Archive now inspects .ctask/session.json before mutating task.yaml. A
fresh lease (heartbeat within 60s) triggers a warning. Interactive
stdin gets a y/N prompt (default N). Non-interactive stdin refuses
with a non-zero exit, which is safer than silently hiding an actively
writing workspace. Stale or missing leases pass through unchanged.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
