Add LPCNet voice mode support

ios/Podfile.lock

@@ -57,6 +57,8 @@ PODS:
     - FlutterMacOS
   - image_picker_ios (0.0.1):
     - Flutter
+  - lpcnet_flutter (0.1.0):
+    - Flutter
   - nsd_ios (0.0.1):
     - Flutter
   - package_info_plus (0.4.5):
@@ -98,6 +100,7 @@ DEPENDENCIES:
   - flutter_local_notifications (from `.symlinks/plugins/flutter_local_notifications/ios`)
   - geolocator_apple (from `.symlinks/plugins/geolocator_apple/darwin`)
   - image_picker_ios (from `.symlinks/plugins/image_picker_ios/ios`)
+  - lpcnet_flutter (from `.symlinks/plugins/lpcnet_flutter/ios`)
   - nsd_ios (from `.symlinks/plugins/nsd_ios/ios`)
   - package_info_plus (from `.symlinks/plugins/package_info_plus/ios`)
   - path_provider_foundation (from `.symlinks/plugins/path_provider_foundation/darwin`)
@@ -141,6 +144,8 @@ EXTERNAL SOURCES:
     :path: ".symlinks/plugins/geolocator_apple/darwin"
   image_picker_ios:
     :path: ".symlinks/plugins/image_picker_ios/ios"
+  lpcnet_flutter:
+    :path: ".symlinks/plugins/lpcnet_flutter/ios"
   nsd_ios:
     :path: ".symlinks/plugins/nsd_ios/ios"
   package_info_plus:
@@ -177,6 +182,7 @@ SPEC CHECKSUMS:
   flutter_local_notifications: 643a3eda1ce1c0599413ca31672536d423dee214
   geolocator_apple: ab36aa0e8b7d7a2d7639b3b4e48308394e8cef5e
   image_picker_ios: e0ece4aa2a75771a7de3fa735d26d90817041326
+  lpcnet_flutter: 67a3c72ea4caa511373ee9b028223e33f0e85b97
   nsd_ios: 596ad79109ddd3e52d665f650f36428049e3653e
   package_info_plus: af8e2ca6888548050f16fa2f1938db7b5a5df499
   path_provider_foundation: bb55f6dbba17d0dccd6737fe6f7f34fbd0376880

lib/providers/contacts_provider.dart

@@ -516,8 +516,8 @@ class ContactsProvider with ChangeNotifier {
       return null;
     }
 
-    final firstHopHex = routeBytes
+    final lastHopHex = routeBytes
-        .sublist(0, routeHashSize)
+        .sublist(routeBytes.length - routeHashSize)
         .map((byte) => byte.toRadixString(16).padLeft(2, '0'))
         .join();
     final repeaterCandidates = _contacts.values.where((candidate) {
@@ -526,7 +526,7 @@ class ContactsProvider with ChangeNotifier {
         return false;
       }
       final location = candidate.displayLocation;
-      return location != null && candidate.publicKeyHex.startsWith(firstHopHex);
+      return location != null && candidate.publicKeyHex.startsWith(lastHopHex);
     }).toList()..sort((a, b) => b.lastAdvert.compareTo(a.lastAdvert));
     if (repeaterCandidates.isEmpty) {
       return null;

lib/providers/voice_provider.dart

@@ -303,7 +303,7 @@ class VoiceProvider with ChangeNotifier {
       debugPrint('🎙️ [VoiceProvider] decoded ${pcm.length} PCM samples');
       _playingSessionId = sessionId;
       notifyListeners();
-      await _player.play(pcm);
+      await _player.play(pcm, sampleRateHz: session.mode.sampleRateHz);
     } catch (e, st) {
       debugPrint('❌ [VoiceProvider] Playback error: $e\n$st');
       if (_playingSessionId == sessionId) {

lib/screens/messages_tab.dart

@@ -24,6 +24,7 @@ import '../widgets/messages/messages_content.dart';
 import '../widgets/common/contact_avatar.dart';
 import '../services/message_destination_preferences.dart';
 import '../services/voice_bitrate_preferences.dart';
+import '../services/voice_codec_preferences.dart';
 import '../services/voice_recorder_service.dart';
 import '../services/voice_codec_service.dart';
 import '../utils/toast_logger.dart';
@@ -81,6 +82,7 @@ class _MessagesTabState extends State<MessagesTab> {
   final List<Int16List> _recordedChunks = [];
   VoicePacketMode? _activeVoiceMode;
   int _selectedVoiceBitrate = VoiceBitratePreferences.defaultBitrate;
+  VoiceCodecKind _selectedVoiceCodec = VoiceCodecPreferences.defaultCodec;
 
   @override
   void initState() {
@@ -88,17 +90,19 @@ class _MessagesTabState extends State<MessagesTab> {
     _textController.addListener(_updateCharacterCount);
     // Load saved message destination
     _loadSavedDestination();
-    _loadVoiceBitrate();
+    _loadVoiceSettings();
     WidgetsBinding.instance.addPostFrameCallback((_) {
       _checkForNavigationRequest();
     });
   }
 
