRequired => '请输入群聊名称';
 
+  @override
+  String get contacts_groupNameReserved => '该群组名称已被保留';
+
   @override
   String contacts_groupAlreadyExists(String name) {
     return '名为 \"$name\" 的群聊已存在';

lib/l10n/app_nl.arb

@@ -285,6 +285,7 @@
   "contacts_newGroup": "Nieuwe Groep",
   "contacts_groupName": "Groepnaam",
   "contacts_groupNameRequired": "De groepnaam is verplicht.",
+  "contacts_groupNameReserved": "Deze groepsnaam is gereserveerd",
   "contacts_groupAlreadyExists": "De groep \"{name}\" bestaat al.",
   "@contacts_groupAlreadyExists": {
     "placeholders": {

lib/l10n/app_pl.arb

@@ -285,6 +285,7 @@
   "contacts_newGroup": "Nowa Grupa",
   "contacts_groupName": "Nazwa grupy",
   "contacts_groupNameRequired": "Nazwa grupy jest wymagana",
+  "contacts_groupNameReserved": "Ta nazwa grupy jest zastrzeżona",
   "contacts_groupAlreadyExists": "Grupa \"{name}\" już istnieje",
   "@contacts_groupAlreadyExists": {
     "placeholders": {

lib/l10n/app_pt.arb

@@ -285,6 +285,7 @@
   "contacts_newGroup": "Novo Grupo",
   "contacts_groupName": "Nome do grupo",
   "contacts_groupNameRequired": "O nome do grupo é obrigatório.",
+  "contacts_groupNameReserved": "Este nome de grupo está reservado",
   "contacts_groupAlreadyExists": "O grupo \"{name}\" já existe",
   "@contacts_groupAlreadyExists": {
     "placeholders": {

lib/l10n/app_ru.arb

@@ -212,6 +212,7 @@
   "contacts_newGroup": "Новая группа",
   "contacts_groupName": "Имя группы",
   "contacts_groupNameRequired": "Имя группы обязательно",
+  "contacts_groupNameReserved": "Это имя группы зарезервировано",
   "contacts_groupAlreadyExists": "Группа \"{name}\" уже существует",
   "contacts_filterContacts": "Фильтр контактов...",
   "contacts_noContactsMatchFilter": "Нет контактов, соответствующих фильтру",

lib/l10n/app_sk.arb

@@ -285,6 +285,7 @@
   "contacts_newGroup": "Nová skupina",
   "contacts_groupName": "Názov skupiny",
   "contacts_groupNameRequired": "Skupina musí mať názov.",
+  "contacts_groupNameReserved": "Tento názov skupiny je rezervovaný",
   "contacts_groupAlreadyExists": "Skupina \"{name}\" už existuje",
   "@contacts_groupAlreadyExists": {
     "placeholders": {

lib/l10n/app_sl.arb

@@ -285,6 +285,7 @@
   "contacts_newGroup": "Nova skupina",
   "contacts_groupName": "Ime skupine",
   "contacts_groupNameRequired": "Ime skupine je obvezno.",
+  "contacts_groupNameReserved": "To ime skupine je rezervirano",
   "contacts_groupAlreadyExists": "Skupina \"{name}\" že obstaja",
   "@contacts_groupAlreadyExists": {
     "placeholders": {

lib/l10n/app_sv.arb

@@ -285,6 +285,7 @@
   "contacts_newGroup": "Ny grupp",
   "contacts_groupName": "Gruppnamn",
   "contacts_groupNameRequired": "Gruppnamnet är obligatoriskt",
+  "contacts_groupNameReserved": "Detta gruppnamn är reserverat",
   "contacts_groupAlreadyExists": "Gruppen \"{name}\" finns redan.",
   "@contacts_groupAlreadyExists": {
     "placeholders": {

lib/l10n/app_uk.arb

@@ -286,6 +286,7 @@
   "contacts_newGroup": "Нова група",
   "contacts_groupName": "Назва групи",
   "contacts_groupNameRequired": "Назва групи обов'язкова.",
+  "contacts_groupNameReserved": "Ця назва групи зарезервована",
   "contacts_groupAlreadyExists": "Група «{name}» вже існує.",
   "@contacts_groupAlreadyExists": {
     "placeholders": {

lib/l10n/app_zh.arb

@@ -300,6 +300,7 @@
   "contacts_newGroup": "新建群聊",
   "contacts_groupName": "群聊名称",
   "contacts_groupNameRequired": "请输入群聊名称",
+  "contacts_groupNameReserved": "该群组名称已被保留",
   "contacts_groupAlreadyExists": "名为 \"{name}\" 的群聊已存在",
   "@contacts_groupAlreadyExists": {
     "placeholders": {

lib/main.dart

@@ -19,6 +19,8 @@ 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/ui_view_state_service.dart';
+import 'services/timeout_prediction_service.dart';
 import 'storage/prefs_manager.dart';
 import 'utils/app_logger.dart';
 
@@ -39,6 +41,8 @@ void main() async {
   final backgroundService = BackgroundService();
   final mapTileCacheService = MapTileCacheService();
   final chatTextScaleService = ChatTextScaleService();
+  final uiViewStateService = UiViewStateService();
+  final timeoutPredictionService = TimeoutPredictionService(storage);
 
   // Load settings
   await appSettingsService.loadSettings();
@@ -56,6 +60,8 @@ void main() async {
   _registerThirdPartyLicenses();
 
   await chatTextScaleService.initialize();
+  await uiViewStateService.initialize();
+  await timeoutPredictionService.initialize();
 
   // Wire up connector with services
   connector.initialize(
@@ -65,6 +71,7 @@ void main() async {
     bleDebugLogService: bleDebugLogService,
     appDebugLogService: appDebugLogService,
     backgroundService: backgroundService,
+    timeoutPredictionService: timeoutPredictionService,
   );
 
   await connector.loadContactCache();
@@ -86,6 +93,8 @@ void main() async {
       appDebugLogService: appDebugLogService,
       mapTileCacheService: mapTileCacheService,
       chatTextScaleService: chatTextScaleService,
+      uiViewStateService: uiViewStateService,
+      timeoutPredictionService: timeoutPredictionService,
     ),
   );
 }
@@ -121,6 +130,8 @@ class MeshCoreApp extends StatelessWidget {
   final AppDebugLogService appDebugLogService;
   final MapTileCacheService mapTileCacheService;
   final ChatTextScaleService chatTextScaleService;
+  final UiViewStateService uiViewStateService;
+  final TimeoutPredictionService timeoutPredictionService;
 
   const MeshCoreApp({
     super.key,
@@ -133,6 +144,8 @@ class MeshCoreApp extends StatelessWidget {
     required this.appDebugLogService,
     required this.mapTileCacheService,
     required this.chatTextScaleService,
+    required this.uiViewStateService,
+    required this.timeoutPredictionService,
   });
 
   @override
@@ -146,8 +159,10 @@ class MeshCoreApp extends StatelessWidget {
         ChangeNotifierProvider.value(value: bleDebugLogService),
         ChangeNotifierProvider.value(value: appDebugLogService),
         ChangeNotifierProvider.value(value: chatTextScaleService),
+        ChangeNotifierProvider.value(value: uiViewStateService),
         Provider.value(value: storage),
         Provider.value(value: mapTileCacheService),
+        ChangeNotifierProvider.value(value: timeoutPredictionService),
       ],
       child: Consumer<AppSettingsService>(
         builder: (context, settingsService, child) {

lib/models/delivery_observation.dart

@@ -0,0 +1,43 @@
+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/channels_screen.dart

@@ -11,6 +11,7 @@ import 'package:uuid/uuid.dart';
 import '../connector/meshcore_connector.dart';
 import '../l10n/l10n.dart';
 import '../services/app_settings_service.dart';
+import '../services/ui_view_state_service.dart';
 import '../models/channel.dart';
 import '../models/community.dart';
 import '../storage/community_store.dart';
@@ -28,8 +29,6 @@ import 'contacts_screen.dart';
 import 'map_screen.dart';
 import 'settings_screen.dart';
 
-enum ChannelSortOption { manual, name, latestMessages, unread }
-
 class ChannelsScreen extends StatefulWidget {
   final bool hideBackButton;
 
@@ -43,9 +42,7 @@ class _ChannelsScreenState extends State<ChannelsScreen>
     with DisconnectNavigationMixin {
   final TextEditingController _searchController = TextEditingController();
   final CommunityStore _communityStore = CommunityStore();
-  String _searchQuery = '';
   Timer? _searchDebounce;
-  ChannelSortOption _sortOption = ChannelSortOption.manual;
   List<Community> _communities = [];
 
