# mcp-l402-gate [Health: Active]

**Category:** 💻 Developer Tools  
**Repository:** https://github.com/zekebuilds-lab/mcp-l402-gate  
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**Directory Page:** https://allmcps.com/mcp/mcp-l402-gate

## Description
L402 Lightning paywall + DoI score gate for MCP tools: challenge, verify, score.

## Claude Desktop Quick Installation
Heuristic fallback — verify the package name and runner against the repository README before running it. Uses `npx` (confidence: low):

```json
"mcpServers": {
  "mcp-l402-gate": {
    "command": "npx",
    "args": ["-y","mcp-l402-gate"]
  }
}
```

## Documentation & README

# @powforge/mcp-l402-gate

[![npm](https://img.shields.io/npm/v/@powforge/mcp-l402-gate.svg)](https://www.npmjs.com/package/@powforge/mcp-l402-gate)
[![license](https://img.shields.io/badge/license-MIT-blue.svg)](#license)
[![node](https://img.shields.io/badge/node-%3E%3D18-brightgreen.svg)](#requirements)

Identity-scored Lightning paywall for MCP server operators.

L402 alone proves the caller paid 10 sats. It does not prove the caller has a reputation, has been around for more than 10 minutes, or that pricing one tool call shifts their economics at all. A fresh wallet pays the same 10 sats as a real user.

This package adds a Depth-of-Identity check on top of the L402 invoice. Drop it in front of an MCP tool and a caller has to (a) settle a Lightning invoice and (b) carry a DoI score above your threshold before the tool body runs. Cheap sybils still pay the toll, but the toll plus the per-pubkey reputation requirement is harder to grind than either piece on its own.

## See it in action

A clone-and-run example server lives at [github.com/zekebuilds-lab/mcp-l402-gate-example](https://github.com/zekebuilds-lab/mcp-l402-gate-example). It exposes one tool, `bitcoin_data`, that fetches the BTC/USD price plus mempool fees from mempool.space, gated by L402 + DoI. Clone it, fill in your LNBits creds, `npm start`, and you have a Lightning-gated MCP server running locally.

## The Gap

Sats4AI's own documentation states the limitation plainly:

> "autonomous agents cannot build reputation or receive preferential treatment across sessions."

`@powforge/mcp-l402-gate` closes that gap by composing L402 payment gating with the DoI oracle's composite identity score. A paying caller is also a known caller, with a per-pubkey reputation that survives across sessions and that costs irreversible work to fake.

## Why not just L402

L402 is great wire format, weak abuse control. Recent MCP billing tools (sats4ai-mcp, invinoveritas, l402-kit, 402-mcp, coinopai-mcp) all ship the same `402 -> macaroon -> paid -> tool body` flow, and an attacker can replay the flow from a fresh node every minute. coinopai-mcp's own author put it: "x402 is payment transport only. It doesn't handle agent identity, rate negotiation, multi-agent splits, or reputation."

PowForge has been shipping the missing piece. The DoI oracle at `https://identity.powforge.dev` returns a Schnorr-signed score for any Nostr pubkey, computed from observable irreversible work across four dimensions (social, access, vouch, economic). This package wires that score into the L402 path so a paying caller is also a costly-to-fake caller.

## Requirements

- Node >= 18
- An LNBits wallet (URL + invoice/read API key) for the Lightning side
- An accessible PowForge oracle URL (default: `https://identity.powforge.dev`)

## 5-line integration (Express)

```js
const express = require('express');
const { mcpL402Middleware } = require('@powforge/mcp-l402-gate');

const app = express();
app.use('/tools/expensive', mcpL402Middleware({
  secret: process.env.GATE_HMAC_SECRET,
  lnbitsUrl: process.env.LNBITS_URL,
  lnbitsApiKey: process.env.LNBITS_INVOICE_KEY,
  satsAmount: 10,
  minScore: 10, // composite >= 10 means "emerging" tier on the oracle
}));

app.post('/tools/expensive', (req, res) => {
  // Reached only when L402 paid AND req.doiScore >= 10
  res.json({ ok: true, doiScore: req.doiScore, l402: req.l402Token });
});
```

The caller passes their pubkey via the `X-Caller-Pubkey` header or `?pubkey=` query string. v0.1.0 treats this as caller-asserted; v0.2.0 will bind it cryptographically via NIP-98.

