## Mobile Rules

- Flutter mobile rules are maintained here.
- If no more specific rule is defined here, follow the root `AGENTS.md`.

## Flutter Design-to-Code Workflow

Before writing any Flutter UI code, follow this sequence:

1. **Get editor state**: Use `pencil_get_editor_state` to confirm the active design.
2. **Get structure**: Use `pencil_batch_get` to inspect node hierarchy and layout.
3. **Get variables**: Use `pencil_get_variables` to fetch colors, typography, and tokens.
4. **Implement**: Match design values and container hierarchy exactly.

## Layout Mapping Rules

Map design layout properties to Flutter explicitly:

1. **Always set `crossAxisAlignment` on `Row`/`Column`**:
   - `alignItems: center` -> `CrossAxisAlignment.center`
   - `alignItems: start` -> `CrossAxisAlignment.start`
   - `alignItems: stretch` -> `CrossAxisAlignment.stretch`
2. **Map full container chain**: From root to leaf, ensure each `alignItems` and `justifyContent` has a Flutter equivalent.
3. **Analyze before coding**: Use `pencil_snapshot_layout` or `pencil_batch_get` to verify each container's alignment settings.

## Centering and Visual Balance

Apply these rules on any screen that relies on centered composition:

1. Centering must be evaluated inside **`SafeArea` bounds**, not full-screen bounds.
2. Avoid relying on proportional `Spacer` values as the only centering mechanism for critical content.
3. For layouts with persistent top/bottom regions (for example headers or footers), center the primary content in the remaining available region.
4. Distinguish geometric centering from visual centering; validate final visual balance with screenshot review.

## Quality Gate

For important screens, add widget tests that reduce layout-regression risk:

1. Verify primary content remains centered relative to the usable viewport.
2. Add at least one constrained viewport scenario (small height or large text scale).

## Prohibitions

- Do not use colors or themes not defined in the design.
- Do not skip design container layers.
- Do not start implementation before retrieving design variables.
- Do not hardcode colors; use design variables.

## UI Feedback System

**MUST use the Toast system for all user feedback messages.**

### Components

| Component | Use Case | Example |
|-----------|----------|---------|
| `Toast.show()` | Global temporary notifications | Success/error feedback after action |
| `AppBanner` | Inline form validation errors | Login form error message |

### Toast Types

```dart
enum ToastType { info, success, warning, error }
```

### Usage Examples

**Global Toast (auto-dismiss):**
```dart
Toast.show(context, '保存成功', type: ToastType.success);
Toast.show(context, '网络错误', type: ToastType.error);
Toast.show(context, '正在加载...', type: ToastType.info, duration: Duration(seconds: 3));
```

**Inline Banner (persistent):**
```dart
AppBanner(message: '邮箱或密码错误', type: ToastType.error)
AppBanner(message: '请检查输入', type: ToastType.warning)
```

### Rules

- Use `Toast` for transient feedback that auto-dismisses
- Use `AppBanner` for persistent inline messages (form errors)
- Do NOT create custom SnackBar, Dialog, or Banner components
- Do NOT use raw `ScaffoldMessenger`