Give every plan a write-restricted Status (draft, reviewed,
done) and an append-only Review Log with UTC ISO 8601 lines.
Make-a-plan creates plans as draft and is the only flow
writing reviewed, on explicit user apply. Review-plan stays
read-only. Implement-plan closes the plan to done with the
issue URL when one exists, in the same commit as the code.
Document the lifecycle in the agents README.
AI-assisted-by: muse-spark-1.3-contributor