Andrew Cheng focused on improving zero-knowledge proof verification across multiple repositories, including risc0/risc0-ethereum and hyperledger/besu. He addressed three critical bugs by aligning Groth16 verifier input handling with snarkjs, refining input validation, and standardizing error handling. Working primarily in Solidity and Java, Andrew removed unnecessary public signal checks in smart contracts to prevent memory access errors and ensure compatibility with external libraries. He also refactored error code usage in Java APIs to enhance maintainability and reduce risk. His work emphasized correctness, interoperability, and long-term maintainability, demonstrating depth in API development, smart contract engineering, and zero-knowledge proof systems.