GitHub Actions scheduler de-prioritises :00 cron firings under load.
Empirical 2026-05-03: the canary's cron was '0,20,40 * * * *' but
actual firings landed at :08, :03, :01, :03 — :20 and :40 silently
dropped. Detection latency degraded from claimed 20 min to actual
~60 min worst case.
Move to '10,30,50 * * * *':
- :10/:30/:50 sit 10 min off the top-of-hour load peak
- Still 5 min from :15 sweep-cf-orphans and :45 sweep-cf-tunnels
(the original constraint that kept us off :15/:45)
- Same 20-min cadence; only the phase changes
No code change beyond the cron expression + comment refresh.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
a306a97dd3