feat: Add fast GPS send logs

lib/providers/app_provider.dart

@@ -2879,8 +2879,13 @@ class AppProvider with ChangeNotifier {
       timestampSeconds: DateTime.now().millisecondsSinceEpoch ~/ 1000,
     );
     debugPrint(
-      '📍 [AppProvider] Sending fast GPS update ($reason): '
-      '${position.latitude}, ${position.longitude} via channel $channelIdx',
+      '📤 [AppProvider] Fast GPS send '
+      'reason=$reason '
+      'sender=$senderKey6 '
+      'channel=$channelIdx '
+      'lat=${position.latitude} '
+      'lon=${position.longitude} '
+      'ts=${packet.timestampSeconds}',
     );
     try {
       await connectionProvider.sendChannelData(
@@ -2888,11 +2893,32 @@ class AppProvider with ChangeNotifier {
         dataType: MeshCoreConstants.dataTypeDev,
         payload: packet.encodeBinary(),
       );
+      debugPrint(
+        '✅ [AppProvider] Fast GPS sent '
+        'sender=$senderKey6 channel=$channelIdx ts=${packet.timestampSeconds}',
+      );
     } catch (e) {
       debugPrint('⚠️ [AppProvider] Fast GPS send failed: $e');
     }
   }
 
+  Future<bool> sendTestFastLocationUpdate() async {
+    if (!connectionProvider.deviceInfo.isConnected) {
+      return false;
+    }
+
+    final position = await locationTrackingService.getCurrentPosition(
+      timeLimit: const Duration(seconds: 10),
+      retryCount: 1,
+    );
+    if (position == null) {
+      return false;
+    }
+
+    await _sendFastLocationUpdate(position, reason: 'test');
+    return true;
+  }
+
   Contact? _resolveVoiceFetchRequester(VoiceFetchRequest request) {
     final liveContact = _resolveContactByPrefixHex(request.requesterKey6);
     if (liveContact != null) {

lib/providers/contacts_provider.dart

@@ -1143,13 +1143,34 @@ class ContactsProvider with ChangeNotifier {
       ),
     );
 
+    debugPrint(
+      '📥 [ContactsProvider] Fast GPS received '
+      'sender=${packet.senderKey6} '
+      'contact=${contact.displayName} '
+      'contactKey=${contact.publicKeyHex} '
+      'lat=${packet.latitude} '
+      'lon=${packet.longitude} '
+      'ts=${packet.timestampSeconds}',
+    );
+
     final updatedContact = contact.copyWith(
       telemetry: updatedTelemetry,
       lastAdvert: packet.timestampSeconds,
+      lastMod: packet.timestampSeconds,
       advLat: _coordinateToAdvertMicrodegrees(packet.latitude),
       advLon: _coordinateToAdvertMicrodegrees(packet.longitude),
     );
     _contacts[contact.publicKeyHex] = updatedContact;
+    _estimatedLocations[contact.publicKeyHex] = LatLng(
+      packet.latitude,
+      packet.longitude,
+    );
+    debugPrint(
+      '✅ [ContactsProvider] Fast GPS applied '
+      'contact=${updatedContact.displayName} '
+      'contactKey=${updatedContact.publicKeyHex} '
+      'lastAdvert=${updatedContact.lastAdvert}',
+    );
     _persistContacts();
     notifyListeners();
   }

lib/screens/settings_screen.dart

@@ -426,6 +426,23 @@ class _SettingsScreenState extends State<SettingsScreen> {
     return 'Channel $channelIdx unavailable';
   }
 
+  Future<void> _sendTestFastLocationUpdate() async {
+    final appProvider = context.read<AppProvider>();
+    final sent = await appProvider.sendTestFastLocationUpdate();
+    if (!mounted) return;
+
+    ScaffoldMessenger.of(context).showSnackBar(
+      SnackBar(
+        content: Text(
+          sent
+              ? 'Test fast GPS update sent.'
+              : 'Unable to send test fast GPS update.',
+        ),
+        backgroundColor: sent ? Colors.green : Colors.orange,
+      ),
+    );
+  }
+
   Future<void> _editFastLocationChannel() async {
     final channels =
         List<Contact>.from(context.read<ContactsProvider>().channels)
@@ -1854,6 +1871,15 @@ class _SettingsScreenState extends State<SettingsScreen> {
               trailing: const Icon(Icons.chevron_right),
               onTap: _editFastLocationChannel,
             ),
+            ListTile(
+              leading: const Icon(Icons.send),
+              title: const Text('Test send update'),
+              subtitle: const Text(
+                'Send one fast GPS update immediately to the configured channel.',
+              ),
+              trailing: const Icon(Icons.chevron_right),
+              onTap: _sendTestFastLocationUpdate,
+            ),
             ListTile(
               leading: Icon(Icons.location_on),
               title: Text(AppLocalizations.of(context)!.locationPermission),