A rule over a key set that only exists at read time cannot declare its keys
at wiring time. Kuma has one monitor per service and the names live in the
gauge, so the rule declares a prefix and the gatherer resolves the family per
tick.
ServiceDownRule now fires on any monitor reading down, names it through
DownServices, and is edge-triggered: a service that stays down is one nudge,
not one per tick with cooldown as the only brake.
claude
4f516657da