During June 2025, hta contributed to the mozilla/gecko-dev repository by developing foundational tests for WebRTC header extension exposure in RTCRtpSender and RTCRtpReceiver. Using JavaScript and leveraging WebRTC APIs, hta implemented an end-to-end test flow that validated the presence of header extensions in getParameters after the offer/answer exchange and confirmed their absence beforehand. This work established baseline coverage for WebRTC parameter exposure, addressing regression safety and enabling faster validation of future changes. The tests, while rudimentary, strengthened the test suite’s reliability and provided essential groundwork for ongoing improvements in WebRTC feature validation and JavaScript-based testing practices.