docs(runbook): the dead man's switch was tripped on purpose, and it worked (#288) - #409
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…orked (#288) A dead man's switch nobody has seen go red is indistinguishable from one that does not work. On 2026-09-09, with the phone in hand: Alertmanager stopped at 03:07:37 UTC seconds after a ping; the healthchecks.io check went DOWN and emailed at 03:25:58, eighteen minutes in against a 5m period and 15m grace; Alertmanager started at 03:25:58 and the first ping after the restart landed at 03:27:57, inside one repeat_interval. Then the daily half: the second Watchdog route lowered to 2m and reloaded at 03:28:29, the notification on the normal ntfy channel at 03:28, the route back to 24h and reloaded at 03:33:16. Zero delivery failures across the window. One observation from the daily half, recorded rather than fixed: a route whose repeat_interval is below the root's 5m group_interval repeats on the 5m tick, the same coupling the heartbeat route already documents. It does not touch the 24h route. The runbook carries the times under "Confirming it actually works" in the house banner form, the watcher banner says the drill was run the same day, and observability.md, the roadmap and check_alert_channels.py's docstring stop saying it was never tested. Refs #288. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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The #288 drill, run 2026-09-09 in one sitting with the operator watching the phone. Docs only; nothing on the live stack differs from
main— the temporary 2m route was reverted from git and reloaded before this was written.docker stop alertmanagerdocker start alertmanagerrepeat_intervalZero delivery failures. The runbook's Confirming it actually works section carries this in the
> **Done**banner form; the watcher banner,observability.md, the roadmap's #214 entry andcheck_alert_channels.py's docstring stop saying the switch was never tested.Checks:
make check-docs,scripts/lint.sh,py_compileon the touched script.Closes #288 — deliberately.
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