# Database — Drift Schema & Conventions

## Tables

### projects
| Column       | Type      | Notes                        |
|--------------|-----------|------------------------------|
| id           | INTEGER   | PK, autoincrement            |
| name         | TEXT      | NOT NULL, unique             |
| color_value  | INTEGER   | NOT NULL (ARGB int)          |
| description  | TEXT      | nullable                     |
| archived_at  | DATETIME  | nullable; null = active      |
| created_at   | DATETIME  | NOT NULL, default now        |

### time_entries
| Column      | Type     | Notes                                |
|-------------|----------|--------------------------------------|
| id          | INTEGER  | PK, autoincrement                    |
| project_id  | INTEGER  | FK → projects.id, NOT NULL           |
| start_time  | DATETIME | NOT NULL                             |
| end_time    | DATETIME | nullable; null = timer still running |
| duration_s  | INTEGER  | seconds; computed on stop            |
| note        | TEXT     | nullable                             |
| created_at  | DATETIME | NOT NULL, default now                |

### tags
| Column | Type    | Notes             |
|--------|---------|-------------------|
| id     | INTEGER | PK, autoincrement |
| name   | TEXT    | NOT NULL, unique  |

### time_entry_tags (junction)
| Column        | Type    | Notes              |
|---------------|---------|--------------------|
| time_entry_id | INTEGER | FK → time_entries  |
| tag_id        | INTEGER | FK → tags          |
| PRIMARY KEY (time_entry_id, tag_id) |  |  |

## Drift Setup

```dart
// lib/core/database/app_database.dart
@DriftDatabase(tables: [Projects, TimeEntries, Tags, TimeEntryTags])
class AppDatabase extends _$AppDatabase {
  AppDatabase() : super(_openConnection());

  @override
  int get schemaVersion => 1;
}

LazyDatabase _openConnection() {
  return LazyDatabase(() async {
    final dir = await getApplicationDocumentsDirectory();
    final file = File(p.join(dir.path, 'timetrack.db'));
    return NativeDatabase.createInBackground(file);
  });
}
```

## DAOs
- `ProjectsDao` — CRUD for projects, watchAll(), watchActive()
- `TimeEntriesDao` — CRUD, watchByProject(), watchByDateRange(), getActiveEntry()
- `TagsDao` — CRUD, watchAll()

## Migration Strategy
- Schema version starts at `1`
- Increment `schemaVersion` for every breaking change
- Add a `MigrationStrategy` with `onUpgrade` steps
- Never drop columns — use nullable columns for additions
- Test migrations with `drift_dev` schema tests

## Riverpod Provider

```dart
@Riverpod(keepAlive: true)
AppDatabase appDatabase(AppDatabaseRef ref) {
  final db = AppDatabase();
  ref.onDispose(db.close);
  return db;
}
```