During March 2026, Alex Carroll developed support for Sandbox SDK preview URLs and WebSocket routing for Hot Module Replacement (HMR) in the Cloudflare Vite plugin within the cloudflare/workers-sdk repository. Using TypeScript and Node.js, Alex ensured that WebSocket requests are correctly forwarded while preserving the original request origin, which is essential for maintaining HMR fidelity in development environments. This feature improved the reliability of the dev-server and enhanced preview testing workflows for Cloudflare Workers SDK users. Alex’s work focused on full stack development and testing, addressing the need for stable, sandboxed development experiences without introducing new bug fixes.