Function runStreamingStructuredOutputImpl

packages/ai/src/activities/chat/index.ts:3136–3207

(
  options: TextActivityOptions<AnyTextAdapter, TSchema, true, TContext>,
  jsonSchema: NonNullable<ReturnType<typeof convertSchemaToJsonSchema>>,
  normalize: (data: unknown) => unknown,
)

>

async function* runStreamingStructuredOutputImpl<
  TSchema extends SchemaInput,
  TContext = unknown,
>(
  options: TextActivityOptions<AnyTextAdapter, TSchema, true, TContext>,
  jsonSchema: NonNullable<ReturnType<typeof convertSchemaToJsonSchema>>,
  normalize: (data: unknown) => unknown,
): StructuredOutputStreamInternal<InferSchemaType<TSchema>> {
  const {
    adapter,
    outputSchema,
    middleware,
    context,
    debug,
    mcp,
    ...textOptions
  } = options
  const model = adapter.model
  const logger = resolveDebugOption(debug)

  // Per issue #605: adapters that natively combine tools + schema-constrained
  // output in one streaming call (modern OpenAI, Anthropic 4.5+, Gemini 3+,
  // Grok 4+) opt in via `supportsCombinedToolsAndSchema()`. The engine then
  // forwards the schema into the regular `chatStream` call and harvests the
  // structured result from the agent loop's accumulated text — no separate
  // finalization round-trip, and the `'structuredOutput'` middleware phase
  // does not fire.
  const nativeCombined =
    adapter.supportsCombinedToolsAndSchema?.(options.modelOptions) === true

  const mcpManager = MCPManager.from(mcp)
  const mcpTools = await mcpManager.discover()
  if (mcpTools.length > 0) {
    textOptions.tools = [...(textOptions.tools ?? []), ...mcpTools]
  }

  // Inputs may be UIMessages (from useChat) or ModelMessages (from server-side
  // callers). TextEngine handles the conversion uniformly.
  const engine = new TextEngine(
    {
      adapter,
      params: { ...textOptions, model, logger } as TextOptions<
        Record<string, unknown>,
        Record<string, unknown>,
        TContext
      >,
      middleware,
      context,
      finalStructuredOutput: {
        jsonSchema,
        yieldChunks: true,
        normalize,
        ...(nativeCombined ? { nativeCombined: true } : {}),
      },
    },
    logger,
  )