Worked on the facebook/pyre-check repository to address a bug in the Pyre Type Checker’s diagnostic error reporting. Focused on replacing generic placeholder codes with specific error names and numeric identifiers, the update enhanced clarity for both developers and downstream tools. The solution involved careful code refactoring and static analysis within a Python codebase, ensuring that error handling was both precise and maintainable. Changes were validated through regression testing and integrated following a disciplined code review process. This targeted improvement reduced debugging time, increased the reliability of diagnostics, and supported smoother integration with external tooling, contributing to overall developer productivity.