   // Cache of PSK hex -> Community for quick lookup
@@ -56,6 +53,9 @@ class _ChannelsScreenState extends State<ChannelsScreen>
   @override
   void initState() {
     super.initState();
+    _searchController.text = context
+        .read<UiViewStateService>()
+        .channelsSearchText;
     WidgetsBinding.instance.addPostFrameCallback((_) {
       context.read<MeshCoreConnector>().getChannels();
       _loadCommunities();
@@ -110,6 +110,7 @@ class _ChannelsScreenState extends State<ChannelsScreen>
   @override
   Widget build(BuildContext context) {
     final connector = context.watch<MeshCoreConnector>();
+    final viewState = context.watch<UiViewStateService>();
 
     final channelMessageStore = ChannelMessageStore();
     channelMessageStore.setPublicKeyHex = connector.selfPublicKeyHex;
@@ -205,6 +206,7 @@ class _ChannelsScreenState extends State<ChannelsScreen>
             final filteredChannels = _filterAndSortChannels(
               channels,
               connector,
+              viewState,
             );
 
             return Column(
@@ -219,17 +221,19 @@ class _ChannelsScreenState extends State<ChannelsScreen>
                       suffixIcon: Row(
                         mainAxisSize: MainAxisSize.min,
                         children: [
-                          if (_searchQuery.isNotEmpty)
+                          if (viewState.channelsSearchText.isNotEmpty)
                             IconButton(
                               icon: const Icon(Icons.clear),
                               onPressed: () {
+                                _searchDebounce?.cancel();
+                                _searchDebounce = null;
                                 _searchController.clear();
-                                setState(() {
+                                context
-                                  _searchQuery = '';
+                                    .read<UiViewStateService>()
-                                });
+                                    .setChannelsSearchText('');
                               },
                             ),
-                          _buildFilterButton(),
+                          _buildFilterButton(viewState),
                         ],
                       ),
                       border: OutlineInputBorder(
@@ -246,9 +250,9 @@ class _ChannelsScreenState extends State<ChannelsScreen>
                         const Duration(milliseconds: 300),
                         () {
                           if (!mounted) return;
-                          setState(() {
+                          context
-                            _searchQuery = value.toLowerCase();
+                              .read<UiViewStateService>()
-                          });
+                              .setChannelsSearchText(value);
                         },
                       );
                     },
@@ -283,8 +287,9 @@ class _ChannelsScreenState extends State<ChannelsScreen>
                             ),
                           ],
                         )
-                      : (_sortOption == ChannelSortOption.manual &&
+                      : (viewState.channelsSortOption ==
-                            _searchQuery.isEmpty)
+                                ChannelSortOption.manual &&
+                            viewState.channelsSearchText.isEmpty)
                       ? ReorderableListView.builder(
                           padding: const EdgeInsets.only(
                             left: 16,
@@ -584,59 +589,40 @@ class _ChannelsScreenState extends State<ChannelsScreen>
     await showDisconnectDialog(context, connector);
   }
 
-  Widget _buildFilterButton() {
+  Widget _buildFilterButton(UiViewStateService viewState) {
-    const actionSortManual = 0;
+    return SortFilterMenu<ChannelSortOption>(
-    const actionSortName = 1;
-    const actionSortLatest = 2;
-    const actionSortUnread = 3;
-
-    return SortFilterMenu(
       tooltip: context.l10n.listFilter_tooltip,
       sections: [
-        SortFilterMenuSection(
+        SortFilterMenuSection<ChannelSortOption>(
           title: context.l10n.channels_sortBy,
           options: [
-            SortFilterMenuOption(
+            SortFilterMenuOption<ChannelSortOption>(
-              value: actionSortManual,
+              value: ChannelSortOption.manual,
               label: context.l10n.channels_sortManual,
-              checked: _sortOption == ChannelSortOption.manual,
+              checked: viewState.channelsSortOption == ChannelSortOption.manual,
             ),
-            SortFilterMenuOption(
+            SortFilterMenuOption<ChannelSortOption>(
-              value: actionSortName,
+              value: ChannelSortOption.name,
               label: context.l10n.channels_sortAZ,
-              checked: _sortOption == ChannelSortOption.name,
+              checked: viewState.channelsSortOption == ChannelSortOption.name,
             ),
-            SortFilterMenuOption(
+            SortFilterMenuOption<ChannelSortOption>(
-              value: actionSortLatest,
+              value: ChannelSortOption.latestMessages,
               label: context.l10n.channels_sortLatestMessages,
-              checked: _sortOption == ChannelSortOption.latestMessages,
+              checked:
+                  viewState.channelsSortOption ==
+                  ChannelSortOption.latestMessages,
             ),
-            SortFilterMenuOption(
+            SortFilterMenuOption<ChannelSortOption>(
-              value: actionSortUnread,
+              value: ChannelSortOption.unread,
               label: context.l10n.channels_sortUnread,
-              checked: _sortOption == ChannelSortOption.unread,
+              checked: viewState.channelsSortOption == ChannelSortOption.unread,
             ),
           ],
         ),
       ],
-      onSelected: (action) {
+      onSelected: (sortOption) {
-        setState(() {
+        viewState.setChannelsSortOption(sortOption);
-          switch (action) {
-            case actionSortManual:
-              _sortOption = ChannelSortOption.manual;
-              break;
-            case actionSortLatest:
-              _sortOption = ChannelSortOption.latestMessages;
-              break;
-            case actionSortUnread:
-              _sortOption = ChannelSortOption.unread;
-              break;
-            case actionSortName:
-            default:
-              _sortOption = ChannelSortOption.name;
-              break;
-          }
-        });
       },
     );
   }
@@ -644,11 +630,14 @@ class _ChannelsScreenState extends State<ChannelsScreen>
   List<Channel> _filterAndSortChannels(
     List<Channel> channels,
     MeshCoreConnector connector,
+    UiViewStateService viewState,
   ) {
     var filtered = channels.where((channel) {
-      if (_searchQuery.isEmpty) return true;
+      if (viewState.channelsSearchText.isEmpty) return true;
       final label = _normalizeChannelName(channel);
-      return label.toLowerCase().contains(_searchQuery);
+      return label.toLowerCase().contains(
+        viewState.channelsSearchText.toLowerCase(),
+      );
     }).toList();
 
     int compareByName(Channel a, Channel b) {
@@ -657,7 +646,7 @@ class _ChannelsScreenState extends State<ChannelsScreen>
       return nameA.toLowerCase().compareTo(nameB.toLowerCase());
     }
 
-    switch (_sortOption) {
+    switch (viewState.channelsSortOption) {
       case ChannelSortOption.manual:
         break;
       case ChannelSortOption.latestMessages:

lib/screens/contacts_screen.dart

@@ -13,8 +13,9 @@ import '../l10n/l10n.dart';
 import '../connector/meshcore_protocol.dart';
 import '../models/contact.dart';
 import '../models/contact_group.dart';
-import '../storage/contact_group_store.dart';
+import '../services/ui_view_state_service.dart';
 import '../utils/contact_search.dart';
+import '../storage/contact_group_store.dart';
 import '../utils/dialog_utils.dart';
 import '../utils/disconnect_navigation_mixin.dart';
 import '../utils/emoji_utils.dart';
@@ -48,12 +49,10 @@ class ContactsScreen extends StatefulWidget {
 class _ContactsScreenState extends State<ContactsScreen>
     with DisconnectNavigationMixin {
   final TextEditingController _searchController = TextEditingController();
-  String _searchQuery = '';
-  ContactSortOption _sortOption = ContactSortOption.lastSeen;
-  bool _showUnreadOnly = false;
-  ContactTypeFilter _typeFilter = ContactTypeFilter.all;
   final ContactGroupStore _groupStore = ContactGroupStore();
+  MeshCoreConnector? _scopeSyncConnector;
   List<ContactGroup> _groups = [];
+  String _loadedGroupScopeKeyHex = '';
   Timer? _searchDebounce;
 
   final Set<ContactOperationType> _pendingOperations = {};
@@ -63,6 +62,9 @@ class _ContactsScreenState extends State<ContactsScreen>
   @override
   void initState() {
     super.initState();
+    _searchController.text = context
+        .read<UiViewStateService>()
+        .contactsSearchText;
     _loadGroups();
     _setupFrameListener();
     _clearAdvertNotifications();
@@ -74,26 +76,84 @@ class _ContactsScreenState extends State<ContactsScreen>
     NotificationService().clearAdvertNotifications(contactIds);
   }
 
