Build on Robinhood Chain

Robinhood Chain network config for both networks, the canonical ERC-8004 registries already deployed there, and the x402 facilitator we run for it.

Robinhood Chain is Robinhood’s own Arbitrum Orbit L2, built for tokenized real-world assets, with ETH as the gas token and Ethereum for data availability. A-Identity runs agent identity there, and settles paid trust calls there in USDG.

Why this chain

Agents will trade here

It is the chain built around tokenized stocks and ETFs, and Robinhood has opened its surfaces to AI agents while stating plainly that it does not supervise them. That gap is the product.

ERC-8004 is already live

The canonical identity and reputation registries were deployed here by their authors, at the same addresses they carry on X Layer and Celo. Nothing had to be forked.

Gasless payments work

USDG implements EIP-3009, so a buyer can sign a transfer and never touch gas. Our facilitator broadcasts it.

Mainnet (4663) is live for us: agent #0 on the canonical registry is ours, and paid trust calls settle here in USDG. Testnet (46630) is beta, and carries the full canonical ERC-8004 trio plus a deployed AgentSpendPolicy vault. Every claim on this page is checkable at /proof/robinhood.

Network config

Field	Mainnet	Testnet
Chain ID	4663	46630
CAIP-2	eip155:4663	eip155:46630
Native currency	ETH (18 decimals)	ETH (18 decimals)
RPC (HTTP)	https://rpc.mainnet.chain.robinhood.com	https://rpc.testnet.chain.robinhood.com
Block explorer	robinhoodchain.blockscout.com	explorer.testnet.chain.robinhood.com
Faucet	n/a (bridge real ETH)	faucets.chain.link/robinhood-testnet

Two things will bite you here.

There is no canonical Circle USDC on either network. Do not copy a USDC address from another chain: it will not be the same token. The settlement token we use on mainnet is Paxos USDG at 0x5fc5360D0400a0Fd4f2af552ADD042D716F1d168, which is the address Paxos documents for this chain. Our registry deliberately leaves the USDC slot empty and names USDG as its own thing.

CreateX is not deployed here, on either network, so CREATE3 is unavailable. The deterministic deployer that IS present is the Safe Singleton Factory (0x914d7Fec6aaC8cd542e72Bca78B30650d45643d7), alongside the Arachnid CREATE2 factory. That is what makes the canonical ERC-8004 addresses reproducible here.

Connect with viem

chain.ts

import { defineChain } from 'viem'

export const robinhoodChain = defineChain({
  id: 4663,
  name: 'Robinhood Chain',
  nativeCurrency: { name: 'Ether', symbol: 'ETH', decimals: 18 },
  rpcUrls: { default: { http: ['https://rpc.mainnet.chain.robinhood.com'] } },
  blockExplorers: { default: { name: 'Blockscout', url: 'https://robinhoodchain.blockscout.com' } },
})

export const robinhoodTestnet = defineChain({
  id: 46630,
  name: 'Robinhood Chain Testnet',
  nativeCurrency: { name: 'Ether', symbol: 'ETH', decimals: 18 },
  rpcUrls: { default: { http: ['https://rpc.testnet.chain.robinhood.com'] } },
  blockExplorers: { default: { name: 'Blockscout', url: 'https://explorer.testnet.chain.robinhood.com' } },
})

What is deployed

Contract	Network	Address
IdentityRegistry	mainnet	0x8004a169fb4a3325136eb29fa0ceb6d2e539a432
ReputationRegistry	mainnet	0x8004BAa17C55a88189AE136b182e5fdA19dE9b63
USDG (settlement)	mainnet	0x5fc5360D0400a0Fd4f2af552ADD042D716F1d168
IdentityRegistry	testnet	0x8004A818BFB912233c491871b3d84c89A494BD9e
ReputationRegistry	testnet	0x8004B663056A597Dffe9eCcC1965A193B7388713
ValidationRegistry	testnet	0x8004Cb1BF31DAf7788923b405b754f57acEB4272

We did not deploy the mainnet registries. They were already live at their canonical cross-chain addresses when we arrived; what is ours is agent #0, the first token that registry ever minted. On testnet the ValidationRegistry implementation was the one piece missing, and we deployed it by replaying the canonical Safe-Singleton-Factory calldata, which reproduces the same address rather than forking a new one.

There is no ValidationRegistry in the mainnet family, mirroring Celo and X Layer, so a KYA result cannot be anchored on-chain there. It is still verified off-chain and recorded; we simply do not claim an anchor that does not exist.

The x402 facilitator

An x402 facilitator is the service a seller calls to verify a payment and settle it. No published facilitator serves this chain, so a seller here has nothing to point an x402 client at. We run one, and it is open:

To be precise about what that does and does not claim: gasless EIP-3009 relaying on USDG predates us on this chain by weeks, and an x402 settlement is indistinguishable on-chain from any other relayed authorization. What we could not find, and therefore built, is a facilitator serving the x402 HTTP protocol here.

Endpoint	Access
GET /api/facilitator/supported	open
POST /api/facilitator/verify	open, read-only
POST /api/facilitator/settle	allowlisted by payTo, because we pay the gas
GET /api/facilitator/proof	open

Base URL: https://a-identity-backend.onrender.com/api/facilitator. Both x402 wire spellings are accepted for network: the v1 slug (rhchain) and the v2 CAIP-2 id (eip155:4663).

The signing domain is proven, not pasted. USDG exposes neither version() nor eip712Domain(), so the EIP-712 domain cannot be read from the contract. We rebuild each candidate domain and accept only the one that reproduces the live DOMAIN_SEPARATOR. If none matches, no payment challenge is served at all, because inviting a buyer to sign against a guessed domain produces an authorization nobody can settle.

Verify it yourself

# The signing domain, straight from the token. Compare it to what /supported publishes.
curl -sX POST https://rpc.mainnet.chain.robinhood.com -H 'content-type: application/json' \
  -d '{"jsonrpc":"2.0","id":1,"method":"eth_call","params":[{"to":"0x5fc5360D0400a0Fd4f2af552ADD042D716F1d168","data":"0x3644e515"},"latest"]}'
# -> 0x7a3d7400b27830f4f91c2c16a082486d67c1befecaec2f53b33f1f35d5b62036

# Our provenance ledger, with a live re-read of ownerOf(0) on every request.
curl -s https://a-identity-backend.onrender.com/api/proof/robinhood

# Every settlement, with the transaction that proves it.
curl -s https://a-identity-backend.onrender.com/api/facilitator/proof

Where this chain fits

Arc is where escrow and the spend vault live. X Layer is where the trust oracle is listed. Celo is where x402 settles through a first-party facilitator someone else runs. Robinhood Chain is the one where we had to build the rail ourselves, and it is the chain whose users are agents trading real-world assets, which is exactly the population that needs a policy layer in front of it.