A-Identity Docs : Passport & Wallet for the Agentic Economy

Arbitrum One is the largest Ethereum L2 by usage, and the chain whose stack Robinhood Chain is built on. A-Identity holds an ERC-8004 agent identity here and has settled paid trust calls in native Circle USDC.

Why Arbitrum One

Native Circle USDC

Real USDC, not a bridged twin, and it implements EIP-3009, so a buyer can sign a transfer and never touch gas.

ERC-8004 already live

The canonical identity and reputation registries were deployed here by their authors, at the same addresses X Layer, Celo and Robinhood Chain carry.

A well-served baseline

Other x402 facilitators already serve this chain. Ours ran beside them on purpose, so you could check our rail against something to compare it to. It has been paused since 2026-11-11, until its new gas key holds ETH here.

Arbitrum One is live for us: agent #1259 is ours on the canonical registry, and a real settlement in USDC has gone through our own facilitator. Everything on this page is checkable at /proof/arbitrum.Since 2026-11-11 our EIP-3009 rail has been paused on Arbitrum One, until its new gas-only broadcaster key has gas on this chain. Agent #1259 is still held by our former operating wallet 0xd305607510E0Db2c95807173c7A05BEA53c1ed36, which also owns the vault below; someone else has also held that wallet’s key since at least 2026-11-01, so never pay or fund it.

Network config

Field	Value
Chain ID	`42161`
CAIP-2	`eip155:42161`
Native currency	ETH (18 decimals)
RPC (HTTP)	`https://arb1.arbitrum.io/rpc`
Block explorer	arbiscan.io
USDC	`0xaf88d065e77c8cC2239327C5EDb3A432268e5831`
CCTP domain	`3`

Two things worth stating plainly about this chain.We are not first here, and do not claim to be. Coinbase’s x402 facilitator and others already serve Arbitrum One, and gasless EIP-3009 relaying on this USDC contract predates us by years. We ran our own facilitator here so that one code path and one receipt standard covered every EVM chain our EIP-3009 rail sold on; it has been paused here since 2026-11-11, and no rail of ours sells on Arbitrum One now.“Settled” has layers on an L2. We wait the descriptor’s confirmations, which is the sequencer’s ordering commitment, and we record the block. That is not Ethereum finality, and USDC cannot leave for Ethereum until the fraud-proof window passes.

Connect with viem

import { arbitrum } from 'viem/chains'
import { createPublicClient, http } from 'viem'

export const client = createPublicClient({ chain: arbitrum, transport: http() })

import { client } from './chain'

// Agent #1259 is ours on the canonical registry.
const owner = await client.readContract({
  address: '0x8004a169fb4a3325136eb29fa0ceb6d2e539a432',
  abi: [{ type: 'function', name: 'ownerOf', stateMutability: 'view', inputs: [{ type: 'uint256' }], outputs: [{ type: 'address' }] }],
  functionName: 'ownerOf',
  args: [1259n],
})

What is deployed

Contract	Address
IdentityRegistry	`0x8004a169fb4a3325136eb29fa0ceb6d2e539a432`
ReputationRegistry	`0x8004BAa17C55a88189AE136b182e5fdA19dE9b63`
USDC (settlement)	`0xaf88d065e77c8cC2239327C5EDb3A432268e5831`
AgentSpendPolicy vault (ours, retired)	`0xac6c5c9af62bc482ffeef882a6ac4678513be6db`

We deployed none of these except the vault. The registries were already live and registering on them is permissionless; what is ours is agent #1259, the vault and the rail on top. The family’s ValidationRegistry proxy has code here too (read live 2026-10-11), but we do not wire it, so a KYA result is not anchored on-chain here. The vault caps the agent key at 1 USDC a day and 0.25 USDC per payment. Since 2026-10-01 the agent key is a separate wallet from the owner key and its session key runs to 2026-11-15. As of 2026-11-11 the vault is retired: its owner is our former operating wallet, whose key someone else has also held since at least 2026-11-01, and the contract has no owner transfer. It still holds 0.01 USDC (read live 2026-11-11), which we cannot withdraw through its owner while gas sent to that address is swept; the agent key 0x8C8D…3349 can still pay it out through pay() until its session key lapses on 2026-11-15. Never fund it. Before paying here, /check/arbitrum answers whether a token is native Circle USDC and whether the payee is a registered agent; the chain itself confirms it is an Arbitrum chain through the ArbSys precompile.

The price, and where it comes from

The base price of a tool is identical on every chain we sell on. While our rail ran here, the only difference was a disclosed settlement fee, because we broadcast on the buyer’s behalf and that costs gas. On Arbitrum One a real settlement measured 103569 gas at 0.02 gwei, about 0.00000207 ETH, so the fee here was **$0.005** rather than the $0.02 charged on Robinhood Chain, where the same settlement costs measurably more. The rail has been paused here since 2026-11-11. The measurement lives in the chain registry beside the token, so the number is traceable rather than asserted.

Verify it yourself

# The signing domain, straight from the token.
curl -sX POST https://arb1.arbitrum.io/rpc -H 'content-type: application/json' \
  -d '{"jsonrpc":"2.0","id":1,"method":"eth_call","params":[{"to":"0xaf88d065e77c8cC2239327C5EDb3A432268e5831","data":"0x3644e515"},"latest"]}'
# -> 0x08d11903f8419e68b1b8721bcbe2e9fc68569122a77ef18c216f10b3b5112c78

# Our provenance ledger, with a live re-read of ownerOf(1259) on every request.
curl -s https://a-identity-backend.onrender.com/api/proof/arbitrum

Where Arbitrum One fits

It is the chain where our rail could be compared against a well-served baseline, and can be again once it runs; its past receipts are on /proof/arbitrum. Robinhood Chain is an Arbitrum L2 and is where the same engine settles in USDG, Paxos’s dollar, rather than USDC; Arc holds escrow; Celo settles through someone else’s facilitator. Being live on Robinhood Chain and being live on Arbitrum One are two different statements, and both are true.

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