Is it server data (API response)?
├── Yes → React Query / Connect Query
│         (caching, refetching, invalidation)
└── No → Is it URL state?
    ├── Yes → React Router
    │         (search params, path params)
    └── No → Is it form state?
        ├── Yes → React Hook Form
        │         (validation, submission)
        └── No → Is it shared across components?
            ├── Yes → Zustand
            │         (global, persisted)
            └── No → useState / useReducer
                      (local component state)