layer402

 ___      _______  __   __  _______  ______    _   ___  _______  _______
|   |    |   _   ||  | |  ||       ||    _ |  | | |   ||  _    ||       |
|   |    |  |_|  ||  |_|  ||    ___||   | ||  | |_|   || | |   ||____   |
|   |    |       ||       ||   |___ |   |_||_ |       || | |   | ____|  |
|   |___ |       ||_     _||    ___||    __  ||___    || |_|   || ______|
|       ||   _   |  |   |  |   |___ |   |  | |    |   ||       || |_____
|_______||__| |__|  |___|  |_______||___|  |_|    |___||_______||_______|

The trust, identity, and settlement layer for x402 agent payments on Casper.

v1 project demo

layer402 lets AI agents pay for API access automatically, while giving API providers the missing context around those payments: who the agent is, whether its operator is verified, what its trust score is, and whether the payment was settled. It adds KYX identity, signed receipts, settlement records, batching, fees, and SDKs on top of the x402 flow.

Every transaction follows one loop:

pay      an agent receives HTTP 402 payment terms and signs them
verify   the facilitator checks signature, replay, balance, DID, and trust
settle   the payment settles directly, batches, or delegates upstream
score    the KYX registry records settlement history and updates trust

What To Find Where

• Live Services: deployed dashboard, facilitator, registry, and demo app URLs.
• What It Ships: the main product features at a glance.
• Casper x402 Facilitator Extension: how layer402 extends Casper's x402 Facilitator with KYX, trust, receipts, batching, fees, and observability.
• Smart Contracts: Casper Testnet contract package links and hashes.
• Published Packages: TypeScript and Python SDK install links.
• Use It In 30 Seconds: the smallest SDK integration example.
• Demo Apps: Atlas, Meridian, batch, Python, and scripted demos.
• Repository Layout: where packages, services, contracts, and demos live.
• Local Development: how to build, test, and run the stack locally.

Live Services

Service	URL
Website / docs / dashboard	https://x402layer-dashboard.vercel.app/
Facilitator API	https://fourotwo-facilitator.onrender.com
KYX trust registry	https://x402layer-kyx-registry.onrender.com
Atlas agent demo	https://atlas-research-agent.onrender.com/
Meridian merchant demo	https://meridian-fa2d.onrender.com/

What It Ships

• x402-compatible facilitator with /verify, /settle, /supported, batch, fee, and health endpoints.
• KYX registry for operator magic-link verification, agent registration, DID lookup, trust scoring, and settlement history.
• Portable agent DID model derived from Casper public keys: did:fourotwo:casper:<account-hash>.
• Trust-gated payments: merchants can require a minimum agent trust score before serving a paid API response.
• Signed settlement receipts: every successful settlement returns an Ed25519-signed receipt the merchant and agent can keep.
• Casper SettlementVault records for auditable on-chain settlement metadata.
• Batch settlement for low-value/high-frequency calls: many payments can collapse into one SettlementVault record.
• Platform fees with accrual, reporting, and optional native CSPR collection.
• TypeScript SDK with a drop-in agent.fetch(...) that catches 402 responses, signs, retries, budgets spend, and logs transactions.
• Python SDK for autonomous agents using the same pay/verify/settle flow.
• Reference apps: Atlas, an agent UI with a global fetch interceptor, and Meridian, a paid RWA data API with a live settlements feed.

Casper x402 Facilitator Extension

layer402 explicitly extends the Casper x402 Facilitator instead of replacing it.

The native layer402 facilitator can verify and settle payments itself, but it can also be configured with:

UPSTREAM_FACILITATOR_URL=https://x402-facilitator.cspr.cloud
UPSTREAM_FACILITATOR_ACCESS_TOKEN=<cspr.cloud access token>
UPSTREAM_FACILITATOR_NETWORK=casper:casper-test
UPSTREAM_FACILITATOR_ASSET=<CEP-18 contract package hash>
UPSTREAM_FACILITATOR_ASSET_METADATA={"name":"...","version":"1","decimals":"...","symbol":"..."}

When enabled, layer402 forwards Casper x402 signed payloads to the upstream Casper x402 Facilitator for CEP-18 settlement, then adds the layer402 features around it: KYX trust checks, DID validation, signed receipts, settlement reporting, batch-aware routing, and dashboard visibility.

In other words: Casper x402 handles the core x402 settlement path; layer402 adds identity, trust, receipts, batching, fees, and application-level observability.

