SpendPreflight — trust and verification tools for stablecoin payments, built for AI agents and the people who run them. Verify a native Base USDC transfer by tx_hash (optional log_index), or exact pay_to + decimal amount + past start/end (max 90 days). Ambiguous matches fail without charge. Signed observation, OFAC flags, confirmations and printable HTML. Not invoice ownership or finality proof.