Experienced Node.js/Express/Mongodb Developer for Refocus Web App Backend & Role-Based Flows

We are seeking an experienced full-stack or backend developer to finalize and enhance the backend of ReFocus, a digital-wellness web application designed for students. The project involves reviewing, cleaning, and completing the existing backend, implementing robust authentication and authorization, developing core features, and assisting with deployment.

Current Project Status:
Frontend: Built with React + Vite and currently deployed on Vercel, functioning as expected.
Backend: Developed using Node.js, Express, Mongoose, JWT for authentication, and MongoDB Atlas for the database. Basic authentication routes are in place but require completion and bug fixes.
User Roles: The application supports multiple user roles including admin, coach, developer, and standard user, each requiring specific access controls.

Key Responsibilities:
1.  Backend Code Review and Refinement: Thoroughly review the existing backend codebase and API structure to ensure best practices, efficiency, and maintainability.
2.  Authentication and Authorization Finalization: Implement and fix login/registration processes, simplify email/password rules, and establish comprehensive role-based access control to ensure each user role (admin, coach, user) can only access their designated dashboards and pages.
3.  Core Feature Implementation: Complete the development of essential features including user profiles with survey data, a challenges system (CRUD operations and user assignment), and a coach application and approval workflow managed by administrators.
4.  API Endpoint Development: Create any missing API endpoints required by the React frontend to ensure full functionality.
5.  Error Handling and API Consistency: Improve global error handling mechanisms and ensure consistent API response formats across all endpoints.
6.  Frontend Integration: Collaborate to connect the finalized backend with the existing React frontend, making necessary endpoint adjustments.
7.  Testing and Documentation: Develop basic tests for critical functionalities and create a comprehensive README file detailing how to set up and run the project.
8.  Backend Deployment Assistance: Provide support in deploying the backend to a suitable platform (e.g., Render) to ensure seamless integration with the Vercel-hosted frontend.

Required Skills and Experience:
Strong proficiency in Node.js, Express.js, MongoDB, Mongoose, and JWT for secure authentication.
Demonstrated ability to work with and improve existing codebases.
Excellent communication skills and experience with Git/GitHub for version control and collaborative development.
Full-stack development experience is a significant advantage.