Crate r402_core 

r402-core

Core types, traits, and wire formats for the x402 payment protocol.

This crate is blockchain-agnostic. It defines the shared data model used by client, server, and facilitator implementations across every chain. Chain specific behavior lives in sibling crates — see crates/README.md.

Modules

• wire — On-the-wire JSON types (offer, facilitator RPC, codecs) and settlement overrides
• facilitator — Facilitator trait, DynFacilitator erasure, verify/settle hooks
• scheme — Payment scheme registry and builder traits
• extensions — Extension framework for x402 protocol extensions
• client — PaymentClient orchestration
• resource_server — Transport-agnostic verify → execute → settle
• chain — CAIP-2 chain identifiers, address, provider abstractions
• amount — Human-readable currency amount parsing ("$0.01" etc.)
• error — Layered errors and machine-readable ErrorReason wire codes

Feature Flags

Flag	Default	Effect
telemetry		Enable tracing instrumentation
cache		Enable moka-backed TTL caches
ext-bazaar		Enable the bazaar resource discovery ext.
ext-payment-id		Enable the payment-identifier idempotency.
ext-eip2612		Enable EIP-2612 gas-sponsoring extra.
ext-erc20-approval		Enable ERC-20 approval gas-sponsoring extra.
metrics		Enable the metrics facade counters.
all-extensions		Enable every built-in extension
full		Enable every feature

License

Licensed under either of MIT or Apache-2.0, at your option.

Re-exports

pub use resource_server::AfterVerifyDecision;

pub use resource_server::BeforeOpDecision;

pub use resource_server::CancelReason;

pub use resource_server::CancellationGuard;

pub use resource_server::DynResourceServerHooks;

pub use resource_server::PaymentHookContext;

pub use resource_server::ResourceServer;

pub use resource_server::ResourceServerHooks;

pub use resource_server::SettleResultContext;

pub use resource_server::SkipHandlerDirective;

pub use resource_server::VerifiedPaymentCanceledContext;

pub use resource_server::VerifyPaymentOutcome;

pub use resource_server::VerifyResultContext;

pub use resource_server::WirePaymentPayload;

pub use client::ClientHooks;

pub use client::CreatedPayment;

pub use client::DynClientHooks;

pub use client::PaymentClient;

pub use client::PaymentCreationContext;

pub use client::PaymentResponseContext;

pub use client::PaymentResponseResult;

pub use error::AsPaymentProblem;

pub use error::ClientError;

pub use error::ErrorReason;

pub use error::FacilitatorError;

pub use error::PaymentProblem;

pub use error::SettlementError;

pub use error::VerificationError;

pub use facilitator::BoxFuture;

pub use facilitator::DynFacilitator;

pub use facilitator::DynFacilitatorHooks;

pub use facilitator::Facilitator;

pub use facilitator::FacilitatorHooks;

pub use facilitator::FailureRecovery;

pub use facilitator::HookDecision;

pub use facilitator::HookedFacilitator;

pub use wire::DEFAULT_ASSET_DECIMALS;

pub use wire::SettlementOverrideError;

pub use wire::SettlementOverrides;

pub use wire::asset_decimals_from_extra;

pub use wire::resolve_settlement_override_amount;

Modules

amount

Human-readable currency amount parsing.

cachecache

Shared cache primitives used by facilitator implementations.

chain

Blockchain-specific types and providers for x402 payment processing.

client

Client-side payment orchestration (official x402Client, V2-only).

error

Layered error types for x402 facilitator operations.

extensions

Extension framework for x402 protocol extensions.

facilitator

Unified asynchronous interface for x402 payment facilitators.

metricsmetrics

Stable metric names emitted by the r402 stack.

resource_server

Resource-server orchestration shared by HTTP and MCP transports.

scheme

Scheme identifiers, registry, and the extensible payment scheme system.

wire

On-the-wire JSON types for the x402 protocol.