The coding agent is an actor, not a feature. Its goal — forty disposable machines now, unreviewed code inside them, a diff back — is what forces class-aware admission, stricter egress defaults and a session record that outlives the VM.
The platform SRE's goal (patch everything without a developer noticing) is only achievable because of ADR-01; on a host-owned design the same goal is a maintenance window.
Engineering finance appears in the cast because cost per active workspace-hour is a requirement, not a report.
Assumptions
A human session lasts about 95 minutes and an agent session about 7; the fleet is sized for the mix, not the average.
1,800 tenants set their own idle timeout and egress posture within platform-defined bounds.
Risks
The reviewer's journey (open a branch running) is the one most likely to be served by a public preview URL, which is the platform's largest self-inflicted exposure.
Two of these actors can spend money without a human in the loop; the ceiling must be enforced at admission, not on an invoice.
