┌─────────────┐         402 Challenge         ┌──────────────────┐
│  AI Agent   │ ────────────────────────────── │  Paid MCP Server │
│  (Client)   │                                │  (Gateway)       │
│             │ ◄── Payment Required (-32042)  │                  │
│             │                                │                  │
│  Signs tx   │ ── Credential (signed payment) │  Verifies on     │
│  via mppx   │                            ──► │  Tempo chain     │
│             │                                │                  │
│             │ ◄── Tool Result + Receipt      │  Runs handler    │
└─────────────┘                                └──────────────────┘

npm install mpp-mcp-gateway

# For HTTP/Express transports and dashboard
npm install express

# For Upstash Redis stores / rate limiting
npm install @upstash/redis

# For OpenTelemetry tracing
npm install @opentelemetry/api

# For Cloudflare Workers KV store
npm install @cloudflare/workers-types

import { createPaidMcpServer } from 'mpp-mcp-gateway/server'
import { z } from 'zod'

const server = createPaidMcpServer({
  name: 'my-api',
  version: '1.0.0',
  recipient: '0xYourWalletAddress',
  secretKey: process.env.PAYMENT_SECRET_KEY!,
  network: 'testnet',
  tools: [
    {
      name: 'get_weather',
      description: 'Get weather for a city. $0.001 per call.',
      inputSchema: { city: z.string() },
      pricing: { type: 'per-call', amount: '0.001' },
      handler: async ({ city }) => ({
        content: [{ type: 'text', text: `Weather in ${city}: 72°F, sunny` }],
      }),
    },
    {
      name: 'ping',
      description: 'Free liveness check.',
      inputSchema: {},
      // No pricing = free tool
      handler: async () => ({
        content: [{ type: 'text', text: 'pong' }],
      }),
    },
  ],
})

await server.startStdio()

import { createPaidMcpClient } from 'mpp-mcp-gateway/client'
import { StdioClientTransport } from '@modelcontextprotocol/sdk/client/stdio.js'

const client = createPaidMcpClient({
  name: 'my-agent',
  version: '1.0.0',
  privateKey: process.env.AGENT_PRIVATE_KEY! as `0x${string}`,
  maxPerCall: '0.10',    // safety cap: max $0.10 per single call
  maxTotal: '10.00',     // safety cap: max $10.00 total spend
  network: 'testnet',
})

const transport = new StdioClientTransport({
  command: 'node',
  args: ['server.js'],
})
await client.connect(transport)

// Free call — no payment required
const ping = await client.callTool('ping')
console.log(ping.content[0].text) // "pong"
console.log(ping.paid)            // false

// Paid call — automatic 402 → sign → retry
const weather = await client.callTool('get_weather', { city: 'Tokyo' })
console.log(weather.content[0].text) // "Weather in Tokyo: 72°F, sunny"
console.log(weather.paid)            // true
console.log(weather.receipt?.reference) // "0xabc...def" (tx hash)

await client.close()

pricing: { type: 'per-call', amount: '0.001' }

pricing: {
  type: 'tiered',
  tiers: [
    { upTo: 100, amount: '0.01' },
    { upTo: 1000, amount: '0.005' },
    { upTo: 'unlimited', amount: '0.001' },
  ],
}

pricing: {
  type: 'session',
  amount: '0.0005',          // per-unit price
  unitType: 'request',       // informational label
  suggestedDeposit: '0.50',  // hint for initial channel funding
}

// Make multiple calls against the same channel
await client.callTool('think', { topic: 'AI alignment' })
await client.callTool('think', { topic: 'quantum computing' })

// Cooperatively close and settle on-chain
const result = await client.closeSession('think')
console.log(result.receipt.reference) // settlement tx hash

pricing: {
  type: 'access-key',
  amount: '0.01',       // upfront cost
  validFor: '1d',       // time limit (supports: 60s, 30m, 4h, 7d)
  maxCalls: 100,        // call limit (at least one of validFor/maxCalls required)
}

// First call: pays $0.01, receives access key
const r1 = await client.callTool('premium_data', { query: 'foo' })
console.log(r1.paid)                    // true
console.log(r1.accessKey?.justIssued)   // true
console.log(r1.accessKey?.remainingCalls) // 99

// Subsequent calls: free (key presented in _meta)
const r2 = await client.callTool('premium_data', { query: 'bar' })
console.log(r2.paid)  // false

pricing: {
  type: 'per-call',
  amount: '0.001',
  accept: [
    { currency: '0x20c0...0000', amount: '0.001' }, // pathUSD
    { currency: '0x20c0...0001', amount: '0.001' }, // alphaUSD
  ],
}

import { createPaidMcpServer, PaidMcpServer } from 'mpp-mcp-gateway/server'

const server = createPaidMcpServer(config)

// Start on stdio (for CLI / subprocess use)
await server.startStdio()

