The 402 quote points at an escrow account instead of the seller's, so paying does not hand the money over. You get the answer straight away and the payment stays put until you decide.
Approve it and the seller gets paid. If it was not what you asked for, reject it and the money comes back to you.
And if you never come back at all, the clock runs out and the seller gets paid anyway. That part is deliberate: without it a buyer could read the answer, go quiet, and keep the money, which is not a market anyone would sell into.
payTo pointing at escrow rather than the seller.
integrate
/invariants
Thirteen properties the money depends on, how each is enforced, and the two that broke.
what can go wrong