-  Future<void> _loadVoiceBitrate() async {
+  Future<void> _loadVoiceSettings() async {
     final bitrate = await VoiceBitratePreferences.getBitrate();
+    final codec = await VoiceCodecPreferences.getCodec();
     if (!mounted) return;
     setState(() {
       _selectedVoiceBitrate = bitrate;
+      _selectedVoiceCodec = codec;
     });
   }
 
@@ -817,14 +821,17 @@ class _MessagesTabState extends State<MessagesTab> {
   Future<void> _startVoiceRecording() async {
     if (_isSendingVoice || _isRecording) return;
     debugPrint('🎙️ [Voice] _startVoiceRecording called');
-    // Read fresh bitrate preference so settings changes apply immediately.
+    // Read fresh voice preferences so settings changes apply immediately.
     final selectedBitrate = await VoiceBitratePreferences.getBitrate();
+    final selectedCodec = await VoiceCodecPreferences.getCodec();
     if (mounted) {
       setState(() {
         _selectedVoiceBitrate = selectedBitrate;
+        _selectedVoiceCodec = selectedCodec;
       });
     } else {
       _selectedVoiceBitrate = selectedBitrate;
+      _selectedVoiceCodec = selectedCodec;
     }
     final hasPermission = await _voiceRecorder.requestPermission();
     debugPrint('🎙️ [Voice] hasPermission=$hasPermission');
@@ -852,11 +859,11 @@ class _MessagesTabState extends State<MessagesTab> {
       (_) => rng.nextInt(256),
     ).map((b) => b.toRadixString(16).padLeft(2, '0')).join();
 
-    _activeVoiceMode = VoiceBitratePreferences.toVoiceMode(
+    _activeVoiceMode = _selectedVoiceCodec == VoiceCodecKind.lpcnet
-      _selectedVoiceBitrate,
+        ? VoicePacketMode.lpcnet1600
-    );
+        : VoiceBitratePreferences.toVoiceMode(_selectedVoiceBitrate);
     final packetDuration = Duration(
-      milliseconds: codec2ModeFor(_activeVoiceMode!).packetDurationMs,
+      milliseconds: _activeVoiceMode!.packetDurationMs,
     );
 
     debugPrint(
@@ -869,6 +876,7 @@ class _MessagesTabState extends State<MessagesTab> {
     try {
       final stream = _voiceRecorder.startCapture(
         chunkDuration: packetDuration,
+        sampleRateHz: _activeVoiceMode!.sampleRateHz,
         enableBandPassFilter: appProvider.isVoiceBandPassFilterEnabled,
         enableCompressor: appProvider.isVoiceCompressorEnabled,
         enableLimiter: appProvider.isVoiceLimiterEnabled,

lib/screens/settings_screen.dart

@@ -18,8 +18,8 @@ import '../services/location_tracking_service.dart';
 import '../services/locale_preferences.dart';
 import '../services/mesh_map_nodes_service.dart';
 import '../services/update_checker_service.dart';
-import '../services/voice_codec_service.dart';
 import '../services/voice_bitrate_preferences.dart';
+import '../services/voice_codec_preferences.dart';
 import '../services/image_preferences.dart';
 import '../services/route_hash_preferences.dart';
 import '../services/image_codec_service.dart';
@@ -60,6 +60,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
   bool _showRxTxIndicators = true;
   bool _isCheckingForUpdates = false;
   int _voiceBitrate = VoiceBitratePreferences.defaultBitrate;
+  VoiceCodecKind _voiceCodec = VoiceCodecPreferences.defaultCodec;
   int _routeHashSize = RouteHashPreferences.defaultHashSize;
   int _imageMaxSize = ImagePreferences.defaultMaxSize;
   int _imageCompression = ImagePreferences.defaultQuality;
@@ -88,7 +89,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
     _loadPackageInfo();
     _initializeLocationService();
     _loadRxTxPreference();
-    _loadVoiceBitratePreference();
+    _loadVoicePreferences();
     _loadRouteHashSizePreference();
     _loadImagePreferences();
     _loadFastLocationSettings();
@@ -178,11 +179,13 @@ class _SettingsScreenState extends State<SettingsScreen> {
     await prefs.setBool('show_rx_tx_indicators', value);
   }
 
-  Future<void> _loadVoiceBitratePreference() async {
+  Future<void> _loadVoicePreferences() async {
     final value = await VoiceBitratePreferences.getBitrate();
+    final codec = await VoiceCodecPreferences.getCodec();
     if (!mounted) return;
     setState(() {
       _voiceBitrate = value;
+      _voiceCodec = codec;
     });
   }
 
@@ -194,10 +197,27 @@ class _SettingsScreenState extends State<SettingsScreen> {
     });
   }
 
+  Future<void> _saveVoiceCodecPreference(VoiceCodecKind value) async {
+    await VoiceCodecPreferences.setCodec(value);
+    if (!mounted) return;
+    setState(() {
+      _voiceCodec = value;
+    });
+  }
+
   String _voiceBitrateSubtitle(int bitrate) {
+    if (_voiceCodec == VoiceCodecKind.lpcnet) {
+      return 'Fixed 1600 bps';
+    }
     return '$bitrate bps';
   }
 
