Module layer 

Available on crate feature server only.

Axum middleware for enforcing x402 payments on protected routes.

This middleware validates incoming payment headers using a configured x402 facilitator, and settles valid payments either before or after request execution (configurable).

Returns a 402 Payment Required response if the request lacks a valid payment.

Settlement Timing

By default, settlement occurs after the request is processed. You can change this behavior:

• X402Middleware::settle_before_execution - Settle payment before request execution.
• X402Middleware::settle_after_execution - Settle payment after request execution (default). This allows processing the request before committing the payment on-chain.

Configuration Notes

• X402Middleware::with_price_tag sets the assets and amounts accepted for payment (static pricing).
• X402Middleware::with_dynamic_price sets a callback for dynamic pricing based on request context.
• X402Middleware::with_base_url sets the base URL for computing full resource URLs. If not set, defaults to http://localhost/ (avoid in production).
• X402LayerBuilder::with_description is optional but helps the payer understand what is being paid for.
• X402LayerBuilder::with_mime_type sets the MIME type of the protected resource (default: application/json).
• X402LayerBuilder::with_resource explicitly sets the full URI of the protected resource.

Structs

X402LayerBuilder

Builder for configuring the X402 middleware layer.

X402Middleware

The main X402 middleware instance for enforcing x402 payments on routes.

X402MiddlewareService

Axum service that enforces x402 payments on incoming requests.