The run's opening request.
Every agent a mention could name.
The running agent's ID.
an agent other than the one running, in which case the user has
already chosen and discovery does not run. It recognises both forms a mention takes by the time a
run starts: the composer's @{"_mode":"mention","type":"agent",...} token, and the "@Agent Name"
text BaseAgent converts that token to (or that the user typed). Names match whole, in any case.
A mention of the running agent itself does not count: it names no one to delegate to.
Whether the request