Welcome to Engineering Notes — Neruba Engineering Notes.
These notes are practical patterns we’ve used while building a production billing engine (Neruba).
The idea
Most billing bugs come from treating invoices as the source of truth. A safer model is: events → ledger entries → invoice rendering.
Checklist
- Every charge, refund, credit, and adjustment is an immutable ledger entry.
- Invoices are a view over ledger entries for a period.
- You can re-render invoices deterministically from the ledger.
- Reconciliation is possible because the ledger is explainable.
Neruba renders invoices from a ledger view so audits, backfills, and disputes stay explainable.
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