The mandate records what the customer allowed. Checkout checks whether the actual merchant offer fits that authority. Payment adds the limits that the chosen instrument and provider can enforce. If the records disagree, the agent should pause the purchase and present the valid offer again.
What happens when the suitcase costs €230?
The customer approved up to €180 including shipping. The suitcase now comes to €230 with delivery. Checkout checks the total, currency and offer against the approval. The earlier approval does not cover this purchase. A payment that could technically go through changes nothing about that authority. The agent can look for an offer within budget or ask the customer to approve €230 explicitly.
Which checks belong in the flow?
Record the task, valid offer, payment approval and confirmation so the purchase can be found across the systems involved. A shared reference helps reconcile those records. Each responsible system still needs to verify the authority for its own step. AP2 distinguishes checkout and payment mandates. The merchant needs to check what its chosen payment integration can enforce.
Test three cases from the same starting point: shipping gets more expensive, the currency changes or payment confirmation is missing after a timeout. In the third case, check the existing status before attempting another payment.