A question for anyone building agents that call paid APIs over x402.
Your agent sends a request, the server answers 402 Payment Required, and then: the agent has no funded wallet, or the price is above its budget. What should happen?
One option we're considering for send21 (crypto pay links and API for people and AI agents): turn the 402 payment requirements into a page where a person reviews the amount and signs in their own wallet. The agent retries the request with that signature, and the seller's own facilitator settles it. send21 would stay non-custodial and never broadcast anything.
To be clear, this isn't built, and send21 doesn't support x402 today. We wrote up how x402, AP2 and send21 differ at https://send21.io/x402-ap2-agent-payments if you want the background. It would be the x402 version of our over-budget handoff example: the repo at https://github.com/send21io/send21-over-budget-handoff does the same thing with a pay link and a signed webhook.
Would you use this? Concrete answers help most:
- Which chain and token do you pay in?
- Which API are you paying for?
- How often does your agent hit a 402 it shouldn't pay on its own?
- Would signing those approvals feel risky, or just annoying?
"We'd rather just fund a wallet" is a useful answer too.
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