seat:<agencyId>:<role>; refused when a GMI already serves it. Until the seat is released no request acquires
a GMI in it and no feedback reaches its GMI.
The parent turn's user: the seat's tools and the tier check see it.
A registered persona, by id (a persistent member), or the definition a launch made for a temporary seat.
The seat's tool orchestrator: a view the launch makes over the shared one.
Optional providerThe seat's provider manager: a view the launch makes over the runtime's; the runtime's own when absent.
Optional maxThe seat's step limit; the GMI's default when absent.
One seat of a team a GMI launched on the full runtime (
launch_agency): what GMIManager.createAgencySeat builds. The launch passes the views the seat runs through, so the manager imports nothing of the launch.