Events arrive over the REST API, a batch import, or a stream. Each carries an idempotency key, so a retry storm from your side never double-counts on ours. Nothing is queued for later — the event is durable before the call returns.
Events are matched to a customer, a subscription and a meter, then aggregated on arrival. Late arrivals are attributed to the period they belong to rather than the one they landed in, and every aggregate keeps a pointer back to the events beneath it.
The customer’s contracted pricing version is applied: tiers, volume breaks, prepaid credits, seats, minimums, overages. Because versions are pinned per customer, changing next quarter’s pricing cannot restate last quarter’s invoice.
A finished invoice, every line traceable to the events that produced it. Push it to Stripe, NetSuite or your own ledger — Tessera does the arithmetic and hands off the result.