James Tan focused on improving the reliability of the OCaml build process within the codecrafters-io/build-your-own-redis repository. He addressed a persistent issue where missing system headers in the Docker image caused build-time and runtime errors for OCaml components. By updating the Dockerfile to ensure linux-headers were installed, James enhanced the stability of the containerized development environment. His work involved system administration and Dockerfile scripting, with careful validation through continuous integration pipelines. Although the scope was limited to a single bug fix, the solution demonstrated a solid understanding of containerization and build tooling, directly improving developer productivity and CI robustness.