Worked on integrating Regression Test Selection (RTS) into the denoland/chromium_build repository, focusing on enhancing build rules and test automation workflows. Used Python scripting and GN build system configuration to reintroduce RTS support, enabling more efficient test selection based on historical data. Developed a use_rts flag that conditionally generates dummy filter files, preventing test runner failures when RTS data is unavailable and reducing CI noise. The approach streamlined the build process and aligned with RTS-driven optimization goals. Demonstrated depth in build system configuration, scripting, and test automation, delivering a targeted tooling improvement that supports more reliable and efficient continuous integration feedback.