An upgrade restarts the app and the Fujitsu dispenser runs an audible
init routine when it does. On sintra that was firing at 10:17 in the
morning, in the room, because `dates = "04:00"` is local time and every
machine inherits America/Guatemala from the shared base config.
The obvious fix is to set the system timezone per machine. This does the
narrower thing instead: systemd 252+ accepts a timezone suffix on a
calendar spec, so the timer follows Europe/Paris and its DST while the
system clock stays a fleet default nobody maintains per host. The only
other consumer of machine-local time is a technician reading the journal
at the machine, and for correlating against relay created_at stamps, UTC
is easier anyway.
The operator dashboard never needed this. It renders timestamps in the
reader's own browser locale, which is why the cassettes tab read
correctly while the journal did not.
Verified by resolving the config for all four hosts, and against
systemd-analyze on sintra itself: 04:00 Europe/Paris is 02:00 UTC in
summer, 04:00 America/Guatemala is 10:00 UTC.
A warning is in the comment because it nearly caught me: the same check
under `nix-shell -p systemd` silently computes EVERY named zone as UTC
while echoing the zone back in its normalized form. It looks accepted and
is wrong. Test on a real system.
