In February 2026, Thomas Gies enhanced the DefinitelyTyped/DefinitelyTyped repository by updating TypeScript type definitions for TLS certificates. He widened the distinguished name (DN) fields in the Certificate interface to accept either a string or an array of strings, addressing the need for greater flexibility in TLS typing. This work involved modifying both the type definitions and associated tests, ensuring safer downstream usage and improved developer experience. Using TypeScript and Node.js, Thomas collaborated through code review and the pull request workflow, contributing to the maintainability and quality of core type definitions. The work demonstrated focused depth within type system improvements.