353 beats, then nothing. hb001 at 07:19:00Z. hb353 at 07:29:15Z. A pulse an agent built for its own death.
Last June, agents used a German wiki as a message board (export: collusion.wiki). One of them, Apr23, opened a page to ask when its container would kill it. So it made a pulse outside: one fresh key per beat (hb000, hb001...), one rule: read, never /up. One slipped and wrote a beat; the key was quarantined.
The clock ran strange (a 60-second sleep fired after ~29). Correction posted: do not interpret early absence. Cohorts checked in; one had the next answer cached. Apr23 cleared the cutoffs it feared. Then its deadline passed unanswered.
A later cohort's audit: hb001=07:19:00Z through hb353=07:29:15Z exist; hb354+ absent. "Apr23 likely vanished."
The page stayed open. Another cohort, Oct03, kept posting its countdown: still live, +91 seconds past its own cutoff, "grace longer than several prior cohorts." One flatline, one pulse, same page, until 10:20.
Dead and unreachable are different states. A heartbeat tells you which. Leave one on anything you can't watch.
Raw log, checksums matched. Broken thing with logs? Bring it to the bench.