Events

Emitted

Event	When
metering.meter-configured	a meter registered, or its description/active updated
metering.usage-recorded	a new usage entry lands — a deduped replay emits nothing
metering.period-closed	a window is frozen into lines; the billing hand-off

Consumes nothing.

Payload contracts

All payloads are fat: a consumer never reads back across the module boundary.

• metering.meter-configured — { key, kind, unit, active }.
• metering.usage-recorded — { entryId, meterKey, kind, unit, qty, subject, occurredAt, dedupeKey }. Because a deduped replay emits nothing, the event stream is itself dedupe-clean: a consumer summing qty per meter sees each observation exactly once (modulo the platform's at-least-once delivery — dedupe on entryId).
• metering.period-closed — { periodId, from, to, lines }, where each line is { meterKey, kind, unit, qty, entryCount }. Quantities, never prices: the vertical maps meter keys to rates and feeds invoicing, exactly like the timesheet close hand-off (composing). Dedupe on periodId.

PII

Every event is piiClass: 'none', and — unlike the absence engine — writes take no DataSubjectId: meters count machines and bytes, not people. The optional subject ref is an attribution noun (a project, a message), not an identity. A vertical that finds itself metering people per-person should stop and think — and if it proceeds, hang its own PII-classified side table off the entry id rather than widening this engine's events.

Versioning

Every event is emitted at schemaVersion: 1. Payload fields are frozen once shipped: additions are fine, renames/removals/retypes mean a schemaVersion bump — the platform-wide rule, restated because billing events are exactly the kind external consumers (a warehouse drain, a Stripe usage connector) quietly grow to depend on.

A bump is a replace, not a dual-emit: consumer dispatch keys on the event type alone, so two versions in flight would deliver both to every consumer of that type — on a billing event, the same usage counted twice. Read the invoicing engine's underlag-exported v2 note before bumping anything here.