Developed and delivered a feature for the picnixz/cpython repository that enables custom HTTP response headers in Python’s built-in http.server module. Focused on backend development and HTTP server management, the work introduced a --header command-line option, allowing users to specify additional headers for cookies, metadata, and client-specific behavior. The implementation involved updating request handling logic to ensure consistent application of custom headers across all response paths, with careful attention to avoiding regressions. Documentation was expanded to include usage examples and security considerations. Collaboration with other contributors strengthened code review and test coverage, laying groundwork for broader header-driven integration scenarios.