delayed fault

A fault committed at one moment and revealed at another, when something finally triggers it: a reboot, a log rotation, a certificate expiry, the first restore anybody attempts. A symptom's timestamp says when the fault became visible, not when it was made. A service started by hand and never enabled runs for weeks; the reboot restarts nothing because there was nothing to restart, and systemctl is-enabled myapp says so in one word: disabled. Dating the fault from the symptom costs a specific half hour. A sudo journalctl --since bounded on the reboot brackets the trigger: it comes back empty, and that emptiness says nothing about a missing enable that is weeks old. sudo journalctl --list-boots, then the boot before it, lead where the machine still worked. When nothing was triggered at all, the region to search is what has never been checked.