Chat sessions

A chat session is one unit of work. It gets its own branch, its own sandbox and its own conversation, and it moves through five statuses:

Status	Meaning
backlog	Written down, not started. Has a prompt but no branch and no sandbox.
active	Running. Has a branch and a sandbox.
under-review	A pull request is open.
completed	Merged or otherwise finished.
archived	Closed. Archiving closes the pull request, unarchiving reopens it.

Sessions carry a priority for triage: urgent, high, medium, low, none. They also carry an owner, so work can be assigned.

Creating a session with a first message does three things in one call: it creates the session, starts its sandbox, and enqueues the first chat job. Creating one with only a title leaves it empty until the first message arrives.