Why architecture matters here
Payment failures are the most expensive kind. A double-charge damages trust; a missed capture leaves money uncollected; a bad reconciliation produces phantom disputes. The architecture matters because each step has a legal and financial contract that must hold end to end.
AP2 formalizes those contracts with signed intent + authorization + capture messages so both sides can prove what was agreed. Reconciliation compares intent to receipt to catch drift. Ledger is the immutable record.
With the architecture in your head you can build payment flows that agents can execute safely.
The architecture: every piece explained
The top strip is the transaction path. Buyer intent is a signed order — what to buy, up to what limit, on which rail. Merchant order describes the SKUs and amount. Authorization holds funds via the underlying rail. Capture commits the hold to settlement.
The middle row is the substrate. Settlement rail is card, bank, or stablecoin — each with its own timing and fees. Reconciliation matches intent to receipt line-by-line. Reversal handles chargebacks, refunds, and disputes. Ledger is the immutable append-only event log of all payment activities.
The lower rows are governance. Dispute + arbitration handles conflicts across buyer, merchant, and issuer. Compliance layers AML/KYC and jurisdictional rules. Ops includes reconciliation SLAs, exception handling for mismatches, and audit reports for regulators.
End-to-end flow
End-to-end: a buyer's agent signs an intent to purchase a subscription up to $12.99 on a stablecoin rail. Merchant's agent produces an order matching the intent. Authorization holds funds on the rail. On successful fulfillment, capture is issued and settles. Reconciliation matches intent, order, authorization, and capture line items. Ledger records every event. A month later, the buyer disputes a charge; the audit trail shows signed intent + authorization + capture; the dispute is closed in favor of the merchant. If a refund had been legitimate, reversal would have been an equally clean signed event.