ChatForge 🤖

An AI-powered conversational platform built with TypeScript and Express, featuring Google Gemini, LangChain, PostgreSQL, Redis, authentication, chat history, rate limiting, and automatic conversation summarization.

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🔋 Features

• 🔐 Authentication & Authorization — JWT authentication with bcrypt password hashing, HTTP-only cookies, and Redis-based JWT blocklisting.
• 🤖 AI Integration — Google Gemini API through LangChain.
• 💬 Chat System — Create chats, send messages, and retrieve chat history.
• 🗄️ PostgreSQL — Stores users, chats, messages, summaries, and lifetime token usage.
• ⚡ Redis — Token-window usage tracking, rate limiting, and JWT blocklisting.
• 📊 Token Tracking — Tracks token usage for users and individual chats.
• ⏱️ Token Limits — Configurable token limits with automatic time-based reset using Redis.
• 📝 Chat Summarization — Automatically summarizes conversations to maintain useful context.
• 🚦 Rate Limiting — Separate rate limiting for authenticated and unauthenticated requests.
• ✅ Validation & Security — Zod validation, Helmet, CORS, and structured logging.

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⚙️ Tech Stack

Backend

• Bun
• Express.js
• TypeScript
• LangChain

AI

• Google Gemini

Database & Infrastructure

• PostgreSQL
• Redis
• Docker & Docker Compose

Authentication & Security

• JWT
• bcrypt
• Zod
• Helmet
• CORS

Other

• Pino
• dotenv

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📊 Token Usage

ChatForge uses Redis for temporary token-window usage and PostgreSQL for lifetime usage.

Redis
└── Current token window
    └── TOKEN_LIMIT
        └── TOKEN_WINDOW_SECONDS

PostgreSQL
└── total_token_used
    └── Lifetime usage

Example configuration:

TOKEN_LIMIT=10000
TOKEN_WINDOW_SECONDS=18000

This allows 10,000 tokens per 5-hour window.

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🗄️ Database Schema

                     USERS
     +-------------------------------+
     | id                            |
     | name                          |
     | age                           |
     | email                         |
     | password                      |
     | total_token_used              |
     | created_at                    |
     | updated_at                    |
     +---------------+---------------+
                     |
                     | 1
                     |
                     | N
                     ▼
                     CHATS
     +-------------------------------+
     | id                            |
     | user_id                       |
     | topic                         |
     | model                         |
     | summary                       |
     | summarized_till_message_number|
     | message_count                 |
     | prompt_tokens                 |
     | completion_tokens             |
     | total_tokens                  |
     | created_at                    |
     | updated_at                    |
     +---------------+---------------+
                     |
                     | 1
                     |
                     | N
                     ▼
                  MESSAGES
     +-------------------------------+
     | id                            |
     | user_id                       |
     | chat_id                       |
     | role                          |
     | content                       |
     | tokens                        |
     | prompt_tokens                 |
     | completion_tokens              |
     | total_tokens                  |
     | created_at                    |
     | updated_at                    |
     +-------------------------------+

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🔗 Database Relationships

1. One User → Many Chats

Each user can create multiple chat sessions.

Example

User
├── Chat 1 (Recursion)
├── Chat 2 (Linked List)
└── Chat 3 (Operating System)

Relationship:

User (1)
    │
    └──────────< Chats (N)

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2. One Chat → Many Messages

Every chat contains multiple messages exchanged between the user and the AI.

Example

Chat

├── User : Explain recursion
├── AI   : Recursion is...
├── User : Give me an example
└── AI   : Sure...

Relationship:

Chat (1)
    │
    └──────────< Messages (N)

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3. One User → Many Messages

Although every message belongs to a chat, storing the user_id in the messages table allows efficient retrieval of messages belonging to a specific user without requiring an additional join with the chats table.

Relationship:

User (1)
    │
    └──────────< Messages (N)

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⚡ Database Indexes

Chats

Optimizes retrieval of a user's most recently updated chats.

CREATE INDEX idx_chats_user_updated
ON chats(user_id, updated_at DESC);

Messages — Chat History

Optimizes loading messages from a specific chat in chronological order.

CREATE INDEX idx_messages_chat_created
ON messages(chat_id, created_at);

Messages — User History

Optimizes retrieval of messages belonging to a specific user.

CREATE INDEX idx_messages_user_created
ON messages(user_id, created_at DESC);

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🐳 Installation

1. Clone the Repository

git clone https://github.com/soumadip-dev/ChatForge.git

cd ChatForge

2. Install Dependencies

bun install

3. Start PostgreSQL & Redis

docker compose up -d --build

4. Configure Environment Variables

Create a .env file:

PORT=8080
NODE_ENV=development

DATABASE_URL=<your-postgresql-url>

LOG_LEVEL=info
CORS_ORIGINS=<your-frontend-url>

JWT_SECRET=<your-jwt-secret>
JWT_ACCESS_EXPIRES_IN=1h

GEMINI_API_KEY=<your-gemini-api-key>
REDIS_URL=<your-redis-url>

TOKEN_LIMIT=10000
TOKEN_WINDOW_SECONDS=18000

5. Run Migrations

bun run migrate

6. Start Development Server

bun run dev

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📜 Available Scripts

bun run dev       # Start development server
bun run migrate   # Run database migrations
bun run build     # Build production bundle
bun run start     # Start production server

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👨‍💻 Author

Soumadip Majila