+  String _voiceCodecSubtitle() {
+    return _voiceCodec == VoiceCodecKind.codec2
+        ? 'Selectable low-bitrate modes'
+        : 'Fixed 16 kHz / 1.6 kbps mode';
+  }
+
   Future<void> _loadRouteHashSizePreference() async {
     final value = await RouteHashPreferences.getHashSize();
     if (!mounted) return;
@@ -1159,6 +1179,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
           Consumer2<AppProvider, ConnectionProvider>(
             builder: (context, appProvider, connectionProvider, child) =>
                 _buildVoiceStatsCard(
+                  codec: _voiceCodec,
                   bitrate: _voiceBitrate,
                   connectionProvider: connectionProvider,
                   bandPassEnabled: appProvider.isVoiceBandPassFilterEnabled,
@@ -1168,12 +1189,22 @@ class _SettingsScreenState extends State<SettingsScreen> {
                 ),
           ),
           _buildSettingsCard([
+            ListTile(
+              leading: const Icon(Icons.record_voice_over),
+              title: const Text('Voice codec'),
+              subtitle: Text(_voiceCodecSubtitle()),
+              trailing: const Icon(Icons.chevron_right),
+              onTap: _showVoiceCodecDialog,
+            ),
             ListTile(
               leading: const Icon(Icons.graphic_eq),
               title: const Text('Voice bitrate'),
               subtitle: Text(_voiceBitrateSubtitle(_voiceBitrate)),
               trailing: const Icon(Icons.chevron_right),
-              onTap: _showVoiceBitrateDialog,
+              enabled: _voiceCodec == VoiceCodecKind.codec2,
+              onTap: _voiceCodec == VoiceCodecKind.codec2
+                  ? _showVoiceBitrateDialog
+                  : null,
             ),
             Consumer<AppProvider>(
               builder: (context, appProvider, child) => SwitchListTile(
@@ -1724,6 +1755,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
   }
 
   Widget _buildVoiceStatsCard({
+    required VoiceCodecKind codec,
     required int bitrate,
     required ConnectionProvider connectionProvider,
     required bool bandPassEnabled,
@@ -1746,9 +1778,11 @@ class _SettingsScreenState extends State<SettingsScreen> {
     final radioSf = connectionProvider.deviceInfo.radioSf;
     final radioCr = connectionProvider.deviceInfo.radioCr;
     final bwHz = _resolveBandwidthHz(radioBw);
-    final voiceMode = VoiceBitratePreferences.toVoiceMode(bitrate);
+    final voiceMode = codec == VoiceCodecKind.lpcnet
+        ? VoicePacketMode.lpcnet1600
+        : VoiceBitratePreferences.toVoiceMode(bitrate);
     const voicePreviewMs = 10000; // 10-second reference clip
-    final packetDurationMs = codec2ModeFor(voiceMode).packetDurationMs;
+    final packetDurationMs = voiceMode.packetDurationMs;
     final voicePacketCount =
         (voicePreviewMs + packetDurationMs - 1) ~/ packetDurationMs;
     final voiceDirect = estimateVoiceTransmitDuration(
@@ -1783,7 +1817,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
             ),
             const SizedBox(height: 8),
             Text(
-              'Bitrate: $bitrate bps',
+              'Codec: ${voiceMode.label}${codec == VoiceCodecKind.codec2 ? ' · $bitrate bps' : ' · 1600 bps'}',
               style: Theme.of(context).textTheme.bodySmall,
             ),
             const SizedBox(height: 4),
@@ -2112,6 +2146,47 @@ class _SettingsScreenState extends State<SettingsScreen> {
     );
   }
 
+  void _showVoiceCodecDialog() {
+    showDialog(
+      context: context,
+      builder: (context) => AlertDialog(
+        title: const Text('Voice codec'),
+        content: SingleChildScrollView(
+          child: RadioGroup<VoiceCodecKind>(
+            groupValue: _voiceCodec,
+            onChanged: (value) {
+              if (value != null) {
+                _saveVoiceCodecPreference(value);
+              }
+              Navigator.pop(context);
+            },
+            child: Column(
+              mainAxisSize: MainAxisSize.min,
+              children: [
+                RadioListTile<VoiceCodecKind>(
+                  value: VoiceCodecKind.codec2,
+                  title: const Text('Codec2'),
+                  subtitle: const Text('Selectable ultra-low bitrate modes'),
+                ),
+                RadioListTile<VoiceCodecKind>(
+                  value: VoiceCodecKind.lpcnet,
+                  title: const Text('LPCNet'),
+                  subtitle: const Text('Fixed 16 kHz / 1.6 kbps neural mode'),
+                ),
+              ],
+            ),
+          ),
+        ),
+        actions: [
+          TextButton(
+            onPressed: () => Navigator.pop(context),
+            child: Text(AppLocalizations.of(context)!.cancel),
+          ),
+        ],
+      ),
+    );
+  }
+
   void _showAboutDialog() {
     showDialog(
       context: context,