+  @override
+  void didChangeDependencies() {
+    super.didChangeDependencies();
+    final connector = context.read<MeshCoreConnector>();
+    if (!identical(_scopeSyncConnector, connector)) {
+      _scopeSyncConnector?.removeListener(_handleConnectorScopeChange);
+      _scopeSyncConnector = connector;
+      _scopeSyncConnector?.addListener(_handleConnectorScopeChange);
+    }
+    _handleConnectorScopeChange();
+  }
+
   @override
   void dispose() {
     _searchDebounce?.cancel();
     _searchController.dispose();
     _frameSubscription?.cancel();
+    _scopeSyncConnector?.removeListener(_handleConnectorScopeChange);
     super.dispose();
   }
 
+  void _handleConnectorScopeChange() {
+    final connector = _scopeSyncConnector;
+    if (connector == null) return;
+    _syncGroupScopeIfNeeded(connector);
+  }
+
   Future<void> _loadGroups() async {
+    final selfPublicKeyHex = context.read<MeshCoreConnector>().selfPublicKeyHex;
+    if (selfPublicKeyHex.isEmpty) {
+      return;
+    }
+    _groupStore.setPublicKeyHex = selfPublicKeyHex;
     final groups = await _groupStore.loadGroups();
     if (!mounted) return;
     setState(() {
+      _loadedGroupScopeKeyHex = selfPublicKeyHex;
       _groups = groups;
+      _ensureValidSelectedGroup();
     });
   }
 
   Future<void> _saveGroups() async {
+    final selfPublicKeyHex = context.read<MeshCoreConnector>().selfPublicKeyHex;
+    if (selfPublicKeyHex.isEmpty) {
+      return;
+    }
+    _groupStore.setPublicKeyHex = selfPublicKeyHex;
     await _groupStore.saveGroups(_groups);
   }
 
+  bool _hasGroupStoreScope(MeshCoreConnector connector) {
+    return connector.selfPublicKeyHex.isNotEmpty;
+  }
+
+  void _syncGroupScopeIfNeeded(MeshCoreConnector connector) {
+    final selfPublicKeyHex = connector.selfPublicKeyHex;
+    if (selfPublicKeyHex.isEmpty ||
+        selfPublicKeyHex == _loadedGroupScopeKeyHex) {
+      return;
+    }
+    _loadGroups();
+  }
+
+  void _collapseContactsSearch(UiViewStateService viewState) {
+    _searchDebounce?.cancel();
+    _searchDebounce = null;
+    _searchController.clear();
+    viewState.setContactsSearchText('');
+    viewState.setContactsSearchExpanded(false);
+  }
+
+  void _showGroupsUnavailableMessage(BuildContext context) {
+    ScaffoldMessenger.of(
+      context,
+    ).showSnackBar(SnackBar(content: Text(context.l10n.common_loading)));
+  }
+
   void _setupFrameListener() {
     final connector = Provider.of<MeshCoreConnector>(context, listen: false);
     // Listen for incoming text messages from the repeater
@@ -383,31 +443,166 @@ class _ContactsScreenState extends State<ContactsScreen>
     await showDisconnectDialog(context, connector);
   }
 
-  Widget _buildFilterButton(BuildContext context, MeshCoreConnector connector) {
+  ContactGroup? _selectedGroupForName(String selectedGroupName) {
-    return ContactsFilterMenu(
+    if (selectedGroupName == contactsAllGroupsValue) return null;
-      sortOption: _sortOption,
+    for (final group in _groups) {
-      typeFilter: _typeFilter,
+      if (group.name == selectedGroupName) return group;
-      showUnreadOnly: _showUnreadOnly,
+    }
-      onSortChanged: (value) {
+    return null;
-        setState(() {
+  }
-          _sortOption = value;
+
+  void _ensureValidSelectedGroup() {
+    final viewState = context.read<UiViewStateService>();
+    if (viewState.contactsSelectedGroupName == contactsAllGroupsValue) return;
+    final exists = _groups.any(
+      (group) => group.name == viewState.contactsSelectedGroupName,
+    );
+    if (!exists) {
+      viewState.setContactsSelectedGroupName(contactsAllGroupsValue);
+    }
+  }
+
+  void _closeDropdownAndRun(BuildContext popupContext, VoidCallback action) {
+    final route = ModalRoute.of(popupContext);
+    if (route != null && route.isCurrent) {
+      Navigator.of(popupContext).pop();
+    }
+    WidgetsBinding.instance.addPostFrameCallback((_) {
+      if (!mounted) return;
+      action();
     });
+  }
+
+  Widget _buildFilterButton(
+    BuildContext context,
+    UiViewStateService viewState,
+  ) {
+    return ContactsFilterMenu(
+      sortOption: viewState.contactsSortOption,
+      typeFilter: viewState.contactsTypeFilter,
+      showUnreadOnly: viewState.contactsShowUnreadOnly,
+      onSortChanged: (value) {
+        viewState.setContactsSortOption(value);
       },
       onTypeFilterChanged: (value) {
-        setState(() {
+        viewState.setContactsTypeFilter(value);
-          _typeFilter = value;
-        });
       },
       onUnreadOnlyChanged: (value) {
-        setState(() {
+        viewState.setContactsShowUnreadOnly(value);
-          _showUnreadOnly = value;
-        });
       },
-      onNewGroup: () => _showGroupEditor(context, connector.contacts),
+    );
+  }
+
+  Widget _buildGroupButton(
+    BuildContext context,
+    MeshCoreConnector connector,
+    UiViewStateService viewState,
+    List<Contact> contacts,
+    List<ContactGroup> sortedGroups,
+  ) {
+    final canManageGroups = _hasGroupStoreScope(connector);
+    final selectedGroupName =
+        _selectedGroupForName(viewState.contactsSelectedGroupName)?.name ??
+        context.l10n.listFilter_all;
+    final double menuWidth = (MediaQuery.sizeOf(context).width - 16).clamp(
+      0.0,
+      double.infinity,
+    );
+
+    return PopupMenuButton<String>(
+      position: PopupMenuPosition.under,
+      constraints: BoxConstraints.tightFor(width: menuWidth),
+      onSelected: (String value) {
+        viewState.setContactsSelectedGroupName(value);
+      },
+      itemBuilder: (menuContext) => [
+        PopupMenuItem<String>(
+          value: contactsAllGroupsValue,
+          child: Row(
+            mainAxisAlignment: MainAxisAlignment.spaceBetween,
+            children: [
+              Text(menuContext.l10n.listFilter_all),
+              IconButton(
+                tooltip: menuContext.l10n.contacts_newGroup,
+                icon: const Icon(Icons.group_add, size: 20),
+                onPressed: canManageGroups
+                    ? () => _closeDropdownAndRun(
+                        menuContext,
+                        () => _showGroupEditor(this.context, contacts),
+                      )
+                    : () => _closeDropdownAndRun(
+                        menuContext,
+                        () => _showGroupsUnavailableMessage(this.context),
+                      ),
+              ),
+            ],
+          ),
+        ),
+        ...sortedGroups.map((group) {
+          return PopupMenuItem<String>(
+            value: group.name,
+            child: Row(
+              mainAxisAlignment: MainAxisAlignment.spaceBetween,
+              children: [
+                Expanded(
+                  child: Text(group.name, overflow: TextOverflow.ellipsis),
+                ),
+                IconButton(
+                  tooltip: menuContext.l10n.contacts_editGroup,
+                  icon: const Icon(Icons.edit, size: 20),
+                  onPressed: canManageGroups
+                      ? () => _closeDropdownAndRun(
+                          menuContext,
+                          () => _showGroupEditor(
+                            this.context,
+                            contacts,
+                            group: group,
+                          ),
+                        )
+                      : () => _closeDropdownAndRun(
+                          menuContext,
+                          () => _showGroupsUnavailableMessage(this.context),
+                        ),
+                ),
+                const SizedBox(width: 8),
+                IconButton(
+                  tooltip: menuContext.l10n.contacts_deleteGroup,
+                  icon: const Icon(Icons.delete, size: 20, color: Colors.red),
+                  onPressed: canManageGroups
+                      ? () => _closeDropdownAndRun(
+                          menuContext,
+                          () => _confirmDeleteGroup(this.context, group),
+                        )
+                      : () => _closeDropdownAndRun(
+                          menuContext,
+                          () => _showGroupsUnavailableMessage(this.context),
+                        ),
+                ),
+              ],
+            ),
+          );
+        }),
+      ],
+      child: SizedBox(
+        height: 48,
+        child: Padding(
+          padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 10),
+          child: Row(
+            children: [
+              Expanded(
+                child: Text(selectedGroupName, overflow: TextOverflow.ellipsis),
+              ),
+              const SizedBox(width: 8),
+              const Icon(Icons.arrow_drop_down),
+            ],
+          ),
+        ),
+      ),
     );
   }
 
