Run your first streamed request

Start the stream

Use the agent and context created in the previous step:

const stream = agent.stream(
  {
    sessionId: "kestrel-session-001",
    message: "Explain the highest-risk parts of this project.",
  },
  context,
);
 
for await (const event of stream) {
  console.log(event.type, event.payload);
}
 
const terminal = await stream.result;
console.log(terminal.type);

Iteration reads live events for this request. stream.result resolves to the terminal event for that same run. Live progress does not replace the terminal result.

Read the event envelope

Validate every envelope before use. Correlate its event type, request, session, run, turn, sequence, and timestamp; never order a durable history by browser arrival time alone.

Render only committed output

Render provider reasoning, concise agent progress, tool activity, and assistant output as distinct UI states. Output deltas are provisional. Commit the final assistant message only from the terminal result's assistantText.

Cancel when the caller leaves

Pass an AbortSignal when the stream belongs to a request that may disconnect:

const stream = agent.stream(
  {
    sessionId: "kestrel-session-001",
    message: "Review the deployment configuration.",
    signal: abortController.signal,
  },
  context,
);

Aborting cancels that upstream run. The terminal promise resolves with run.cancelled, which should remain visible as a deliberate outcome rather than being converted into a generic network error.

Reconnect or replay

For observation that survives a request, subscribe using a server-owned actor and resume from the last accepted cursor. Consumers must tolerate duplicate delivery and apply each persisted event idempotently.

Verify termination

Interrupt one stream and let another complete. Each accepted run must produce exactly one valid terminal outcome—completed, failed, cancelled, or waiting—and the UI must not synthesize a second outcome from a disconnect.

Use a durable background subscription when observation must continue after the original request ends.