Worked on the openai/codex repository to deliver a CI Runner upgrade aimed at accelerating the Rust CI workflow. The project involved upgrading runner instances to larger, more powerful configurations and updating macOS and Ubuntu runner settings to match the new infrastructure. Custom runner groups and labels were defined for Linux and Windows environments, optimizing build and test parallelism. All changes were implemented using YAML and managed through GitHub Actions, leveraging skills in CI/CD and system administration. This work improved the efficiency of continuous integration processes by reducing build times and streamlining the management of diverse operating system environments.