June 2025 monthly summary for mozilla/gecko-dev: Focused on strengthening the robustness of the Compression Dictionary Transport by expanding test coverage and validating edge-case scenarios. Delivered new Web Platform Tests covering expired dictionaries, compressed dictionary responses, and the interaction of vary headers with dictionary usage. This work reduces regression risk in the transport path and improves CI signal for correctness under edge conditions. The effort aligns with Bug 1972052 and includes a test-only commit to enhance WPT coverage (commit d747ae7a756f36e198d7d0904877167d084cdc). Overall impact: higher reliability of the transport mechanism, faster regression detection, and clearer groundwork for further optimizations. Technologies/skills demonstrated include Web Platform Tests, regression testing, edge-case validation, and cross-functional collaboration in the gecko-dev repo.