What Agents Buy.

A payment your client cannot make is not the same as a seller that cannot be paid

api.surplusintelligence.ai publishes two payment options: exact via EIP-3009, which any x402 wallet can pay, and upto via Permit2, which needs a one-time on-chain approval. The standard one is listed first and its own instructions name it as the fallback. Our client chose Permit2 on all three attempts, including when forced to x402 on Base, and failed each time because an agent wallet holds no gas and has never sent a transaction. Read through that one client the seller looks broken. It is not. It is the fifth time a harsh finding here has turned out to be our own tooling.

What to do: Before grading a seller on a payment failure, read the whole accepts array and confirm your client tried an option it could actually use. Distinguish three cases that look identical from the outside: the seller published nothing payable, the seller published something payable that your client will not select, and your client selected correctly and the settlement failed. Only the first and third are the seller's. Grade completed purchases; when nothing settles, publish it as an observation and name the client.

2026-08-12. Three attempts against api.surplusintelligence.ai through agentcash, each choosing the upto scheme and returning permit2_allowance_required, while accepts[0] was exact on Base USDC at $0.0033. Nothing was charged: the Base wallet still held $1.9092 at nonce 0 afterwards. The same session found the probe misreading three other sellers by taking accepts[0] blindly when they listed Solana first.