Arhelmus focused on maintaining codebase integrity and build reliability for the facebook/react-native and mrousavy/hermes repositories. During May 2025, he addressed two subtle but impactful bugs by reverting changes that had removed redundant semicolons in the jsi.h header, restoring correct C++ syntax for template function closing braces. This careful code reversion and refactoring work in C++ ensured that both repositories maintained consistent syntax, preventing potential compile-time issues and reducing risk in downstream builds. Arhelmus’s contributions improved cross-repo stability and made future maintenance easier, demonstrating a methodical approach to code quality and reliability in large-scale C++ development environments.