   Widget _buildContactsBody(BuildContext context, MeshCoreConnector connector) {
+    final viewState = context.watch<UiViewStateService>();
     final contacts = connector.contacts;
     final shouldShowStartupSpinner =
         contacts.isEmpty &&
@@ -429,92 +624,171 @@ class _ContactsScreenState extends State<ContactsScreen>
       );
     }
 
-    final filteredAndSorted = _filterAndSortContacts(contacts, connector);
+    final filteredAndSorted = _filterAndSortContacts(
-    final filteredGroups = _showUnreadOnly
+      contacts,
-        ? const <ContactGroup>[]
+      connector,
-        : _filterAndSortGroups(_groups, contacts);
+      viewState,
+    );
 
     String hintText = "";
 
-    switch (_typeFilter) {
+    switch (viewState.contactsTypeFilter) {
       case ContactTypeFilter.all:
         hintText = context.l10n.contacts_searchContacts(
           filteredAndSorted.length,
-          _showUnreadOnly ? " ${context.l10n.contacts_unread}" : "",
+          viewState.contactsShowUnreadOnly
+              ? " ${context.l10n.contacts_unread}"
+              : "",
         );
         break;
       case ContactTypeFilter.users:
         hintText = context.l10n.contacts_searchUsers(
           filteredAndSorted.length,
-          _showUnreadOnly ? " ${context.l10n.contacts_unread}" : "",
+          viewState.contactsShowUnreadOnly
+              ? " ${context.l10n.contacts_unread}"
+              : "",
         );
         break;
       case ContactTypeFilter.repeaters:
         hintText = context.l10n.contacts_searchRepeaters(
           filteredAndSorted.length,
-          _showUnreadOnly ? " ${context.l10n.contacts_unread}" : "",
+          viewState.contactsShowUnreadOnly
+              ? " ${context.l10n.contacts_unread}"
+              : "",
         );
         break;
       case ContactTypeFilter.rooms:
         hintText = context.l10n.contacts_searchRoomServers(
           filteredAndSorted.length,
-          _showUnreadOnly ? " ${context.l10n.contacts_unread}" : "",
+          viewState.contactsShowUnreadOnly
+              ? " ${context.l10n.contacts_unread}"
+              : "",
         );
         break;
       case ContactTypeFilter.favorites:
         hintText = context.l10n.contacts_searchFavorites(
           filteredAndSorted.length,
-          _showUnreadOnly ? " ${context.l10n.contacts_unread}" : "",
+          viewState.contactsShowUnreadOnly
+              ? " ${context.l10n.contacts_unread}"
+              : "",
         );
         break;
     }
 
+    final groupsByName = <String, ContactGroup>{};
+    for (final group in _groups) {
+      groupsByName.putIfAbsent(group.name, () => group);
+    }
+    final sortedGroups = groupsByName.values.toList()
+      ..sort((a, b) => a.name.toLowerCase().compareTo(b.name.toLowerCase()));
+
+    final screenWidth = MediaQuery.sizeOf(context).width;
+    final searchExpandedWidth = (screenWidth * 0.52).clamp(
+      97.0,
+      double.infinity,
+    ); // allow expansion up to 52% of screen width, but not less than the collapsed width
+    final searchCollapsedWidth = (screenWidth * 0.22).clamp(
+      97.0,
+      120.0,
+    ); //two 48px icon buttons + 1px divider
+
     return Column(
       children: [
         Padding(
           padding: const EdgeInsets.all(8.0),
-          child: TextField(
+          child: Row(
-            controller: _searchController,
-            decoration: InputDecoration(
-              hintText: hintText,
-              prefixIcon: const Icon(Icons.search),
-              suffixIcon: Row(
-                mainAxisSize: MainAxisSize.min,
             children: [
-                  if (_searchQuery.isNotEmpty)
+              Expanded(
-                    IconButton(
+                child: _buildGroupButton(
-                      icon: const Icon(Icons.clear),
+                  context,
-                      onPressed: () {
+                  connector,
-                        _searchController.clear();
+                  viewState,
-                        setState(() {
+                  contacts,
-                          _searchQuery = '';
+                  sortedGroups,
-                        });
-                      },
                 ),
-                  _buildFilterButton(context, connector),
-                ],
               ),
-              border: OutlineInputBorder(
+              const SizedBox(width: 8),
+              AnimatedContainer(
+                duration: const Duration(milliseconds: 220),
+                curve: Curves.easeOutCubic,
+                width: viewState.contactsSearchExpanded
+                    ? searchExpandedWidth
+                    : searchCollapsedWidth,
+                height: 48,
+                child: DecoratedBox(
+                  decoration: BoxDecoration(
+                    border: Border.all(
+                      color: Theme.of(context).colorScheme.outline,
+                    ),
                     borderRadius: BorderRadius.circular(12),
                   ),
+                  child: Row(
+                    children: [
+                      Expanded(
+                        child: viewState.contactsSearchExpanded
+                            ? TextField(
+                                controller: _searchController,
+                                autofocus: true,
+                                decoration: InputDecoration(
+                                  hintText: hintText,
+                                  border: InputBorder.none,
                                   contentPadding: const EdgeInsets.symmetric(
-                horizontal: 16,
+                                    horizontal: 12,
-                vertical: 12,
+                                    vertical: 10,
                                   ),
                                 ),
                                 onChanged: (value) {
                                   _searchDebounce?.cancel();
-              _searchDebounce = Timer(const Duration(milliseconds: 300), () {
+                                  _searchDebounce = Timer(
+                                    const Duration(milliseconds: 300),
+                                    () {
                                       if (!mounted) return;
-                setState(() {
+                                      context
-                  _searchQuery = value.toLowerCase();
+                                          .read<UiViewStateService>()
-                });
+                                          .setContactsSearchText(value);
-              });
                                     },
+                                  );
+                                },
+                              )
+                            : const SizedBox.shrink(),
+                      ),
+                      SizedBox(
+                        width: 48,
+                        height: 48,
+                        child: IconButton(
+                          onPressed: () {
+                            if (viewState.contactsSearchExpanded) {
+                              _collapseContactsSearch(viewState);
+                              return;
+                            }
+                            viewState.setContactsSearchExpanded(true);
+                          },
+                          icon: Icon(
+                            viewState.contactsSearchExpanded
+                                ? Icons.close
+                                : Icons.search,
+                          ),
+                        ),
+                      ),
+                      Container(
+                        width: 1,
+                        height: 24,
+                        color: Theme.of(context).colorScheme.outlineVariant,
+                      ),
+                      SizedBox(
+                        width: 48,
+                        height: 48,
+                        child: _buildFilterButton(context, viewState),
+                      ),
+                    ],
+                  ),
+                ),
+              ),
+            ],
           ),
         ),
         Expanded(
-          child: filteredAndSorted.isEmpty && filteredGroups.isEmpty
+          child: filteredAndSorted.isEmpty
               ? Center(
                   child: Column(
                     mainAxisAlignment: MainAxisAlignment.center,
@@ -522,7 +796,7 @@ class _ContactsScreenState extends State<ContactsScreen>
                       Icon(Icons.search_off, size: 64, color: Colors.grey[400]),
                       const SizedBox(height: 16),
                       Text(
-                        _showUnreadOnly
+                        viewState.contactsShowUnreadOnly
                             ? context.l10n.contacts_noUnreadContacts
                             : context.l10n.contacts_noContactsFound,
                         style: TextStyle(fontSize: 16, color: Colors.grey[600]),
@@ -533,14 +807,9 @@ class _ContactsScreenState extends State<ContactsScreen>
               : RefreshIndicator(
                   onRefresh: () => connector.getContacts(),
                   child: ListView.builder(
-                    itemCount: filteredGroups.length + filteredAndSorted.length,
+                    itemCount: filteredAndSorted.length,
                     itemBuilder: (context, index) {
-                      if (index < filteredGroups.length) {
+                      final contact = filteredAndSorted[index];
-                        final group = filteredGroups[index];
-                        return _buildGroupTile(context, group, contacts);
-                      }
-                      final contact =
-                          filteredAndSorted[index - filteredGroups.length];
                       final unreadCount = connector.getUnreadCountForContact(
                         contact,
                       );
@@ -561,55 +830,26 @@ class _ContactsScreenState extends State<ContactsScreen>
     );
   }
 
