Quickstart

This walks the full round trip: set up clients on Arc Testnet, run the poisoning firewall and refuse on a block, send a code-gated protected transfer, and let the recipient claim it. If the recipient looks like a poisoning lookalike or has baited you with a zero-value transfer, the send is refused before any funds move.

sendProtected already runs the firewall for you by default. Step 2 below runs check explicitly so you can show the verdict in your UI and decide before you build the transfer. Both paths are fail-closed.

Set up viem clients on arcTestnet

A ClientPair is a viem public client for reads and a wallet client for writes, both on arcTestnet. See Installation for the peer dependency and RPC details.

import { createPublicClient, createWalletClient, http } from 'viem';
import { privateKeyToAccount } from 'viem/accounts';
import { arcTestnet, RPC_URL } from '@ctrl-arcz/sdk';

const account = privateKeyToAccount('0x...'); // or a browser wallet account
const owner = account.address;

const publicClient = createPublicClient({ chain: arcTestnet, transport: http(RPC_URL) });
const walletClient = createWalletClient({ account, chain: arcTestnet, transport: http(RPC_URL) });

const clients = { publicClient, walletClient };

Run the firewall and refuse on a block

check(sender, target) returns a RiskReport with a level of safe, warning, or block. Pass the public client so it can also read your verified recipients from the contract. Stop on a block: a lookalike is beaten only by not sending.

import { check } from '@ctrl-arcz/sdk';

const recipient = '0x...';

const report = await check(owner, recipient, { client: publicClient });

if (report.level === 'block') {
  // A lookalike, a zero-value bait, or a scan that could not rule a lookalike out.
  console.warn('Refused:', report.reasons.map((r) => r.code));
  return;
}
if (!report.complete) {
  // A data source did not answer. The report is never "safe" when incomplete.
  console.warn('Incomplete scan:', report.reasons);
}

Send a code-gated protected transfer

Register an integrator config once (it is content-addressed, so calling it on every boot is free), mint a claim secret, then sendProtected. The recipient will need the short code to claim.

import {
  defineConfig,
  registerConfig,
  generateClaimCode,
  approveUsdc,
  sendProtected,
} from '@ctrl-arcz/sdk';
import { parseUnits } from 'viem';

const { configId } = await registerConfig(clients, defineConfig({ recallWindow: 3600 }));
const secret = generateClaimCode(); // { secret, code, salt, claimHash }

const amount = parseUnits('5', 6); // 5 USDC, 6 decimals
await approveUsdc(clients, amount);

const { transferId, txHash } = await sendProtected(clients, {
  configId,
  to: recipient,
  amount,
  claimHash: secret.claimHash,
});

sendProtected re-runs the firewall itself and throws RiskBlockedError on a block before it submits, so no funds move on a block even if you skip step 2.Deliver secret.secret, the grouped string (A4K7-9QMX-2PR6-TH8D), to the recipient as a person, over a channel the recipient controls. It carries all 80 bits; the salt is derived from it, so there is no second half to send. A wrong or poisoned recipient cannot claim without it, and you can cancel to reclaim.

Recipient claims with the code

The recipient, using their own ClientPair, redeems the transfer with the code and salt you delivered.

import { claim } from '@ctrl-arcz/sdk';

await claim(recipientClients, transferId, secret.code, secret.salt);

A wrong code does not revert on-chain (the attempt counter must survive the 5-guess lockout), so claim inspects the receipt and throws a typed error on a wrong code or a lockout rather than silently “succeeding.”

What just happened

Layer 1 - firewall

The scan refused a lookalike or bait recipient before any funds moved.

Layer 2 - escrow

Funds were held by the contract, claimable only with the code, refundable to you.

Payer privacy

To pay from a disposable address that stores no payer identity, use Private Pay.

Pay a merchant privately: Private Pay.
Every function and return shape: SDK reference.

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Layer 1 - firewall

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