Function useGeneration

packages/ai-react/src/use-generation.ts:97–215

(
  options: Omit<UseGenerationOptions<TInput, TResult>, 'onResult'> & {
    onResult?: (result: TResult) => TTransformed
  },
)

// default, leaving the parameter `any` — a hard error under `strict`. See
// issue #848.
export function useGeneration<
  TInput extends Record<string, any>,
  TResult,
  TTransformed = void,
>(
  options: Omit<UseGenerationOptions<TInput, TResult>, 'onResult'> & {
    onResult?: (result: TResult) => TTransformed
  },
): UseGenerationReturn<InferGenerationOutputFromReturn<TResult, TTransformed>> {
  type TOutput = InferGenerationOutputFromReturn<TResult, TTransformed>
  const hookId = useId()
  const clientId = options.id || hookId

  const [result, setResult] = useState<TOutput | null>(null)
  const [isLoading, setIsLoading] = useState(false)
  const [error, setError] = useState<Error | undefined>(undefined)
  const [status, setStatus] = useState<GenerationClientState>('idle')

  const optionsRef = useRef(options)
  optionsRef.current = options

  const client = useMemo(() => {
    const opts = optionsRef.current

    // Conditional spread for `body` (strict-optional in target;
    // local source is `Record<string, any> | undefined`). Callbacks
    // wrap optional ones in non-returning bodies so `?.()`'s
    // implicit `undefined` doesn't pollute the function return type.
    const clientOptions: GenerationClientOptions<TInput, TResult, TOutput> = {
      id: clientId,
      body: opts.body,
      devtoolsBridgeFactory: createGenerationDevtoolsBridge,
      devtools: {
        hookName: 'useGeneration',
        framework: 'react',
        ...opts.devtools,
      },
      // The transform's raw return type (`TTransformed`) and the stored output
      // (`TOutput`, with null/void/undefined stripped) are identical at runtime;
      // the cast bridges the relationship that the conditional type hides.
      onResult: ((r: TResult) => optionsRef.current.onResult?.(r)) as (
        result: TResult,
      ) => TOutput | null | void,
      onError: (e: Error) => {
        optionsRef.current.onError?.(e)
      },
      onProgress: (p: number, m?: string) => {
        optionsRef.current.onProgress?.(p, m)
      },
      onChunk: (c: StreamChunk) => {
        optionsRef.current.onChunk?.(c)
      },
      onResultChange: setResult,
      onLoadingChange: setIsLoading,
      onErrorChange: setError,
      onStatusChange: setStatus,
    }