Builds and debugs React user interfaces: components, state, effects, forms and data loading, written the way React 19 expects. Use when someone asks to "create a React app", "build a React component", "fix a useEffect bug", "stop unnecessary re-renders", "upgrade to React 19", "turn on the React Compiler", "use Server Components", "handle a form with Actions" or "test a React component". Covers Actions, use, useActionState, useOptimistic, ref as a prop, Server and Client Components, Suspense, error boundaries, keys, and project setup with Vite now that Create React App is deprecated.
