Vercel AI SDK - Darwin

Create server-only tools that call the Darwin SDK or REST API. Keep the public Search schema separate from Act thread writes so the UI can render different confirmation behavior.

Recommended application state

selected Search agent and optional nested capability
durable threadId, revision, and last consumed cursor
stable idempotencyKey values for identical mutation retries
current typed events and operation states

Stream explanatory model text separately from the authoritative thread state. A finished text stream does not mean external work completed.

UI responsibilities

Darwin response	UI treatment
Search results	Comparable selection cards in canonical order.
`awaiting_user`	A focused input request.
`connection_required` or `payment_required`	A user-triggered link to Darwin’s first-party flow.
`approval_required`	Exact review terms with explicit approve and reject controls.
`completed` or `stopped`	A terminal result with no further polling.

Keep the stream reconnectable and the thread state durable. A page refresh should call get_thread with the stored threadId and cursor, not create a new thread.

Last modified on October 1, 2026