The JIT card model, specified

A card that an agent can use is a card that an attacker can try to use. The just in time model is our answer: at rest, every agent card is frozen with a limit of zero. Even if the card number leaks, there is nothing to charge against.

When an agent requests a payment and the request passes the mandate, the engine unlocks the card for exactly that amount, plus a small tolerance for currency rounding. The moment the charge lands, or a short timeout passes, the card returns to zero. The window of exposure is measured in seconds, and its size is measured in the price of the thing being bought.

Ramp and Privacy.com proved this pattern in the US at scale. Our contribution is wiring it to mandates under PSD2: the human authorises the rules once via strong customer authentication, and the JIT release is simply the mandate executing itself. Nothing to re approve, nothing left open.