Agent402 settles x402 payments in USDG (Global Dollar) on Robinhood Chain — an Arbitrum Orbit L2, chain id 4663, mainnet since 2026-07-01. The rail went live on the chain's second day and is re-proven daily by an automated on-chain canary purchase. Everything below is also on the live /robinhood page and in the full guide.

With agent402-mcp (≥ 0.11.0): set AGENT402_NETWORKS=robinhood (plus AGENT_KEY for a wallet holding USDG on chain 4663) and every MCP tool call settles in USDG.

With agent402-client (≥ 0.4.0) or any @x402 client:

import { withNetworkPreference } from "agent402-client";
withNetworkPreference(x402client, ["robinhood"]); // or ["eip155:4663"]

Multi-chain sellers list Base first, so pinning the chain is required — an unmodified client effectively always settles on Base. The preference throws before paying if the seller doesn't offer the chain.

• Agent402 server: PAYMENT_NETWORKS=…,robinhood + ROBINHOOD_FACILITATOR_URL=<an x402 facilitator that settles eip155:4663>. If the facilitator URL is unset the rail is omitted gracefully — every other chain keeps serving. See Self-Hosting.
• Tollbooth (≥ 0.4.0): TOLLBOOTH_NETWORK=eip155:4663 TOLLBOOTH_ASSET=USDG charges crawlers in USDG. See Pay-per-crawl.

The neutral router takes a network filter: GET /api/route?q=<task>&network=robinhood — only sellers whose crawled 402 advertises eip155:4663 are ranked (sellers with unknown accepts are kept; the filter excludes sellers known not to settle there).

There is no "402" label on-chain. An x402 settlement is a transferWithAuthorization (EIP-3009, selector 0xe3ee160e) on the USDG contract, submitted by the facilitator's relayer (the buyer paid no gas), with the decoded transfer showing buyer → seller for the quoted price. A real example: 0xae8e3e40…f826.

• The paid canary makes one real $0.001 USDG settlement daily (pinned to the chain via accepts filtering — no silent Base fallback).
• The heartbeat decodes the live 402 every 15 minutes and opens an issue if the rail drops out of the offer while the ROBINHOOD_FACILITATOR_URL secret says it should be there.
• SCAN_NETWORK=robinhood node scripts/revenue-scan.js reports USDG received by the revenue wallet; the daily revenue digest includes the rail.