Payment Checkout & Ledger Service  ·  View 09 of 24  ·  Structure

Integration Surface

Four inbound interfaces, four outbound, and only one of them may create money movement.

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Inbound Checkout SDK Merchant server API Provider callbacks Settlement files Payment Checkout & Ledger Service Authorization plane Ledger plane Money operations Outbound Card acquirers A2A rail Merchant webhooks Settlement bank confirm intents callbacks daily file authorize collect webhooks payout Integration Surface — Every Interface In and Out External / third party Application we own Data store synchronous batch event / async Four inbound interfaces, four outbound. Dispute notices arrive on the provider-callback interface, sanctions screening sits inside the payout interface, and the nightly finance extract reads the projections rather than the ledger. The finance ops console is an internal surface, not an integration point. Only the merchant server API may create money movement. v 1.0 · owner Payments Platform Architecture · date 2026-10

Decisions

  • Only the merchant server API can create a payment or a refund. The checkout SDK can confirm an existing intent and nothing more (ADR-15).
  • Provider callbacks are verified and persisted raw before interpretation, so a parser bug never destroys evidence (ADR-05).
  • The nightly finance extract reads projections, never the ledger, so a reporting workload cannot contend with posting (ADR-16).

Interface contracts

  • Settlement files arrive over SFTP with a per-provider arrival SLA and a late-file alarm; ingest is idempotent and re-runnable.
  • Merchant webhooks are at-least-once with a per-object sequence number and 72 hours of retry, then a pull-based catch-up API.
  • Egress to every money network leaves through an allowlisted proxy on static IPs.

Accepted clutter

  • The route checker reports one warning on this page: the 'payout' and 'webhooks' labels sit close to adjacent lines. It is inherent to a hub fan and is the only warning in the 24-view set.
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Solution Architecture v1.0 · open source, self-hosted on Kubernetes across two in-country data centres · Payments Platform Architecture · 2026-10 · 24 views · 18 architecture decision records09-integration-surface