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By the end of this page you will know what @rail402.dev/conformance proves, how to run it against a deployment, and how to read the verdict of a dual run. Acceptance for an x402 facilitator is tested at the wire level: a reviewer points stock upstream client code at your deployment rather than reading a claim. @rail402.dev/conformance automates that. It clones the upstream x402 e2e suite, installs a proxy that points the suite at your facilitator, and runs the suite with unmodified upstream clients.
It ships the x402-stellar-conformance binary.
This measures interoperability against the real x402 suite, so it needs a reachable facilitator and, for a full settlement run, funded stellar:testnet accounts. Nothing here settles on mainnet.

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What it does

  1. Clones the upstream x402 repository at a pinned spec commit.
  2. Installs the Rail402 proxy config, so the suite’s stock clients target your facilitator instead of a remote one.
  3. Runs the upstream e2e scenarios (a stock client requesting a 402, signing, and retrying) and records the outcome per scenario.
The result is a wire-level record, including settled transaction hashes, that a reviewer can reproduce rather than trust.

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Running it

1

Install the proxy

Clone the upstream suite and wire its clients to your facilitator.
2

Run against a deployment

Point the suite at a facilitator URL and run the scenarios.
3

Run the dual comparison

Run the suite twice, at the pinned spec and at the latest upstream main, and compare.
The dual run is what turns conformance into ongoing maintenance. Running the suite at both the pinned commit and the latest upstream main catches a break introduced by an upstream spec change, not only a break in your own code.

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Dual-run verdicts

A dual run emits one of four verdicts.
blocked is not a pass. It means the measurement did not happen. Treat a blocked verdict as unknown, never as green.

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Next steps

How it works

The verify and settle loop the suite exercises.

Run a facilitator

Stand up the deployment you point the suite at.

Packages

Where conformance sits among the packages.

Error registry

The codes a failing scenario reports.