Crate r402_evm 

EIP-155 (EVM) chain support for the x402 payment protocol.

This crate provides implementations of the x402 payment protocol for EVM chains with the “exact” payment scheme based on ERC-3009 transferWithAuthorization.

Features

• CAIP-2 Addressing: Uses CAIP-2 chain IDs (e.g., eip155:8453) for chain identification
• ERC-3009 Payments: Gasless token transfers using transferWithAuthorization
• Smart Wallet Support: EIP-1271 for deployed wallets, EIP-6492 for counterfactual wallets
• Multiple Signers: Round-robin signer selection for load distribution
• Nonce Management: Automatic nonce tracking with pending transaction awareness

Architecture

The crate is organized into several modules:

• chain - Core EVM chain types, providers, and configuration
• signer / permit2 / asset / signature - primitives shared by every scheme
• exact - EIP-155 “exact” payment scheme
• upto - EIP-155 “upto” payment scheme (Permit2, usage-based)
• auth_capture - authorize / capture / charge (commerce-payments escrow)
• batch_settlement - capital-backed channel vouchers

Feature Flags

• server - Server-side price tag generation
• client - Client-side payment signing
• facilitator - Facilitator-side payment verification and settlement
• telemetry - OpenTelemetry tracing support

Re-exports

pub use error::Eip155ExactError;facilitator

pub use asset::AssetTransferMethod;

pub use asset::VALIDATOR_ADDRESS;

pub use auth_capture::Eip155AuthCapture;

pub use auth_capture::Eip155AuthCaptureFacilitator;facilitator

pub use auth_capture::Eip155AuthCaptureClient;client

pub use auth_capture::sign_auth_capture;client

pub use batch_settlement::Eip155BatchSettlement;

pub use batch_settlement::ChannelStore;facilitator

pub use batch_settlement::Eip155BatchSettlementFacilitator;facilitator

pub use batch_settlement::MemoryChannelStore;facilitator

pub use batch_settlement::compute_channel_id;facilitator

pub use batch_settlement::Eip155BatchSettlementClient;client

pub use batch_settlement::sign_voucher;client

pub use batch_settlement::sign_voucher_payload;client

pub use eip2612::EIP2612_GAS_SPONSORING_KEY;

pub use eip2612::EIP2612_GAS_SPONSORING_VERSION;

pub use eip2612::Eip2612ParseError;

pub use eip2612::Eip2612SignedPermit;

pub use erc20_approval::ERC20_APPROVAL_GAS_SPONSORING_KEY;

pub use erc20_approval::ERC20_APPROVAL_GAS_SPONSORING_VERSION;

pub use erc20_approval::Erc20ApprovalGasSponsoringInfo;

pub use erc20_approval::Erc20ApprovalParseError;

pub use exact::Eip155Exact;

pub use exact::client::Eip155ExactClient;client

pub use exact::client::Eip155ExactClientBuilder;client

pub use permit2::PERMIT2_ADDRESS;

pub use permit2::Permit2TokenPermissions;

pub use permit2::Permit2Approver;client

pub use permit2::permit2_allowance_calldata;client

pub use permit2::permit2_approval_calldata;client

pub use signature::StructuredSignatureFormatError;facilitator

pub use signer::SignerLike;client

pub use upto::Eip155Upto;

pub use upto::client::Eip155UptoClient;client

pub use upto::client::Eip2612SigningParams;client

pub use upto::client::sign_eip2612_permit;client

Modules

asset

Shared EVM transfer-method and validator constants.

auth_capture

EIP-155 auth-capture scheme (Base commerce-payments escrow).

batch_settlement

EIP-155 batch-settlement scheme (request-path voucher accounting).

chain

EVM chain support for x402 payments via EIP-155.

eip2612

EIP-2612 gas-sponsoring extension wire types (exact + upto).

erc20_approval

erc20ApprovalGasSponsoring extension wire types.

errorfacilitator

Shared EVM facilitator errors (exact and upto).

exact

EIP-155 “exact” payment scheme implementation.

permit2

Canonical Uniswap Permit2 address, wire permissions, and client auto-approve.

signaturefacilitator

Shared EOA / EIP-1271 / EIP-6492 signature parsing and payment time windows.

signerclient

Alloy signer abstraction used by every EVM scheme client.

upto

EIP-155 “upto” payment scheme implementation.

Structs

USDC

Ergonomic accessors for USDC token deployments on well-known EVM chains.

USDM

Ergonomic accessors for USDM (MegaUSD) token deployments on EVM chains.

Constants

EVM_DEFAULT_CLOCK_SKEW_TOLERANCE_SECS

Default clock-skew tolerance (seconds) applied to EIP-712 time-window checks.

Statics

EVM_NETWORKS

Well-known EVM (EIP-155) networks with their names and CAIP-2 identifiers.

Functions

usdc_evm_deployment

Returns the USDC deployment for a specific EVM chain, if known.

usdc_evm_deployments

Returns all known USDC deployments on EVM chains.

usdm_evm_deployment

Returns the USDM deployment for a specific EVM chain, if known.

usdm_evm_deployments

Returns all known USDM deployments on EVM chains.