fix: migrate offline sync outbox into authenticated account

lib/services/sync/sync_outbox.dart

@@ -12,12 +12,13 @@ class SyncOutbox {
   Future<void> _saveChain = Future<void>.value();
   bool _isLoaded = false;
 
-  /// The namespace must be tied to the current Firebase UID (or a local
+  /// The namespace is account-scoped. Pending work recorded before login is
-  /// signed-out namespace). This prevents one account's sync state from being
+  /// migrated from the local namespace into the newly authenticated account
-  /// mistaken for another account's state on the same device.
+  /// so offline rides do not become stranded when the user signs in later.
   SyncOutbox(this._prefs, {String? storageNamespace})
       : _storageNamespace = _normalizeNamespace(storageNamespace) {
     load();
+    if (_storageNamespace != 'local') _migrateLocalPendingItems();
   }
 
   static String _normalizeNamespace(String? value) {
@@ -57,6 +58,43 @@ class SyncOutbox {
     _isLoaded = true;
   }
 
+  void _migrateLocalPendingItems() {
+    final localKey = '${_outboxStorageKeyPrefix}_local';
+    final rawJson = _prefs.getString(localKey);
+    if (rawJson == null || rawJson.trim().isEmpty) return;
+
+    var migrated = 0;
+    try {
+      final decoded = jsonDecode(rawJson);
+      if (decoded is List) {
+        for (final entry in decoded) {
+          try {
+            final map = entry is Map<String, dynamic> ? entry : Map<String, dynamic>.from(entry as Map);
+            final item = SyncItem.fromJson(map);
+            // Local namespace work cannot legitimately be cloud-synced yet;
+            // keep only pending work and rebind it to the current provider.
+            if (item.status.isPending) {
+              _items[item.key] = item.status == SyncStatus.uploading
+                  ? item.copyWith(status: SyncStatus.queued, clearNextRetry: true)
+                  : item;
+              migrated++;
+            }
+          } catch (itemError) {
+            debugPrint('[SyncOutbox] Skipped local migration item: $itemError');
+          }
+        }
+      }
+    } catch (e) {
+      debugPrint('[SyncOutbox] Local outbox migration skipped: $e');
+      return;
+    }
+
+    if (migrated > 0) {
+      _prefs.setString(storageKey, jsonEncode(_items.values.map((e) => e.toJson()).toList()));
+      _prefs.remove(localKey);
+    }
+  }
+
   Future<bool> _save() {
     final operation = _saveChain.then((_) async {
       if (_items.length > maxOutboxCapacity) {
@@ -88,9 +126,7 @@ class SyncOutbox {
     final key = '$normalizedProvider:$localRideId';
     final existing = _items[key];
     if (existing != null) {
-      if (existing.status == SyncStatus.synced || existing.status == SyncStatus.queued || existing.status == SyncStatus.uploading) {
+      if (existing.status == SyncStatus.synced || existing.status == SyncStatus.queued || existing.status == SyncStatus.uploading) return existing;
-        return existing;
-      }
       final rearmed = existing.copyWith(status: SyncStatus.queued, clearLastError: true, clearNextRetry: true);
       _items[key] = rearmed;
       await _save();