Worked on the nestjs/nest repository to enhance backend development workflows by introducing reactive streaming capabilities and improving development experience. Implemented a change to GrpcStreamMethod so that local gRPC calls now return an Observable, aligning with reactive programming patterns and enabling more flexible streaming. Improved the robustness of file-type validation by refining module resolution logic, ensuring compatibility with legacy Node.js environments. Added Hot Module Replacement support to an ES Module-based NestJS example, allowing live updates during development without full reloads. These contributions leveraged TypeScript, Node.js, and Webpack, focusing on runtime reliability, developer experience, and maintainability of core NestJS features.