## MCP tool wrapping

```js
const { mcpL402Tool } = require('@powforge/mcp-l402-gate');

const expensiveTool = mcpL402Tool({
  secret: process.env.GATE_HMAC_SECRET,
  lnbitsUrl: process.env.LNBITS_URL,
  lnbitsApiKey: process.env.LNBITS_INVOICE_KEY,
  satsAmount: 10,
  minScore: 10,
}, {
  name: 'image_render',
  description: 'Render an image. 10 sats. Requires DoI score >= 10.',
  inputSchema: {
    type: 'object',
    properties: {
      prompt: { type: 'string' },
      pubkey: { type: 'string' },
      auth: { type: 'object', properties: { macaroon: { type: 'string' }, preimage: { type: 'string' } } },
    },
    required: ['prompt', 'pubkey'],
  },
}, async (args, ctx) => {
  // Runs only when paid AND ctx.doiScore >= 10
  return { image_url: `https://example/r/${args.prompt}`, billed_to: ctx.doiScore };
});

// Register expensiveTool with your MCP server. On first call without args.auth,
// the tool returns { paid: false, challenge: { macaroon, invoice, ... } }.
// The MCP client pays the invoice, then re-calls with args.auth set.
```

## Config reference

| Field | Default | Notes |
|-------|---------|-------|
| `secret` | required | HMAC key for macaroon signing. Rotate periodically. |
| `lnbitsUrl` | required | LNBits base URL. |
| `lnbitsApiKey` | required | LNBits invoice/read key. NEVER pass admin key. |
| `satsAmount` | 10 | Invoice amount per call. |
| `minScore` | 10 | Reject paid callers below this composite score. |
| `failClosed` | true | If oracle errors, reject the call. Set false to fall through with `req.doiScoreError`. |
| `oracleUrl` | https://identity.powforge.dev | Override for self-hosted oracles. |
| `scope` | mcp-l402-gate:call | L402 macaroon scope. |
| `ttlSeconds` | 600 | Macaroon validity. |
| `scoreField` | composite | Which envelope field to compare to minScore. |
| `callerPubkeyHeader` | x-caller-pubkey | HTTP header carrying the caller's asserted pubkey. |
| `oracleAuth` | optional | `{macaroon, preimage}` if your oracle is itself L402-paywalled. |
| `createInvoiceFn` | optional | Test seam. Async `(memo) => {payment_hash, bolt11}`. |
| `checkPaidFn` | optional | Test seam. Async `(payment_hash) => boolean`. |
| `lookupScoreFn` | optional | Test seam. Async `(pubkey) => {composite, rank, depth}`. |

## Score thresholds (composite)

Same buckets the oracle reports as `rank`:

| Threshold | Rank | Use it when |
|-----------|------|-------------|
| 0 | unknown | You only want pay-to-call. Skip this package and use L402 directly. |
| 10 | emerging | First-call abuse hurts. Default for most public MCP tools. |
| 40 | active | The tool burns real GPU or has expensive side effects. |
| 100 | established | Compliance-sensitive or single-tenant SaaS-style endpoints. |
| 200 | trusted | High-trust admin tooling. |

## Failure modes

| Status | Body | Meaning |
|--------|------|---------|
| 402 | `{error: "payment required", macaroon, invoice, payment_hash}` | First call. Pay the invoice, retry with `Authorization: L402 <macaroon>:<preimage>`. |
| 401 | `{error: "invalid macaroon", reason}` | Macaroon malformed, expired, wrong scope, or wrong signature. |
| 401 | `{error: "preimage does not match payment hash"}` | Preimage failed sha256 check against the macaroon's payment hash. |
| 409 | `{error: "macaroon already redeemed"}` | Replay guard fired. Mint a fresh macaroon. |
| 400 | `{error: "caller_pubkey_required"}` | No `X-Caller-Pubkey` header or `?pubkey=` query. |
| 403 | `{error: "score_too_low", score, min, rank}` | Caller paid but DoI score is below threshold. |
| 503 | `{error: "oracle_unavailable", mode: "fail_closed"}` | Oracle error and `failClosed` is on (the default). |
| 502 | `{error: "invoice provider unavailable"}` | LNBits unreachable on first-call mint. |

## Why this is a separate package

The L402 macaroon mint and verify code, the LNBits client, and the oracle client are all already shipping inside other PowForge packages. The point of `@powforge/mcp-l402-gate` is to make the composition trivial: one factory, one config object, one middleware OR one tool wrapper. Operators do not have to assemble three packages by hand to get a defended endpoint.

## Tests

```
npm test
```

16 unit tests, no real network. The macaroon HMAC is real; LNBits and oracle are stubbed.

## License

MIT.

## Links

- PowForge oracle (live): https://identity.powforge.dev
- Identity SDK: [@powforge/identity](https://www.npmjs.com/package/@powforge/identity) on npm
- MCP identity tools: [@powforge/mcp-identity](https://www.npmjs.com/package/@powforge/mcp-identity) on npm