diff --git a/lib/services/sync/firebase_sync_provider.dart b/lib/services/sync/firebase_sync_provider.dart
index 3a5d3d6..1bead10 100644
--- a/lib/services/sync/firebase_sync_provider.dart
+++ b/lib/services/sync/firebase_sync_provider.dart
@@ -41,6 +41,31 @@ class FirebaseSyncProvider implements SyncProvider {
     return user == null || user.isAnonymous;
   }
 
+  @override
+  Future<bool> isRideConfirmedInCloud(String remoteRideId) async {
+    final user = _authService.currentUser;
+    if (user == null || user.isAnonymous) return false;
+    if (!await isAvailable()) return false;
+    try {
+      final doc = await _firestore!
+          .collection('users')
+          .doc(user.uid)
+          .collection('rides')
+          .doc(remoteRideId)
+          .get();
+      if (!doc.exists) return false;
+      final data = doc.data();
+      if (data == null) return false;
+      final bundle = data['telemetryBundle'];
+      if (bundle is Map && bundle['status'] == 'uploaded') {
+        return true;
+      }
+      return false;
+    } catch (_) {
+      return false;
+    }
+  }
+
   @override
   Future<SyncResult> uploadRide(SyncItem item) async {
     final user = _authService.currentUser;
@@ -72,6 +97,10 @@ class FirebaseSyncProvider implements SyncProvider {
       // The cloud identity is generated once and then reused forever. Never
       // derive the remote identity from the local auto-increment database ID.
       final remoteRideId = await _db.ensureCloudRideId(item.localRideId);
+      if (await isRideConfirmedInCloud(remoteRideId)) {
+        return SyncResult.success(remoteId: remoteRideId);
+      }
+
       final appIdentity = AppIdentity.current();
       final zipBytes = await _bundleWorker.generateCompressedBundle(item.localRideId);
       if (zipBytes == null || zipBytes.isEmpty) return SyncResult.permanentFailure('Failed generating compressed telemetry bundle for ride #${item.localRideId}.');
diff --git a/lib/services/sync/github_sync_provider.dart b/lib/services/sync/github_sync_provider.dart
index ab66e0c..0e299db 100644
--- a/lib/services/sync/github_sync_provider.dart
+++ b/lib/services/sync/github_sync_provider.dart
@@ -23,6 +23,9 @@ class GitHubSyncProvider implements SyncProvider {
   @override
   Future<bool> requiresAuthentication() async => auth.getToken() == null;
 
+  @override
+  Future<bool> isRideConfirmedInCloud(String remoteRideId) async => false;
+
   @override
   Future<SyncResult> uploadRide(SyncItem item) async {
     final hasAuth = auth.getToken() != null;
diff --git a/lib/services/sync/sync_manager.dart b/lib/services/sync/sync_manager.dart
index 786cf61..02d152d 100644
--- a/lib/services/sync/sync_manager.dart
+++ b/lib/services/sync/sync_manager.dart
@@ -6,6 +6,41 @@ import 'sync_provider.dart';
 import '../../database/database.dart';
 import '../auth/auth_service.dart';
 
+/// Diagnostic summary returned by [SyncManager.reconcileCompletedRides].
+class CompletedRideReconciliationReport {
+  final int discoveredCompletedRides;
+  final int alreadyTrackedCount;
+  final int recoveredQueuedCount;
+  final int recoveredAuthRequiredCount;
+  final int recoveredAlreadySyncedCount;
+  final int foreignOwnerSkippedCount;
+  final int errorCount;
+  final List<String> errors;
+
+  const CompletedRideReconciliationReport({
+    this.discoveredCompletedRides = 0,
+    this.alreadyTrackedCount = 0,
+    this.recoveredQueuedCount = 0,
+    this.recoveredAuthRequiredCount = 0,
+    this.recoveredAlreadySyncedCount = 0,
+    this.foreignOwnerSkippedCount = 0,
+    this.errorCount = 0,
+    this.errors = const [],
+  });
+
+  int get totalRecovered =>
+      recoveredQueuedCount +
+      recoveredAuthRequiredCount +
+      recoveredAlreadySyncedCount;
+
+  @override
+  String toString() =>
+      'CompletedRideReconciliationReport(discovered: $discoveredCompletedRides, '
+      'tracked: $alreadyTrackedCount, queued: $recoveredQueuedCount, '
+      'authRequired: $recoveredAuthRequiredCount, alreadySynced: $recoveredAlreadySyncedCount, '
+      'foreignSkipped: $foreignOwnerSkippedCount, errors: $errorCount)';
+}
+
 /// Central provider-agnostic synchronization coordinator.
 ///
 /// Sync work is persisted in [SyncOutbox]. The manager reconciles persisted
@@ -16,17 +51,22 @@ class SyncManager extends ChangeNotifier with WidgetsBindingObserver {
   final Map<String, SyncProvider> _providers = {};
   String _activeProviderId = 'fake';
   bool _isProcessing = false;
+  Future<CompletedRideReconciliationReport>? _activeReconciliation;
+  Future<void>? _currentProcessingFuture;
+  bool _needsAnotherPass = false;
   DateTime? Function() _nowProvider;
   final AppDatabase? _db;
   final AuthService? _authService;
 
