Heejong contributed to the semgrep/semgrep-interfaces and semgrep/semgrep-rules repositories, focusing on schema enhancements and security rule validation. In semgrep-interfaces, Heejong implemented fully qualified name fields in the rule schema using OCaml and YAML, enabling more precise rule identification while maintaining backward compatibility for legacy CLI consumers. For semgrep-rules, Heejong strengthened the No-Auth-Over-HTTP security rule by updating tests and standardizing rule ID comments, using Python to improve test coverage and maintainability. The work demonstrated careful attention to data modeling, schema definition, and security analysis, addressing both feature development and bug fixes with a focus on long-term maintainability.