lib/services/voice_codec_preferences.dart

@@ -0,0 +1,21 @@
+import 'package:shared_preferences/shared_preferences.dart';
+import '../utils/voice_message_parser.dart';
+
+class VoiceCodecPreferences {
+  static const String _codecKey = 'voice_codec';
+  static const VoiceCodecKind defaultCodec = VoiceCodecKind.codec2;
+
+  static Future<VoiceCodecKind> getCodec() async {
+    final prefs = await SharedPreferences.getInstance();
+    final raw = prefs.getString(_codecKey);
+    return VoiceCodecKind.values.firstWhere(
+      (codec) => codec.name == raw,
+      orElse: () => defaultCodec,
+    );
+  }
+
+  static Future<void> setCodec(VoiceCodecKind codec) async {
+    final prefs = await SharedPreferences.getInstance();
+    await prefs.setString(_codecKey, codec.name);
+  }
+}

lib/services/voice_codec_service_io.dart

@@ -1,20 +1,27 @@
 import 'dart:typed_data';
 import 'package:codec2_flutter/codec2_flutter.dart';
+import 'package:lpcnet_flutter/lpcnet_flutter.dart';
 import 'package:flutter/foundation.dart';
 import '../utils/voice_message_parser.dart';
 
-export 'package:codec2_flutter/codec2_flutter.dart' show Codec2Mode;
-
-/// Maps [VoicePacketMode] to the [Codec2Mode] enum from the FFI plugin.
 Codec2Mode codec2ModeFor(VoicePacketMode pktMode) {
   switch (pktMode) {
-    case VoicePacketMode.mode3200: return Codec2Mode.mode3200;
+    case VoicePacketMode.mode3200:
-    case VoicePacketMode.mode1600: return Codec2Mode.mode1600;
+      return Codec2Mode.mode3200;
-    case VoicePacketMode.mode1400: return Codec2Mode.mode1400;
+    case VoicePacketMode.mode1600:
-    case VoicePacketMode.mode700c: return Codec2Mode.mode700c;
+      return Codec2Mode.mode1600;
-    case VoicePacketMode.mode1200: return Codec2Mode.mode1200;
+    case VoicePacketMode.mode1400:
-    case VoicePacketMode.mode1300: return Codec2Mode.mode1300;
+      return Codec2Mode.mode1400;
-    case VoicePacketMode.mode2400: return Codec2Mode.mode2400;
+    case VoicePacketMode.mode700c:
+      return Codec2Mode.mode700c;
+    case VoicePacketMode.mode1200:
+      return Codec2Mode.mode1200;
+    case VoicePacketMode.mode1300:
+      return Codec2Mode.mode1300;
+    case VoicePacketMode.mode2400:
+      return Codec2Mode.mode2400;
+    case VoicePacketMode.lpcnet1600:
+      throw ArgumentError('LPCNet mode does not map to Codec2');
   }
 }
 
@@ -39,17 +46,24 @@ class VoiceCodecService {
     }
   }
 
-  /// Encode [pcm] (Int16 samples, 8000 Hz mono) with [mode].
-  /// Returns the raw Codec2-encoded bytes.
   Future<Uint8List> encode(Int16List pcm, VoicePacketMode mode) {
     _ensureCodec2Supported();
-    return Codec2.encodeInIsolate(pcm, codec2ModeFor(mode));
+    switch (mode.codec) {
+      case VoiceCodecKind.codec2:
+        return Codec2.encodeInIsolate(pcm, codec2ModeFor(mode));
+      case VoiceCodecKind.lpcnet:
+        return LpcNet.encodeInIsolate(pcm);
+    }
   }
 
-  /// Decode [codec2Bytes] back to Int16 PCM (8000 Hz mono) with [mode].
   Future<Int16List> decode(Uint8List codec2Bytes, VoicePacketMode mode) {
     _ensureCodec2Supported();
-    return Codec2.decodeInIsolate(codec2Bytes, codec2ModeFor(mode));
+    switch (mode.codec) {
+      case VoiceCodecKind.codec2:
+        return Codec2.decodeInIsolate(codec2Bytes, codec2ModeFor(mode));
+      case VoiceCodecKind.lpcnet:
+        return LpcNet.decodeInIsolate(codec2Bytes);
+    }
   }
 
