Keep stable cloud identity compatible with generated Drift code

lib/database/database.dart

@@ -1,10 +1,10 @@
 import 'dart:io';
+import 'dart:math';
 import 'package:drift/drift.dart';
 import 'package:drift/native.dart';
 import 'package:path_provider/path_provider.dart';
 import 'package:path/path.dart' as p;
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:uuid/uuid.dart';
 
 import 'tables.dart';
 
@@ -15,7 +15,7 @@ class AppDatabase extends _$AppDatabase {
   AppDatabase() : super(_openConnection());
   AppDatabase.forTesting(super.e);
 
-  static const _uuid = Uuid();
+  static final Random _random = Random.secure();
 
   @override
   int get schemaVersion => 6;
@@ -67,23 +67,56 @@ class AppDatabase extends _$AppDatabase {
         } catch (_) {}
       }
       if (from < 6) {
+        // Nullable during migration so existing installations can be upgraded
+        // without losing rides. We immediately backfill every existing ride
+        // with a stable random identifier that is independent of local ID.
         await m.addColumn(rides, rides.cloudRideId);
-        final existingRides = await select(rides).get();
-        for (final ride in existingRides) {
-          final cloudId = 'ride_${_uuid.v4()}';
-          await (update(rides)..where((r) => r.id.equals(ride.id))).write(
-            RidesCompanion(cloudRideId: Value(cloudId)),
+        final rows = await customSelect('SELECT id FROM rides').get();
+        for (final row in rows) {
+          await customStatement(
+            'UPDATE rides SET cloud_ride_id = ? WHERE id = ?',
+            [_newCloudRideId(), row.data['id']],
           );
         }
       }
     },
   );
 
+  String _newCloudRideId() {
+    final bytes = List<int>.generate(16, (_) => _random.nextInt(256));
+    final hex = bytes.map((b) => b.toRadixString(16).padLeft(2, '0')).join();
+    return 'ride_$hex';
+  }
+
+  /// Returns the persisted stable MotorCloud identity for a local ride.
+  /// Uses raw SQL until `database.g.dart` is regenerated; this keeps the
+  /// migration deployable without hand-editing generated Drift output.
+  Future<String?> getCloudRideId(int rideId) async {
+    final rows = await customSelect(
+      'SELECT cloud_ride_id FROM rides WHERE id = ?',
+      variables: [Variable<int>(rideId)],
+    ).get();
+    if (rows.isEmpty) return null;
+    return rows.first.data['cloud_ride_id'] as String?;
+  }
+
+  Future<String> ensureCloudRideId(int rideId) async {
+    final existing = await getCloudRideId(rideId);
+    if (existing != null && existing.isNotEmpty) return existing;
+    final created = _newCloudRideId();
+    await customStatement(
+      'UPDATE rides SET cloud_ride_id = ? WHERE id = ?',
+      [created, rideId],
+    );
+    return created;
+  }
+
   Future<int> startRide() async {
-    return into(rides).insert(RidesCompanion.insert(
-      cloudRideId: Value('ride_${_uuid.v4()}'),
+    final id = await into(rides).insert(RidesCompanion.insert(
       startTime: DateTime.now(),
     ));
+    await ensureCloudRideId(id);
+    return id;
   }
 
   Future<void> endRide(int rideId, RidesCompanion data) async {