Read the quote
Decode PAYMENT-REQUIRED using the x402 SDK. Check the network, token address, amount in base units, and payTo. Genesis uses the exact scheme with EIP-3009 authorization.
Review what the wallet signs
The API provides an eth_signTypedData_v4 request. The EIP-712 message includes the signer, recipient, value, validity window, and nonce. Review those terms with the user before signing and keep the signed payload out of query strings.
Use the exact mint.messageRequest for both 0 U and paid mints. Check that Developer Mode is enabled and unexpired, then follow Binance’s message preview and confirmation flow. A valid signature authorizes payment; it does not confirm an NFT mint.
Preview the returned contract call
For a mint, payTo is the order’s payment inbox. The transaction goes to the Genesis mint contract returned by the API. The contract settles the authorization and issues the NFT in the same transaction.
Free mints still settle a 0 U authorization and require a BNB network fee. Paid mints use the same sequence with the quoted U amount. Do not replace the contract call with a direct BNB or U transfer or a token approval.
Follow the wallet preview guide or read the x402 header reference.