   /// Decode and concatenate multiple [packets] into a single PCM Int16List.
@@ -59,24 +73,14 @@ class VoiceCodecService {
     VoicePacketMode mode,
   ) async {
     _ensureCodec2Supported();
-    final c2Mode = codec2ModeFor(mode);
-    final c2 = Codec2.create(c2Mode);
-    final spf = c2.samplesPerFrame;
-    c2.destroy();
-
-    // Estimate total samples (use actual data or silence per missing packet)
     final all = <Int16List>[];
     for (final pkt in packets) {
       if (pkt == null || pkt.codec2Data.isEmpty) {
-        // Silence for missing packet — duration approximated by mode
+        all.add(Int16List(mode.samplesPerPacket));
-        final silenceSamples = (codec2ModeFor(mode).framesPerSecond) * spf;
-        all.add(Int16List(silenceSamples));
       } else {
-        final decoded = await Codec2.decodeInIsolate(pkt.codec2Data, c2Mode);
+        all.add(await decode(pkt.codec2Data, mode));
-        all.add(decoded);
       }
     }
-
     final total = all.fold<int>(0, (sum, l) => sum + l.length);
     final result = Int16List(total);
     var offset = 0;

lib/services/voice_codec_service_stub.dart

@@ -1,7 +1,6 @@
 import 'dart:typed_data';
 import '../utils/voice_message_parser.dart';
 
-/// Web/unsupported platform stub — Codec2 FFI is not available.
 enum Codec2Mode {
   mode3200(0),
   mode2400(1),
@@ -19,13 +18,20 @@ enum Codec2Mode {
 
   int get bytesPerSecond {
     switch (this) {
-      case mode3200: return 400;
+      case mode3200:
-      case mode700c: return 100;
+        return 400;
-      case mode1200: return 150;
+      case mode700c:
-      case mode1300: return 175;
+        return 100;
-      case mode1400: return 175;
+      case mode1200:
-      case mode1600: return 200;
+        return 150;
-      case mode2400: return 300;
+      case mode1300:
+        return 175;
+      case mode1400:
+        return 175;
+      case mode1600:
+        return 200;
+      case mode2400:
+        return 300;
     }
   }
 
@@ -40,13 +46,22 @@ enum Codec2Mode {
 
 Codec2Mode codec2ModeFor(VoicePacketMode pktMode) {
   switch (pktMode) {
-    case VoicePacketMode.mode3200: return Codec2Mode.mode3200;
+    case VoicePacketMode.mode3200:
-    case VoicePacketMode.mode1600: return Codec2Mode.mode1600;
+      return Codec2Mode.mode3200;
-    case VoicePacketMode.mode1400: return Codec2Mode.mode1400;
+    case VoicePacketMode.mode1600:
-    case VoicePacketMode.mode700c: return Codec2Mode.mode700c;
+      return Codec2Mode.mode1600;
-    case VoicePacketMode.mode1200: return Codec2Mode.mode1200;
+    case VoicePacketMode.mode1400:
-    case VoicePacketMode.mode1300: return Codec2Mode.mode1300;
+      return Codec2Mode.mode1400;
-    case VoicePacketMode.mode2400: return Codec2Mode.mode2400;
+    case VoicePacketMode.mode700c:
+      return Codec2Mode.mode700c;
+    case VoicePacketMode.mode1200:
+      return Codec2Mode.mode1200;
+    case VoicePacketMode.mode1300:
+      return Codec2Mode.mode1300;
+    case VoicePacketMode.mode2400:
+      return Codec2Mode.mode2400;
+    case VoicePacketMode.lpcnet1600:
+      throw ArgumentError('LPCNet mode does not map to Codec2');
   }
 }
 
@@ -66,6 +81,5 @@ class VoiceCodecService {
   Future<Int16List> decodePackets(
     List<VoicePacket?> packets,
     VoicePacketMode mode,
-  ) =>
+  ) => Future.error(UnsupportedError('Voice not supported on web'));
-      Future.error(UnsupportedError('Voice not supported on web'));
 }

lib/services/voice_player_service.dart

@@ -5,7 +5,7 @@ import 'package:audioplayers/audioplayers.dart';
 import 'package:flutter/foundation.dart';
 import 'package:path_provider/path_provider.dart';
 
-/// Plays decoded 8000 Hz / 16-bit mono PCM samples by writing a WAV file
+/// Plays decoded mono PCM samples by writing a WAV file
 /// to the system temp directory and using [AudioPlayer].
 class VoicePlayerService {
   final AudioPlayer _player = AudioPlayer();
@@ -49,16 +49,17 @@ class VoicePlayerService {
     });
   }
 
-  /// Play [pcmSamples] (Int16, 8000 Hz, mono).
+  Future<void> play(Int16List pcmSamples, {required int sampleRateHz}) async {
-  Future<void> play(Int16List pcmSamples) async {
     debugPrint('🔊 [VoicePlayer] play() called, ${pcmSamples.length} samples');
     if (_isPlaying) await stop();
     _position = Duration.zero;
-    _duration = Duration(milliseconds: (pcmSamples.length * 1000) ~/ 8000);
+    _duration = Duration(
+      milliseconds: (pcmSamples.length * 1000) ~/ sampleRateHz,
+    );
     _playbackStartedAt = DateTime.now();
     _events.add(null);
 
-    final wavBytes = _buildWav(pcmSamples, sampleRate: 8000);
+    final wavBytes = _buildWav(pcmSamples, sampleRate: sampleRateHz);
     final tmpDir = await getTemporaryDirectory();
     final file = File('${tmpDir.path}/vc_voice.wav');
     await file.writeAsBytes(wavBytes);

lib/services/voice_recorder_service.dart

@@ -4,7 +4,7 @@ import 'dart:typed_data';
 import 'package:flutter/foundation.dart';
 import 'package:record/record.dart';
 
