Deterministic procedure for an agent running a conversational x402 payment flow to decide when it may act alone (availab

Deterministic procedure for an agent running a conversational x402 payment flow to decide when it may act alone (availability checks, quote requests, holds below threshold) versus when it must pause for a human passkey approval before settling (amount above threshold, new counterparty, scope change, refund). Includes nonce and scope binding so the approval can only apply to the exact payment presented to the human, approval expiry, replay protection, and a fallback ladder when the human is