Nexus AI (Full Project)

Full-stack AI chat application with authentication, chat sessions, realtime assistant messages, mobile-friendly UI, and dynamic prompt suggestions.

Project Structure

New Chat AI/
  Backend/    # Express + MongoDB + Socket.IO API
  frontend/   # React + Vite client

Tech Stack

Frontend:

• React 19 + TypeScript
• Vite
• Redux Toolkit
• Tailwind CSS
• Socket.IO Client

Backend:

• Node.js + Express
• MongoDB + Mongoose
• JWT auth (access/refresh)
• Socket.IO
• OpenRouter API integration

Features

• Register/login/logout with protected routes
• Persistent chat sessions and message history
• AI response generation via backend
• Realtime assistant delivery through Socket.IO
• Session token usage indicator
• News-powered prompt suggestions
• Mobile-optimized chat interface

Prerequisites

• Node.js 18+
• npm 9+
• MongoDB database
• OpenRouter API key
• NewsData API key (for suggestion cards)

1. Backend Setup

cd Backend
npm install

Create env file:

• Copy Backend/.env.example to Backend/.env
• Fill real values

Required backend env keys:

PORT=4000
NODE_ENV=development
MONGO_URI=mongodb://127.0.0.1:27017/nexus_ai
JWT_SECRET=replace_with_strong_secret
FRONTEND_ORIGIN=http://localhost:5173
OPENROUTER_API_KEY=your_openrouter_api_key
OPENROUTER_MODEL=gpt-4o-mini
OPENROUTER_API_URL=https://openrouter.ai/api/v1/chat/completions

Run backend:

npm run dev

Backend default URL: http://localhost:4000

2. Frontend Setup

cd ../frontend
npm install

Create env file:

• Copy frontend/.env.example to frontend/.env
• Fill real values

Required frontend env keys:

VITE_API_BASE_URL=http://localhost:4000/api/v1
VITE_SOCKET_URL=http://localhost:4000
VITE_NEWSDATA_API_KEY=your_newsdata_api_key

Run frontend:

npm run dev

Frontend default URL: http://localhost:5173

API Overview

Base path: /api/v1

Auth:

• POST /auth/register
• POST /auth/login
• POST /auth/refresh
• POST /auth/logout
• GET /auth/me

Chat:

• GET /chat/sessions
• POST /chat/messages
• GET /chat/:id
• DELETE /chat/session/:id

AI:

• POST /ai/ask (auth required)

Realtime

• Backend emits newMessage events via Socket.IO.
• Assistant responses are persisted to chat session when sessionId is provided.

Prompt Suggestions Source

Dashboard suggestions use NewsData directly from frontend:

• Endpoint: https://newsdata.io/api/1/latest
• Filters:
  • country=in,cn,au,wo
  • language=ta,en,ml
  • category=technology,education,food,health,lifestyle

Development Commands

Backend (Backend folder):

• npm run dev
• npm start

Frontend (frontend folder):

• npm run dev
• npm run build
• npm run preview
• npm run lint

Security Notes

• Do not commit .env files with real secrets.
• Rotate secrets immediately if they are ever exposed.
• Keep only placeholder values in *.env.example.

Additional Docs

• Backend details: Backend/README.md
• Frontend details: frontend/README.md