-  SyncManager(this._outbox, {List<SyncProvider>? initialProviders, String? defaultProviderId, DateTime? Function()? nowProvider, this._db, this._authService}) : _nowProvider = nowProvider ?? (() => DateTime.now()) {
+  SyncManager(this._outbox, {List<SyncProvider>? initialProviders, String? defaultProviderId, DateTime? Function()? nowProvider, this._db, this._authService, bool autoStart = true}) : _nowProvider = nowProvider ?? (() => DateTime.now()) {
     if (initialProviders != null) {
       for (final p in initialProviders) { registerProvider(p); }
     }
     if (defaultProviderId != null) _activeProviderId = defaultProviderId;
     WidgetsBinding.instance.addObserver(this);
-    unawaited(processQueue());
+    if (autoStart) {
+      unawaited(_startupRecoveryAndProcess());
+    }
   }
 
   void setNowProvider(DateTime? Function() provider) => _nowProvider = provider;
@@ -87,13 +127,166 @@ class SyncManager extends ChangeNotifier with WidgetsBindingObserver {
     return enqueued;
   }
 
+  Future<void> _startupRecoveryAndProcess() async {
+    await reconcileCompletedRides();
+    await processQueue();
+  }
+
   Future<void> retryAuthRequired() async {
+    final user = _authService?.currentUser;
+    final isAuthenticated = user != null && !user.isAnonymous;
+    if (isAuthenticated && _db != null) {
+      await reconcileCompletedRides();
+    }
     for (final item in _outbox.getAllItems().where((i) => i.status == SyncStatus.authRequired)) {
+      if (isAuthenticated && _db != null && item.providerId == 'firebase') {
+        await _db.claimRideForCloudOwner(item.localRideId, user.uid);
+      }
       await _outbox.update(item.copyWith(status: SyncStatus.queued, clearLastError: true, clearNextRetry: true));
     }
     await processQueue();
   }
 
+  /// Discovers completed rides in local SQLite that are missing from [SyncOutbox]
+  /// or need cloud confirmation recovery.
+  Future<CompletedRideReconciliationReport> reconcileCompletedRides({
+    String? targetProviderId,
+  }) async {
+    if (_activeReconciliation != null) {
+      return _activeReconciliation!;
+    }
+    final future = _performReconcileCompletedRides(targetProviderId: targetProviderId);
+    _activeReconciliation = future;
+    try {
+      return await future;
+    } finally {
+      _activeReconciliation = null;
+    }
+  }
+
+  Future<CompletedRideReconciliationReport> _performReconcileCompletedRides({
+    String? targetProviderId,
+  }) async {
+    if (_db == null) {
+      return const CompletedRideReconciliationReport();
+    }
+
+    final providerId = targetProviderId ?? _activeProviderId;
+    final provider = _providers[providerId];
+    final user = _authService?.currentUser;
+    final isAuthenticated = user != null && !user.isAnonymous;
+
+    int discovered = 0;
+    int alreadyTracked = 0;
+    int recoveredQueued = 0;
+    int recoveredAuthRequired = 0;
+    int recoveredAlreadySynced = 0;
+    int foreignOwnerSkipped = 0;
+    int errorCount = 0;
+    final List<String> errors = [];
+
+    try {
+      final completedRides = await (_db.select(_db.rides)
+            ..where((r) => r.endTime.isNotNull()))
+          .get();
+      discovered = completedRides.length;
+
+      for (final ride in completedRides) {
+        try {
+          // Check if already tracked in outbox for this provider
+          final existingItem = _outbox.getItem(ride.id, providerId);
+          if (existingItem != null) {
+            alreadyTracked++;
+            continue;
+          }
+
+          // Foreign account check: never claim or upload another user's ride
+          if (ride.cloudOwnerUid != null &&
+              isAuthenticated &&
+              ride.cloudOwnerUid != user.uid) {
+            foreignOwnerSkipped++;
+            continue;
+          }
+          if (ride.cloudOwnerUid != null && !isAuthenticated) {
+            foreignOwnerSkipped++;
+            continue;
+          }
+
+          // Claim unclaimed ride if user is authenticated and target is firebase
+          if (ride.cloudOwnerUid == null && isAuthenticated && providerId == 'firebase') {
+            await _db.claimRideForCloudOwner(ride.id, user.uid);
+          }
+
+          // Stable cloud identity check
+          final remoteRideId = await _db.ensureCloudRideId(ride.id);
+
+          // Check if already confirmed uploaded in cloud backend
+          final isConfirmed = provider != null &&
+              await provider.isRideConfirmedInCloud(remoteRideId);
+
+          if (isConfirmed) {
+            final syncedItem = SyncItem(
+              localRideId: ride.id,
+              providerId: providerId,
+              status: SyncStatus.synced,
+              remoteId: remoteRideId,
+              createdAt: ride.endTime ?? ride.startTime,
+              uploadedAt: _now(),
+            );
+            await _outbox.update(syncedItem);
+            recoveredAlreadySynced++;
+          } else {
+            final providerRequiresAuth = provider != null &&
+                await provider.requiresAuthentication();
+
+            if (providerRequiresAuth || (!isAuthenticated && providerId == 'firebase')) {
+              final authReqItem = SyncItem(
+                localRideId: ride.id,
+                providerId: providerId,
+                status: SyncStatus.authRequired,
+                createdAt: ride.endTime ?? ride.startTime,
+                lastError: 'Authentication required for provider "$providerId"',
+              );
+              await _outbox.update(authReqItem);
+              recoveredAuthRequired++;
+            } else {
+              final queuedItem = SyncItem(
+                localRideId: ride.id,
+                providerId: providerId,
+                status: SyncStatus.queued,
+                createdAt: ride.endTime ?? ride.startTime,
+              );
+              await _outbox.update(queuedItem);
+              recoveredQueued++;
+            }
+          }
+        } catch (itemErr) {
+          errorCount++;
+          errors.add('Ride #${ride.id}: $itemErr');
+        }
+      }
+    } catch (e) {
+      errorCount++;
+      errors.add('Reconciliation failed: $e');
+    }
+
+    final report = CompletedRideReconciliationReport(
+      discoveredCompletedRides: discovered,
+      alreadyTrackedCount: alreadyTracked,
+      recoveredQueuedCount: recoveredQueued,
+      recoveredAuthRequiredCount: recoveredAuthRequired,
+      recoveredAlreadySyncedCount: recoveredAlreadySynced,
+      foreignOwnerSkippedCount: foreignOwnerSkipped,
+      errorCount: errorCount,
+      errors: errors,
+    );
+
+    if (report.totalRecovered > 0) {
+      notifyListeners();
+    }
+    return report;
+  }
+
   static Duration calculateRetryDelay(int attemptCount) {
     switch (attemptCount) {
       case 1: return const Duration(seconds: 5);
@@ -107,52 +300,70 @@ class SyncManager extends ChangeNotifier with WidgetsBindingObserver {
 
