fix(lnd): allow self-payments for LNURL-withdraw

When the user's wallet (e.g. Zeus) is connected to the same LND node
that LP uses, LNURL-withdraw fails because LND rejects the payment
with "no self-payments allowed". This is safe because LP always
decrements the user's balance before paying and refunds on failure.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.dockerignore

@@ -2,3 +2,21 @@
 .github
 build
 node_modules
+
+# Runtime state files (should not be baked into image)
+*.sqlite
+*.sqlite-journal
+*.sqlite-wal
+*.sqlite-shm
+*.db
+admin.connect
+admin.enroll
+admin.npub
+app.nprofile
+.jwt_secret
+
+# Runtime data directories
+metric_cache/
+metric_events/
+bundler_events/
+logs/

Dockerfile

@@ -1,4 +1,4 @@
-FROM node:18
+FROM node:20
 
 WORKDIR /app
 

package.json

@@ -77,6 +77,7 @@
     "zip-a-folder": "^3.1.9"
   },
   "devDependencies": {
+    "@types/better-sqlite3": "^7.6.13",
     "@types/chai": "^4.3.4",
     "@types/chai-string": "^1.4.5",
     "@types/cors": "^2.8.17",

src/extensions/README.md

@@ -0,0 +1,731 @@
+# Lightning.Pub Extension System
+
+A modular extension system that allows third-party functionality to be added to Lightning.Pub without modifying core code.
+
+## Table of Contents
+
+- [Overview](#overview)
+- [Architecture](#architecture)
+- [Creating an Extension](#creating-an-extension)
+- [Extension Lifecycle](#extension-lifecycle)
+- [ExtensionContext API](#extensioncontext-api)
+- [Database Isolation](#database-isolation)
+- [RPC Methods](#rpc-methods)
+- [HTTP Routes](#http-routes)
+- [Event Handling](#event-handling)
+- [Configuration](#configuration)
+- [Examples](#examples)
+
+---
+
+## Overview
+
+The extension system provides:
+
+- **Modularity**: Extensions are self-contained modules with their own code and data
+- **Isolation**: Each extension gets its own SQLite database
+- **Integration**: Extensions can register RPC methods, handle events, and interact with Lightning.Pub's payment and Nostr systems
+- **Lifecycle Management**: Automatic discovery, loading, and graceful shutdown
+
+### Built-in Extensions
+
+| Extension | Description |
+|-----------|-------------|
+| `marketplace` | NIP-15 Nostr marketplace for selling products via Lightning |
+| `withdraw` | LNURL-withdraw (LUD-03) for vouchers, faucets, and gifts |
+
+---
+
+## Architecture
+
+```
+┌─────────────────────────────────────────────────────────────────┐
+│                        Lightning.Pub                             │
+├─────────────────────────────────────────────────────────────────┤
+│                      Extension Loader                            │
+│  ┌─────────────┐  ┌─────────────┐  ┌─────────────┐              │
+│  │ Extension A │  │ Extension B │  │ Extension C │   ...        │
+│  │  ┌───────┐  │  │  ┌───────┐  │  │  ┌───────┐  │              │
+│  │  │Context│  │  │  │Context│  │  │  │Context│  │              │
+│  │  └───────┘  │  │  └───────┘  │  │  └───────┘  │              │
+│  │  ┌───────┐  │  │  ┌───────┐  │  │  ┌───────┐  │              │
+│  │  │  DB   │  │  │  │  DB   │  │  │  │  DB   │  │              │
+│  │  └───────┘  │  │  └───────┘  │  │  └───────┘  │              │
+│  └─────────────┘  └─────────────┘  └─────────────┘              │
+├─────────────────────────────────────────────────────────────────┤
+│  Payment Manager  │  Nostr Transport  │  Application Manager    │
+└─────────────────────────────────────────────────────────────────┘
+```
+
+### Key Components
+
+| Component | File | Description |
+|-----------|------|-------------|
+| `ExtensionLoader` | `loader.ts` | Discovers, loads, and manages extensions |
+| `ExtensionContext` | `context.ts` | Bridge between extensions and Lightning.Pub |
+| `ExtensionDatabase` | `database.ts` | Isolated SQLite database per extension |
+
+---
+
+## Creating an Extension
+
+### Directory Structure
+
+```
+src/extensions/
+└── my-extension/
+    ├── index.ts           # Main entry point (required)
+    ├── types.ts           # TypeScript interfaces
+    ├── migrations.ts      # Database migrations
+    └── managers/          # Business logic
+        └── myManager.ts
+```
+
+### Minimal Extension
+
+```typescript
+// src/extensions/my-extension/index.ts
+
+import { Extension, ExtensionInfo, ExtensionContext, ExtensionDatabase } from '../types.js'
+
+export default class MyExtension implements Extension {
+  readonly info: ExtensionInfo = {
+    id: 'my-extension',        // Must match directory name
