Worked on backend stability in the upstash/workflow-js repository, focusing on resolving a compatibility issue between Fastify examples and the QStash development server. Addressed a bug where missing HTTP headers prevented seamless integration by implementing logic to iterate over and forward all necessary headers from the web response to the Fastify reply. This solution restored end-to-end compatibility, improving the developer experience and enabling more reliable local development and integration testing. Utilized TypeScript and Node.js to enhance API integration workflows, demonstrating attention to maintainability and robust cross-service communication in backend systems. The work reduced support overhead and improved code quality.