Lumen ✦

Your calm AI companion 🍵

Lumen is a full-stack AI chat application built with the MERN stack. It features per-user authentication, persistent chat history, and a clean aesthetic UI — all containerized with Docker and backed by a CI pipeline.

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Features

• JWT Authentication — secure register, login and logout
• Per-user chat history — your conversations are saved and isolated per account
• AI responses — powered by OpenAI GPT-4o-mini
• Persistent threads — chat history survives across sessions and devices
• Dockerized — run the entire app with one command
• CI Pipeline — every push to main triggers an automated build via GitHub Actions

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Tech Stack

Layer	Technology
Frontend	React, Vite
Backend	Node.js, Express
Database	MongoDB Atlas
Auth	JWT (JSON Web Tokens)
AI	OpenAI API (GPT-4o-mini)
Containerization	Docker, docker-compose
CI/CD	GitHub Actions

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Getting Started

Prerequisites

• Docker and Docker Compose installed
• OpenAI API key
• MongoDB Atlas connection string

Run locally with Docker

1. Clone the repo

git clone https://github.com/Nithu2912/Lumen.git
cd Lumen

2. Create a .env file inside the Backend folder:

OPENAI_API_KEY=your_openai_api_key
MONGODB_URI=your_mongodb_connection_string
JWT_SECRET=your_jwt_secret

3. Run with Docker Compose

docker-compose up --build

4. Open your browser

Frontend: http://localhost:5173
Backend:  http://localhost:8080

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Project Structure

Lumen/
├── Backend/
│   ├── middleware/       # JWT auth middleware
│   ├── models/           # MongoDB schemas (User, Thread)
│   ├── routes/           # API routes (auth, chat)
│   ├── utils/            # OpenAI API integration
│   ├── Dockerfile
│   └── server.js
├── Frontend/
│   ├── src/
│   │   ├── context/      # Auth context
│   │   ├── pages/        # Login, Register
│   │   └── components/   # Sidebar, ChatWindow, Chat
│   └── Dockerfile
├── .github/
│   └── workflows/
│       └── deploy.yml    # GitHub Actions CI pipeline
└── docker-compose.yml

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API Endpoints

Auth

Method	Endpoint	Description
POST	/api/auth/register	Register a new user
POST	/api/auth/login	Login and get JWT token

Chat

Method	Endpoint	Description
POST	/api/chat	Send a message (protected)
GET	/api/thread	Get all threads for current user (protected)
GET	/api/thread/:id	Get messages for a thread (protected)
DELETE	/api/thread/:id	Delete a thread (protected)

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CI/CD Pipeline

Every push to main triggers a GitHub Actions workflow that:

• Installs backend dependencies
• Builds the frontend
• Confirms the app compiles successfully

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Environment Variables

Variable	Description
OPENAI_API_KEY	Your OpenAI API key
MONGODB_URI	MongoDB Atlas connection string
JWT_SECRET	Secret key for signing JWT tokens

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Author

Built by Nithu — from curiosity about OpenAI to a full production-ready stack.

"One thing led to another and I ended up building a full stack AI chat app. No plan. No roadmap. Just curiosity."

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