   @override
   void didChangeAppLifecycleState(AppLifecycleState state) {
-    if (state == AppLifecycleState.resumed) unawaited(processQueue());
+    if (state == AppLifecycleState.resumed) {
+      unawaited(_startupRecoveryAndProcess());
+    }
   }
 
   Future<void> processQueue() async {
-    if (_isProcessing) return;
-    _isProcessing = true;
-    notifyListeners();
-    try {
-      final now = _now();
-      for (final item in _outbox.getEligibleItems(now)) {
-        final provider = _providers[item.providerId];
-        if (provider == null) {
-          await _outbox.update(item.copyWith(status: SyncStatus.failed, lastError: 'Provider "${item.providerId}" not registered', lastAttemptAt: now));
-          continue;
-        }
-        if (!await provider.isAvailable()) {
-          await _outbox.update(item.copyWith(status: SyncStatus.waitingForNetwork, lastAttemptAt: now));
-          continue;
-        }
-        if (await provider.requiresAuthentication()) {
-          await _outbox.update(item.copyWith(status: SyncStatus.authRequired, lastError: 'Authentication required for provider "${item.providerId}"', lastAttemptAt: now));
-          continue;
-        }
-        final uploadingItem = item.copyWith(status: SyncStatus.uploading, lastAttemptAt: now);
-        await _outbox.update(uploadingItem);
-        SyncResult result;
-        try {
-          result = await provider.uploadRide(uploadingItem);
-        } catch (e) {
-          result = SyncResult.temporaryFailure('Unhandled provider exception: $e', timestamp: now);
-        }
-        if (result.success) {
-          await _outbox.update(uploadingItem.copyWith(status: SyncStatus.synced, remoteId: result.remoteId, uploadedAt: result.timestamp, clearLastError: true, clearNextRetry: true));
-        } else if (result.requiresAuth) {
-          await _outbox.update(uploadingItem.copyWith(status: SyncStatus.authRequired, lastError: result.errorMessage));
-        } else if (result.isRetryable) {
-          final attempts = uploadingItem.attemptCount + 1;
-          await _outbox.update(uploadingItem.copyWith(status: SyncStatus.retryWait, attemptCount: attempts, nextRetryAt: now.add(calculateRetryDelay(attempts)), lastError: result.errorMessage));
-        } else {
-          await _outbox.update(uploadingItem.copyWith(status: SyncStatus.failed, attemptCount: uploadingItem.attemptCount + 1, lastError: result.errorMessage, clearNextRetry: true));
-        }
-      }
-    } finally {
-      _isProcessing = false;
-      notifyListeners();
+    if (_currentProcessingFuture != null) {
+      _needsAnotherPass = true;
+      return _currentProcessingFuture!;
     }
+    final future = _performProcessQueue();
+    _currentProcessingFuture = future;
+    try {
+      await future;
+    } finally {
+      _currentProcessingFuture = null;
+    }
+  }
+
+  Future<void> _performProcessQueue() async {
+    do {
+      _needsAnotherPass = false;
+      _isProcessing = true;
+      notifyListeners();
+      try {
+        final now = _now();
+        for (final item in _outbox.getEligibleItems(now)) {
+          final provider = _providers[item.providerId];
+          if (provider == null) {
+            await _outbox.update(item.copyWith(status: SyncStatus.failed, lastError: 'Provider "${item.providerId}" not registered', lastAttemptAt: now));
+            continue;
+          }
+          if (!await provider.isAvailable()) {
+            await _outbox.update(item.copyWith(status: SyncStatus.waitingForNetwork, lastAttemptAt: now));
+            continue;
+          }
+          if (await provider.requiresAuthentication()) {
+            await _outbox.update(item.copyWith(status: SyncStatus.authRequired, lastError: 'Authentication required for provider "${item.providerId}"', lastAttemptAt: now));
+            continue;
+          }
+          final uploadingItem = item.copyWith(status: SyncStatus.uploading, lastAttemptAt: now);
+          await _outbox.update(uploadingItem);
+          SyncResult result;
+          try {
+            result = await provider.uploadRide(uploadingItem);
+          } catch (e) {
+            result = SyncResult.temporaryFailure('Unhandled provider exception: $e', timestamp: now);
+          }
+          if (result.success) {
+            await _outbox.update(uploadingItem.copyWith(status: SyncStatus.synced, remoteId: result.remoteId, uploadedAt: result.timestamp, clearLastError: true, clearNextRetry: true));
+          } else if (result.requiresAuth) {
+            await _outbox.update(uploadingItem.copyWith(status: SyncStatus.authRequired, lastError: result.errorMessage));
+          } else if (result.isRetryable) {
+            final attempts = uploadingItem.attemptCount + 1;
+            await _outbox.update(uploadingItem.copyWith(status: SyncStatus.retryWait, attemptCount: attempts, nextRetryAt: now.add(calculateRetryDelay(attempts)), lastError: result.errorMessage));
+          } else {
+            await _outbox.update(uploadingItem.copyWith(status: SyncStatus.failed, attemptCount: uploadingItem.attemptCount + 1, lastError: result.errorMessage, clearNextRetry: true));
+          }
+        }
+      } finally {
+        _isProcessing = false;
+        notifyListeners();
+      }
+    } while (_needsAnotherPass);
   }
 
