KPI weekly-cron staleness alert: last-success-timestamp check that pages if no kpiCronReport appEvent in >8 days. Weekly crons (0 9 * * 1) can fail silently for ~7d before anyone notices (PLUTO-39 showed how easily a weekly gap reads as 'dead'). Defensive observability add, NOT a bugfix. Touches email/alert path → audit pre-push.