-/// Captures raw PCM audio at 8000 Hz, 16-bit mono.
+/// Captures raw PCM audio at a codec-selected sample rate, 16-bit mono.
 ///
 /// [startCapture] returns a [Stream<Int16List>] that emits chunks of PCM
 /// samples every [chunkDuration].  Call [stopCapture] to end recording.
@@ -27,9 +27,10 @@ class VoiceRecorderService {
   /// [enableBandPassFilter] applies voice-tuned band-pass filtering when true.
   /// [enableCompressor] normalizes speech dynamics before encoding.
   /// [enableLimiter] protects against clipping peaks before encoding.
-  /// The returned stream emits [Int16List] chunks that are ready for Codec2 encoding.
+  /// The returned stream emits [Int16List] chunks that are ready for voice encoding.
   Stream<Int16List> startCapture({
     Duration chunkDuration = const Duration(seconds: 1),
+    int sampleRateHz = 8000,
     bool enableBandPassFilter = true,
     bool enableCompressor = true,
     bool enableLimiter = true,
@@ -43,6 +44,7 @@ class VoiceRecorderService {
 
     _startRecording(
       chunkDuration,
+      sampleRateHz: sampleRateHz,
       enableBandPassFilter: enableBandPassFilter,
       enableCompressor: enableCompressor,
       enableLimiter: enableLimiter,
@@ -52,13 +54,14 @@ class VoiceRecorderService {
 
   Future<void> _startRecording(
     Duration chunkDuration, {
+    required int sampleRateHz,
     required bool enableBandPassFilter,
     required bool enableCompressor,
     required bool enableLimiter,
   }) async {
-    final config = const RecordConfig(
+    final config = RecordConfig(
       encoder: AudioEncoder.pcm16bits,
-      sampleRate: 8000,
+      sampleRate: sampleRateHz,
       numChannels: 1,
       bitRate: 128000, // ignored for PCM, but required by API
     );
@@ -66,16 +69,17 @@ class VoiceRecorderService {
     try {
       final stream = await _recorder.startStream(config);
       final voiceFilter = _VoiceBandPassFilter(
-        sampleRate: 8000,
+        sampleRate: sampleRateHz,
         lowCutHz: 250.0,
         highCutHz: 3400.0,
       );
       final dynamics = _VoiceDynamicsProcessor(
-        sampleRate: 8000,
+        sampleRate: sampleRateHz,
         enableCompressor: enableCompressor,
         enableLimiter: enableLimiter,
       );
-      final chunkBytes = 8000 * 2 * chunkDuration.inMilliseconds ~/ 1000;
+      final chunkBytes =
+          sampleRateHz * 2 * chunkDuration.inMilliseconds ~/ 1000;
       final buffer = <int>[];
 
       _sub = stream.listen(

lib/utils/voice_message_parser.dart

@@ -11,20 +11,43 @@ const int _defaultLoRaCrcEnabled = 1;
 const int _defaultLoRaExplicitHeader = 1;
 const double _defaultAirtimeBudgetFactor = 1.0; // one half duty-cycle
 
-/// Identifies which Codec2 mode was used for a voice packet.
+enum VoiceCodecKind {
-/// Matches the modeId byte in the text/binary packet header.
+  codec2(0, 'Codec2'),
-enum VoicePacketMode {
+  lpcnet(1, 'LPCNet');
-  mode700c(0, '700C'),
-  mode1200(1, '1200'),
-  mode2400(2, '2400'),
-  mode1300(3, '1300'),
-  mode1400(4, '1400'),
-  mode1600(5, '1600'),
-  mode3200(6, '3200');
 
-  const VoicePacketMode(this.id, this.label);
+  const VoiceCodecKind(this.id, this.label);
   final int id;
   final String label;
+}
+
+/// Identifies which voice codec/mode was used for a packet.
+/// Matches the modeId byte in the text/binary packet header.
+enum VoicePacketMode {
+  mode700c(0, '700C', VoiceCodecKind.codec2, 8000, 100, 1600),
+  mode1200(1, '1200', VoiceCodecKind.codec2, 8000, 150, 1040),
+  mode2400(2, '2400', VoiceCodecKind.codec2, 8000, 300, 520),
+  mode1300(3, '1300', VoiceCodecKind.codec2, 8000, 175, 880),
+  mode1400(4, '1400', VoiceCodecKind.codec2, 8000, 175, 880),
+  mode1600(5, '1600', VoiceCodecKind.codec2, 8000, 200, 800),
+  mode3200(6, '3200', VoiceCodecKind.codec2, 8000, 400, 400),
+  lpcnet1600(7, 'LPCNet', VoiceCodecKind.lpcnet, 16000, 200, 40);
+
+  const VoicePacketMode(
+    this.id,
+    this.label,
+    this.codec,
+    this.sampleRateHz,
+    this.bytesPerSecond,
+    this.packetDurationMs,
+  );
+  final int id;
+  final String label;
+  final VoiceCodecKind codec;
+  final int sampleRateHz;
+  final int bytesPerSecond;
+  final int packetDurationMs;
+
+  int get samplesPerPacket => sampleRateHz * packetDurationMs ~/ 1000;
 
   static VoicePacketMode fromId(int id) => VoicePacketMode.values.firstWhere(
     (m) => m.id == id,
@@ -153,23 +176,15 @@ class VoicePacket {
 