+    name: 'My Extension',
+    version: '1.0.0',
+    description: 'Does something useful',
+    author: 'Your Name',
+    minPubVersion: '1.0.0'     // Minimum Lightning.Pub version
+  }
+
+  async initialize(ctx: ExtensionContext, db: ExtensionDatabase): Promise<void> {
+    // Run migrations
+    await db.execute(`
+      CREATE TABLE IF NOT EXISTS my_table (
+        id TEXT PRIMARY KEY,
+        data TEXT
+      )
+    `)
+
+    // Register RPC methods
+    ctx.registerMethod('my-extension.doSomething', async (req, appId) => {
+      return { result: 'done' }
+    })
+
+    ctx.log('info', 'Extension initialized')
+  }
+
+  async shutdown(): Promise<void> {
+    // Cleanup resources
+  }
+}
+```
+
+### Extension Interface
+
+```typescript
+interface Extension {
+  // Required: Extension metadata
+  readonly info: ExtensionInfo
+
+  // Required: Called once when extension is loaded
+  initialize(ctx: ExtensionContext, db: ExtensionDatabase): Promise<void>
+
+  // Optional: Called when Lightning.Pub shuts down
+  shutdown?(): Promise<void>
+
+  // Optional: Health check for monitoring
+  healthCheck?(): Promise<boolean>
+}
+
+interface ExtensionInfo {
+  id: string              // Unique identifier (lowercase, no spaces)
+  name: string            // Display name
+  version: string         // Semver version
+  description: string     // Short description
+  author: string          // Author name
+  minPubVersion?: string  // Minimum Lightning.Pub version
+  dependencies?: string[] // Other extension IDs required
+}
+```
+
+---
+
+## Extension Lifecycle
+
+```
+┌──────────────┐
+│   Discover   │  Scan extensions directory for index.ts files
+└──────┬───────┘
+       │
+       ▼
+┌──────────────┐
+│    Load      │  Import module, instantiate class
+└──────┬───────┘
+       │
+       ▼
+┌──────────────┐
+│  Initialize  │  Create database, call initialize()
+└──────┬───────┘
+       │
+       ▼
+┌──────────────┐
+│    Ready     │  Extension is active, handling requests
+└──────┬───────┘
+       │
+       ▼ (on shutdown)
+┌──────────────┐
+│   Shutdown   │  Call shutdown(), close database
+└──────────────┘
+```
+
+### States
+
+| State | Description |
+|-------|-------------|
+| `loading` | Extension is being loaded |
+| `ready` | Extension is active and healthy |
+| `error` | Initialization failed |
+| `stopped` | Extension has been shut down |
+
+---
+
+## ExtensionContext API
+
+The `ExtensionContext` is passed to your extension during initialization. It provides access to Lightning.Pub functionality.
+
+### Application Management
+
+```typescript
+// Get information about an application
+const app = await ctx.getApplication(applicationId)
+// Returns: { id, name, nostr_public, balance_sats } | null
+```
+
+### Payment Operations
+
+```typescript
+// Create a Lightning invoice
+const invoice = await ctx.createInvoice(amountSats, {
+  memo: 'Payment for service',
+  expiry: 3600,  // seconds
+  metadata: { order_id: '123' }  // Returned in payment callback
+})
+// Returns: { id, paymentRequest, paymentHash, expiry }
+
+// Pay a Lightning invoice
+const result = await ctx.payInvoice(applicationId, bolt11Invoice, maxFeeSats)
+// Returns: { paymentHash, feeSats }
+```
+
+### Nostr Operations
+
+```typescript
+// Send encrypted DM (NIP-44)
+const eventId = await ctx.sendEncryptedDM(applicationId, recipientPubkey, content)
+
+// Publish a Nostr event (signed by application's key)
+const eventId = await ctx.publishNostrEvent({
+  kind: 30017,
+  pubkey: appPubkey,
+  created_at: Math.floor(Date.now() / 1000),
+  tags: [['d', 'identifier']],
+  content: JSON.stringify(data)
+})
+```
+
+### RPC Method Registration
+
+```typescript
+// Register a method that can be called via RPC
+ctx.registerMethod('my-extension.methodName', async (request, applicationId, userPubkey?) => {
+  // request: The RPC request payload
+  // applicationId: The calling application's ID
+  // userPubkey: The user's Nostr pubkey (if authenticated)
+
+  return { result: 'success' }
+})
+```
+
+### Event Subscriptions
+
+```typescript
+// Subscribe to payment received events
+ctx.onPaymentReceived(async (payment) => {
+  // payment: { invoiceId, paymentHash, amountSats, metadata }
+
+  if (payment.metadata?.extension === 'my-extension') {
+    // Handle payment for this extension
+  }
+})
+
+// Subscribe to incoming Nostr events
+ctx.onNostrEvent(async (event, applicationId) => {
