Flutter cross-platform development guide covering widget patterns, Riverpod/Bloc state management, GoRouter navigation, performance optimization, and platform-specific implementations. Includes const optimization, responsive layouts, testing strategies, and DevTools profiling. Use when: building Flutter apps, implementing state management (Riverpod/Bloc), setting up GoRouter navigation, creating custom widgets, optimizing performance, writing widget tests, cross-platform development.

Flutter跨平台开发指南，涵盖小部件模式、Riverpod/Bloc状态管理、GoRouter导航、性能优化和平台特定实现。包含const优化、响应式布局、测试策略和DevTools性能分析。适用于构建Flutter应用、实现状态管理（Riverpod/Bloc）、配置GoRouter导航、创建自定义小部件、优化性能、编写小部件测试和跨平台开发。