Worked on the grafana/k6-DefinitelyTyped repository to deliver stricter TypeScript validation for OrderFormMarketingData, focusing on improving data integrity and analytics reliability in order forms. The approach involved tightening type definitions to require essential marketing properties, converting UTM fields to non-nullable types, and defining marketingTags as a string array. These changes, implemented and merged as a breaking change, enhanced type safety and reduced the risk of runtime data gaps. Leveraging TypeScript and API development skills, the work improved the quality of marketing data, supporting more reliable attribution and downstream analytics while demonstrating strong code-quality and collaborative development practices.