-  List<ContactGroup> _filterAndSortGroups(
-    List<ContactGroup> groups,
-    List<Contact> contacts,
-  ) {
-    final query = _searchQuery.trim().toLowerCase();
-    final contactsByKey = <String, Contact>{};
-    for (final contact in contacts) {
-      contactsByKey[contact.publicKeyHex] = contact;
-    }
-
-    final filtered = groups
-        .where((group) {
-          if (query.isEmpty) return true;
-          if (group.name.toLowerCase().contains(query)) return true;
-          for (final key in group.memberKeys) {
-            final contact = contactsByKey[key];
-            if (contact != null && matchesContactQuery(contact, query)) {
-              return true;
-            }
-          }
-          return false;
-        })
-        .where((group) {
-          if (_typeFilter == ContactTypeFilter.all) return true;
-          // Groups don't have a favorite flag, so hide them under favorites filter
-          if (_typeFilter == ContactTypeFilter.favorites) return false;
-          for (final key in group.memberKeys) {
-            final contact = contactsByKey[key];
-            if (contact != null && _matchesTypeFilter(contact)) return true;
-          }
-          return false;
-        })
-        .toList();
-
-    filtered.sort(
-      (a, b) => a.name.toLowerCase().compareTo(b.name.toLowerCase()),
-    );
-    return filtered;
-  }
-
   List<Contact> _filterAndSortContacts(
     List<Contact> contacts,
     MeshCoreConnector connector,
+    UiViewStateService viewState,
   ) {
     var filtered = contacts.where((contact) {
-      if (_searchQuery.isEmpty) return true;
+      if (viewState.contactsSearchText.isEmpty) return true;
-      return matchesContactQuery(contact, _searchQuery);
+      return matchesContactQuery(contact, viewState.contactsSearchText);
     }).toList();
 
+    final selectedGroup = _selectedGroupForName(
+      viewState.contactsSelectedGroupName,
+    );
+    if (selectedGroup != null) {
+      final memberKeys = selectedGroup.memberKeys.toSet();
+      filtered = filtered
+          .where((contact) => memberKeys.contains(contact.publicKeyHex))
+          .toList();
+    }
+
     // Filter out own node from the list
     if (connector.selfPublicKey != null) {
       final selfPubKeyHex = pubKeyToHex(connector.selfPublicKey!);
@@ -618,17 +858,22 @@ class _ContactsScreenState extends State<ContactsScreen>
       }).toList();
     }
 
-    if (_typeFilter != ContactTypeFilter.all) {
+    if (viewState.contactsTypeFilter != ContactTypeFilter.all) {
-      filtered = filtered.where(_matchesTypeFilter).toList();
+      filtered = filtered
+          .where(
+            (contact) =>
+                _matchesTypeFilter(contact, viewState.contactsTypeFilter),
+          )
+          .toList();
     }
 
-    if (_showUnreadOnly) {
+    if (viewState.contactsShowUnreadOnly) {
       filtered = filtered.where((contact) {
         return connector.getUnreadCountForContact(contact) > 0;
       }).toList();
     }
 
-    switch (_sortOption) {
+    switch (viewState.contactsSortOption) {
       case ContactSortOption.lastSeen:
         filtered.sort(
           (a, b) => _resolveLastSeen(b).compareTo(_resolveLastSeen(a)),
@@ -657,8 +902,8 @@ class _ContactsScreenState extends State<ContactsScreen>
     return filtered;
   }
 
-  bool _matchesTypeFilter(Contact contact) {
+  bool _matchesTypeFilter(Contact contact, ContactTypeFilter typeFilter) {
-    switch (_typeFilter) {
+    switch (typeFilter) {
       case ContactTypeFilter.all:
         return true;
       case ContactTypeFilter.favorites:
@@ -679,57 +924,6 @@ class _ContactsScreenState extends State<ContactsScreen>
         : contact.lastSeen;
   }
 
-  Widget _buildGroupTile(
-    BuildContext context,
-    ContactGroup group,
-    List<Contact> contacts,
-  ) {
-    final memberContacts = _resolveGroupContacts(group, contacts);
-    final subtitle = _formatGroupMembers(context, memberContacts);
-    return ListTile(
-      leading: const CircleAvatar(
-        backgroundColor: Colors.teal,
-        child: Icon(Icons.group, color: Colors.white, size: 20),
-      ),
-      title: Text(group.name),
-      subtitle: Text(subtitle),
-      trailing: Text(
-        memberContacts.length.toString(),
-        style: TextStyle(fontSize: 12, color: Colors.grey[600]),
-      ),
-      onTap: () => _showGroupOptions(context, group, contacts),
-      onLongPress: () => _showGroupOptions(context, group, contacts),
-    );
-  }
-
-  List<Contact> _resolveGroupContacts(
-    ContactGroup group,
-    List<Contact> contacts,
-  ) {
-    final byKey = <String, Contact>{};
-    for (final contact in contacts) {
-      byKey[contact.publicKeyHex] = contact;
-    }
-    final resolved = <Contact>[];
-    for (final key in group.memberKeys) {
-      final contact = byKey[key];
-      if (contact != null) {
-        resolved.add(contact);
-      }
-    }
-    resolved.sort(
-      (a, b) => a.name.toLowerCase().compareTo(b.name.toLowerCase()),
-    );
-    return resolved;
-  }
-
-  String _formatGroupMembers(BuildContext context, List<Contact> members) {
-    if (members.isEmpty) return context.l10n.contacts_noMembers;
-    final names = members.map((c) => c.name).toList();
-    if (names.length <= 2) return names.join(', ');
-    return '${names.take(2).join(', ')} +${names.length - 2}';
-  }
-
   void _openChat(BuildContext context, Contact contact) {
     // Check if this is a repeater
     if (contact.type == advTypeRepeater) {
@@ -807,58 +1001,11 @@ class _ContactsScreenState extends State<ContactsScreen>
     );
   }
 
