StructuredOutputStream

type StructuredOutputStream<T> = AsyncIterable<
  | Exclude<StreamChunk, CustomEvent>
  | StructuredOutputStartEvent
| StructuredOutputCompleteEvent<T>>;

Defined in: packages/ai/src/types.ts:1999

Public type for streams returned by chat({ outputSchema, stream: true }).

Yields all standard StreamChunk lifecycle events plus the typed structured-output CUSTOM event emitted through this path:

• structured-output.complete — terminal event with typed value.object: T

User-actionable waits, such as tool approval and client tool input, are represented by RUN_FINISHED.outcome.type === 'interrupt'.

Each variant has a literal name, so a single discriminated narrow gives you a typed value with no helper or cast:

for await (const chunk of stream) {
  if (chunk.type === 'CUSTOM' && chunk.name === 'structured-output.complete') {
    chunk.value.object // typed as T
  }
}

Caveat: tools can emit arbitrary user-defined custom events via the emitCustomEvent(name, value) context API. Those flow through this stream at runtime but are intentionally absent from this type — including a bare CustomEvent (whose value: any would poison the union) would collapse chunk.value back to any after the narrow. If you rely on emitCustomEvent plus outputSchema + stream: true, branch on CUSTOM outside the literal-name narrows or cast explicitly.

Type Parameters#

T#

T = unknown