flutter

# Flutter Standards ## P0 — Design System Enforcement (CRITICAL) Zero tolerance for hardcoded design values. Before any UI work, identify the project's Theme Archetype by checking `main.dart`: - **Theme-Driven**: `VThemeData(...).toThemeData()` → use `Theme.of(context).textTheme` - **Token-Driven**: Use static tokens (`VTypography.*`) only when no global theme bridge exists or when defining the theme itself **Rules:** - **Colors**: Use tokens (`VColors.*`, `AppColors.*`). Never `Color(0xFF...)` or `Colors.red`. - **Spacing**: Use tokens (`VSpacing.*`). Never magic numbers like `16` or `24`. - **Typography**: Prefer `Theme.of(context).textTheme.*` for adaptive UI. Use `VTypography.*` only for theme definitions. Never inline `TextStyle`. - **Borders**: Use tokens (`VBorders.*`). Never raw `BorderRadius.circular(n)`. - **Components**: Use DLS widgets (`VButton`) over raw Material widgets (`ElevatedButton`) when available. Detail → `refs/design-system.md` ## P0 — Error Handling (CRITICAL) - **Repositories return `Either<Failure, T>`** — no exceptions propagate to UI or BLoC. - **Catch in Infrastructure only** — convert `DioException` / external errors to typed `Left(Failure)`. - **Fold in BLoC** — `.fold(failure, success)` to emit states. No try/catch in BLoC. - **Typed failures** — `@freezed` union failures (e.g., `UnauthorizedFailure`). Never `Left('string')`. - **Crashlytics routing** — all `catch` blocks route via `AppLogger.error(...)` for observability. - **`on Type ...