Des contributed to the DefinitelyTyped/DefinitelyTyped repository by enhancing the webextension-polyfill TypeScript typings for WebExtension APIs. Over the course of a month, Des focused on improving API typing consistency by introducing Promise<void> return types for several key asynchronous methods. This update aligned the typings with the latest WebExtension definitions, reducing the risk of runtime type errors and enabling safer asynchronous handling for extension developers. The work involved deep knowledge of TypeScript, API development, and web extension architecture, resulting in a merged pull request that improved downstream reliability and provided a smoother developer experience for those relying on DefinitelyTyped typings.