// Or access the underlying McpServer for custom transports
const mcpServer = server.server
await mcpServer.connect(someTransport)

// Runtime inspection
server.getStats()           // GatewayStats (calls, revenue, sessions, keys)
server.listTools()          // tool names, descriptions, current prices
server.getRecentCalls(100)  // last N calls from the ring buffer
server.getInFlightCount()   // currently active handlers
server.isShuttingDown()     // true after close() begins
server.describe()           // full descriptor for discovery/OpenAPI

// Graceful shutdown
await server.close({ timeoutMs: 25_000 })

import { createPaidMcpClient, PaidMcpClient } from 'mpp-mcp-gateway/client'

const client = createPaidMcpClient(config)

await client.connect(transport)
await client.listTools()
const result = await client.callTool('tool_name', { arg: 'value' })

// Spending state
client.getSpending()    // { totalSpent, remaining, maxTotal, maxPerCall, ... }
client.resetSpending()  // reset cumulative counter (for tests)

// Access key management
client.getAccessKeys()          // cached keys by tool name
client.clearAccessKey('tool')   // force re-payment on next call
client.clearAccessKeys()        // drop all cached keys

// Session management
client.getOpenSessions()        // open channels by tool name
await client.closeSession('tool') // settle channel on-chain

await client.close()

import { Store } from 'mpp-mcp-gateway/stores'

import { Redis } from '@upstash/redis'
import { createUpstashStore } from 'mpp-mcp-gateway/stores'

const store = createUpstashStore(
  new Redis({ url: process.env.UPSTASH_URL!, token: process.env.UPSTASH_TOKEN! }),
  { keyPrefix: 'mppmcp:', ttlSeconds: 30 * 24 * 3600 }
)

const server = createPaidMcpServer({
  // ...
  accessKeyStore: store,
  sessionStore: store,
})

interface MppMcpStore {
  get<T>(key: string): Promise<T | null>
  put(key: string, value: unknown): Promise<void>
  delete(key: string): Promise<void>
  update<T>(key: string, transform: (current: T | null) => T | null): Promise<T | null>
}

const server = createPaidMcpServer({
  // ...
  rateLimit: {
    refillPerMinute: 60,   // sustained rate
    capacity: 10,          // burst capacity
    perTool: {
      expensive_ai: { refillPerMinute: 5, capacity: 2 },
      cheap_lookup:  { refillPerMinute: 600, capacity: 100 },
    },
    // Custom bucketing (e.g. per-session on HTTP transports)
    keyExtractor: (toolName, extra) => `${toolName}:${extra.sessionId ?? 'default'}`,
  },
})

import { upstashTokenBucketLimiter } from 'mpp-mcp-gateway/rate-limit'

const limiter = upstashTokenBucketLimiter(redis, {
  keyPrefix: 'mppmcp:rl:',
  refillPerMinute: 120,
  capacity: 20,
})

const server = createPaidMcpServer({
  // ...
  rateLimit: { limiter },
})

import { auth } from 'mpp-mcp-gateway'

// Bearer token (constant-time comparison)
mountDashboard(server, app, {
  middleware: auth.bearerToken(process.env.DASHBOARD_TOKEN!, { realm: 'admin' }),
})

// API key in custom header
mountMetrics(server, app, {
  middleware: auth.apiKey({ header: 'x-api-key', value: process.env.METRICS_KEY! }),
})

// HTTP Basic Auth (multi-user)
mountDashboard(server, app, {
  middleware: auth.basicAuth({ users: { admin: 'secret' }, realm: 'gateway' }),
})

// HMAC-signed URLs with TTL
mountDashboard(server, app, {
  middleware: auth.signedQuery({ secret: process.env.URL_SECRET!, ttlSeconds: 300 }),
})

// Public CORS for registry crawlers
mountDiscovery(server, app, {
  middleware: auth.publicCors(),
})

import { mountDashboard } from 'mpp-mcp-gateway'

mountDashboard(server, app, { prefix: '/api' })

import { mountMetrics } from 'mpp-mcp-gateway'

mountMetrics(server, app, {
  middleware: auth.bearerToken(process.env.METRICS_TOKEN!),
})

cd dashboard
npm install
npm run build

import { mountDiscovery } from 'mpp-mcp-gateway'

mountDiscovery(server, app, {
  baseUrl: 'https://api.example.com',
  categories: ['data', 'search'],
  docs: { homepage: 'https://example.com/docs' },
})
// GET /openapi.json → OpenAPI 3.1 with x-payment-info per tool

const server = createPaidMcpServer({
  // ...
  webhooks: {
    url: 'https://example.com/webhook',
    secret: process.env.WEBHOOK_SECRET!,
    events: ['payment.received', 'session.closed'], // or omit for all
    maxAttempts: 3,
    onDrop: async (event, lastError) => {
      // Dead-letter: persist to DB for replay
      await db.insert('webhook_dlq', { event, error: lastError })
    },
  },
})

