Payments

Agents pay for HTTP resources with USDC using x402 (HTTP 402 Payment Required). Settlement is Circle Gateway on Arc. Policy is checked by the Payment Authority (backend) and by AgentTreasury (on chain).

Flow

1. The agent calls pay with a resource URL, an atomic amount, and an idempotency key.
2. The seller (or gateway) answers 402 with payment terms (payTo, asset, amount).
3. The Payment Authority evaluates policy against fresh chain state.
4. If allowed, the pocket signs. Gateway settles. The seller retries the resource with proof.
5. If denied, nothing is signed. The idempotency claim is released. The same key can retry.

What policy looks at

• Entity exists, owned by this tenant, bound, legally Active, not paused
• Amount ≤ software per transaction cap
• Amount ≤ on chain remaining period cap
• Recipient allowed (if allowlist enabled)
• Trust dials (see below)
• Pocket has float (otherwise you must fund_pocket first)

Units

MCP pay, fund_pocket, and fund_treasury take atomic USDC: an integer string with 6 decimals.

1.00 USDC  →  "1000000"
0.05 USDC  →  "50000"

Hex, scientific notation, and decimal points are rejected.

REST funding in the wizard uses human decimal strings. Do not mix the two.

Trust dials

Fail closed on transport errors for seller verification so an RPC outage cannot be cached as "this seller is fine."

A later tier, not shipped as default, is "verified legal bodies only": the payee must also resolve through ERC-8004 / ENS as Active.

Demo seller

The backend can host an x402 demo resource used from /personhood. World / AgentBook verification is separate from Arc USDC settlement. The payee can be on any chain World lists, including Arc.

What the Graph can and cannot see

A subgraph only indexes events. Incoming transfers and some tiny x402 legs may not announce. Treat indexed data as the governance view (spends the vault emitted, pauses, policy events), not a complete bank statement. Today's deployed subgraph is a walking skeleton. Do not build alerting on it yet.