Real-Time Chat & Calls Integration

We have a Simple Social Networking website like Facebook. The Website is built on MERN stack.

Core features I expect:
• Text messaging with live delivery and read receipts
• File sharing for images, docs, and short media clips
• Rich emojis and reactions so users can respond instantly
• Group chat rooms that scale smoothly
• One-to-one and group audio calls
• One-to-one and group video calls, all browser-to-browser & to our mobile app that is built on Flutter

The stack is React, Node, Express, MongoDB & Nextjs.. You’re free to use Socket.io, WebRTC, Getstream or any comparable open-source technology to keep latency low and quality high, but the final code must remain in JavaScript/TypeScript and fit the existing folder structure.

Deliverables
1. Clean, modular backend services for chat and calls
2. React components/hooks for the UI, styled to match the current site
3. A concise setup guide plus comments inside the codebase
4. Short test script or demo page showing all features in action

I already handle user auth with JWT, so your module should authenticate sockets against that token. Everything must be responsive, work in the latest Chrome, Firefox, and Edge, Mobile browser and degrade quality gracefully on slower networks to maintain the latency.

Thank you.