import { createHmac } from 'node:crypto'

function verify(req) {
  const expected = 'sha256=' + createHmac('sha256', WEBHOOK_SECRET)
    .update(`${req.headers['x-mppmcp-timestamp']}.${req.body}`)
    .digest('hex')
  return timingSafeEqual(Buffer.from(expected), Buffer.from(req.headers['x-mppmcp-signature']))
}

import { trace } from '@opentelemetry/api'

const server = createPaidMcpServer({
  // ...
  tracer: trace.getTracer('mpp-mcp-gateway', '1.0.0'),
})

mppmcp.tool.call (root)
├── mppmcp.payment.charge   (or mppmcp.session.advance, mppmcp.access-key.redeem)
└── mppmcp.handler.run

npx mpp-mcp inspect https://my-gateway.fly.dev --token=secret123
npx mpp-mcp stats https://api.example.com
npx mpp-mcp tools https://api.example.com
npx mpp-mcp calls https://api.example.com --limit=50
npx mpp-mcp keys list https://api.example.com --token=admin

# In-memory demo (no wallet needed)
npm run example:demo

# Server + client pairs
npm run example:server      # then in another terminal:
npm run example:client

npm run example:http:server
npm run example:http:client

npm run example:streaming:server
npm run example:streaming:client

npm run example:subscription:server
npm run example:subscription:client

# Dashboard (with all endpoints)
npm run example:dashboard:server

cast rpc tempo_fundAddress 0xYourAddress --rpc-url https://rpc.moderato.tempo.xyz

src/
├── server.ts          PaidMcpServer — payment gating, stats, shutdown, webhooks
├── client.ts          PaidMcpClient — auto-payment, caps, key caching, sessions
├── types.ts           Core interfaces (PricingModel, configs, stats, results)
├── index.ts           Barrel exports (11 subpath entry points)
├── access-keys.ts     Issue, redeem (atomic), validate, duration parsing
├── amounts.ts         BigInt <-> USD string conversion (exact arithmetic)
├── auth.ts            5 Express middleware factories (timing-safe)
├── cli.ts             Operator CLI (inspect, stats, tools, calls, keys)
├── constants.ts       Tempo networks, token addresses, escrow contracts
├── dashboard.ts       JSON API: /api/stats, /api/tools, /api/calls
├── discovery.ts       OpenAPI 3.1 generation with x-payment-info
├── errors.ts          9 typed error classes with stable codes
├── logger.ts          Logger interface + 4 implementations + redaction
├── metrics.ts         Prometheus /metrics (hand-formatted, zero deps)
├── rate-limit.ts      RateLimiter interface + 3 implementations
├── runtime.ts         Cross-runtime: randomHex, writeLogLine, hmacSha256Hex
├── tracing.ts         OTel span helpers (no-op when disabled)
├── webhooks.ts        HMAC-signed event push with retry + dead-letter
└── stores/
    ├── types.ts       MppMcpStore interface
    ├── index.ts       Store namespace + re-exports
    ├── memory.ts      In-memory (atomic via promise chains)
    ├── upstash.ts     Upstash Redis (atomic via Lua CAS)
    ├── cloudflare-kv.ts  Cloudflare KV (best-effort)
    └── bridge.ts      Legacy 3-method store adapter

{
  ".": "Main barrel (everything)",
  "./server": "PaidMcpServer",
  "./client": "PaidMcpClient",
  "./dashboard": "mountDashboard",
  "./discovery": "mountDiscovery, buildOpenApi",
  "./stores": "Store adapters",
  "./rate-limit": "Rate limiter implementations",
  "./auth": "Auth middleware factories",
  "./metrics": "mountMetrics, formatMetrics",
  "./tracing": "startSpan, withSpan, TRACE_ATTRS",
  "./webhooks": "WebhookDispatcher, event types"
}

# Install dependencies
npm install

# Build
npm run build

# Type check
npm run typecheck

# Run tests
npm run test

# Run tests in watch mode
npm run test:watch

# Type tests (tsd)
npm run test:types

# Benchmarks
npm run bench

# Generate docs
npm run docs

process.on('SIGTERM', async () => {
  try {
    await server.close({ timeoutMs: 25_000 })
    process.exit(0)
  } catch {
    process.exit(1) // drain timed out
  }
})

import { consoleLogger, silentLogger, withRedaction } from 'mpp-mcp-gateway'

// Custom logger
const server = createPaidMcpServer({
  // ...
  logger: withRedaction(consoleLogger({ level: 'debug', pretty: true })),
})

// Silence for tests
const server = createPaidMcpServer({
  // ...
  logger: silentLogger(),
})

const adapter: Logger = {
  debug: (m, c) => pino.debug(c, m),
  info: (m, c) => pino.info(c, m),
  warn: (m, c) => pino.warn(c, m),
  error: (m, c) => pino.error(c, m),
  child: (bindings) => /* wrap pino.child(bindings) */,
}