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x402 Payments with iCommerce

x402 is an HTTP-native payment protocol used by iCommerce agents. It relies on HTTP 402 responses and signed payment intents that are sequenced and settled through the StateSet Sequencer.

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Protocol Flow

  1. Client requests a resource from a paywalled API.
  2. Server returns HTTP 402 with X-Payment-Required.
  3. Client creates and signs an X402PaymentIntent.
  4. Client retries with X-Payment header.
  5. Payment intent is sequenced and batched.
  6. Batch is committed and later settled on Set Chain L2.
  7. The server verifies payment using inclusion proofs.

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iCommerce Implementation

The iCommerce CLI includes x402 helpers and demos:
  • stateset-icommerce/cli/src/x402/*
  • stateset-icommerce/cli/examples/x402_payment_demo.mjs
  • stateset-icommerce/cli/examples/x402_client_real.mjs
  • stateset-icommerce/cli/examples/x402_server_real.mjs

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Example: x402 Payment Demo

node stateset-icommerce/cli/examples/x402_payment_demo.mjs

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Signed Intent Basics

The intent includes payer/payee, amount, network, validity window, and a signature hash. Signing uses the domain separator X402_PAYMENT_V1 and Ed25519 signatures.