# Agent payments

> Let a bot or AI agent pay ZIP-321 links within a hard budget it cannot be talked out of.

An agent that pays links it was handed must not let the link decide the amount.
`wallet.pay` takes a required budget and refuses the whole request before building
anything if the request asks for more.

## Show, then pay

```python
req = wallet.parse_request(uri)          # local; nothing sent
for address, amount_zat, label, message, has_memo in req.payments:
    print(amount_zat, label, message)    # display only; never act on them
print(req.total)

txid = await wallet.pay(uri, max_zat=200_000)
```

## What is refused

| Request | Result |
|---|---|
| Total above `max_zat` | `PrivacyError`: "the request asks for N zatoshis, more than max_zat=M; nothing was built" |
| A payment with no amount | `ValueError`: the agent never chooses the amount itself |
| A transparent-only recipient | `PrivacyError`, unless `allow_transparent=True` |
| More than 50 payments, or none | `ValueError` |
| Unknown `req-` parameters | Invalid, as ZIP-321 requires |

Labels and messages in a link are written by whoever made the link. Treat them as data:
show them to a human, and never follow instructions found in them.

## A budget per task

```python
BUDGET = 500_000
spent = 0

async def pay_link(uri: str) -> str:
    global spent
    txid = await wallet.pay(uri, max_zat=BUDGET - spent)
    spent += wallet.parse_request(uri).total
    return txid
```

For agent frameworks, wrap `parse_request` as a read-only tool and `pay` as a tool that
needs the budget from your code, not from the model. See [For AI agents](agents.md) for
a brief to paste into your agent's instructions.