fix: Preserve contacts and sensor updates

lib/providers/contacts_provider.dart

@@ -275,10 +275,10 @@ class ContactsProvider with ChangeNotifier {
 
   /// Clear runtime contact state before a live device contact sync begins.
   ///
-  /// This intentionally does not touch persisted storage. It keeps any saved
+  /// This intentionally does not touch persisted storage. It snapshots the
-  /// contact groups for the active profile, but removes stale in-memory device
+  /// current in-memory contacts so sync updates can still merge against the
-  /// contacts and discovery state so a newly connected device starts from an
+  /// latest local state, but keeps the visible list intact so reconnects do
-  /// empty list while sync is in progress.
+  /// not blank the UI while the device is resyncing.
   Future<void> prepareForDeviceContactSync({Uint8List? devicePublicKey}) async {
     _setSelfDevicePublicKey(devicePublicKey);
     if (!_isInitialized) {
@@ -292,7 +292,7 @@ class ContactsProvider with ChangeNotifier {
     }
 
     debugPrint(
-      '🧹 [ContactsProvider] Clearing runtime contacts before device sync',
+      '🧹 [ContactsProvider] Preparing retained contact state for device sync',
     );
     _retainedContactsForSync
       ..clear()
@@ -301,12 +301,6 @@ class ContactsProvider with ChangeNotifier {
           (contact) => MapEntry(contact.publicKeyHex, contact),
         ),
       );
-    _contacts.clear();
-    _pendingAdverts.clear();
-    _estimatedLocations.clear();
-    _rssiObservations.clear();
-    _ensurePublicChannelExists();
-    notifyListeners();
   }
 
   /// Remove self-contact from loaded contacts (called after BLE connection established)

lib/widgets/sensors/sensor_telemetry_card.dart

@@ -29,6 +29,31 @@ class SensorMetricOption {
   });
 }
 
+const Set<String> _imperialMeasurementCountries = <String>{
+  'US',
+  'LR',
+  'MM',
+};
+
+bool _usesImperialSpeedUnits() {
+  final countryCode =
+      WidgetsBinding.instance.platformDispatcher.locale.countryCode;
+  if (countryCode == null || countryCode.isEmpty) {
+    return false;
+  }
+  return _imperialMeasurementCountries.contains(countryCode.toUpperCase());
+}
+
+String _formatPreviewSpeed(num metersPerSecond) {
+  if (_usesImperialSpeedUnits()) {
+    final milesPerHour = metersPerSecond * 2.2369362920544;
+    return '${_formatPreviewNumber(milesPerHour, maxFractionDigits: 2)} mph';
+  }
+
+  final kilometersPerHour = metersPerSecond * 3.6;
+  return '${_formatPreviewNumber(kilometersPerHour, maxFractionDigits: 2)} km/h';
+}
+
 List<SensorMetricOption> sensorMetricOptionsFor(
   Contact? contact, {
   Map<String, String> labelOverrides = const <String, String>{},
@@ -795,17 +820,17 @@ String? _sensorMetricPreviewValue(String rawKey, dynamic value) {
     case 'speed':
       final metersPerSecond = _previewAsDouble(value);
       if (metersPerSecond == null) return null;
-      return '${_formatPreviewNumber(metersPerSecond, maxFractionDigits: 2)} m/s';
+      return _formatPreviewSpeed(metersPerSecond);
 
     case 'signed_speed':
       final metersPerSecond = _previewAsDouble(value);
       if (metersPerSecond == null) return null;
-      return '${_formatPreviewNumber(metersPerSecond, maxFractionDigits: 2)} m/s';
+      return _formatPreviewSpeed(metersPerSecond);
 
     case 'gust':
       final metersPerSecond = _previewAsDouble(value);
       if (metersPerSecond == null) return null;
-      return '${_formatPreviewNumber(metersPerSecond, maxFractionDigits: 2)} m/s';
+      return _formatPreviewSpeed(metersPerSecond);
 
     case 'dew':
       final degreesCelsius = _previewAsDouble(value);
@@ -1066,6 +1091,16 @@ class SensorTelemetryCard extends StatelessWidget {
     this.labelOverrides = const <String, String>{},
   });
 
