People and agents on Celo sign payment links and transfer calls they cannot read. A link that says 10 USDC can encode 10e18 units, point at a fee adapter instead of the token, or use another chain's id. Vigía reads the transaction, compares it with what the payer expects, and returns ok or "don't sign it" with a reason code. Agents call POST /api/check and pay 0.01 per check through x402, in USDC, USD₮ or USA₮, settled by Celo's facilitator. People open /pay?link=... in MiniPay or a browser, see the verdict, and only get a Pay button when the check passes; it signs from the person's own wallet, pays gas in the stablecoin through fee abstraction and carries our attribution tag.
