Signed Snapshot

VALUE: A tamper-evident snapshot of a series with its sources and fetch time — a data point you can defend later, not just cite.

PRICE: $0.30 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.