NewSubscriptionMetrics(subscription) returns a *SubscriptionMetrics whose method
set (Pushed/PushSkipped/Dropped/ChannelFull) satisfies the Observer interface of
gitea.unbound.se/shiny/subscriptions structurally — otelsetup does not import
that library. Services wire it via subscriptions.WithObserver so the
cross-service subscription push path (ADR-0012) reports outcomes as metrics
instead of only the library's skip/drop warn logs.
One Int64Counter `subscription.notifications` labelled by (subscription, outcome)
only — the subscriber key (company id / user email) is deliberately NOT a label
to avoid unbounded cardinality. skip-rate = skipped/(pushed+skipped).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
argoyle