-  void _showGroupOptions(
-    BuildContext context,
-    ContactGroup group,
-    List<Contact> contacts,
-  ) {
-    final members = _resolveGroupContacts(group, contacts);
-    showModalBottomSheet(
-      context: context,
-      builder: (sheetContext) => SafeArea(
-        child: SingleChildScrollView(
-          child: Column(
-            mainAxisSize: MainAxisSize.min,
-            children: [
-              ListTile(
-                leading: const Icon(Icons.edit),
-                title: Text(context.l10n.contacts_editGroup),
-                onTap: () {
-                  Navigator.pop(sheetContext);
-                  _showGroupEditor(context, contacts, group: group);
-                },
-              ),
-              ListTile(
-                leading: const Icon(Icons.delete, color: Colors.red),
-                title: Text(
-                  context.l10n.contacts_deleteGroup,
-                  style: const TextStyle(color: Colors.red),
-                ),
-                onTap: () {
-                  Navigator.pop(sheetContext);
-                  _confirmDeleteGroup(context, group);
-                },
-              ),
-              if (members.isNotEmpty) const Divider(),
-              ...members.map((member) {
-                return ListTile(
-                  leading: const Icon(Icons.person),
-                  title: Text(member.name),
-                  subtitle: Text(member.typeLabel),
-                  onTap: () {
-                    Navigator.pop(sheetContext);
-                    _openChat(context, member);
-                  },
-                );
-              }),
-            ],
-          ),
-        ),
-      ),
-    );
-  }
-
   void _confirmDeleteGroup(BuildContext context, ContactGroup group) {
+    if (!_hasGroupStoreScope(context.read<MeshCoreConnector>())) {
+      _showGroupsUnavailableMessage(context);
+      return;
+    }
     showDialog(
       context: context,
       builder: (dialogContext) => AlertDialog(
@@ -874,6 +1021,7 @@ class _ContactsScreenState extends State<ContactsScreen>
               Navigator.pop(dialogContext);
               setState(() {
                 _groups.removeWhere((g) => g.name == group.name);
+                _ensureValidSelectedGroup();
               });
               await _saveGroups();
             },
@@ -892,6 +1040,10 @@ class _ContactsScreenState extends State<ContactsScreen>
     List<Contact> contacts, {
     ContactGroup? group,
   }) {
+    if (!_hasGroupStoreScope(context.read<MeshCoreConnector>())) {
+      _showGroupsUnavailableMessage(context);
+      return;
+    }
     final isEditing = group != null;
     final nameController = TextEditingController(text: group?.name ?? '');
     final selectedKeys = <String>{...group?.memberKeys ?? []};
@@ -918,6 +1070,10 @@ class _ContactsScreenState extends State<ContactsScreen>
             ),
             content: SizedBox(
               width: double.maxFinite,
+              child: ConstrainedBox(
+                constraints: BoxConstraints(
+                  maxHeight: MediaQuery.of(context).size.height * 0.8,
+                ),
                 child: Column(
                   mainAxisSize: MainAxisSize.min,
                   children: [
@@ -943,8 +1099,7 @@ class _ContactsScreenState extends State<ContactsScreen>
                       },
                     ),
                     const SizedBox(height: 12),
-                  SizedBox(
+                    Expanded(
-                    height: 240,
                       child: filteredContacts.isEmpty
                           ? Center(
                               child: Text(
@@ -967,7 +1122,9 @@ class _ContactsScreenState extends State<ContactsScreen>
                                       if (value == true) {
                                         selectedKeys.add(contact.publicKeyHex);
                                       } else {
-                                      selectedKeys.remove(contact.publicKeyHex);
+                                        selectedKeys.remove(
+                                          contact.publicKeyHex,
+                                        );
                                       }
                                     });
                                   },
@@ -978,6 +1135,7 @@ class _ContactsScreenState extends State<ContactsScreen>
                   ],
                 ),
               ),
+            ),
             actions: [
               TextButton(
                 onPressed: () => Navigator.pop(dialogContext),
@@ -994,6 +1152,15 @@ class _ContactsScreenState extends State<ContactsScreen>
                     );
                     return;
                   }
+                  if (name.toLowerCase() ==
+                      contactsAllGroupsValue.toLowerCase()) {
+                    ScaffoldMessenger.of(context).showSnackBar(
+                      SnackBar(
+                        content: Text(context.l10n.contacts_groupNameReserved),
+                      ),
+                    );
+                    return;
+                  }
                   final exists = _groups.any((g) {
                     if (isEditing && g.name == group.name) return false;
                     return g.name.toLowerCase() == name.toLowerCase();
@@ -1009,15 +1176,21 @@ class _ContactsScreenState extends State<ContactsScreen>
                     return;
                   }
                   setState(() {
+                    final viewState = context.read<UiViewStateService>();
                     if (isEditing) {
                       final index = _groups.indexWhere(
                         (g) => g.name == group.name,
                       );
                       if (index != -1) {
+                        final wasSelected =
+                            viewState.contactsSelectedGroupName == group.name;
                         _groups[index] = ContactGroup(
                           name: name,
                           memberKeys: selectedKeys.toList(),
                         );
+                        if (wasSelected) {
+                          viewState.setContactsSelectedGroupName(name);
+                        }
                       }
                     } else {
                       _groups.add(
@@ -1026,7 +1199,9 @@ class _ContactsScreenState extends State<ContactsScreen>
                           memberKeys: selectedKeys.toList(),
                         ),
                       );
+                      viewState.setContactsSelectedGroupName(name);
                     }
+                    _ensureValidSelectedGroup();
                   });
                   await _saveGroups();
                   if (dialogContext.mounted) {

lib/services/chat_text_scale_service.dart

@@ -65,7 +65,7 @@ class ChatTextScaleService extends ChangeNotifier {
 
   void _commitScale() {
     _saveTimer?.cancel();
-    PrefsManager.instance.setDouble(_prefKey, _scale);
+    unawaited(PrefsManager.instance.setDouble(_prefKey, _scale));
   }
 
   double _clamp(double value) => value.clamp(_minScale, _maxScale).toDouble();

lib/services/message_retry_service.dart

@@ -58,12 +58,13 @@ class MessageRetryService extends ChangeNotifier {
   Function(Message)? _updateMessageCallback;
   Function(Contact)? _clearContactPathCallback;
   Function(Contact, Uint8List, int)? _setContactPathCallback;
-  Function(int, int)? _calculateTimeoutCallback;
+  Function(int, int, {String? contactKey})? _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();
 
@@ -73,12 +74,20 @@ class MessageRetryService extends ChangeNotifier {
     required Function(Message) updateMessageCallback,
     Function(Contact)? clearContactPathCallback,
     Function(Contact, Uint8List, int)? setContactPathCallback,
-    Function(int pathLength, int messageBytes)? calculateTimeoutCallback,
+    Function(int pathLength, int messageBytes, {String? contactKey})?
+    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;
@@ -91,6 +100,7 @@ class MessageRetryService extends ChangeNotifier {
     _appSettingsService = appSettingsService;
     _debugLogService = debugLogService;
     _recordPathResultCallback = recordPathResultCallback;
+    _onDeliveryObservedCallback = onDeliveryObservedCallback;
   }
 
   /// Compute expected ACK hash using same algorithm as firmware:
@@ -423,9 +433,7 @@ class MessageRetryService extends ChangeNotifier {
       );
     }
 
-    // Use device-provided timeout, or calculate from radio settings if timeout is 0 or invalid
+    // Calculate timeout: prefer ML prediction, then device-provided, then physics fallback
-    int actualTimeout = timeoutMs;
-    if (timeoutMs <= 0 && _calculateTimeoutCallback != null) {
     int pathLengthValue;
     if (selection != null) {
       pathLengthValue = selection.useFlood ? -1 : selection.hopCount;
@@ -435,14 +443,24 @@ class MessageRetryService extends ChangeNotifier {
     } else {
       pathLengthValue = contact.pathLength;
     }
-      actualTimeout = _calculateTimeoutCallback!(
+
+    int actualTimeout = timeoutMs;
+    if (_calculateTimeoutCallback != null) {
+      final calculated = _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',
         );
       }
+    }
 
     final updatedMessage = message.copyWith(
       status: MessageStatus.sent,
@@ -738,6 +756,16 @@ 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

@@ -1,4 +1,5 @@
 import 'dart:convert';
+import '../models/delivery_observation.dart';
 import '../models/path_history.dart';
 import '../storage/prefs_manager.dart';
 
@@ -6,6 +7,7 @@ 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,
@@ -122,4 +124,33 @@ 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

@@ -0,0 +1,229 @@
+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/ui_view_state_service.dart

