3D Secure Multi-card Payment

Run the normal 3D Secure initiation, verification, and completion flow separately for every card. Initiate each payment with POST /payment/v1/card-payments/3ds-init and use the same conversationId for all cards in the order.

All current 3D request fields remain valid. Set paymentPhase to PRE_AUTH, paymentType to MULTI_CARD_PAYMENT, and paymentOrder to the card's sequence number. Set paidPrice to the amount charged to the current card.

Complete each card's 3D flow through /3ds-verify and /3ds-complete. After every pre-authorization succeeds, close the grouped authorization through the multi-card post-authorization endpoint.