Runs and checkpoints the case lead only, through the Codex app-server's own session history.
What it holds
--store DIR plus a command.
init --room R --model M [--effort] [--auth-source] [--host-sandbox]
copies the room into workspace/room, builds its run there,
and writes STORE.json and the first checkpoint.
turn --message lead|collect|finish [--batch] [--summary] | --prompt-file F --label L
starts or resumes the lead, waits for a completed reply, shuts the
runtime down, exports the transcript to
run/out/_transcript.jsonl, saves
final_message.md, and commits a checkpoint.
fork --checkpoint C --name N makes a native fork without a
model turn. Also restore, verify,
status, recover, recover-run.
Who writes it, and when
The yard's author. start_yard_lead.py calls
init and the first turn.
Why it exists
"Every successful turn shuts down the runtime, exports its complete native rollout, and commits one checkpoint." "Brief writers and fleet coders are external; only their filesystem outputs travel." It fails closed if the Codex binary, Python or platform changed.
Where
_tools/codex_lead.py.
It imports checkpoints and calls
verify_room.py; both are in _tools/.
Checked against: _tools/codex_lead.py, CHECKPOINTS.md