402fly-core

Core Python implementation of the X402 payment protocol for autonomous AI agent payments.

Overview

The 402fly-core package provides the fundamental building blocks for implementing the X402 payment protocol. This package handles payment processing on the Solana blockchain, including transaction creation, verification, and error handling.

Features

• Payment request and authorization models
• Solana blockchain payment processing
• Comprehensive error handling for payment workflows
• Protocol primitives and data structures
• Transaction verification and validation

Installation

pip install 402fly-core

Core Components

Payment Models

from 402fly_core import PaymentRequest, PaymentAuthorization

# PaymentRequest: Represents a payment requirement
# PaymentAuthorization: Represents completed payment details

Payment Processor

from 402fly_core import SolanaPaymentProcessor
from solders.keypair import Keypair

# Initialize payment processor
keypair = Keypair()  # Your wallet keypair
processor = SolanaPaymentProcessor(
    wallet_keypair=keypair,
    rpc_url="https://api.devnet.solana.com"
)

# Process payments (typically used by higher-level packages)

Error Handling

from 402fly_core import (
    Fly402Error,
    PaymentRequiredError,
    PaymentExpiredError,
    InsufficientFundsError,
    PaymentVerificationError,
    TransactionBroadcastError,
    InvalidPaymentRequestError,
)

try:
    # Payment operations
    pass
except PaymentRequiredError as e:
    print(f"Payment required: {e}")
except InsufficientFundsError as e:
    print(f"Insufficient funds: {e}")

Usage

This package is typically used as a dependency by higher-level packages like:

• 402fly-client: HTTP client with automatic payment handling
• 402fly-fastapi: FastAPI middleware for payment-required endpoints
• 402fly-langchain: LangChain agent integration
• 402fly-langgraph: LangGraph workflow integration

For most use cases, you'll want to use one of these higher-level packages rather than using 402fly-core directly.

Documentation

For complete API reference and guides, see:

• Documentation
• GitHub Repository

Testing

pytest tests/

License

MIT License - See LICENSE file for details.