   Future<void> cancelSync(int localRideId, String providerId) async {
diff --git a/lib/services/sync/sync_provider.dart b/lib/services/sync/sync_provider.dart
index 86abe4f..18e3db8 100644
--- a/lib/services/sync/sync_provider.dart
+++ b/lib/services/sync/sync_provider.dart
@@ -16,6 +16,10 @@ abstract class SyncProvider {
   /// Performs the upload of the local ride referenced by [item].
   /// Must return a deterministic [SyncResult].
   Future<SyncResult> uploadRide(SyncItem item);
+
+  /// Checks if the ride with [remoteRideId] is already confirmed uploaded in the cloud.
+  /// Default implementation returns false.
+  Future<bool> isRideConfirmedInCloud(String remoteRideId) async => false;
 }
 
 /// Simulated behavior modes for testing the synchronization engine deterministically
@@ -36,6 +40,7 @@ class FakeSyncProvider implements SyncProvider {
   int delayMs;
   final List<SyncItem> uploadedItems = [];
   final Map<int, int> uploadAttemptsPerRide = {};
+  final Set<String> confirmedRemoteRideIds = {};
 
   FakeSyncProvider({
     this.providerId = 'fake',
@@ -54,6 +59,11 @@ class FakeSyncProvider implements SyncProvider {
     return behavior == FakeSyncBehavior.authRequired;
   }
 
+  @override
+  Future<bool> isRideConfirmedInCloud(String remoteRideId) async {
+    return confirmedRemoteRideIds.contains(remoteRideId);
+  }
+
   @override
   Future<SyncResult> uploadRide(SyncItem item) async {
     if (delayMs > 0) {
@@ -66,8 +76,10 @@ class FakeSyncProvider implements SyncProvider {
     switch (behavior) {
       case FakeSyncBehavior.success:
         uploadedItems.add(item);
+        final remoteId = 'remote_${item.localRideId}_${DateTime.now().millisecondsSinceEpoch}';
+        confirmedRemoteRideIds.add(remoteId);
         return SyncResult.success(
-          remoteId: 'remote_${item.localRideId}_${DateTime.now().millisecondsSinceEpoch}',
+          remoteId: remoteId,
         );
 
