Mark Carroll focused on improving API clarity and test infrastructure across the goat-sdk/goat and Zilliqa/zq2 repositories. He streamlined the PlunderSwap API by removing an unused toAddress parameter, reducing complexity and potential confusion for developers integrating swap operations. In Zilliqa/zq2, Mark introduced a gas exemption address within the chain specification, enabling cost-free legacy ERC-20 interoperability testing in non-production environments. His work leveraged TypeScript, Rust, and configuration management skills to enhance cross-repository collaboration and testing readiness. These targeted changes reduced the API surface area, lowered integration risk, and accelerated quality assurance workflows, reflecting a thoughtful and pragmatic engineering approach.