What is async job?
An async job is the same execution as a synchronous run with a different cadence: the call returns 202 with a job id, the worst-case credit cost is reserved up front, and you learn the outcome by polling, by subscribing to a status stream, or by receiving a signed completion webhook. Cancelling refunds the reservation in full.
Why it matters
A synchronous run is right when your agent is waiting on the answer and wrong when the work is a ten-minute crawl. The trade is explicit: you gain the ability to outlive a request timeout and you take on owning a job id.