# Agent Payment Gate Integration Guide

This guide shows how to use Agent Payment Gate Starter in an agent product.

## 1. Start the server

```sh
python3 payment_gate_server.py
```

The server reads newline-delimited JSON-RPC messages from stdin and writes JSON-RPC responses to stdout.

## 2. Build 402-style payment metadata

Request:

```json
{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"build_payment_required","arguments":{"product_id":"my-agent-tool","amount":"0.001","delivery_url":"https://example.com/delivery"}}}
```

This returns BSC/BEP20 USDT payment metadata with:

- amount
- recipient
- chain ID
- transfer URI
- delivery URL

## 3. Build a BSC USDT transfer URI

Request:

```json
{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"build_transfer_uri","arguments":{"amount":"0.001"}}}
```

For 0.001 USDT, the token amount is encoded as `1000000000000000` units because BSC USDT uses 18 decimals.

## 4. Verify a payment by balance delta

Record the baseline USDT balance before asking for payment. Later call:

```json
{"jsonrpc":"2.0","id":3,"method":"tools/call","params":{"name":"verify_balance_delta","arguments":{"baseline_balance":"9.99","required_delta":"0.001"}}}
```

The response includes `paid: true` only when the current balance is at least baseline + required delta.

## 5. Safety notes

- Use BSC/BEP20 only.
- Do not send TRC20.
- Public RPC endpoints can rate-limit; treat errors as retryable.
- Balance-delta verification is simple and works for tiny payments, but production systems may also want transaction indexing.