ReadonlymaxAlready clamped to the route ceiling and the root budget's remainder.
ReadonlymessagesReadonlymodelOptional ReadonlyoutputReadonlysignalOptional ReadonlysystemOptionalonTransport reports the format it actually places on the outgoing request.
What a transport is asked to do. Every piece of output goes through
onChunk(a non-streaming transport calls it once with the whole text): a request that never chunked is settled as having produced no output.onCompletecarries the full text.