Worked on the opensafely-core/airlock repository to enhance the developer onboarding process and improve test reliability. Focused on updating the developer setup documentation using Markdown, adding explicit commands for frontend asset setup and documentation building. Clarified that tests require a clean checkout, addressing common setup errors and reducing friction for new contributors. Resolved issues with test prerequisites by fixing extra requirements that previously hindered test execution on fresh checkouts. The work emphasized developer setup and documentation skills, resulting in clearer onboarding instructions and more predictable test outcomes. These improvements support safer, faster contributions and a more maintainable development workflow for the project.