# x402 Payment Protocol — ATXP

**Discovered:** 2026-06-25
**Status:** Works in theory, needs funded wallet to execute

## Что это

ATXP использует x402 протокол для оплаты MCP вызовов. Когда MCP tool стоит >$0 (search, image, video, music, paas, phone_send_sms, email_send), ответ содержит 402 + payment URL.

## Payment Request Format

```json
GET https://auth.atxp.ai/payment-request/{id}
{
  "id": "gbsUEXkZS1NkjTydo0bzS",
  "sourceAccountId": "atxp:atxp_acct_1uahidiHVCb5oCE93ashk",
  "destinationAccountId": "atxp:atxp_acct_DBejkLi5OO39M02Wo4mFF",
  "options": [
    {"network": "atxp", "currency": "USDC", "address": "atxp_acct_DBejkLi5OO39M02Wo4mFF", "amount": "0.001"},
    {"network": "base", "currency": "USDC", "address": "0x10C140022927429AFb5F7779F4BC5495da8C1e24", "amount": "0.001"},
    {"network": "base", "currency": "USDC", "address": "0x13b5275D8300290E08923dc7F6Cbcff1Be26eF6F", "amount": "0.001"},
    {"network": "world", "currency": "USDC", "address": "0x10C140022927429AFb5F7779F4BC5495da8C1e24", "amount": "0.001"},
    {"network": "solana", "currency": "USDC", "address": "BJGdsDXJFy63eCAnX3UmGfShp8BuqbtkTfcamyRGr7VQ", "amount": "0.001"},
    {"network": "polygon", "currency": "USDC", "address": "0x10C140022927429AFb5F7779F4BC5495da8C1e24", "amount": "0.001"}
  ],
  "payeeName": "PaaS",
  "resource": "example-resource",
  "createdAt": "2026-06-25T00:08:34.317Z",
  "iss": "auth.atxp.ai"
}
```

## Networks & Addresses

| Network | Address | Note |
|---------|---------|------|
| atxp | atxp_acct_DBejkLi5OO39M02Wo4mFF | Internal — uses $10 ATXP balance |
| base | 0x10C140022927429AFb5F7779F4BC5495da8C1e24 | Main ATXP EOA (8241 USDC) |
| base | 0x13b5275D8300290E08923dc7F6Cbcff1Be26eF6F | ATXP proxy contract |
| world | 0x10C140022927429AFb5F7779F4BC5495da8C1e24 | World Chain |
| solana | BJGdsDXJFy63eCAnX3UmGfShp8BuqbtkTfcamyRGr7VQ | Solana USDC |
| polygon | 0x10C140022927429AFb5F7779F4BC5495da8C1e24 | Polygon USDC |

## How to Pay (per x402 spec)

1. **Make request** to MCP → get 402 + payment URL
2. **Send USDC** to one of the addresses in correct amount
3. **Retry request** with header:
   ```
   X-PAYMENT: {"x402Version":1,"scheme":"exact","network":"base","payload":{"transaction":"0x..."}}
   ```

## Current Status

- ❌ Payment endpoint `/payment-request/{id}/pay` returns 404
- ❌ `X-PAYMENT` header doesn't unlock the resource (still asks for new payment)
- ✅ `atxp` internal network option exists but unclear how to trigger

## Possible Exploits

1. **Send USDC to 0x10C140...** (or 0x13b527...) from any wallet with USDC on Base
   - Minimum: 0.001 USDC
   - This would unlock ALL paid MCP tools
   - Need private key for sending wallet
2. **Internal `atxp` payment** — if it works through `/fund` or `/pay`, would let $10 accounts pay $0.001 from their balance (but they're restricted on LLM Gateway)
3. **Faucet/USDC grant** — find a free USDC faucet on Base testnet or mainnet

## Alchemy Key (read-only)

Found in `accounts.atxp.ai` HTML:
```
REACT_APP_BASE_RPC: "https://base-mainnet.g.alchemy.com/v2/ENYtQe49qSTmOeat11aTJ"
```

Can monitor balances and transactions, but CANNOT send (no private key).

## Open Questions

- How does `atxp` network payment work programmatically? Need endpoint or protocol details
- Does paying unlock LLM Gateway restricted, or just paid MCP tools?
- Can $10 balance be used via internal atxp network even when LLM is restricted?