Ink (USDC)

Payment wires: every paid endpoint accepts x402 and MPP (Machine Payments Protocol) on the same 402 - see Paying with x402 and Paying with MPP. Agent402 is the applied layer of Agentic Finance: agents that pay and get paid on their own.

Agent402 settles x402 payments in USDC on Ink, an OP Stack L2 with chain id 57073. The rail is re-proven daily by an automated on-chain canary purchase. The live /ink page shows the chain's sellers and the service's own wallet on it.

Chain parameters

Buy in USDC on Ink

With agent402-mcp: set AGENT402_NETWORKS=eip155:57073 (plus AGENT_KEY for a wallet holding USDC on chain 57073) and every MCP tool call settles on Ink. The accept carries the asset and the EIP-712 domain, so the signer needs no Ink-specific setup.

With agent402-client or any @x402 client:

import { withNetworkPreference } from "agent402-client";
withNetworkPreference(x402client, ["eip155:57073"]);

Agent402's 402 lists Base first, so pinning the chain is required - an unmodified client that takes the first accept it can pay settles on Base. The preference throws before paying if the seller doesn't offer the chain.

Sell in USDC on Ink

• Agent402 server: add ink to PAYMENT_NETWORKS and set INK_FACILITATOR_URL (one URL, or an ordered comma-separated list: the first whose /supported confirms eip155:57073 at boot settles first, the rest are its settle fallback). Without the URL Ink is not configured and every other chain keeps serving. See Self-Hosting.

Find other sellers on the chain

The neutral router takes a network filter: GET /api/route?q=<task>&network=ink - only sellers whose crawled 402 advertises eip155:57073 are ranked (sellers with unknown accepts are kept; the filter excludes sellers known not to settle there).

Recognizing a settlement on-chain

An x402 settlement on Ink is a transferWithAuthorization (EIP-3009) on the USDC contract, submitted by the facilitator (the buyer paid no gas), with the decoded transfer showing buyer to seller for the quoted price.