Amount is what actually moved, as an exact 18-decimal-place USD string. It is NOT the atomic-unit figure the client signed: the challenge quotes the asset's own units (USDC's 6 dp) and truncates to fit them, while the ledger moves this exact value.
ID is the settle-once key: "x402_" + keccak(from|nonce) in hex. It is DERIVED, not minted, so a client that re-submits the same authorization addresses the same settlement and is served again for free rather than charged twice. It is also the id GET /v1/x402/settlements/:id takes.
Network is the CAIP-2 identifier the payment was settled under, e.g. "eip155:36963". Its eip155 reference is the chain id in the EIP-712 domain the payer signed, so it is not a label — changing it invalidates the signature.
Nonce is the client-chosen nonce from the authorization, hex — up to 32 bytes, left-padded to the contract's bytes32. It is the replay anchor: the token contract refuses a second on-chain transfer for one (from, nonce), and this rail refuses a second settlement for the same pair, so a ledger settlement inherits the identical guarantee.
Payer is the payer ORG — the tenant whose ledger was debited — and not an address. It is the org the request was authenticated as, so it answers who is billed, which the payer address alone cannot.
SettledAt is when this settlement was CLAIMED, in unix seconds — the moment the authorization was accepted, which is also the moment the time window it carried stopped applying. A settlement finished later by reconciliation keeps this instant.
TxHash is the chain transaction hash, present only for a "chain" settlement. Empty on a ledger settlement — that is the normal case today, and it means the money moved without a chain, not that it failed. The wire's PAYMENT-RESPONSE transaction falls back to ID when this is empty.
