During June 2025, work centered on enhancing cookie management in the mozilla/gecko-dev repository by developing comprehensive Web Platform CookieStore Domain Parsing Tests. This effort focused on validating the behavior of cookieStore.set across various host types, including IDNA, IP addresses, and mixed-case domains, to ensure accurate domain parsing and robust cross-domain cookie handling. Using JavaScript and HTML, the developer expanded Web Platform Testing coverage, introducing tests with the testonly flag to prevent regressions. Although no high-severity bugs were addressed, the contribution improved the reliability and maintainability of cookie handling logic, supporting long-term stability in web platform implementations.