LangChain Agent Example

Example LangChain agent with autonomous X402 payment capabilities.

Setup

1. Install dependencies:

   pip install -r requirements.txt
   

2. Set OpenAI API key:

   export OPENAI_API_KEY='your-key-here'
   

3. Create and fund wallet:

   # Run the script once to generate wallet
   python main.py
   
   # Fund the wallet with SOL (for transaction fees)
   solana airdrop 1 YOUR_WALLET_ADDRESS --url devnet
   
   # You'll also need USDC on devnet for payments
   # Use a faucet or swap service
   

4. Start the FastAPI server (in another terminal):

   cd ../fastapi-server
   python main.py
   

5. Run the agent examples:

   python main.py
   

What it does

The examples demonstrate three scenarios:

Example 1: Simple Agent

Creates an agent using the convenience function that can autonomously detect and pay for 402 responses.

Example 2: Custom Tools

Shows how to combine X402 payment capabilities with other LangChain tools.

Example 3: Multi-API

Demonstrates an agent making multiple payments to different APIs in a single workflow.

Key Features

• Autonomous Payments: Agent detects 402 responses and pays automatically
• Safety Limits: max_payment parameter prevents overspending
• Transparent: Verbose mode shows payment decisions
• Flexible: Works with any X402-enabled API