The Pay-now screen only checked that the typed repay amount was a positive decimal, so a customer could submit more than they owe and receive a raw REPAY_EXCEEDS_DEBT 409 from the server. Cap the typed amount at the quote's maxAmount, disable Confirm, and show an inline hint. MAX is unaffected: it is a mode the server floors to the live debt, not a number typed against the quote.
Co-Authored-By: Claude Opus 4.8 noreply@anthropic.com