Joon S. Lee developed foundational z/OS compatibility for the gitlabhq/gitlab-runner repository, focusing on enabling cross-platform builds for enterprise CI environments. He updated build constraints, introduced z/OS-specific logic, and adjusted file operations to support mainframe systems, all implemented in Go with a backend development focus. The work addressed the technical challenge of expanding GitLab Runner’s platform support, laying the groundwork for future mainframe integration. While two dependencies remain to be updated for full build readiness, Joon’s contributions established a robust starting point for z/OS support, reducing future rework and aligning the project with evolving enterprise infrastructure needs.