Gateway authorises
Auth adapter verifies the client; the gateway materialises a
candidate grant and writes it to the audit chain.
Scheduler picks a roost
Picks the first roost that satisfies the grant’s driver +
isolation-class + capability requirements.
Roost spawns the agent
Pulls the driver implementation, applies the isolation class,
spawns the CLI with the grant’s args.
Output streams back
OutputEvents flow over SSE: gateway → client. The roost journals
every event for replay.