Web Development

The "Secure-by-Design" Challenge
Prompt:

"Act as a Senior Full-Stack Architect and Security Engineer. I need to build a real-time collaborative markdown editor using the MERN stack and Socket.io.

Please provide:

Architecture Design: A high-level overview of how the frontend and backend should handle concurrent edits without data loss.

Security Audit: Identify the top 3 specific vulnerabilities (e.g., XSS, NoSQL Injection, or WebSocket hijacking) this app might face and provide the exact code snippets (Express/Node) to mitigate them.

Authentication: Explain how to implement a secure JWT rotation strategy to ensure user sessions remain safe even if a token is intercepted