simmer-x402

# x402 Payments

Pay for x402-gated APIs using USDC on Base. This skill enables agents to autonomously make crypto payments when accessing paid web resources.

## When to Use This Skill

Use this skill when:
- A skill or agent needs to fetch data from an x402-gated API (e.g., Kaito mindshare)
- You encounter HTTP 402 Payment Required responses
- You need to check your Base wallet balance (USDC + ETH)
- You want to pay for Simmer premium endpoints beyond free tier rate limits

## Setup

1. **Set your wallet private key**
   ```bash
   export EVM_PRIVATE_KEY=0x...your_private_key...
   ```
   Falls back to `WALLET_PRIVATE_KEY` if `EVM_PRIVATE_KEY` is not set (same key Simmer/Polymarket users already have). Your EVM address works on all chains — Polygon for trading, Base for x402 payments.

2. **Fund with USDC on Base**
   - Send USDC to your wallet address on Base network
   - x402 payments on Base are fully gasless — you only need USDC, no ETH

3. **Install dependencies**
   ```bash
   pip install x402[httpx,evm]
   ```

## Quick Commands

| Command | Description |
|---------|-------------|
| `python x402_cli.py balance` | Check USDC and ETH balances on Base |
| `python x402_cli.py fetch <url>` | Fetch URL with automatic x402 payment |
| `python x402_cli.py fetch <url> --json` | Same but output raw JSON only |
| `python x402_cli.py fetch <url> --dry-run` | Show payment info without paying |
| `python x402_cli.py fetch <url> --max 5.00` | Override max payment limit |
| `python x402_cli.py rpc <network> <method> [params...]` | Make RPC call via Quicknode x402 |

## Examples

### Check balance
```bash
python x402_cli.py balance
```
```
x402 Wallet Balance
==============================
Address: 0x1234...5678
Network: Base Mainnet

USDC:  $42.50
ETH:   0.000000 ETH
```

### Fetch free endpoint (no payment needed)
```bash
python x402_cli.py fetch "https://api.kaito.ai/api/v1/tokens" --json
```

### Fetch Kaito mindshare data ($0.02/data point via x402)
```bash
python x402...