react-dev

# React TypeScript Type-safe React = compile-time guarantees = confident refactoring. <when_to_use> - Building typed React components - Implementing generic components - Typing event handlers, forms, refs - Using React 19 features (Actions, Server Components, use()) - Router integration (TanStack Router, React Router) - Custom hooks with proper typing NOT for: non-React TypeScript, vanilla JS React </when_to_use> <react_19_changes> React 19 breaking changes require migration. Key patterns: **ref as prop** - forwardRef deprecated: ```typescript // React 19 - ref as regular prop type ButtonProps = { ref?: React.Ref<HTMLButtonElement>; } & React.ComponentPropsWithoutRef<'button'>; function Button({ ref, children, ...props }: ButtonProps) { return <button ref={ref} {...props}>{children}</button>; } ``` **useActionState** - replaces useFormState: ```typescript import { useActionState } from 'react'; type FormState = { errors?: string[]; success?: boolean }; function Form() { const [state, formAction, isPending] = useActionState(submitAction, {}); return <form action={formAction}>...</form>; } ``` **use()** - unwraps promises/context: ```typescript function UserProfile({ userPromise }: { userPromise: Promise<User> }) { const user = use(userPromise); // Suspends until resolved return <div>{user.name}</div>; } ``` See [react-19-patterns.md](references/react-19-patterns.md) for useOptimistic, useTransition, migration checklist. </react_19_changes> <compo...