Function useOpenUIState

packages/react-lang/src/hooks/useOpenUIState.ts:69–507

(
  {
    response,
    library,
    isStreaming,
    onAction,
    onStateUpdate,
    initialState,
    toolProvider,
    onError,
  }: UseOpenUIStateOptions,
  renderDeep: (value: unknown) => React.ReactNode,
)

 * under formName as plain values.
 */
export function useOpenUIState(
  {
    response,
    library,
    isStreaming,
    onAction,
    onStateUpdate,
    initialState,
    toolProvider,
    onError,
  }: UseOpenUIStateOptions,
  renderDeep: (value: unknown) => React.ReactNode,
): OpenUIState {
  // ─── Streaming parser (incremental — caches completed statements) ───
  const sp = useMemo(() => createStreamingParser(library.toJSONSchema(), library.root), [library]);

  // ─── Parse result ───
  const parseExceptionRef = useRef<OpenUIError | null>(null);
  const result = useMemo<ParseResult | null>(() => {
    parseExceptionRef.current = null;
    if (!response) return null;
    try {
      return sp.set(response);
    } catch (e) {
      const msg = e instanceof Error ? e.message : String(e);
      parseExceptionRef.current = {
        source: "parser",
        code: "parse-exception",
        message: `Parser crashed: ${msg}`,
        hint: "The response may contain syntax the parser cannot handle",
      };
      return null;
    }
  }, [sp, response]);

  // ─── Store (holds everything: $bindings + form fields) ───
  const store = useMemo<Store>(() => createStore(), []);

  // ─── QueryManager ───
  const queryManager = useMemo<QueryManager>(
    () => createQueryManager(toolProvider ?? null),
    [toolProvider],
  );

  useEffect(() => {
    queryManager.activate();
    return () => queryManager.dispose();
  }, [queryManager]);

  // ─── Initialize Store ───
  const storeInitKeyRef = useRef<unknown>(Symbol());
  useEffect(() => {
    if (!result?.stateDeclarations && !initialState) return;
    const key = `${JSON.stringify(result?.stateDeclarations)}::${JSON.stringify(initialState)}`;
    if (storeInitKeyRef.current === key) return;
    storeInitKeyRef.current = key;

    // Split initialState: $-prefixed keys are bindings, everything else is form state