Zequan Wu focused on improving build reliability and code quality across several repositories, including denoland/chromium_build, google/swiftshader, and espressif/llvm-project. He addressed compiler warnings and removed obsolete workarounds in C and C++ code, streamlining build system configurations and reducing CI noise without altering core functionality. In the llvm-project, Zequan reverted a LoopVectorizer optimization to prevent crashes at -O2 and enhanced test robustness by relaxing sanitizer library checks, ensuring more stable releases. His work demonstrated depth in debugging, compiler development, and code refactoring, prioritizing maintainability and predictable builds through targeted bug fixes and thoughtful code analysis.