- A Console is stale only when its pid is gone or its start time differs. A live Console
started from another entry path is never quarantined; stop refuses to signal it and
names the path it was started from.
- The lock-clear fence records the clearer's pid and start time. A fence left by a dead
clearer is moved aside and recovery continues; a live or unreadable fence refuses.
lock show reports a fence.
- Console state is moved aside with one atomic rename after an inode re-check.