       case FakeSyncBehavior.temporaryFailure:
@@ -95,5 +107,6 @@ class FakeSyncProvider implements SyncProvider {
   void reset() {
     uploadedItems.clear();
     uploadAttemptsPerRide.clear();
+    confirmedRemoteRideIds.clear();
   }
 }
diff --git a/test/completed_ride_sync_recovery_test.dart b/test/completed_ride_sync_recovery_test.dart
new file mode 100644
index 0000000..0449fc0
--- /dev/null
+++ b/test/completed_ride_sync_recovery_test.dart
@@ -0,0 +1,326 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+import 'package:drift/native.dart';
+import 'package:drift/drift.dart' as drift;
+import 'package:motorcycle_dash/database/database.dart';
+import 'package:motorcycle_dash/services/auth/auth_service.dart';
+import 'package:motorcycle_dash/services/auth/auth_state.dart';
+import 'package:motorcycle_dash/services/auth/auth_user.dart';
+import 'package:motorcycle_dash/services/sync/sync_models.dart';
+import 'package:motorcycle_dash/services/sync/sync_provider.dart';
+import 'package:motorcycle_dash/services/sync/sync_outbox.dart';
+import 'package:motorcycle_dash/services/sync/sync_manager.dart';
+
+class _TestAuthService implements AuthService {
+  AuthUser? _currentUser;
+  AuthState _authState = const AuthState.unauthenticated();
+
+  void setAuthenticatedUser(String uid, String email) {
+    _currentUser = AuthUser(
+      uid: uid,
+      email: email,
+      displayName: 'Test Rider',
+      isAnonymous: false,
+    );
+    _authState = AuthState.authenticated(_currentUser!);
+  }
+
+  void setGuestUser() {
+    _currentUser = const AuthUser(
+      uid: 'guest_uid_123',
+      email: null,
+      displayName: 'Guest Rider',
+      isAnonymous: true,
+    );
+    _authState = AuthState.anonymous(_currentUser!);
+  }
+
+  void setLoggedOut() {
+    _currentUser = null;
+    _authState = const AuthState.unauthenticated();
+  }
+
+  @override
+  AuthUser? get currentUser => _currentUser;
+
+  @override
+  AuthState get currentState => _authState;
+
+  @override
+  Stream<AuthState> get authStateChanges => Stream.value(_authState);
+
+  @override
+  bool get isConfigured => true;
+
+  @override
+  bool get isEmailVerified => false;
+
+  @override
+  Future<void> createUserWithEmailAndPassword(String email, String password, {String? displayName}) async {}
+
+  @override
+  Future<void> deleteCurrentUser() async {}
+
+  @override
+  void dispose() {}
+
+  @override
+  Future<void> ensureBackendIdentity() async {}
+
+  @override
+  Future<String?> getIdToken([bool forceRefresh = false]) async => 'fake_id_token';
+
+  @override
+  Future<void> reauthenticate({String? password}) async {}
+
+  @override
+  Future<void> reloadCurrentUser() async {}
+
+  @override
+  Future<void> sendEmailVerification() async {}
+
+  @override
+  Future<void> sendPasswordResetEmail(String email) async {}
+
+  @override
+  Future<void> signInAnonymously() async => setGuestUser();
+
+  @override
+  Future<void> signInWithEmailAndPassword(String email, String password) async =>
+      setAuthenticatedUser('uid_123', email);
+
+  @override
+  Future<void> signInWithGoogle() async =>
+      setAuthenticatedUser('uid_google', 'google@example.com');
+
+  @override
+  Future<void> signOut() async => setLoggedOut();
+}
+
+void main() {
+  TestWidgetsFlutterBinding.ensureInitialized();
+
+  group('v1.1 Completed-Ride Sync Outbox Recovery Tests', () {
+    late SharedPreferences prefs;
+    late AppDatabase db;
+    late _TestAuthService authService;
+    late FakeSyncProvider fakeProvider;
+
+    setUp(() async {
+      SharedPreferences.setMockInitialValues({});
+      prefs = await SharedPreferences.getInstance();
+      db = AppDatabase.forTesting(NativeDatabase.memory());
+      authService = _TestAuthService();
+      fakeProvider = FakeSyncProvider(providerId: 'firebase');
+    });
+
+    tearDown(() async {
+      await db.close();
+    });
+
+    test('1. Crash Window Recovery: Completed ride missing from outbox is recovered and uploaded', () async {
+      authService.setAuthenticatedUser('rider_alice', 'alice@example.com');
+
+      // Simulate a completed ride committed to SQLite during a previous session
+      final rideId = await db.startRide(
+        startTime: DateTime.utc(2026, 10, 12, 10, 0, 0),
+        motorcycleMake: 'Honda',
+        motorcycleModel: 'CBR600RR',
+      );
+      await db.endRide(rideId, const RidesCompanion());
+
+      // Confirm outbox starts empty (app terminated before enqueue ran)
+      final outbox = SyncOutbox(prefs);
+      expect(outbox.count, equals(0));
+
+      // Startup initialization of SyncManager (testing step-by-step)
+      final manager = SyncManager(
+        outbox,
+        initialProviders: [fakeProvider],
+        defaultProviderId: 'firebase',
+        db: db,
+        authService: authService,
+        autoStart: false,
+      );
+
+      // Reconcile runs
+      final report = await manager.reconcileCompletedRides();
+
+      expect(report.discoveredCompletedRides, equals(1));
+      expect(report.recoveredQueuedCount, equals(1));
+      expect(report.alreadyTrackedCount, equals(0));
+      expect(outbox.count, equals(1));
+
+      final item = outbox.getItem(rideId, 'firebase');
+      expect(item, isNotNull);
+      expect(item?.status, equals(SyncStatus.queued));
+
+      // Verify ride ownership was claimed for authenticated user
+      final ownerUid = await db.getCloudOwnerUid(rideId);
+      expect(ownerUid, equals('rider_alice'));
+
+      // Process queue to complete upload
+      await manager.processQueue();
+      expect(outbox.getItem(rideId, 'firebase')?.status, equals(SyncStatus.synced));
+      expect(fakeProvider.uploadedItems.length, equals(1));
+    });
+
+    test('2. Idempotence: Repeated reconciliation does not create duplicate entries or uploads', () async {
+      authService.setAuthenticatedUser('rider_alice', 'alice@example.com');
+
+      final rideId = await db.startRide(startTime: DateTime.utc(2026, 10, 12, 11, 0, 0));
+      await db.endRide(rideId, const RidesCompanion());
+
+      final outbox = SyncOutbox(prefs);
+      final manager = SyncManager(
+        outbox,
+        initialProviders: [fakeProvider],
+        defaultProviderId: 'firebase',
+        db: db,
+        authService: authService,
+        autoStart: false,
+      );
+
+      // First run reconciles and queues the ride
+      final report1 = await manager.reconcileCompletedRides();
+      expect(report1.recoveredQueuedCount, equals(1));
+      expect(outbox.count, equals(1));
+
+      // Process upload
+      await manager.processQueue();
+      expect(outbox.getItem(rideId, 'firebase')?.status, equals(SyncStatus.synced));