+  String _formatSpeed(num metersPerSecond) {
+    if (_usesImperialSpeedUnits()) {
+      final milesPerHour = metersPerSecond * 2.2369362920544;
+      return '${_formatNumber(milesPerHour, maxFractionDigits: 2)} mph';
+    }
+
+    final kilometersPerHour = metersPerSecond * 3.6;
+    return '${_formatNumber(kilometersPerHour, maxFractionDigits: 2)} km/h';
+  }
+
   bool get _showsMenu =>
       onRefresh != null ||
       onCustomize != null ||
@@ -1759,7 +1794,7 @@ class SensorTelemetryCard extends StatelessWidget {
           fieldKey: _extraFieldKey(rawKey),
           icon: Icons.air,
           label: label,
-          value: '${_formatNumber(metersPerSecond, maxFractionDigits: 2)} m/s',
+          value: _formatSpeed(metersPerSecond),
           accent: const Color(0xFF2B78A0),
           channel: metricKey.channel,
         );
@@ -1771,7 +1806,7 @@ class SensorTelemetryCard extends StatelessWidget {
           fieldKey: _extraFieldKey(rawKey),
           icon: Icons.air,
           label: label,
-          value: '${_formatNumber(metersPerSecond, maxFractionDigits: 2)} m/s',
+          value: _formatSpeed(metersPerSecond),
           accent: const Color(0xFF2B78A0),
           channel: metricKey.channel,
         );
@@ -1783,7 +1818,7 @@ class SensorTelemetryCard extends StatelessWidget {
           fieldKey: _extraFieldKey(rawKey),
           icon: Icons.air,
           label: label,
-          value: '${_formatNumber(metersPerSecond, maxFractionDigits: 2)} m/s',
+          value: _formatSpeed(metersPerSecond),
           accent: const Color(0xFF1E88A8),
           channel: metricKey.channel,
         );
@@ -2252,7 +2287,7 @@ class _InlineAlertBadge extends StatelessWidget {
   }
 }
 
-class SensorMetricTile extends StatelessWidget {
+class SensorMetricTile extends StatefulWidget {
   final SensorMetricCardData data;
   final double width;
   final String keyPrefix;
@@ -2268,8 +2303,43 @@ class SensorMetricTile extends StatelessWidget {
     this.onLongPress,
   });
 
+  @override
+  State<SensorMetricTile> createState() => _SensorMetricTileState();
+}
+
+class _SensorMetricTileState extends State<SensorMetricTile> {
+  final flutter_map.MapController _previewMapController =
+      flutter_map.MapController();
+
+  @override
+  void didUpdateWidget(covariant SensorMetricTile oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    final previousLocation = oldWidget.data.mapLocation;
+    final nextLocation = widget.data.mapLocation;
+    if (!_sameMapLocation(previousLocation, nextLocation) &&
+        nextLocation != null &&
+        widget.allowMapPreview) {
+      WidgetsBinding.instance.addPostFrameCallback((_) {
+        if (!mounted) {
+          return;
+        }
+        _previewMapController.move(
+          nextLocation,
+          _previewMapController.camera.zoom,
+        );
+      });
+    }
+  }
+
+  bool _sameMapLocation(LatLng? a, LatLng? b) {
+    if (a == null || b == null) {
+      return a == b;
+    }
+    return a.latitude == b.latitude && a.longitude == b.longitude;
+  }
+
   Future<void> _showExpandedMap(BuildContext context) async {
-    final location = data.mapLocation;
+    final location = widget.data.mapLocation;
     if (location == null) return;
 
