React to ShadowJS: Complete API table

The table maps React 19 APIs to ShadowJS. Renamed APIs keep the same role; replaced APIs use a different model. Unavailable features are marked explicitly, with the relevant behavior explained in the sections below.

React 19 export	ShadowJS	Status
`useState`	`useSignal` from `@shadow-js/core`	RENAMED
`useReducer`	`useReducer(reducer, initial)`	NEW
`useContext`	`useContext(Ctx)`	SAME
`useRef`	plain `let`, or `createRef()` for elements	RECIPE
`useEffect`	`useEffect(fn)`, `useEffect(deps, fn, { defer })`	SAME
`useLayoutEffect`	`useRenderEffect(compute, apply)`	RENAMED
`useInsertionEffect`	`useRenderEffect`	RENAMED
`useImperativeHandle`	`useImperativeHandle(ref, create)`	NEW
`useMemo`	`useMemo(fn, { equals, lazy, name })`	SAME
`useCallback`	plain function	RECIPE
`useDebugValue`	`name` option on hooks; devtools hook	RECIPE
`useDeferredValue`	`useDeferredValue(source, options?)`	SAME
`useTransition`	`useTransition()` returns `[isPending, start]`	SAME
`useId`	`useId()`	SAME
`useSyncExternalStore`	`useExternalStore(subscribe, getSnapshot, { getServerSnapshot })`	RENAMED
`useActionState`	`useAction(action, initialState)` returns `[state, dispatch, pending]`	RENAMED
`useOptimistic`	`useOptimistic(source, reducer)`	PARTIAL
`useEffectEvent`	`useEvent(handler)`	RENAMED
`use` (promise or context)	`useContext(Ctx)`; `useResource(...)`	RECIPE
`useFormStatus` (react-dom)	not in core/web; `@shadow-js/forms` state	REJECTED
`Fragment` (`<>`)	`Fragment` from `@shadow-js/web` (fragments are compile-time arrays)	SAME
`Suspense`	`Suspense`	SAME
`StrictMode`	none	REJECTED
`Profiler`	devtools hook (`DEVTOOLS_EVENT`)	REJECTED
`Activity`	`<Activity mode="visible" \| "hidden">`	NEW
`ViewTransition`	`startViewTransition(update)` helper	PARTIAL
`Children` namespace (see A-07 below)	`children(...)` helper methods	RENAMED
`Component` (class)	function components	REJECTED
`PureComponent` (class)	function components	REJECTED
`lazy`	`lazy` from `@shadow-js/web`	PARTIAL
`memo`	none (components run once)	RECIPE
`forwardRef`	`ref` is a prop; `createRef` and `useImperativeHandle`	RECIPE
`createContext`	`createContext(default)`; `<Ctx value={v}>`; `Ctx.Provider`	SAME
`createContext`	`createContext`	SAME
`createRef`	`createRef<T>()` (callable and `.current`)	NEW
`forwardRef`	none (see R-C12)	RECIPE
`memo`	none (see R-C11)	RECIPE
`lazy`	`lazy`	SAME
`startTransition`	`startTransition(fn)`	SAME
`Children.count` / `Children.map` / `Children.forEach` / `Children.only` / `Children.toArray`	`children(() => props.children)` with `count()`, `map()`, `forEach()`, `only()`, `toArray()`	NEW
`cloneElement`	`mergeProps` in a wrapper component	RECIPE
`createElement`	JSX (compiler output)	REJECTED
`createFactory` (legacy)	none	REJECTED
`isValidElement`	`node instanceof Node`	RECIPE
`cache`	`cache(fn, { limit })`	NEW
`cacheSignal` (RSC)	none	REJECTED
`captureOwnerStack`	none	REJECTED
`addTransitionType`	none	NOT-1.0
`act` (from `react`, and `react-dom/test-utils`)	`act(callback)` from `@shadow-js/testing`	NEW
`use` (see R-H19)	see R-H19	RECIPE
`version`	none (use the package version)	REJECTED
`__CLIENT_INTERNALS` / unstable internals	none	REJECTED
`createPortal`	`Portal` from `@shadow-js/web`	RENAMED
`flushSync`	`flushSync` from `@shadow-js/core`	SAME
`unstable_batchedUpdates`	`batch`	RENAMED
`preconnect`	`preconnect(href, { crossOrigin })`	NEW
`prefetchDNS`	`prefetchDNS(href)`	NEW
`preload`	`preload(href, { as, type, media, crossOrigin })`	NEW
`preloadModule`	`preloadModule(href, { crossOrigin })`	NEW
`preinit`	`preinit(href, { as: "style" or "script" })`	NEW
`preinitModule`	`preinitModule(href, { crossOrigin })`	NEW
`useFormStatus`	see R-H20	REJECTED
`createRoot` (client)	`render(() => <App />, container)`	RENAMED
`hydrateRoot`	`hydrate(() => <App />, container, { renderId, data })`	RENAMED
`root.render(element)`	the function passed to `render`, or a signal	RENAMED
`root.unmount()`	the dispose function returned by `render`	RENAMED
`render` (legacy)	`render`	RENAMED
`hydrate` (legacy)	`hydrate`	RENAMED
`findDOMNode`	none	REJECTED
`unmountComponentAtNode`	dispose function	REJECTED
`version` (react-dom)	none	REJECTED
`react-dom/client` `createRoot` / `hydrateRoot`	`render` / `hydrate`	RENAMED
`renderToString`	`renderToString` (`@shadow-js/web/server`)	SAME
`renderToStaticMarkup`	`renderToString`	PARTIAL
`renderToReadableStream`	`renderToStream` (Web stream)	RENAMED
`renderToPipeableStream`	`renderToStream(...).pipe(writable)`	PARTIAL
`renderToNodeStream` (legacy)	none	REJECTED
`renderToStaticNodeStream` (legacy)	none	REJECTED
`prerender`	none in core/web; Dusk static output	DEFERRED
`prerenderToNodeStream`	none	DEFERRED
`resume`	none	REJECTED
`resumeToPipeableStream`	none	REJECTED
`renderToStringAsync` (Solid; listed for the server row)	`renderToStringAsync`	PARTIAL
`react/jsx-runtime` `jsx`, `jsxs`, `Fragment`	`@shadow-js/web/jsx-runtime`	SAME
`react/jsx-dev-runtime` `jsxDEV`	`@shadow-js/web/jsx-dev-runtime`	SAME
`ref` as a prop, cleanup returned from a ref callback	`ref={...}` (compiled); cleanup through `use()`	NEW
`<title>`, `<meta>`, `<link>`, `<style>` in the tree (metadata hoisting)	`Title`, `Meta`, `Link`, `Style`, `Base` and `useHead`	SAME
Form `action` prop (`<form action={fn}>`)	`useAction` in components; form state in `@shadow-js/forms`	PARTIAL
`useId` in the context of SSR keys	`useId`	SAME