Multibyte: some path fixes

- Validate encoded path hop counts before saving or sending custom paths
- Fix multi-byte path reversal by reversing hops instead of raw bytes
- Decode raw log path lengths using packed path_len format
- Localize path hash mode options and optimize map anchor lookup

lib/connector/meshcore_connector.dart

@@ -2598,6 +2598,24 @@ class MeshCoreConnector extends ChangeNotifier {
     }
   }
 
+  bool _isPathLenValidForCurrentMode(int pathLen, List<int> pathBytes) {
+    return _isPathLenValidForMode(pathLen, pathBytes, _pathHashByteWidth);
+  }
+
+  int? _encodePathLenForCurrentMode(int pathLen, List<int> pathBytes) {
+    if (pathLen < 0 || pathLen == 0xFF) return pathLen;
+    if (!_isPathLenValidForCurrentMode(pathLen, pathBytes)) {
+      appLogger.warn(
+        'Invalid path_len for mode: pathLen=$pathLen, '
+        'bytesLen=${pathBytes.length}, width=$_pathHashByteWidth',
+        tag: 'Connector',
+      );
+      return null;
+    }
+    final mode = (_pathHashByteWidth - 1) & 0x03;
+    return (pathLen & 0x3F) | (mode << 6);
+  }
+
   Future<void> refreshDeviceInfo() async {
     if (!isConnected) return;
     if (PlatformInfo.isWeb &&
@@ -2797,11 +2815,10 @@ class MeshCoreConnector extends ChangeNotifier {
     try {
       if (!isConnected) return;
 
-      final mode = _pathHashByteWidth - 1;
-      if (pathLen < 0 || pathLen > 0x3F) {
+      final encodedPathLen = _encodePathLenForCurrentMode(pathLen, customPath);
+      if (encodedPathLen == null) {
         return;
       }
-      final encodedPathLen = pathLen | (mode << 6);
       await sendFrame(
         buildUpdateContactPathFrame(
           contact.publicKey,
@@ -2863,11 +2880,11 @@ class MeshCoreConnector extends ChangeNotifier {
               : (updatedFlags & ~contactFlagTeleEnv))
         : updatedFlags;
 
-    final mode = _pathHashByteWidth - 1;
-    final encodedPathLen =
-        (latestContact.pathLength >= 0 && latestContact.pathLength != 0xFF)
-        ? (latestContact.pathLength | (mode << 6))
-        : latestContact.pathLength;
+    final encodedPathLen = _encodePathLenForCurrentMode(
+      latestContact.pathLength,
+      latestContact.path,
+    );
+    if (encodedPathLen == null) return;
     await sendFrame(
       buildUpdateContactPathFrame(
         latestContact.publicKey,
@@ -2955,6 +2972,19 @@ class MeshCoreConnector extends ChangeNotifier {
       tag: 'Connector',
     );
 
+    if (pathLen != null &&
+        pathLen >= 0 &&
+        (pathBytes == null ||
+            !_isPathLenValidForCurrentMode(pathLen, pathBytes))) {
+      appLogger.warn(
+        'setPathOverride: invalid path for ${contact.name}: '
+        'pathLen=$pathLen, bytesLen=${pathBytes?.length ?? 0}, '
+        'width=$_pathHashByteWidth',
+        tag: 'Connector',
+      );
+      return;
+    }
+
     // Update contact with new path override
     _contacts[index] = _contacts[index].copyWith(
       pathOverride: pathLen,
@@ -3208,11 +3238,11 @@ class MeshCoreConnector extends ChangeNotifier {
   Future<void> importDiscoveredContact(Contact contact) async {
     if (!isConnected) return;
 
-    final mode = _pathHashByteWidth - 1;
-    final encodedPathLen =
-        (contact.pathLength >= 0 && contact.pathLength != 0xFF)
-        ? (contact.pathLength | (mode << 6))
-        : contact.pathLength;
+    final encodedPathLen = _encodePathLenForCurrentMode(
+      contact.pathLength,
+      contact.path,
+    );
+    if (encodedPathLen == null) return;
     await sendFrame(
       buildUpdateContactPathFrame(
         contact.publicKey,
@@ -6535,6 +6565,18 @@ int _decodePathHashWidth(int pathLenRaw) {
   return ((pathLenRaw >> 6) & 0x03) + 1;
 }
 
+bool _isPathLenValidForMode(
+  int pathLen,
+  List<int> pathBytes,
+  int pathHashWidth,
+) {
+  if (pathLen < 0 || pathLen > 0x3F) return false;
+  final width = pathHashWidth.clamp(1, 4).toInt();
+  final maxHopCountByBytes = maxPathSize ~/ width;
+  if (pathLen > maxHopCountByBytes) return false;
+  return pathBytes.length <= maxPathSize && pathBytes.length == pathLen * width;
+}
+
 Uint8List _reversePathByHop(Uint8List pathBytes, int pathHashWidth) {
   if (pathBytes.isEmpty) return Uint8List(0);
   final width = pathHashWidth.clamp(1, 4).toInt();

lib/screens/map_screen.dart

@@ -700,6 +700,16 @@ class _MapScreenState extends State<MapScreen> {
     int pathHashByteWidth,
   ) {
     final result = <_GuessedLocation>[];
+    final hopWidth = pathHashByteWidth.clamp(1, 4).toInt();
+    final anchorsByPrefix = <String, List<Contact>>{};
+    for (final repeater in withLocation) {
+      if (repeater.type != advTypeRepeater) continue;
+      if (repeater.publicKey.length < hopWidth) continue;
+      final prefix = PathHelper.formatHopHex(
+        repeater.publicKey.sublist(0, hopWidth),
+      );
+      anchorsByPrefix.putIfAbsent(prefix, () => []).add(repeater);
+    }
 
     for (final contact in allContacts) {
       if (contact.hasLocation) continue;
@@ -722,21 +732,13 @@ class _MapScreenState extends State<MapScreen> {
       ];
       for (final pathBytes in pathSets) {
         if (pathBytes.isEmpty) continue;
-        final hopWidth = pathHashByteWidth.clamp(1, 4);
         final lastHop = pathBytes.sublist(max(0, pathBytes.length - hopWidth));
         if (lastHop.isEmpty) continue;
 
