Three new Prometheus alert rules for the print-services group, all routed
to thermal_print via alert_channel label (Grafana contact point ->
irc-notify -> Print.Web /api/print/alert):
- PrintPaperRollLow (warning, 5-10% remaining, 5m for)
- PrintPaperRollCritical (critical, <=5% remaining, 2m for)
- PrintJobDeadLetter (warning, any new dead-letter in 15m)
Source-of-truth gauge is print_paper_remaining_percent (Print.Web OTEL),
which is hydrated from the active PaperRoll row at process startup
(Print.Web@<TBD> HydrateMetricsAsync) so the gauge isn't blind for an
arbitrary window after every deploy.
Self-referential humor: low-roll alerts route to the printer that's
running out of paper, so it announces its own paper-out warning on its
remaining paper.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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