The first batching pass (bacac06) left critical-severity alerts on the
immediate-print path. That's still per-event spam for any persistent
critical (e.g. PrintPaperRollCritical fires every 30s Grafana evaluation
cycle when paper is <5%). Caught immediately after deploy: CUPS queue grew
0 → 8 jobs in 8 minutes from a single firing PrintPaperRollCritical.
This commit aligns with the operator's verbatim ask ("one alert an hour"):
- Critical-severity alerts now go into the digest buffer, NOT the
immediate-print path. The digest payload already shows severity tags
per alertname, so the operator still sees "[critical] X" in the printout.
- The explicit `alert_channel=thermal_print_immediate` label still bypasses
batching, but only on NEW fingerprint arrival — it triggers a flush of
the CURRENT digest (with the new alert included), then clears. Repeat
webhooks for the same fingerprint dedupe in the buffer until the next
hourly tick OR until the alert resolves. No fingerprint can spam.
- `add_to_digest` now returns bool (True = buffer grew, False = dedup /
resolution / disabled) so the immediate-label path can flush only on
state transitions.
Net effect: max 1 thermal print per BATCH_INTERVAL_MIN per alert fingerprint,
regardless of severity. Rules that genuinely need same-second paper opt in
via `alert_channel=thermal_print_immediate` (currently zero rules use this).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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