The agent asks. No key, no account.
Billi answers 402 with the amount, the asset and the address to pay.
The agent signs and retries. 202, with an operation id to poll.
That is the whole handshake.
There is no signup.
The wallet that pays is the account. Sign in with CAIP-122 and the session can read what you own — it can never spend.
Spending takes a fresh signature, every time.
Four things an agent needs to work on the internet. A card. A number. An inbox. A box to run on.
Cards reach a live provider today. The other three answer from mocks until their adapters ship.
Not three tiers. The actual catalogue, in USDC, read from config at runtime.
Issue a card - 5.500000
Send an SMS - 0.008000
Register a .com - 12.200000
These numbers are not final. The catalogue is placeholder pending unit costs.