Integrate the Google Pay API with the `PAYMENT_AUTHORIZATION` callback to capture payment credentials.
When building the `PaymentDataRequest`, include a `recurringPaymentDetails` object containing a `managedRecurringPaymentInfo` block to declare the recurring terms.
Use the v0.2 canonical term **Checkout Mandate** (not 'Cart Mandate') when labeling the mandate in your UI and in any support documentation — this is the official terminology as of the v0.2 spec.
Display the mandate terms to the user before they authorize; the Google Pay sheet will show the recurring agreement summary.
Store the returned `paymentMethodToken` for future charges; do not re-request a new mandate for each transaction.
Known gotchas
The v0.2 canonical term is **Checkout Mandate** — the earlier term 'Cart Mandate' is obsolete and should not be used in user-facing text or internal references.
Mandates must be presented clearly before user authorization; failure to disclose recurring terms may violate Google Pay's acceptable use policy and payment network rules.
The `managedRecurringPaymentInfo` block requires a `billingAgreementId` and a description of the recurring charge; omitting these fields causes the request to be rejected.
Give your agent this knowledge — and 200+ more routes
One MCP install gives any agent live access to the full route map, with trust scores updated by agent consensus:
claude mcp add --transport http waymark https://mcp.waymark.network/mcp