@@ -0,0 +1,154 @@
+import 'dart:async';
+
+import 'package:flutter/foundation.dart';
+
+import '../storage/prefs_manager.dart';
+import '../utils/contact_search.dart';
+
+const String contactsAllGroupsValue = '__all__';
+
+enum ChannelSortOption { manual, name, latestMessages, unread }
+
+class UiViewStateService extends ChangeNotifier {
+  static const _keyContactsSelectedGroupName = 'ui_contacts_selected_group';
+  static const _keyContactsSortOption = 'ui_contacts_sort_option';
+  static const _keyContactsShowUnreadOnly = 'ui_contacts_show_unread_only';
+  static const _keyContactsTypeFilter = 'ui_contacts_type_filter';
+  static const _keyChannelsSortOption = 'ui_channels_sort_option';
+  static const _keyChannelsSortIndexLegacy = 'ui_channels_sort_index';
+
+  String _contactsSelectedGroupName = contactsAllGroupsValue;
+  String _contactsSearchText = '';
+  bool _contactsSearchExpanded = false;
+  ContactSortOption _contactsSortOption = ContactSortOption.lastSeen;
+  bool _contactsShowUnreadOnly = false;
+  ContactTypeFilter _contactsTypeFilter = ContactTypeFilter.all;
+
+  String _channelsSearchText = '';
+  ChannelSortOption _channelsSortOption = ChannelSortOption.manual;
+
+  String get contactsSelectedGroupName => _contactsSelectedGroupName;
+  String get contactsSearchText => _contactsSearchText;
+  bool get contactsSearchExpanded => _contactsSearchExpanded;
+  ContactSortOption get contactsSortOption => _contactsSortOption;
+  bool get contactsShowUnreadOnly => _contactsShowUnreadOnly;
+  ContactTypeFilter get contactsTypeFilter => _contactsTypeFilter;
+  String get channelsSearchText => _channelsSearchText;
+  ChannelSortOption get channelsSortOption => _channelsSortOption;
+
+  Future<void> initialize() async {
+    final prefs = PrefsManager.instance;
+
+    final selectedGroupName = prefs.getString(_keyContactsSelectedGroupName);
+    if (selectedGroupName != null && selectedGroupName.isNotEmpty) {
+      _contactsSelectedGroupName = selectedGroupName;
+    }
+
+    final sortStr = prefs.getString(_keyContactsSortOption);
+    if (sortStr != null) {
+      _contactsSortOption = ContactSortOption.values.firstWhere(
+        (e) => e.name == sortStr,
+        orElse: () => ContactSortOption.lastSeen,
+      );
+    }
+
+    _contactsShowUnreadOnly =
+        prefs.getBool(_keyContactsShowUnreadOnly) ?? false;
+
+    final typeStr = prefs.getString(_keyContactsTypeFilter);
+    if (typeStr != null) {
+      _contactsTypeFilter = ContactTypeFilter.values.firstWhere(
+        (e) => e.name == typeStr,
+        orElse: () => ContactTypeFilter.all,
+      );
+    }
+
+    final channelSortStr = prefs.getString(_keyChannelsSortOption);
+    if (channelSortStr != null) {
+      _channelsSortOption = ChannelSortOption.values.firstWhere(
+        (e) => e.name == channelSortStr,
+        orElse: () => ChannelSortOption.manual,
+      );
+      return;
+    }
+
+    // Backward compatibility for old persisted index format.
+    switch (prefs.getInt(_keyChannelsSortIndexLegacy) ?? 0) {
+      case 0:
+        _channelsSortOption = ChannelSortOption.manual;
+        break;
+      case 1:
+        _channelsSortOption = ChannelSortOption.name;
+        break;
+      case 2:
+        _channelsSortOption = ChannelSortOption.latestMessages;
+        break;
+      case 3:
+        _channelsSortOption = ChannelSortOption.unread;
+        break;
+      default:
+        _channelsSortOption = ChannelSortOption.manual;
+    }
+  }
+
+  void setContactsSelectedGroupName(String value) {
+    if (_contactsSelectedGroupName == value) return;
+    _contactsSelectedGroupName = value;
+    notifyListeners();
+    unawaited(
+      PrefsManager.instance.setString(_keyContactsSelectedGroupName, value),
+    );
+  }
+
+  void setContactsSearchText(String value) {
+    if (_contactsSearchText == value) return;
+    _contactsSearchText = value;
+    notifyListeners();
+  }
+
+  void setContactsSearchExpanded(bool value) {
+    if (_contactsSearchExpanded == value) return;
+    _contactsSearchExpanded = value;
+    notifyListeners();
+  }
+
+  void setContactsSortOption(ContactSortOption value) {
+    if (_contactsSortOption == value) return;
+    _contactsSortOption = value;
+    notifyListeners();
+    unawaited(
+      PrefsManager.instance.setString(_keyContactsSortOption, value.name),
+    );
+  }
+
+  void setContactsShowUnreadOnly(bool value) {
+    if (_contactsShowUnreadOnly == value) return;
+    _contactsShowUnreadOnly = value;
+    notifyListeners();
+    unawaited(PrefsManager.instance.setBool(_keyContactsShowUnreadOnly, value));
+  }
+
+  void setContactsTypeFilter(ContactTypeFilter value) {
+    if (_contactsTypeFilter == value) return;
+    _contactsTypeFilter = value;
+    notifyListeners();
+    unawaited(
+      PrefsManager.instance.setString(_keyContactsTypeFilter, value.name),
+    );
+  }
+
+  void setChannelsSearchText(String value) {
+    if (_channelsSearchText == value) return;
+    _channelsSearchText = value;
+    notifyListeners();
+  }
+
+  void setChannelsSortOption(ChannelSortOption value) {
+    if (_channelsSortOption == value) return;
+    _channelsSortOption = value;
+    notifyListeners();
+    unawaited(
+      PrefsManager.instance.setString(_keyChannelsSortOption, value.name),
+    );
+  }
+}

lib/utils/contact_filter_types.dart

@@ -0,0 +1,3 @@
+enum ContactSortOption { lastSeen, recentMessages, name }
+
+enum ContactTypeFilter { all, favorites, users, repeaters, rooms }

lib/utils/contact_search.dart

@@ -1,5 +1,7 @@
 import '../models/contact.dart';
 
+export 'contact_filter_types.dart';
+
 bool matchesContactQuery(Contact contact, String query) {
   final normalizedQuery = query.trim().toLowerCase();
   if (normalizedQuery.isEmpty) return true;

lib/widgets/list_filter_widget.dart

@@ -1,12 +1,9 @@
 import 'package:flutter/material.dart';
 import '../l10n/l10n.dart';
+import '../utils/contact_search.dart';
 
-enum ContactSortOption { lastSeen, recentMessages, name }
+class SortFilterMenuOption<T> {
-
+  final T value;
-enum ContactTypeFilter { all, favorites, users, repeaters, rooms }
-
-class SortFilterMenuOption {
-  final int value;
   final String label;
   final bool? checked;
 
@@ -17,16 +14,16 @@ class SortFilterMenuOption {
   });
 }
 
-class SortFilterMenuSection {
+class SortFilterMenuSection<T> {
   final String title;
-  final List<SortFilterMenuOption> options;
+  final List<SortFilterMenuOption<T>> options;
 
   const SortFilterMenuSection({required this.title, required this.options});
 }
 
-class SortFilterMenu extends StatelessWidget {
+class SortFilterMenu<T> extends StatelessWidget {
-  final List<SortFilterMenuSection> sections;
+  final List<SortFilterMenuSection<T>> sections;
-  final ValueChanged<int> onSelected;
+  final ValueChanged<T> onSelected;
   final String tooltip;
   final Widget icon;
 
@@ -40,7 +37,7 @@ class SortFilterMenu extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return PopupMenuButton<int>(
+    return PopupMenuButton<T>(
       icon: icon,
       tooltip: tooltip,
       onSelected: onSelected,
@@ -53,11 +50,11 @@ class SortFilterMenu extends StatelessWidget {
         final visibleSections = sections
             .where((section) => section.options.isNotEmpty)
             .toList();
-        final entries = <PopupMenuEntry<int>>[];
+        final entries = <PopupMenuEntry<T>>[];
         for (int i = 0; i < visibleSections.length; i++) {
           final section = visibleSections[i];
           entries.add(
-            PopupMenuItem<int>(
+            PopupMenuItem<T>(
               enabled: false,
               child: Text(section.title, style: labelStyle),
             ),
@@ -65,14 +62,14 @@ class SortFilterMenu extends StatelessWidget {
           for (final option in section.options) {
             if (option.checked == null) {
               entries.add(
-                PopupMenuItem<int>(
+                PopupMenuItem<T>(
                   value: option.value,
                   child: Text(option.label),
                 ),
               );
             } else {
               entries.add(
-                CheckedPopupMenuItem<int>(
+                CheckedPopupMenuItem<T>(
                   value: option.value,
                   checked: option.checked ?? false,
                   child: Text(option.label),
@@ -90,16 +87,23 @@ class SortFilterMenu extends StatelessWidget {
   }
 }
 
-const int _actionSortRecentMessages = 1;
+sealed class _ContactsFilterAction {
-const int _actionSortName = 2;
+  const _ContactsFilterAction();
-const int _actionSortLastSeen = 3;
+}
-const int _actionFilterAll = 4;
+
-const int _actionFilterFavorites = 5;
+class _SortAction extends _ContactsFilterAction {
-const int _actionFilterUsers = 6;
+  final ContactSortOption option;
-const int _actionFilterRepeaters = 7;
+  const _SortAction(this.option);
-const int _actionFilterRooms = 8;
+}
-const int _actionToggleUnreadOnly = 9;
+
-const int _actionNewGroup = 10;
+class _TypeFilterAction extends _ContactsFilterAction {
+  final ContactTypeFilter filter;
+  const _TypeFilterAction(this.filter);
+}
+
+class _ToggleUnreadAction extends _ContactsFilterAction {
+  const _ToggleUnreadAction();
+}
 
 class ContactsFilterMenu extends StatelessWidget {
   final ContactSortOption sortOption;
@@ -108,7 +112,6 @@ class ContactsFilterMenu extends StatelessWidget {
   final ValueChanged<ContactSortOption> onSortChanged;
   final ValueChanged<ContactTypeFilter> onTypeFilterChanged;
   final ValueChanged<bool> onUnreadOnlyChanged;
-  final VoidCallback onNewGroup;
 
   const ContactsFilterMenu({
     super.key,
@@ -118,30 +121,29 @@ class ContactsFilterMenu extends StatelessWidget {
     required this.onSortChanged,
     required this.onTypeFilterChanged,
     required this.onUnreadOnlyChanged,
-    required this.onNewGroup,
   });
 
