Expert frontend engineering with simplified pragmatic architecture, React 19, TanStack ecosystem, and Zustand state management. **ALWAYS use when implementing ANY frontend features.** Use when setting up project structure, creating pages and state management, designing gateway injection patterns, setting up HTTP communication and routing, organizing feature modules, or optimizing performance. **ALWAYS use when implementing Gateway Pattern (Interface + HTTP + Fake), Context API injection, Zustand stores, TanStack Router, or feature-based architecture.**