EVM V1 Implementation

This package contains the V1 implementation of the EVM mechanism for x402.

Key Differences from V2

1. Version Support: Only supports x402 version 1 (v2 supports version 2)

2. ValidAfter Buffer: V1 subtracts 10 minutes from the current time for validAfter to ensure the transaction is immediately valid. V2 uses the current time directly.

3. Default Validity Window: V1 uses a 10-minute window by default, V2 uses 1 hour.

4. Price Parsing: V1 has simpler price parsing logic, defaulting to USDC for the network.

Usage

import (
    x402 "github.com/coinbase/x402/go"
    evmv1 "github.com/coinbase/x402/go/mechanisms/evm/exact/v1"
)

// Register V1 client
client := x402.Newx402Client()
client = evmv1.RegisterClient(client, signer)

// Register V1 facilitator  
facilitator := x402.Newx402Facilitator()
facilitator = evmv1.RegisterFacilitator(facilitator, signer)

// Register V1 server
server := x402.Newx402ResourceServer(
    evmv1.RegisterServer(),
)

Migration to V2

To migrate from V1 to V2:

1. Update x402 version in payment requirements from 1 to 2
2. Remove any custom validAfter buffer logic (V2 handles this)
3. Update imports from evm/v1 to evm
4. Test thoroughly, especially around timing windows

Compatibility

V1 is maintained for backward compatibility with existing integrations. New implementations should use V2 (the parent evm package).