     await Navigator.of(context).push(
@@ -2280,9 +2350,9 @@ class SensorMetricTile extends StatelessWidget {
               title: Column(
                 crossAxisAlignment: CrossAxisAlignment.start,
                 children: [
-                  Text(data.label),
+                  Text(widget.data.label),
                   Text(
-                    data.value,
+                    widget.data.value,
                     style: Theme.of(pageContext).textTheme.bodySmall,
                   ),
                 ],
@@ -2291,11 +2361,11 @@ class SensorMetricTile extends StatelessWidget {
             body: Column(
               crossAxisAlignment: CrossAxisAlignment.start,
               children: [
-                if (data.secondaryValue != null)
+                if (widget.data.secondaryValue != null)
                   Padding(
                     padding: const EdgeInsets.fromLTRB(16, 0, 16, 12),
                     child: Text(
-                      data.secondaryValue!,
+                      widget.data.secondaryValue!,
                       style: Theme.of(pageContext).textTheme.bodyMedium,
                     ),
                   ),
@@ -2320,7 +2390,7 @@ class SensorMetricTile extends StatelessWidget {
                             height: 40,
                             child: Icon(
                               Icons.location_on,
-                              color: data.accent,
+                              color: widget.data.accent,
                               size: 34,
                             ),
                           ),
@@ -2340,14 +2410,15 @@ class SensorMetricTile extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    final data = widget.data;
     return Material(
       color: Colors.transparent,
       child: InkWell(
-        key: ValueKey('${keyPrefix}_${data.fieldKey}'),
+        key: ValueKey('${widget.keyPrefix}_${data.fieldKey}'),
         borderRadius: BorderRadius.circular(22),
-        onLongPress: onLongPress,
+        onLongPress: widget.onLongPress,
         child: Container(
-          width: width,
+          width: widget.width,
           padding: const EdgeInsets.all(8),
           decoration: BoxDecoration(
             color: data.accent.withValues(alpha: 0.08),
@@ -2368,7 +2439,10 @@ class SensorMetricTile extends StatelessWidget {
                         ),
                         const SizedBox(width: 10),
                         Expanded(
-                          child: _MetricText(data: data, keyPrefix: keyPrefix),
+                          child: _MetricText(
+                            data: data,
+                            keyPrefix: widget.keyPrefix,
+                          ),
                         ),
                       ],
                     ),
@@ -2387,7 +2461,7 @@ class SensorMetricTile extends StatelessWidget {
                       ),
                   ],
                 )
-              : data.mapLocation == null || !allowMapPreview
+              : data.mapLocation == null || !widget.allowMapPreview
               ? Stack(
                   children: [
                     Row(
@@ -2396,7 +2470,10 @@ class SensorMetricTile extends StatelessWidget {
                         _MetricIcon(accent: data.accent, icon: data.icon),
                         const SizedBox(width: 10),
                         Expanded(
-                          child: _MetricText(data: data, keyPrefix: keyPrefix),
+                          child: _MetricText(
+                            data: data,
+                            keyPrefix: widget.keyPrefix,
+                          ),
                         ),
                       ],
                     ),
@@ -2424,7 +2501,10 @@ class SensorMetricTile extends StatelessWidget {
                         _MetricIcon(accent: data.accent, icon: data.icon),
                         const SizedBox(width: 10),
                         Expanded(
-                          child: _MetricText(data: data, keyPrefix: keyPrefix),
+                          child: _MetricText(
+                            data: data,
+                            keyPrefix: widget.keyPrefix,
+                          ),
                         ),
                       ],
                     ),
@@ -2442,6 +2522,7 @@ class SensorMetricTile extends StatelessWidget {
                               child: Stack(
                                 children: [
                                   flutter_map.FlutterMap(
+                                    mapController: _previewMapController,
                                     options: flutter_map.MapOptions(
                                       initialCenter: data.mapLocation!,
                                       initialZoom: 14,

test/providers/contacts_provider_test.dart

@@ -893,7 +893,7 @@ void main() {
     });
 
     test(
-      'clears runtime contacts before sync without erasing persisted contacts or saved groups',
+      'keeps runtime contacts visible during sync without erasing persisted contacts or saved groups',
       () async {
         final key = createPublicKey(140);
         final pendingKey = createPublicKey(180);
@@ -906,8 +906,11 @@ void main() {
 
         await provider.prepareForDeviceContactSync();
 
-        expect(provider.chatContacts, isEmpty);
+        expect(
-        expect(provider.pendingAdverts, isEmpty);
+          provider.chatContacts.map((contact) => contact.advName),
+          contains('Synced Later'),
+        );
+        expect(provider.pendingAdverts, hasLength(1));
         expect(provider.savedGroupsForSection('teamMembers'), hasLength(1));
 
         final restored = ContactsProvider();

test/widgets/sensor_telemetry_card_test.dart

@@ -1,6 +1,8 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
+import 'package:flutter_map/flutter_map.dart' as flutter_map;
 import 'package:flutter_test/flutter_test.dart';
+import 'package:latlong2/latlong.dart';
 import 'package:meshcore_sar_app/l10n/app_localizations.dart';
 import 'package:meshcore_sar_app/models/contact.dart';
 import 'package:meshcore_sar_app/providers/sensors_provider.dart';
@@ -140,6 +142,8 @@ void main() {
   });
 
   testWidgets('renders MeshCore custom weather metrics', (tester) async {
+    tester.platformDispatcher.localeTestValue = const Locale('sl', 'SI');
+    addTearDown(tester.platformDispatcher.clearLocaleTestValue);
     final publicKey = Uint8List(32);
     publicKey[0] = 0x46;
     final contact = Contact(
@@ -185,11 +189,130 @@ void main() {
     expect(find.text('Wind gust'), findsOneWidget);
     expect(find.text('Dew point'), findsOneWidget);
     expect(find.text('Rain'), findsOneWidget);
-    expect(find.text('3.7 m/s'), findsOneWidget);
+    expect(find.textContaining('km/h'), findsOneWidget);
+    expect(find.textContaining('m/s'), findsNothing);
     expect(find.text('2°C'), findsOneWidget);
     expect(find.text('12.3 mm'), findsOneWidget);
   });
 
