What ctx.awaitCompletion's send gets: the token, and the URL that completes it over HTTP when the engine serves its API.
ctx.awaitCompletion
send
Optional
POST the value as JSON here (…/v1/fail/<token> fails it).
POST
…/v1/fail/<token>
What
ctx.awaitCompletion'ssendgets: the token, and the URL that completes it over HTTP when the engine serves its API.