During June 2025, Cao Doan focused on stabilizing the React Native iOS build pipeline in the facebook/react-native repository, addressing compatibility issues with Xcode 26. By replacing deprecated tgmath.h headers with cmath and adding missing string imports, Cao resolved a persistent build failure that had blocked CI reliability and delayed Xcode upgrades for iOS projects. This targeted bug fix, implemented using C++ and Objective-C++, improved cross-language header management and ensured smoother integration with evolving toolchains. The work demonstrated careful attention to build hygiene and contributed to a more robust development environment, supporting ongoing productivity for the React Native iOS community.