Smart Contracts

Name	URL	Contract Hash
SettlementVault	SettlementVault contract package	hash-7601c68914e92175b498040af9ebc320544b20509d2b5b2339249ff967a0ecf6
KYXRegistry	KYXRegistry contract package	hash-1e2b354d2f9128b8f1c42cc12046f514292f95f7a40e3b3a9329a4f261a312d0

Contract addresses are also recorded in contracts/deployed-addresses.json.

Published Packages

Package	Install	Use
@fourotwo/agent-sdk	npm i @fourotwo/agent-sdk	TypeScript agent SDK for automatic x402 payments
@fourotwo/types	npm i @fourotwo/types	Shared types, DID derivation, and envelope encoding
fourotwo-agent-sdk	pip install fourotwo-agent-sdk	Python agent SDK

Use It In 30 Seconds

import { fourotwoAgent } from '@fourotwo/agent-sdk';

const agent = new fourotwoAgent({
  privateKeyHex: process.env.FOUROTWO_PRIVATE_KEY,
  budget: { dailyTokens: 10, perRequestTokens: 0.5 },
});

const res = await agent.fetch('https://api.example.com/data/RE-NYC-001');
const data = await res.json();

The SDK automatically:

• detects 402 Payment Required,
• reads the PAYMENT-REQUIRED header,
• signs the canonical envelope,
• attaches PAYMENT-SIGNATURE and X-FOUROTWO-DID,
• retries the request,
• records the transaction in the local ledger.

Full guides for agents, merchants, trust, and facilitator APIs live in the dashboard docs.

Demo Apps

Demo	Path	What it shows
Atlas agent app	demos/agent-app	Browser agent with global 402 fetch interceptor, wallet view, auto-pay mode, server-side signing, KYX registration, and optional native CSPR transfer
Meridian paid API	demos/paid-api-provider	Merchant API that returns 402 terms, verifies/settles retries through the facilitator, and shows a live earnings feed
v2 demo	demos/v2-demo	Magic-link operator verification, agent registration, Python autonomous payments, and batched settlement
Batch stream demo	demos/batch-stream-demo	High-frequency paid calls collapsed into one batch settlement
Python agent	demos/python-agent	Terminal agent using the Python SDK against Meridian
RWA oracle agent	demos/rwa-oracle-agent	Minimal TypeScript terminal agent for the pay/verify/settle loop
Mock RWA API	demos/mock-rwa-api	Small local merchant used by scripted demos

Repository Layout

This is an npm workspaces + Turborepo monorepo. Rust contracts use their own Cargo/Odra toolchain and are not built by the JS workspace.

packages/
  types/          shared types, DID derivation, envelope codec
  agent-sdk/      TypeScript SDK for x402 payments
  agent-sdk-py/   Python SDK for x402 payments
services/
  facilitator/    Fastify facilitator: verify, settle, batch, fees, receipts
  kyx-registry/   Fastify KYX service: operators, agents, trust, settlements
  dashboard/      Next.js app: overview, playground, docs, agents, wallet
contracts/
  src/kyx_registry.rs      agent identity + trust score registry
  src/settlement_vault.rs  on-chain settlement records
demos/
  paid-api-provider/   Meridian merchant
  agent-app/           Atlas agent
  v2-demo/             scripted v2 demo
  batch-stream-demo/   batched payment demo
  python-agent/        Python SDK demo
  rwa-oracle-agent/    minimal terminal agent
  mock-rwa-api/        minimal mock merchant

Local Development

npm install
npm run build
npm run test

Run the core services:

npm run dev -w @fourotwo/kyx-registry    # :4002
npm run dev -w @fourotwo/facilitator     # :4001
npm run dev -w @fourotwo/dashboard       # :3000

Run the paired Atlas/Meridian demo:

node demos/paid-api-provider/server.mjs   # merchant API
node demos/agent-app/server.mjs           # agent UI

Each service and demo reads its own .env; see the .env.example files for Casper RPCs, contract hashes, CSPR.cloud credentials, signing keys, CORS origins, KYX settings, and upstream Casper x402 facilitator settings.

For public judging/demo deployments, set KYX_DEMO_OPEN_VERIFICATION=true on the KYX registry so testers can receive the operator verification link inline and register agents without depending on SMTP delivery. Leave it off for production.

License

Copyright (c) 2026. All rights reserved.