Rosie Watson developed two feature enhancements for the RevenueCat/purchases-js repository, focusing on expanding variable flexibility and improving promotional offer controls. She implemented support for number and boolean custom variables using TypeScript and React, enabling more dynamic data handling and laying the foundation for future dashboard integration. Rosie also introduced promo offers visibility overrides, refining the logic that determines promo availability and updating the demo UI to support variable-type configuration. Her work addressed marketing strategy needs by allowing more precise promo targeting and reducing risk in the paywall flow, demonstrating depth in front end development and thoughtful attention to testing.