diff --git a/lib/services/github/github_sync_service.dart b/lib/services/github/github_sync_service.dart
index 47c5ec9..03fdcb9 100644
--- a/lib/services/github/github_sync_service.dart
+++ b/lib/services/github/github_sync_service.dart
@@ -36,10 +36,10 @@ class GitHubUploadResult {
 
 /// Compatibility facade for the historical ride-detail sync service.
 ///
-/// MotorSignal cloud backup is Firebase Authentication + Firestore + R2.
-/// The old GitHub PAT exporter remains available only through the explicit
-/// `uploadRideToGitHub` developer/export path and is never used by the normal
-/// History -> Upload Now action.
+/// Normal MotorSignal cloud backup is Firebase Authentication + Firestore + R2.
+/// The historical GitHub PAT exporter remains available only through the
+/// explicit `uploadRideToGitHub` developer/export path and is never used by
+/// the normal History -> Upload Now action.
 class GitHubSyncService extends ChangeNotifier {
   final AppDatabase _db;
   final GitHubAuthService _githubAuth;
@@ -51,12 +51,17 @@ class GitHubSyncService extends ChangeNotifier {
   String _statusMessage = '';
   final Set<int> _uploadQueue = {};
 
+  /// Keeps the historical constructor compatible with tests/callers that pass
+  /// an HTTP client as the optional fourth argument. Production additionally
+  /// supplies the shared Firebase AuthService as the fifth argument.
   GitHubSyncService(
     this._db,
     this._githubAuth,
-    this._authService,
-    this._prefs, [http.Client? client],
-  ) : _client = client ?? http.Client();
+    this._prefs, [
+    http.Client? client,
+    AuthService? authService,
+  ])  : _authService = authService ?? FirebaseAuthService(),
+        _client = client ?? http.Client();
 
   GitHubUploadState get state => _state;
   String get statusMessage => _statusMessage;
@@ -69,21 +74,18 @@ class GitHubSyncService extends ChangeNotifier {
   }
 
   bool isRideUploaded(int rideId) {
-    final scoped = _userScopedKey('motorcloud_uploaded_ride', rideId);
-    if (scoped == null) return false;
-    return _prefs.getBool(scoped) ?? false;
+    final key = _userScopedKey('motorcloud_uploaded_ride', rideId);
+    return key != null && (_prefs.getBool(key) ?? false);
   }
 
   String? getRideCommitSha(int rideId) {
-    final scoped = _userScopedKey('motorcloud_ride_remote_id', rideId);
-    if (scoped == null) return null;
-    return _prefs.getString(scoped);
+    final key = _userScopedKey('motorcloud_ride_remote_id', rideId);
+    return key == null ? null : _prefs.getString(key);
   }
 
   String? getRideUploadTimestamp(int rideId) {
-    final scoped = _userScopedKey('motorcloud_uploaded_at_ride', rideId);
-    if (scoped == null) return null;
-    return _prefs.getString(scoped);
+    final key = _userScopedKey('motorcloud_uploaded_at_ride', rideId);
+    return key == null ? null : _prefs.getString(key);
   }
 
   void queueRideForUpload(int rideId) {
@@ -105,23 +107,23 @@ class GitHubSyncService extends ChangeNotifier {
 
   /// Normal History -> Upload Now operation.
   ///
-  /// This deliberately ignores any configured GitHub PAT. A user's ride must
-  /// be written to that user's MotorCloud account, not to a public developer
-  /// repository. Authentication and ownership are enforced by Firebase/R2.
+  /// Deliberately ignores any configured GitHub PAT. A user's ride must be
+  /// written to that user's MotorCloud account, never to the developer's
+  /// public repository.
   Future<GitHubUploadResult> uploadRide(int rideId, {bool isManual = false}) async {
     return _uploadToMotorCloud(rideId);
   }
 
   /// Explicit legacy/developer export. Not used by the normal ride UI.
   Future<GitHubUploadResult> uploadRideToGitHub(int rideId) async {
-    final githubToken = _githubAuth.getToken();
-    if (githubToken == null || githubToken.isEmpty) {
+    final token = _githubAuth.getToken();
+    if (token == null || token.isEmpty) {
       return GitHubUploadResult(
         success: false,
         message: 'GitHub export requires an explicitly configured GitHub token.',
       );
     }
-    return _uploadToGitHub(rideId, githubToken);
+    return _uploadToGitHub(rideId, token);
   }
 
   Future<GitHubUploadResult> _uploadToMotorCloud(int rideId) async {
@@ -137,7 +139,12 @@ class GitHubSyncService extends ChangeNotifier {
       _state = GitHubUploadState.success;
       _statusMessage = 'Ride #$rideId is already backed up to your MotorCloud account.';
       notifyListeners();
-      return GitHubUploadResult(success: true, message: _statusMessage, commitSha: getRideCommitSha(rideId), targetPath: 'MotorCloud');
+      return GitHubUploadResult(
+        success: true,
+        message: _statusMessage,
+        commitSha: getRideCommitSha(rideId),
+        targetPath: 'MotorCloud',
+      );
     }
 
     _state = GitHubUploadState.uploading;
@@ -145,25 +152,25 @@ class GitHubSyncService extends ChangeNotifier {
     notifyListeners();
 
     try {
-      final provider = FirebaseSyncProvider(
-        db: _db,
-        authService: _authService,
-      );
-      final result = await provider.uploadRide(
-        SyncItem(
-          localRideId: rideId,
-          providerId: 'firebase',
-          createdAt: DateTime.now(),
-        ),
-      );
+      final provider = FirebaseSyncProvider(db: _db, authService: _authService);
+      final result = await provider.uploadRide(SyncItem(
+        localRideId: rideId,
+        providerId: 'firebase',
+        createdAt: DateTime.now(),
+      ));
 
       if (result.success) {
-        final uploadedKey = _userScopedKey('motorcloud_uploaded_ride', rideId)!;
-        final timestampKey = _userScopedKey('motorcloud_uploaded_at_ride', rideId)!;
-        final remoteIdKey = _userScopedKey('motorcloud_ride_remote_id', rideId)!;
-        await _prefs.setBool(uploadedKey, true);
-        await _prefs.setString(timestampKey, DateTime.now().toIso8601String());
-        if (result.remoteId != null) await _prefs.setString(remoteIdKey, result.remoteId!);
+        await _prefs.setBool(_userScopedKey('motorcloud_uploaded_ride', rideId)!, true);
+        await _prefs.setString(
+          _userScopedKey('motorcloud_uploaded_at_ride', rideId)!,
+          DateTime.now().toIso8601String(),
+        );
+        if (result.remoteId != null) {
+          await _prefs.setString(
+            _userScopedKey('motorcloud_ride_remote_id', rideId)!,
+            result.remoteId!,
+          );
+        }
         _uploadQueue.remove(rideId);
         _state = GitHubUploadState.success;
         _statusMessage = 'Ride #$rideId backed up to your MotorCloud account';
@@ -323,7 +330,7 @@ class GitHubSyncService extends ChangeNotifier {
 final githubSyncServiceProvider = ChangeNotifierProvider<GitHubSyncService>((ref) {
   final db = ref.watch(databaseProvider);
   final githubAuth = ref.watch(githubAuthServiceProvider);
-  final authService = ref.watch(authServiceProvider);
   final prefs = ref.watch(sharedPreferencesProvider);
-  return GitHubSyncService(db, githubAuth, authService, prefs);
+  final authService = ref.watch(authServiceProvider);
+  return GitHubSyncService(db, githubAuth, prefs, null, authService);
 });