flutter-development

CIEL ADAPTATION: Flutter Development (Patterns & Review)

This skill formalizes the development and review of Flutter/Dart applications. It combines idiomatic implementation patterns with a rigorous quality checklist.

Implementation Standards

1. Null Safety: Avoid !. Prefer ?., ??, or Dart 3 pattern matching (switch (user) { ... }).
2. Immutability: Use sealed classes for state hierarchies and freezed for boilerplate-free copyWith.
3. Widget Purity: Extract sub-widgets to Classes, NOT private methods (enables const propagation and element reuse).
4. Reactivity: check mounted after every await before using BuildContext.

State Management Decision Matrix

• Simple/Atomic: ValueNotifier or Provider.
• Complex/Async: BLoC/Cubit (Event-driven) or Riverpod (Functional/Derived).
• Hard Gate: Never store BuildContext in a state manager or singleton.

Quality Checklist (The Auditor Gate)

• No print() in production; use log().
• Widgets under 100 lines.
• Colors/Fonts from Theme.of(context), never hardcoded hex.
• const constructors used at every possible boundary.

Anti-Patterns

• Boolean Flag Soup: Using isLoading, isError flags instead of a sealed AsyncState type.
• Deep Nesting: Nesting more than 5 levels of widgets (Extract to sub-classes).
• Bang-Operator Abuse: Using ! to "fix" nullability errors instead of proper guarding.