September 2025: Delivered substantial improvements to JSON parsing reliability and test coverage across ruby/json and ruby/ruby. Key features include JSON parsing enhancements with on_load callbacks using proc and clarified usage in JSON.load/JSON.unsafe_load, plus expanded test coverage that enables branch coverage and enforces full file tracking. Major bugs fixed include NoMethodError when a proc is passed to JSON.unsafe_load, supported by new tests and updated documentation. The impact is higher runtime reliability for data handling, more actionable test metrics, and clearer guidance for developers, enabling faster, safer changes in critical JSON workflows. Technologies demonstrated: Ruby, JSON parsing internals, test coverage tooling (branch coverage, full-file tracking), documentation practices, and cross-repo collaboration.