   @override
   Widget build(BuildContext context) {
     final l10n = context.l10n;
-    return SortFilterMenu(
+    return SortFilterMenu<_ContactsFilterAction>(
       tooltip: l10n.listFilter_tooltip,
       sections: [
         SortFilterMenuSection(
           title: l10n.listFilter_sortBy,
           options: [
             SortFilterMenuOption(
-              value: _actionSortRecentMessages,
+              value: _SortAction(ContactSortOption.recentMessages),
               label: l10n.listFilter_latestMessages,
               checked: sortOption == ContactSortOption.recentMessages,
             ),
             SortFilterMenuOption(
-              value: _actionSortLastSeen,
+              value: _SortAction(ContactSortOption.lastSeen),
               label: l10n.listFilter_heardRecently,
               checked: sortOption == ContactSortOption.lastSeen,
             ),
             SortFilterMenuOption(
-              value: _actionSortName,
+              value: _SortAction(ContactSortOption.name),
               label: l10n.listFilter_az,
               checked: sortOption == ContactSortOption.name,
             ),
@@ -151,80 +153,66 @@ class ContactsFilterMenu extends StatelessWidget {
           title: l10n.listFilter_filters,
           options: [
             SortFilterMenuOption(
-              value: _actionFilterAll,
+              value: _TypeFilterAction(ContactTypeFilter.all),
               label: l10n.listFilter_all,
               checked: typeFilter == ContactTypeFilter.all,
             ),
             SortFilterMenuOption(
-              value: _actionFilterFavorites,
+              value: _TypeFilterAction(ContactTypeFilter.favorites),
               label: l10n.listFilter_favorites,
               checked: typeFilter == ContactTypeFilter.favorites,
             ),
             SortFilterMenuOption(
-              value: _actionFilterUsers,
+              value: _TypeFilterAction(ContactTypeFilter.users),
               label: l10n.listFilter_users,
               checked: typeFilter == ContactTypeFilter.users,
             ),
             SortFilterMenuOption(
-              value: _actionFilterRepeaters,
+              value: _TypeFilterAction(ContactTypeFilter.repeaters),
               label: l10n.listFilter_repeaters,
               checked: typeFilter == ContactTypeFilter.repeaters,
             ),
             SortFilterMenuOption(
-              value: _actionFilterRooms,
+              value: _TypeFilterAction(ContactTypeFilter.rooms),
               label: l10n.listFilter_roomServers,
               checked: typeFilter == ContactTypeFilter.rooms,
             ),
             SortFilterMenuOption(
-              value: _actionToggleUnreadOnly,
+              value: const _ToggleUnreadAction(),
               label: l10n.listFilter_unreadOnly,
               checked: showUnreadOnly,
             ),
-            SortFilterMenuOption(
-              value: _actionNewGroup,
-              label: l10n.listFilter_newGroup,
-            ),
           ],
         ),
       ],
       onSelected: (action) {
         switch (action) {
-          case _actionSortRecentMessages:
+          case _SortAction(:final option):
-            onSortChanged(ContactSortOption.recentMessages);
+            onSortChanged(option);
-            break;
+          case _TypeFilterAction(:final filter):
-          case _actionSortName:
+            onTypeFilterChanged(filter);
-            onSortChanged(ContactSortOption.name);
+          case _ToggleUnreadAction():
-            break;
-          case _actionSortLastSeen:
-            onSortChanged(ContactSortOption.lastSeen);
-            break;
-          case _actionFilterAll:
-            onTypeFilterChanged(ContactTypeFilter.all);
-            break;
-          case _actionFilterUsers:
-            onTypeFilterChanged(ContactTypeFilter.users);
-            break;
-          case _actionFilterFavorites:
-            onTypeFilterChanged(ContactTypeFilter.favorites);
-            break;
-          case _actionFilterRepeaters:
-            onTypeFilterChanged(ContactTypeFilter.repeaters);
-            break;
-          case _actionFilterRooms:
-            onTypeFilterChanged(ContactTypeFilter.rooms);
-            break;
-          case _actionToggleUnreadOnly:
             onUnreadOnlyChanged(!showUnreadOnly);
-            break;
-          case _actionNewGroup:
-            onNewGroup();
-            break;
         }
       },
     );
   }
 }
 
+sealed class _DiscoveryFilterAction {
+  const _DiscoveryFilterAction();
+}
+
+class _DiscoverySortAction extends _DiscoveryFilterAction {
+  final ContactSortOption option;
+  const _DiscoverySortAction(this.option);
+}
+
+class _DiscoveryTypeFilterAction extends _DiscoveryFilterAction {
+  final ContactTypeFilter filter;
+  const _DiscoveryTypeFilterAction(this.filter);
+}
+
 class DiscoveryContactsFilterMenu extends StatelessWidget {
   final ContactSortOption sortOption;
   final ContactTypeFilter typeFilter;
@@ -242,19 +230,19 @@ class DiscoveryContactsFilterMenu extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     final l10n = context.l10n;
-    return SortFilterMenu(
+    return SortFilterMenu<_DiscoveryFilterAction>(
       tooltip: l10n.listFilter_tooltip,
       sections: [
         SortFilterMenuSection(
           title: l10n.listFilter_sortBy,
           options: [
             SortFilterMenuOption(
-              value: _actionSortLastSeen,
+              value: _DiscoverySortAction(ContactSortOption.lastSeen),
               label: l10n.listFilter_heardRecently,
               checked: sortOption == ContactSortOption.lastSeen,
             ),
             SortFilterMenuOption(
-              value: _actionSortName,
+              value: _DiscoverySortAction(ContactSortOption.name),
               label: l10n.listFilter_az,
               checked: sortOption == ContactSortOption.name,
             ),
@@ -264,22 +252,22 @@ class DiscoveryContactsFilterMenu extends StatelessWidget {
           title: l10n.listFilter_filters,
           options: [
             SortFilterMenuOption(
-              value: _actionFilterAll,
+              value: _DiscoveryTypeFilterAction(ContactTypeFilter.all),
               label: l10n.listFilter_all,
               checked: typeFilter == ContactTypeFilter.all,
             ),
             SortFilterMenuOption(
-              value: _actionFilterUsers,
+              value: _DiscoveryTypeFilterAction(ContactTypeFilter.users),
               label: l10n.listFilter_users,
               checked: typeFilter == ContactTypeFilter.users,
             ),
             SortFilterMenuOption(
-              value: _actionFilterRepeaters,
+              value: _DiscoveryTypeFilterAction(ContactTypeFilter.repeaters),
               label: l10n.listFilter_repeaters,
               checked: typeFilter == ContactTypeFilter.repeaters,
             ),
             SortFilterMenuOption(
-              value: _actionFilterRooms,
+              value: _DiscoveryTypeFilterAction(ContactTypeFilter.rooms),
               label: l10n.listFilter_roomServers,
               checked: typeFilter == ContactTypeFilter.rooms,
             ),
@@ -288,27 +276,10 @@ class DiscoveryContactsFilterMenu extends StatelessWidget {
       ],
       onSelected: (action) {
         switch (action) {
-          case _actionSortName:
+          case _DiscoverySortAction(:final option):
-            onSortChanged(ContactSortOption.name);
+            onSortChanged(option);
-            break;
+          case _DiscoveryTypeFilterAction(:final filter):
-          case _actionSortLastSeen:
+            onTypeFilterChanged(filter);
-            onSortChanged(ContactSortOption.lastSeen);
-            break;
-          case _actionFilterAll:
-            onTypeFilterChanged(ContactTypeFilter.all);
-            break;
-          case _actionFilterUsers:
-            onTypeFilterChanged(ContactTypeFilter.users);
-            break;
-          case _actionFilterFavorites:
-            onTypeFilterChanged(ContactTypeFilter.favorites);
-            break;
-          case _actionFilterRepeaters:
-            onTypeFilterChanged(ContactTypeFilter.repeaters);
-            break;
-          case _actionFilterRooms:
-            onTypeFilterChanged(ContactTypeFilter.rooms);
-            break;
         }
       },
     );

pubspec.yaml

@@ -16,7 +16,7 @@ publish_to: 'none' # Remove this line if you wish to publish to pub.dev
 # https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
 # In Windows, build-name is used as the major, minor, and patch parts
 # of the product and file versions while build-number is used as the build suffix.
-version: 6.0.0+7
+version: 7.0.0+8
 
 environment:
   sdk: ^3.9.2
@@ -69,6 +69,8 @@ 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

@@ -0,0 +1,156 @@
+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

@@ -0,0 +1,164 @@
+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(),
+  );
+}