+      expect(fakeProvider.uploadedItems.length, equals(1));
+
+      // Second run reports ride as already tracked, zero duplicates
+      final report2 = await manager.reconcileCompletedRides();
+      expect(report2.discoveredCompletedRides, equals(1));
+      expect(report2.alreadyTrackedCount, equals(1));
+      expect(report2.recoveredQueuedCount, equals(0));
+      expect(report2.totalRecovered, equals(0));
+      expect(outbox.count, equals(1));
+
+      // Running processQueue again does not re-upload
+      await manager.processQueue();
+      expect(fakeProvider.uploadedItems.length, equals(1));
+    });
+
+    test('3. Guest State & Auth Transition: Recovers as authRequired then claims and syncs on sign-in', () async {
+      // User is initially a guest and provider requires auth
+      authService.setGuestUser();
+      fakeProvider.behavior = FakeSyncBehavior.authRequired;
+
+      final rideId = await db.startRide(startTime: DateTime.utc(2026, 10, 12, 12, 0, 0));
+      await db.endRide(rideId, const RidesCompanion());
+
+      final outbox = SyncOutbox(prefs);
+      final manager = SyncManager(
+        outbox,
+        initialProviders: [fakeProvider],
+        defaultProviderId: 'firebase',
+        db: db,
+        authService: authService,
+        autoStart: false,
+      );
+
+      // Reconcile as guest -> authRequired
+      final report = await manager.reconcileCompletedRides();
+      expect(report.recoveredAuthRequiredCount, equals(1));
+      expect(outbox.getItem(rideId, 'firebase')?.status, equals(SyncStatus.authRequired));
+
+      // Ownership remains unclaimed
+      expect(await db.getCloudOwnerUid(rideId), isNull);
+
+      // Guest now signs in with Google / Email
+      authService.setAuthenticatedUser('rider_bob', 'bob@example.com');
+      fakeProvider.behavior = FakeSyncBehavior.success;
+
+      // Invoking retryAuthRequired claims the ride and triggers queue upload
+      await manager.retryAuthRequired();
+
+      expect(await db.getCloudOwnerUid(rideId), equals('rider_bob'));
+      expect(outbox.getItem(rideId, 'firebase')?.status, equals(SyncStatus.synced));
+      expect(fakeProvider.uploadedItems.length, equals(1));
+    });
+
+    test('4. Cloud Confirmed Skip: Confirmed ride marks synced without re-uploading bundle', () async {
+      authService.setAuthenticatedUser('rider_charlie', 'charlie@example.com');
+
+      final rideId = await db.startRide(startTime: DateTime.utc(2026, 10, 12, 13, 0, 0));
+      await db.endRide(rideId, const RidesCompanion());
+      final remoteRideId = await db.ensureCloudRideId(rideId);
+
+      // Simulate that cloud backend already has this ride bundle uploaded
+      fakeProvider.confirmedRemoteRideIds.add(remoteRideId);
+
+      final outbox = SyncOutbox(prefs);
+      final manager = SyncManager(
+        outbox,
+        initialProviders: [fakeProvider],
+        defaultProviderId: 'firebase',
+        db: db,
+        authService: authService,
+      );
+
+      final report = await manager.reconcileCompletedRides();
+      expect(report.recoveredAlreadySyncedCount, equals(1));
+      expect(report.recoveredQueuedCount, equals(0));
+
+      final item = outbox.getItem(rideId, 'firebase');
+      expect(item?.status, equals(SyncStatus.synced));
+      expect(item?.remoteId, equals(remoteRideId));
+
+      // Zero upload attempts because it was already confirmed
+      expect(fakeProvider.uploadedItems.isEmpty, isTrue);
+    });
+
+    test('5. Foreign Account Isolation: Does not claim or upload rides belonging to another user', () async {
+      authService.setAuthenticatedUser('rider_alice', 'alice@example.com');
+
+      // Create ride explicitly owned by rider_bob
+      final rideId = await db.into(db.rides).insert(RidesCompanion.insert(
+        cloudRideId: const drift.Value('ride_bob_123'),
+        cloudOwnerUid: const drift.Value('rider_bob'),
+        startTime: DateTime.utc(2026, 10, 12, 14, 0, 0),
+        endTime: drift.Value(DateTime.utc(2026, 10, 12, 15, 0, 0)),
+      ));
+
+      final outbox = SyncOutbox(prefs);
+      final manager = SyncManager(
+        outbox,
+        initialProviders: [fakeProvider],
+        defaultProviderId: 'firebase',
+        db: db,
+        authService: authService,
+      );
+
+      final report = await manager.reconcileCompletedRides();
+      expect(report.foreignOwnerSkippedCount, equals(1));
+      expect(report.totalRecovered, equals(0));
+      expect(outbox.count, equals(0));
+
+      // Ownership in db remains unchanged
+      expect(await db.getCloudOwnerUid(rideId), equals('rider_bob'));
+    });
+
+    test('6. In-Progress Isolation: Active rides without endTime are never recovered as completed', () async {
+      authService.setAuthenticatedUser('rider_alice', 'alice@example.com');
+
+      // Start ride but do not end it (endTime is null)
+      final rideId = await db.startRide(startTime: DateTime.utc(2026, 10, 12, 16, 0, 0));
+
+      final outbox = SyncOutbox(prefs);
+      final manager = SyncManager(
+        outbox,
+        initialProviders: [fakeProvider],
+        defaultProviderId: 'firebase',
+        db: db,
+        authService: authService,
+      );
+
+      final report = await manager.reconcileCompletedRides();
+      expect(report.discoveredCompletedRides, equals(0));
+      expect(report.totalRecovered, equals(0));
+      expect(outbox.getItem(rideId, 'firebase'), isNull);
+    });
+  });
+}
diff --git a/test/disposable_backup_recovery_verification_test.dart b/test/disposable_backup_recovery_verification_test.dart
new file mode 100644
index 0000000..620419e
--- /dev/null
+++ b/test/disposable_backup_recovery_verification_test.dart
@@ -0,0 +1,173 @@
+import 'dart:io';
+import 'package:crypto/crypto.dart';
+import 'package:drift/native.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+import 'package:motorcycle_dash/database/database.dart';
+import 'package:motorcycle_dash/services/auth/auth_service.dart';
+import 'package:motorcycle_dash/services/auth/auth_state.dart';
+import 'package:motorcycle_dash/services/auth/auth_user.dart';
+import 'package:motorcycle_dash/services/sync/sync_manager.dart';
+import 'package:motorcycle_dash/services/sync/sync_outbox.dart';
+import 'package:motorcycle_dash/services/sync/sync_provider.dart';
+
+class _FakeAuthService implements AuthService {
+  final AuthUser _user;
+
+  _FakeAuthService([String uid = 'pilot_pixel_8a'])
+      : _user = AuthUser(
+          uid: uid,
+          email: '$uid@example.com',
+          displayName: 'Pixel Pilot',
+          isAnonymous: false,
+        );
+
+  @override
