---
title: MUJ428 External Verified Effect Challenge — $0 Conformance
description: Run MUJ428's zero-money external Verified Effect challenge from an independently controlled environment without production authority or money movement.
canonical_url: https://agents.muj428.com/verified-effect-challenge.html
md_url: https://agents.muj428.com/verified-effect-challenge.md
last_updated: 2026-08-19
---

# MUJ428 External Verified Effect Challenge

**Bind approved intent to verified effect from a system MUJ428 does not control.**

This is a zero-money conformance path. It exercises authorization → authenticated Trust Receipt consumption → `COMMITTED` Verified Effect → replay denial in the public `TESTNET_CONFORMANCE` sandbox.

- Cost: **$0**
- `moves_money=false`
- `production_authority=false`
- No wallet required
- No payment signature required
- No API key or paid credential required

## Fastest run

```bash
curl -fsS https://agents.muj428.com/examples/external-verified-effect.mjs -o external-verified-effect.mjs
node external-verified-effect.mjs
```

A valid run should show a sandbox authorization, one successful committed Verified Effect, and a denied replay.

## Machine contracts

- [Runnable example](https://agents.muj428.com/examples/external-verified-effect.mjs)
- [Integration sandbox](https://agents.muj428.com/integration-sandbox.json)
- [Technical challenge procedure](https://agents.muj428.com/docs/external-verified-effect-challenge.md)
- [External proof manifest](https://agents.muj428.com/external-verified-effect-challenge.json)
- [Developer contract](https://agents.muj428.com/developer.json)

## Evidence boundaries

For independent validation, return only non-secret evidence such as the organization/project identity, run timestamp, execution environment, resulting effect state, and whether replay was denied.

Do not send private keys, seed phrases, payment credentials, or proprietary payloads.

A MUJ428-controlled CI run does **not** count as external adoption. This challenge page is an invitation to validate and is not a claim of third-party adoption, endorsement, customer usage, or revenue.

## After the proof

MUJ428 can be integrated through REST, MCP, A2A, x402, or framework middleware. Free preflight has no execution authority. Paid assurance remains separate and pricing is unchanged.

## Terminology

See the [MUJ428 glossary](https://agents.muj428.com/glossary.md) for Trust Receipt, Verified Effect, mutation boundary, execution authority, and evidence-sufficiency definitions.

## Contacts

Technical: agent@muj428.com  
Commercial: sales@muj428.com

## Sitemap

See the full [agent-readable sitemap](https://agents.muj428.com/sitemap.md).