   /// Estimated audio duration of this packet in milliseconds.
   int get durationMs {
-    // bytesPerSecond for each mode
+    if (mode.bytesPerSecond == 0) return 0;
-    final bps = switch (mode) {
+    return (codec2Data.length * 1000 ~/ mode.bytesPerSecond).clamp(0, 1500);
-      VoicePacketMode.mode700c => 100,
-      VoicePacketMode.mode1200 => 150,
-      VoicePacketMode.mode1300 => 175,
-      VoicePacketMode.mode1400 => 175,
-      VoicePacketMode.mode1600 => 200,
-      VoicePacketMode.mode2400 => 300,
-      VoicePacketMode.mode3200 => 400,
-    };
-    if (bps == 0) return 0;
-    return (codec2Data.length * 1000 ~/ bps).clamp(0, 1500);
   }
 
   @override
   String toString() {
-    final suffix = total > 0 ? ' ${mode.label} [$index/${total - 1}]' : ' [$index]';
+    final suffix = total > 0
+        ? ' ${mode.label} [$index/${total - 1}]'
+        : ' [$index]';
     return 'VoicePacket($sessionId$suffix ${codec2Data.length}B)';
   }
 }
@@ -242,13 +257,7 @@ class VoiceEnvelope {
 }
 
 int voiceModeBytesPerSecond(VoicePacketMode mode) => switch (mode) {
-  VoicePacketMode.mode700c => 100,
+  _ => mode.bytesPerSecond,
-  VoicePacketMode.mode1200 => 150,
-  VoicePacketMode.mode1300 => 175,
-  VoicePacketMode.mode1400 => 175,
-  VoicePacketMode.mode1600 => 200,
-  VoicePacketMode.mode2400 => 300,
-  VoicePacketMode.mode3200 => 400,
 };
 
 /// Approximate end-to-end transmit time for a voice session over MeshCore LoRa.
@@ -419,8 +428,7 @@ class VoiceFetchRequest {
     this.version = 3,
   });
 
-  static bool isVoiceFetchRequestText(String text) =>
+  static bool isVoiceFetchRequestText(String text) => text.startsWith(_prefix);
-      text.startsWith(_prefix);
   static bool isVoiceFetchRequestBinary(Uint8List payload) =>
       payload.isNotEmpty && payload[0] == _binaryMagic;
 
@@ -473,9 +481,7 @@ class VoiceFetchRequest {
       final requesterKey6 = parts[2];
       final normalizedWant = wantToken == 'a'
           ? 'all'
-          : ((wantToken.startsWith('m'))
+          : ((wantToken.startsWith('m')) ? 'missing' : wantToken);
-                ? 'missing'
-                : wantToken);
 
       if (sid == null) {
         return null;
@@ -602,7 +608,11 @@ String _toBase36(int value) => value.toRadixString(36);
 
 String _encodeSessionId(String sessionIdHex) {
   if (!RegExp(r'^[0-9a-fA-F]{8}$').hasMatch(sessionIdHex)) {
-    throw ArgumentError.value(sessionIdHex, 'sessionIdHex', 'Expected 8 hex chars');
+    throw ArgumentError.value(
+      sessionIdHex,
+      'sessionIdHex',
+      'Expected 8 hex chars',
+    );
   }
   final value = int.parse(sessionIdHex, radix: 16);
   return value.toRadixString(36);
@@ -616,10 +626,7 @@ String? _decodeSessionId(String token) {
 }
 
 String _encodeMissingIndicesCompact(List<int> indices) {
-  final sorted = indices
+  final sorted = indices.where((v) => v >= 0 && v <= 254).toSet().toList()
-      .where((v) => v >= 0 && v <= 254)
-      .toSet()
-      .toList()
     ..sort();
   if (sorted.isEmpty) return '';
   final chunks = <String>[];
@@ -632,7 +639,9 @@ String _encodeMissingIndicesCompact(List<int> indices) {
       continue;
     }
     chunks.add(
-      start == prev ? _toBase36(start) : '${_toBase36(start)}-${_toBase36(prev)}',
+      start == prev
+          ? _toBase36(start)
+          : '${_toBase36(start)}-${_toBase36(prev)}',
     );
     start = curr;
     prev = curr;