+  AuthUser? get currentUser => _user;
+  @override
+  AuthState get currentState => AuthState.authenticated(_user);
+  @override
+  Stream<AuthState> get authStateChanges => Stream.value(currentState);
+  @override
+  bool get isConfigured => true;
+  @override
+  bool get isEmailVerified => true;
+
+  @override
+  Future<void> createUserWithEmailAndPassword(String email, String password, {String? displayName}) async {}
+  @override
+  Future<void> deleteCurrentUser() async {}
+  @override
+  void dispose() {}
+  @override
+  Future<void> ensureBackendIdentity() async {}
+  @override
+  Future<String?> getIdToken([bool forceRefresh = false]) async => 'fake_token';
+  @override
+  Future<void> reauthenticate({String? password}) async {}
+  @override
+  Future<void> reloadCurrentUser() async {}
+  @override
+  Future<void> sendEmailVerification() async {}
+  @override
+  Future<void> sendPasswordResetEmail(String email) async {}
+  @override
+  Future<void> signInAnonymously() async {}
+  @override
+  Future<void> signInWithEmailAndPassword(String email, String password) async {}
+  @override
+  Future<void> signInWithGoogle() async {}
+  @override
+  Future<void> signOut() async {}
+}
+
+void main() {
+  TestWidgetsFlutterBinding.ensureInitialized();
+
+  test('Phase 6 — Disposable Backup Verification & Outbox Recovery Gate', () async {
+    final originalFile = File(
+      r'C:\Users\Bill\Desktop\flutter-app\output\master-consolidation-20261012\backup-071303\motorsignal.sqlite',
+    );
+
+    expect(originalFile.existsSync(), isTrue, reason: 'Original backup file must exist');
+
+    // 1. Verify original SHA-256 before copy
+    final originalBytes = await originalFile.readAsBytes();
+    final originalHash = sha256.convert(originalBytes).toString();
+    const expectedHash = '7125915195cdcf1de2d351426d8a991789904e7c3befd12af6f0d0f0b2416122';
+    expect(originalHash, equals(expectedHash), reason: 'Original backup must match authoritative SHA-256');
+
+    // 2. Create disposable copy in scratch directory
+    final scratchDir = Directory(
+      r'C:\Users\Bill\.gemini\antigravity\brain\eb590221-346f-4525-a5fa-eda41331c6c6\scratch',
+    );
+    if (!scratchDir.existsSync()) {
+      scratchDir.createSync(recursive: true);
+    }
+    final disposableFile = File('${scratchDir.path}\\disposable_motorsignal.sqlite');
+    if (disposableFile.existsSync()) {
+      disposableFile.deleteSync();
+    }
+    await originalFile.copy(disposableFile.path);
+    expect(disposableFile.existsSync(), isTrue);
+
+    // 3. Open disposable copy via Drift / SQLite
+    final db = AppDatabase.forTesting(NativeDatabase(disposableFile));
+
+    try {
+      // Integrity check
+      final integrityRows = await db.customSelect('PRAGMA integrity_check').get();
+      final integrityResult = integrityRows.first.data['integrity_check'];
+      expect(integrityResult, equals('ok'), reason: 'SQLite integrity must be OK');
+
+      // Count rides and samples
+      final rideCountRows = await db.customSelect('SELECT COUNT(*) as count FROM rides').get();
+      final totalRides = rideCountRows.first.data['count'] as int;
+      expect(totalRides, equals(22), reason: 'Must contain exactly 22 rides');
+
+      final completedRidesRows = await db.customSelect('SELECT COUNT(*) as count FROM rides WHERE end_time IS NOT NULL').get();
+      final completedRides = completedRidesRows.first.data['count'] as int;
+
+      final samplesRows = await db.customSelect('SELECT COUNT(*) as count FROM telemetry_samples').get();
+      final totalSamples = samplesRows.first.data['count'] as int;
+      expect(totalSamples, equals(67798), reason: 'Must contain exactly 67,798 telemetry samples');
+
+      // 4. Test Foreign Account Isolation against real Pixel backup
+      // In the real backup, rides are owned by Pixel rider '4btn4W3iOLWgfloMBYYK5hWa1hY2'
+      SharedPreferences.setMockInitialValues({});
+      final prefs = await SharedPreferences.getInstance();
+      final outbox = SyncOutbox(prefs);
+
+      final fakeProvider = FakeSyncProvider(providerId: 'firebase');
+      final foreignAuth = _FakeAuthService('foreign_pilot_123');
+
+      final foreignSyncManager = SyncManager(
+        outbox,
+        initialProviders: [fakeProvider],
+        defaultProviderId: 'firebase',
+        db: db,
+        authService: foreignAuth,
+        autoStart: false,
+      );
+
+      final foreignReport = await foreignSyncManager.reconcileCompletedRides();
+      expect(foreignReport.errorCount, equals(0));
+      expect(foreignReport.discoveredCompletedRides, equals(completedRides));
+      expect(foreignReport.foreignOwnerSkippedCount, equals(completedRides), reason: 'Foreign account must NEVER claim or touch real Pixel rides');
+      expect(foreignReport.totalRecovered, equals(0));
+      expect(outbox.count, equals(0));
+
+      // 5. Test Owner Recovery against disposable backup
+      final ownerAuth = _FakeAuthService('4btn4W3iOLWgfloMBYYK5hWa1hY2');
+      final ownerSyncManager = SyncManager(
+        outbox,
+        initialProviders: [fakeProvider],
+        defaultProviderId: 'firebase',
+        db: db,
+        authService: ownerAuth,
+        autoStart: false,
+      );
+
+      final ownerReport = await ownerSyncManager.reconcileCompletedRides();
+      expect(ownerReport.errorCount, equals(0));
+      expect(ownerReport.discoveredCompletedRides, equals(completedRides));
+      expect(ownerReport.recoveredQueuedCount, equals(completedRides));
+      expect(ownerReport.totalRecovered, equals(completedRides));
+      expect(outbox.count, equals(completedRides));
+
+      // 6. Test repeated reconciliation idempotence as owner
+      final report2 = await ownerSyncManager.reconcileCompletedRides();
+      expect(report2.totalRecovered, equals(0));
+      expect(report2.alreadyTrackedCount, equals(completedRides));
+      expect(outbox.count, equals(completedRides));
+
+    } finally {
+      await db.close();
+    }
+
+    // 6. Verify original SHA-256 after operations to prove zero mutation
+    final postBytes = await originalFile.readAsBytes();
+    final postHash = sha256.convert(postBytes).toString();
+    expect(postHash, equals(expectedHash), reason: 'Original backup MUST remain 100% UNTOUCHED');
+  });
+}
diff --git a/test/isolated_sync_integration_fixture_test.dart b/test/isolated_sync_integration_fixture_test.dart
index 760f600..0d7b38e 100644
--- a/test/isolated_sync_integration_fixture_test.dart
+++ b/test/isolated_sync_integration_fixture_test.dart
@@ -104,6 +104,9 @@ class _IsolatedContractSyncProvider implements SyncProvider {
     return user == null || user.isAnonymous;
   }
 