-        for (final repeater in withLocation) {
-          if (repeater.type != advTypeRepeater) continue;
-          if (repeater.publicKey.length < lastHop.length) continue;
-          if (!listEquals(
-            repeater.publicKey.sublist(0, lastHop.length),
-            lastHop,
-          )) {
-            continue;
-          }
+        final repeaters = anchorsByPrefix[PathHelper.formatHopHex(lastHop)];
+        if (repeaters != null && repeaters.isNotEmpty) {
+          final repeater = repeaters.first;
           anchorSet.add(LatLng(repeater.latitude!, repeater.longitude!));
-          break;
         }
       }
 
@@ -2304,10 +2306,17 @@ class _MapScreenState extends State<MapScreen> {
       connector.pathHashByteWidth.clamp(1, pubKeySize),
       contact.publicKey.length,
     ).toInt();
+    final hopPrefix = contact.publicKey.sublist(0, hopWidth);
+    for (final existingHop in PathHelper.splitPathBytes(
+      _pathTrace,
+      connector.pathHashByteWidth,
+    )) {
+      if (listEquals(existingHop, hopPrefix)) {
+        return;
+      }
+    }
     setState(() {
-      _pathTrace.addAll(
-        contact.publicKey.sublist(0, hopWidth),
-      ); // Add the hop-width prefix of the public key to the trace
+      _pathTrace.addAll(hopPrefix); // Add the hop-width pubkey prefix.
       _pathTraceHopWidths.add(hopWidth);
       _pathTraceContacts.add(
         contact.copyWith(

lib/screens/settings_screen.dart

@@ -580,11 +580,23 @@ class _SettingsScreenState extends State<SettingsScreen> {
                   labelText: l10n.repeater_pathHashMode,
                   border: const OutlineInputBorder(),
                 ),
-                items: const [
-                  DropdownMenuItem(value: 0, child: Text('0 - 1 byte')),
-                  DropdownMenuItem(value: 1, child: Text('1 - 2 bytes')),
-                  DropdownMenuItem(value: 2, child: Text('2 - 3 bytes')),
-                  DropdownMenuItem(value: 3, child: Text('3 - 4 bytes')),
+                items: [
+                  DropdownMenuItem(
+                    value: 0,
+                    child: Text(l10n.repeater_pathHashModeOption0),
+                  ),
+                  DropdownMenuItem(
+                    value: 1,
+                    child: Text(l10n.repeater_pathHashModeOption1),
+                  ),
+                  DropdownMenuItem(
+                    value: 2,
+                    child: Text(l10n.repeater_pathHashModeOption2),
+                  ),
+                  DropdownMenuItem(
+                    value: 3,
+                    child: Text(l10n.repeater_pathHashModeOption3),
+                  ),
                 ],
                 onChanged: (value) {
                   if (value == null) return;

lib/widgets/path_selection_dialog.dart

@@ -126,7 +126,8 @@ class _PathSelectionDialogState extends State<PathSelectionDialog> {
         .toList();
     final pathBytesList = <int>[];
     final invalidPrefixes = <String>[];
-    final hexCharsPerHop = widget.pathHashByteWidth.clamp(1, 4) * 2;
+    final pathHashByteWidth = widget.pathHashByteWidth.clamp(1, 4).toInt();
+    final hexCharsPerHop = pathHashByteWidth * 2;
 
     for (final id in pathIds) {
       if (id.length < hexCharsPerHop) {
@@ -157,8 +158,12 @@ class _PathSelectionDialogState extends State<PathSelectionDialog> {
       return;
     }
 
-    // Check max path size in bytes, as defined by the protocol.
-    if (pathBytesList.length > maxPathSize) {
+    final hopCount = pathBytesList.length ~/ pathHashByteWidth;
+    final maxHopCountByBytes = maxPathSize ~/ pathHashByteWidth;
+    final maxHopCount = maxHopCountByBytes < 0x3F ? maxHopCountByBytes : 0x3F;
+
+    // path_len stores hop count in 6 bits and the path buffer is byte-limited.
+    if (hopCount > maxHopCount || pathBytesList.length > maxPathSize) {
       showDismissibleSnackBar(
         context,
         content: Text(l10n.path_tooLong),
@@ -235,7 +240,7 @@ class _PathSelectionDialogState extends State<PathSelectionDialog> {
                   helperText: l10n.path_helperMaxHops,
                 ),
                 textCapitalization: TextCapitalization.characters,
-                maxLength: 191, // 64 hops * 2 chars + 63 commas
+                maxLength: 188, // 63 one-byte hops * 2 chars + 62 commas
               ),
               const SizedBox(height: 16),
               const Divider(),