initiate a payment via TrueLayer Payments (PIS)

Steps

1. Enable the payments product in the TrueLayer Console and ensure your application has the payments scope; obtain a client_credentials access token by posting to the token endpoint with grant_type=client_credentials.
2. Create a payment by POSTing to the payments API endpoint with a JSON body specifying amount_in_minor (pence/cents), currency, payment_method (bank_transfer), beneficiary details (account number and sort code or IBAN), and a unique idempotency_key header.
3. Receive the payment_id and a resource_token from the creation response; use the resource_token (not your main access token) to initialise the TrueLayer Payments hosted UI or direct payment flow.
4. Redirect or embed the TrueLayer hosted payment page passing the resource_token so the user can select their bank and authorise the payment via SCA.
5. After the user completes authorisation, they are redirected to your return_uri; retrieve the final payment status by polling GET /payments/{payment_id} using your client_credentials token until status is 'executed' or a terminal failure state.
6. Subscribe to payment webhooks to receive asynchronous status updates (e.g., authorized, executed, failed) rather than relying solely on polling.