Worked on core enhancements in both the puma/puma and ruby/ruby repositories, focusing on system programming and concurrency in Ruby. Delivered a lightweight feature for puma/puma that introduced an environment variable to disable SIGUSR2 signal trapping, improving compatibility with Java Flight Recorder and deployment flexibility. This change included automated testing to ensure correct signal handler behavior. In ruby/ruby, contributed a dedicated test to verify Ractor-safe access to RbConfig constants, confirming integer values and proper concurrent handling. Emphasized robust testing and configuration management throughout, with all changes designed to minimize risk and reinforce correctness in production environments using Ruby.