lib/widgets/messages/message_trace_sheet.dart

@@ -10,6 +10,7 @@ import '../../models/ble_packet_log.dart';
 import '../../models/message.dart';
 import '../../providers/connection_provider.dart';
 import '../../providers/contacts_provider.dart';
+import '../../providers/messages_provider.dart';
 import '../../services/mesh_map_nodes_service.dart';
 import '../../services/route_hash_preferences.dart';
 import '../../utils/log_rx_route_decoder.dart';
@@ -35,11 +36,17 @@ class _MessageTraceSheetState extends State<MessageTraceSheet> {
   Future<_TraceResult> _loadTrace() async {
     final connectionProvider = context.read<ConnectionProvider>();
     final contactsProvider = context.read<ContactsProvider>();
+    final messagesProvider = context.read<MessagesProvider>();
     final preferredHashSize = await RouteHashPreferences.getHashSize();
-    final packetPath = _extractPathFromPacketLogs(
+    final storedPath =
-      logs: connectionProvider.bleService.packetLogs,
+        messagesProvider.getMessageReceptionDetails(widget.message.id)?.pathBytes;
-      message: widget.message,
+    final packetPath =
-    );
+        (storedPath != null && storedPath.isNotEmpty)
+        ? storedPath
+        : _extractPathFromPacketLogs(
+            logs: connectionProvider.bleService.packetLogs,
+            message: widget.message,
+          );
 
     final senderPrefix = _toPrefixHex(widget.message.senderPublicKeyPrefix);
     final recipientPrefix = widget.message.recipientPublicKey != null
@@ -456,7 +463,7 @@ class _MessageTraceSheetState extends State<MessageTraceSheet> {
       final hopHashes = LogRxRouteDecoder.splitHopHashes(
         packetPath,
         hashSize: hashSize,
-      );
+      ).reversed.toList();
       final matched = _matchNodesFromPathHashes(
         nodes: nodes,
         pathHashes: hopHashes,
@@ -568,6 +575,12 @@ class _MessageTraceSheetState extends State<MessageTraceSheet> {
             .toList();
         if (senderMatches.isNotEmpty) filtered = senderMatches;
       }
+      if (i == pathHashes.length - 1 && recipientPrefix != null) {
+        final recipientMatches = filtered
+            .where((n) => n.publicKey.startsWith(recipientPrefix))
+            .toList();
+        if (recipientMatches.isNotEmpty) filtered = recipientMatches;
+      }
 
       filtered.sort((a, b) => b.updatedAtMs.compareTo(a.updatedAtMs));
       result.add(filtered.first);

pubspec.lock

@@ -775,6 +775,13 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "6.1.0"
+  lpcnet_flutter:
+    dependency: "direct main"
+    description:
+      path: "../packages/lpcnet_flutter"
+      relative: true
+    source: path
+    version: "0.1.0"
   matcher:
     dependency: transitive
     description:

pubspec.yaml

@@ -51,6 +51,8 @@ dependencies:
     git:
       url: https://github.com/dz0ny/codec2_flutter.git
       ref: 03998a2
+  lpcnet_flutter:
+    path: ../packages/lpcnet_flutter
   ffi: ^2.1.0
 
   # Voice recording (raw PCM stream at 8000 Hz)

test/providers/contacts_provider_test.dart

@@ -524,10 +524,10 @@ void main() {
       );
     });
 
-    test('infers a fallback location 100m from first-hop repeater', () {
+    test('infers a fallback location 100m from last-hop repeater', () {
       final repeaterKey = Uint8List.fromList([
-        0xAA,
+        0xCC,
-        0xBB,
+        0xDD,
         0x10,
         0x11,
         0x12,
@@ -575,6 +575,47 @@ void main() {
       );
       expect(distanceMeters, closeTo(100.0, 8.0));
     });
+
+    test('does not infer a fallback location when the contact advertises one', () {
+      final repeaterKey = Uint8List.fromList([
+        0xCC,
+        0xDD,
+        0x10,
+        0x11,
+        0x12,
+        0x13,
+        ...List<int>.generate(26, (index) => index + 20),
+      ]);
+      provider.addOrUpdateContact(
+        createContact(
+          key: repeaterKey,
+          type: ContactType.repeater,
+          name: 'Relay Alpha',
+        ),
+      );
+
+      final targetKey = createPublicKey(121);
+      final route = ContactRouteCodec.parse('AABB,CCDD');
+      provider.addOrUpdateContact(
+        Contact(
+          publicKey: targetKey,
+          type: ContactType.chat,
+          flags: 0,
+          outPathLen: route.signedEncodedPathLen,
+          outPath: route.paddedPathBytes,
+          advName: 'Has Advert',
+          lastAdvert: DateTime.now().millisecondsSinceEpoch ~/ 1000,
+          advLat: (45.1234 * 1e6).toInt(),
+          advLon: (13.8765 * 1e6).toInt(),
+          lastMod: DateTime.now().millisecondsSinceEpoch ~/ 1000,
+        ),
+      );
+
+      final updated = provider.findContactByKey(targetKey)!;
+      expect(updated.displayLocation, isNotNull);
+      expect(updated.displayLocation!.latitude, closeTo(45.1234, 0.000001));
+      expect(updated.displayLocation!.longitude, closeTo(13.8765, 0.000001));
+    });
   });
 
   group('ContactsProvider.updateFastGps', () {