Worked on improving threading correctness and compatibility in the emscripten-core/emscripten repository, focusing on multi-threaded builds using C++ and Emscripten. Addressed a bug by gating thread-affinity checks behind the __EMSCRIPTEN_PTHREADS__ macro rather than _REENTRANT, ensuring these checks only execute when pthreads are enabled. This approach reduced unnecessary checks in non-pthread configurations, enhancing build reliability across different platforms. Maintained clear traceability to the original commit and related issue for future code reviews. The work demonstrated attention to detail in multi-threading and build configuration, leveraging expertise in C++ development and Emscripten to improve codebase maintainability.