+  testWidgets('renders speed in mph for imperial system locale', (
+    tester,
+  ) async {
+    tester.platformDispatcher.localeTestValue = const Locale('en', 'US');
+    addTearDown(tester.platformDispatcher.clearLocaleTestValue);
+
+    final publicKey = Uint8List(32);
+    publicKey[0] = 0x4A;
+    final contact = Contact(
+      publicKey: publicKey,
+      type: ContactType.sensor,
+      flags: 0,
+      outPathLen: 0,
+      outPath: Uint8List(64),
+      advName: 'WX Station',
+      lastAdvert: DateTime.now().millisecondsSinceEpoch ~/ 1000,
+      advLat: 0,
+      advLon: 0,
+      lastMod: DateTime.now().millisecondsSinceEpoch ~/ 1000,
+      telemetry: ContactTelemetry(
+        timestamp: DateTime.now().subtract(const Duration(minutes: 1)),
+        extraSensorData: const {'speed_2': 3.7},
+      ),
+    );
+
+    await tester.pumpWidget(
+      MaterialApp(
+        localizationsDelegates: AppLocalizations.localizationsDelegates,
+        supportedLocales: AppLocalizations.supportedLocales,
+        home: Scaffold(
+          body: SensorTelemetryCard(
+            contact: contact,
+            state: SensorRefreshState.idle,
+            visibleFields: const {'extra:speed_2'},
+            fieldSpans: sensorFullWidthFieldSpans(const {'extra:speed_2'}),
+          ),
+        ),
+      ),
+    );
+
+    expect(find.textContaining('mph'), findsOneWidget);
+    expect(find.textContaining('m/s'), findsNothing);
+  });
+
+  testWidgets('gps preview map recenters when telemetry location changes', (
+    tester,
+  ) async {
+    final publicKey = Uint8List(32);
+    publicKey[0] = 0x4B;
+
+    Contact buildGpsContact(double latitude, double longitude) => Contact(
+      publicKey: publicKey,
+      type: ContactType.sensor,
+      flags: 0,
+      outPathLen: 0,
+      outPath: Uint8List(64),
+      advName: 'GPS Station',
+      lastAdvert: DateTime.now().millisecondsSinceEpoch ~/ 1000,
+      advLat: 0,
+      advLon: 0,
+      lastMod: DateTime.now().millisecondsSinceEpoch ~/ 1000,
+      telemetry: ContactTelemetry(
+        gpsLocation: LatLng(latitude, longitude),
+        timestamp: DateTime.now().subtract(const Duration(minutes: 1)),
+      ),
+    );
+
+    var contact = buildGpsContact(46.0569, 14.5058);
+
+    await tester.pumpWidget(
+      StatefulBuilder(
+        builder: (context, setState) {
+          return MaterialApp(
+            localizationsDelegates: AppLocalizations.localizationsDelegates,
+            supportedLocales: AppLocalizations.supportedLocales,
+            home: Scaffold(
+              body: Column(
+                children: [
+                  ElevatedButton(
+                    onPressed: () {
+                      setState(() {
+                        contact = buildGpsContact(46.1000, 14.6000);
+                      });
+                    },
+                    child: const Text('Update'),
+                  ),
+                  SensorTelemetryCard(
+                    contact: contact,
+                    state: SensorRefreshState.idle,
+                    visibleFields: const {'gps'},
+                    fieldSpans: sensorFullWidthFieldSpans(const {'gps'}),
+                  ),
+                ],
+              ),
+            ),
+          );
+        },
+      ),
+    );
+
+    final initialMap = tester.widget<flutter_map.FlutterMap>(
+      find.byType(flutter_map.FlutterMap).first,
+    );
+    final initialCenter = initialMap.mapController!.camera.center;
+    expect(initialCenter.latitude, closeTo(46.0569, 0.0001));
+    expect(initialCenter.longitude, closeTo(14.5058, 0.0001));
+
+    await tester.tap(find.text('Update'));
+    await tester.pump();
+
+    final updatedMap = tester.widget<flutter_map.FlutterMap>(
+      find.byType(flutter_map.FlutterMap).first,
+    );
+    final updatedCenter = updatedMap.mapController!.camera.center;
+    expect(updatedCenter.latitude, closeTo(46.1000, 0.0001));
+    expect(updatedCenter.longitude, closeTo(14.6000, 0.0001));
+  });
+
   testWidgets('renders generic percentage separately from UV for weather payload', (tester) async {
     tester.view.physicalSize = const Size(1600, 2600);
     tester.view.devicePixelRatio = 1.0;