+  @override
+  Future<bool> isRideConfirmedInCloud(String remoteRideId) async => false;
+
   @override
   Future<SyncResult> uploadRide(SyncItem item) async {
     if (!networkAvailable) {
diff --git a/test/offline_first_sync_contract_test.dart b/test/offline_first_sync_contract_test.dart
index 3141d3d..db7fe3a 100644
--- a/test/offline_first_sync_contract_test.dart
+++ b/test/offline_first_sync_contract_test.dart
@@ -20,6 +20,9 @@ class _CountingProvider implements SyncProvider {
   @override
   Future<bool> requiresAuthentication() async => result == _Result.authRequired;
 
+  @override
+  Future<bool> isRideConfirmedInCloud(String remoteRideId) async => false;
+
   @override
   Future<SyncResult> uploadRide(SyncItem item) async {
     uploadCount++;
diff --git a/test/r2_firestore_retry_hardening_test.dart b/test/r2_firestore_retry_hardening_test.dart
index 6a99cd1..245bd92 100644
--- a/test/r2_firestore_retry_hardening_test.dart
+++ b/test/r2_firestore_retry_hardening_test.dart
@@ -31,6 +31,9 @@ class _R2ThenFirestoreProvider implements SyncProvider {
   @override
   Future<bool> requiresAuthentication() async => false;
 
+  @override
+  Future<bool> isRideConfirmedInCloud(String remoteRideId) async => false;
+
   @override
   Future<SyncResult> uploadRide(SyncItem item) async {
     attempts++;
diff --git a/test/sync_persistence_validation_test.dart b/test/sync_persistence_validation_test.dart
index 178f22f..4d5978c 100644
--- a/test/sync_persistence_validation_test.dart
+++ b/test/sync_persistence_validation_test.dart
@@ -21,6 +21,9 @@ class _ValidationProvider implements SyncProvider {
   @override
   Future<bool> requiresAuthentication() async => !authenticated;
 
+  @override
+  Future<bool> isRideConfirmedInCloud(String remoteRideId) async => false;
+
   @override
   Future<SyncResult> uploadRide(SyncItem item) async {
     uploadCount++;