The ServerCompletionCallback the provider's completionEndpoint derives:
POST { sessionRef, clientToken, billingDetails? } to the host route that
mounts @payfanout/server's createCompletionHandler, and resolve with the
returned PaymentInfo. A non-2xx response is rebuilt into a PayFanoutError
so the error code/message/retryable survive the wire and drive the UI
(localizeError, retry affordances). Exported so hosts writing a custom
transport can reuse the exact contract.
The ServerCompletionCallback the provider's
completionEndpointderives: POST{ sessionRef, clientToken, billingDetails? }to the host route that mounts @payfanout/server'screateCompletionHandler, and resolve with the returnedPaymentInfo. A non-2xx response is rebuilt into aPayFanoutErrorso the errorcode/message/retryablesurvive the wire and drive the UI (localizeError, retry affordances). Exported so hosts writing a custom transport can reuse the exact contract.