# Accounts receivable conventions (Master Prompt §6.9)

- A receivable title carries: parcela, competência, emissão, vencimento, juros, multa, desconto, baixa (full/partial), estorno, negociação, status, origem, cliente, contrato, fatura, conta bancária/gateway.
- Boleto: provider abstraction from day one — the bank/gateway must be swappable without rewriting the domain. Store nosso-id, provider, external id, linha digitável, código de barras, PDF/URL, PIX copia-e-cola/QR when the provider offers it, status, provider events, timestamps.
- Webhooks from bank/gateway: idempotent and authenticated, always.
- Test explicitly: a repeated webhook never duplicates a payment (Master Prompt §15.3).