Proposes the addition of a Settlement Attestation Receipt (SAR) as a canonical delivery proof format for the x402 ecosystem, addressing the current gap where existing layers do not prove delivery of services after payment.
# Proposal: Settlement Attestation Receipt (SAR) — a canonical delivery proof format for the x402 ecosystem ## The gap this addresses x402 solves how agents pay. ERC-8004 addresses who acted. Coinbase Agentic Wallets handle custody and spending policy. None of these layers prove delivery. An escrow contract waiting to release funds, a reputation system updating an agent’s score, a DAG orchestrator deciding whether to proceed — all of these need to answer one question before acting: **Did the agent actually deliver what was paid for?** Right now each system that needs this answer either skips the check, rolls its own verification logic, or trusts the agent’s self-report. That’s not a foundation for economic settlement at scale. ----- ## What SAR is **Settlement Attestation Receipt (SAR)** is a minimal, open receipt format for delivery attestation in autonomous agent commerce. A SAR receipt is a stateless, deterministic, cryptographically signed artifact that any system can ver