flutter-3listed

# Flutter 3+ ## When to activate - Building Flutter applications for iOS, Android, web, or desktop - Architecting state management with Riverpod 2 - Configuring navigation with go_router - Implementing platform channels for native code integration - Optimizing widget rebuild performance - Running `flutter build` for production artifacts ## When NOT to use - React Native, Expo, or other non-Flutter mobile frameworks - Dart-only CLI tools or server-side Dart with no Flutter widgets - When the question is about Xcode/Android Studio configuration unrelated to Flutter build tooling ## Instructions ### Widget Rebuild Optimization Every `setState`, provider change, or inherited widget notification rebuilds the widget subtree. Minimize the blast radius: **Lift state down.** Keep stateful widgets as close as possible to the UI that depends on them. A single top-level `StatefulWidget` rebuilds the entire tree. **Use `const` constructors.** Widgets constructed with `const` are skipped during rebuild if their configuration hasn't changed. ```dart // Good — these don't rebuild when parent rebuilds const Text('Static label'), const SizedBox(height: 16), const Icon(Icons.star), ``` **Extract heavy subtrees.** Pull stable subtrees into their own widget class. Flutter skips unchanged widgets when their `==` returns true (automatic for `const` instances). **Use `RepaintBoundary` for animations.** Wrap animated subtrees to isolate their GPU layer from the rest of the tree. ```dart Re