nethermindeth/aztec-fpc

This project implements FPC (Fee Payment Contract), a system for operators to collect transaction fees directly in tokens on Aztec L2 via private transfers. It consists of a Noir smart contract (`FPCMultiAsset`) and two TypeScript services: an attestation service that signs fee quotes and a top-up service that manages L1->L2 bridge operations for the operator's balance. The system enables fully private fee payment flows where users transfer tokens directly to operators as payment for transaction fees, with configurable rate limiting and security features for production deployment.