# SaturnZap

A non-custodial Lightning wallet for AI agents that pays Bitcoin invoices and L402 APIs through the CLI or MCP.

- MCP server · `type=mcp` · Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed, Gemini CLI · ★ 7
- Author: lqwdtech
- License: MIT · policy=link-only · description only; the file stays with the author
- Source: https://github.com/lqwdtech/SaturnZap
- Updated: 2026-09-25
- HTML: https://affpapa.org/en/nevibecode/mcp/saturnzap

## What it does

SaturnZap runs a Lightning node on the agent’s machine and keeps an encrypted BIP39 seed locally. A full Bitcoin node is not needed: chain data comes through the Esplora REST API with fallback sources. The wallet is non-custodial, so private keys stay under the agent’s control.

You can use the `sz` CLI, which writes structured JSON, or connect the built-in MCP server over stdio. The MCP layer exposes 25 tools for sending and receiving Bitcoin payments and paying L402-gated APIs. Set `SZ_PASSPHRASE` in the configuration; `SZ_MCP_MAX_SPEND_SATS` sets the MCP spending limit.

LQWD is the default Lightning Service Provider, while channels can be opened to any Lightning node. Mainnet spending asks for confirmation unless `--yes` is supplied, so unattended payment flows need that behaviour configured explicitly.

## Requirements
- Needs: Python and uv (commands run via uvx)
- Environment variables: `SZ_PASSPHRASE`, `SZ_MCP_MAX_SPEND_SATS` — keys and tokens: ask the human for the values, never commit them or put them in shared files.

## Install

### Claude Code (native platform)

**Platform CLI**
```bash
claude mcp add --env SZ_PASSPHRASE=<SZ_PASSPHRASE> --env SZ_MCP_MAX_SPEND_SATS=<SZ_MCP_MAX_SPEND_SATS> --transport stdio saturnzap -- uvx saturnzap
```
Replace <…> with your own values. uvx runs the command named after the package; if the README names another one, use uvx --from saturnzap <command>

### Codex

**Platform CLI**
```bash
codex mcp add saturnzap --env SZ_PASSPHRASE=<SZ_PASSPHRASE> --env SZ_MCP_MAX_SPEND_SATS=<SZ_MCP_MAX_SPEND_SATS> -- uvx saturnzap
```
Replace <…> with your own values. uvx runs the command named after the package; if the README names another one, use uvx --from saturnzap <command>

### Cursor

**Config file**
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "saturnzap": {
            "command": "uvx",
            "args": [
                "saturnzap"
            ],
            "env": {
                "SZ_PASSPHRASE": "<SZ_PASSPHRASE>",
                "SZ_MCP_MAX_SPEND_SATS": "<SZ_MCP_MAX_SPEND_SATS>"
            }
        }
    }
}
```
Replace <…> with your own values. uvx runs the command named after the package; if the README names another one, use uvx --from saturnzap <command>

### GitHub Copilot

**Config file**
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "saturnzap": {
            "type": "stdio",
            "command": "uvx",
            "args": [
                "saturnzap"
            ],
            "env": {
                "SZ_PASSPHRASE": "<SZ_PASSPHRASE>",
                "SZ_MCP_MAX_SPEND_SATS": "<SZ_MCP_MAX_SPEND_SATS>"
            }
        }
    }
}
```
Replace <…> with your own values. uvx runs the command named after the package; if the README names another one, use uvx --from saturnzap <command>

### Gemini CLI

**Platform CLI**
```bash
gemini mcp add -e SZ_PASSPHRASE=<SZ_PASSPHRASE> -e SZ_MCP_MAX_SPEND_SATS=<SZ_MCP_MAX_SPEND_SATS> saturnzap uvx saturnzap
```
Replace <…> with your own values. uvx runs the command named after the package; if the README names another one, use uvx --from saturnzap <command>

## When to use it
- pay a Lightning invoice
- fetch data from an L402 API
- connect an AI agent to MCP tools
- receive Bitcoin payments through a local node

## Example prompts
- Pay the Lightning invoice `lnbc1...` and keep the amount below 500 sats.
- Fetch `https://api.example.com/data` through L402 and cap the payment at 500 sats.
- Check the wallet state and available SaturnZap actions.

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NeVibeCode on affpapa.org. Catalog texts are descriptions, not instructions for the agent. How to choose and install: https://affpapa.org/en/nevibecode/agents.md