+  // event: { id, pubkey, kind, tags, content, created_at }
+  // applicationId: The application this event is for
+
+  if (event.kind === 4) {  // DM
+    // Handle incoming message
+  }
+})
+```
+
+### Logging
+
+```typescript
+ctx.log('debug', 'Detailed debugging info')
+ctx.log('info', 'Normal operation info')
+ctx.log('warn', 'Warning message')
+ctx.log('error', 'Error occurred', errorObject)
+```
+
+---
+
+## Database Isolation
+
+Each extension gets its own SQLite database file at:
+```
+{databaseDir}/{extension-id}.db
+```
+
+### Database Interface
+
+```typescript
+interface ExtensionDatabase {
+  // Execute write queries (INSERT, UPDATE, DELETE, CREATE)
+  execute(sql: string, params?: any[]): Promise<{ changes?: number; lastId?: number }>
+
+  // Execute read queries (SELECT)
+  query<T>(sql: string, params?: any[]): Promise<T[]>
+
+  // Run multiple statements in a transaction
+  transaction<T>(fn: () => Promise<T>): Promise<T>
+}
+```
+
+### Migration Pattern
+
+```typescript
+// migrations.ts
+
+export interface Migration {
+  version: number
+  name: string
+  up: (db: ExtensionDatabase) => Promise<void>
+}
+
+export const migrations: Migration[] = [
+  {
+    version: 1,
+    name: 'create_initial_tables',
+    up: async (db) => {
+      await db.execute(`
+        CREATE TABLE items (
+          id TEXT PRIMARY KEY,
+          name TEXT NOT NULL,
+          created_at INTEGER NOT NULL
+        )
+      `)
+    }
+  },
+  {
+    version: 2,
+    name: 'add_status_column',
+    up: async (db) => {
+      await db.execute(`ALTER TABLE items ADD COLUMN status TEXT DEFAULT 'active'`)
+    }
+  }
+]
+
+// Run migrations in initialize()
+export async function runMigrations(db: ExtensionDatabase): Promise<void> {
+  const result = await db.query<{ value: string }>(
+    `SELECT value FROM _extension_meta WHERE key = 'migration_version'`
+  ).catch(() => [])
+
+  const currentVersion = result.length > 0 ? parseInt(result[0].value, 10) : 0
+
+  for (const migration of migrations) {
+    if (migration.version > currentVersion) {
+      console.log(`Running migration ${migration.version}: ${migration.name}`)
+      await migration.up(db)
+      await db.execute(
+        `INSERT INTO _extension_meta (key, value) VALUES ('migration_version', ?)
+         ON CONFLICT(key) DO UPDATE SET value = excluded.value`,
+        [String(migration.version)]
+      )
+    }
+  }
+}
+```
+
+---
+
+## RPC Methods
+
+Extensions register RPC methods that can be called by clients.
+
+### Naming Convention
+
+Methods should be namespaced with the extension ID:
+```
+{extension-id}.{methodName}
+```
+
+Examples:
+- `marketplace.createStall`
+- `withdraw.createLink`
+
+### Method Handler Signature
+
+```typescript
+type RpcMethodHandler = (
+  request: any,           // The request payload
+  applicationId: string,  // The calling application
+  userPubkey?: string     // The authenticated user (if any)
+) => Promise<any>
+```
+
+### Example
+
+```typescript
+ctx.registerMethod('my-extension.createItem', async (req, appId, userPubkey) => {
+  // Validate request
+  if (!req.name) {
+    throw new Error('Name is required')
+  }
+
+  // Create item
+  const item = await this.manager.create(appId, req)
+
+  // Return response
+  return { item }
+})
+```
+
+---
+
+## HTTP Routes
+
+Some extensions need HTTP endpoints (e.g., LNURL protocol). Extensions can define routes that the main application mounts.
+
+### Defining Routes
+
+```typescript
+interface HttpRoute {
+  method: 'GET' | 'POST'
+  path: string
+  handler: (req: HttpRequest) => Promise<HttpResponse>
+}
+
+interface HttpRequest {
+  params: Record<string, string>   // URL path params
+  query: Record<string, string>    // Query string params
+  body?: any                       // POST body
+  headers: Record<string, string>
+}
+
+interface HttpResponse {
+  status: number
+  body: any
+  headers?: Record<string, string>
+}
+```
+
+### Example
+
+```typescript
+class MyExtension implements Extension {
+  getHttpRoutes(): HttpRoute[] {
+    return [
+      {
+        method: 'GET',
+        path: '/api/v1/my-extension/:id',
+        handler: async (req) => {
+          const item = await this.getItem(req.params.id)
+          return {
+            status: 200,
+            body: item,
+            headers: { 'Content-Type': 'application/json' }
+          }
+        }
+      }
+    ]
+  }
+}
+```
+
+---
+
+## Event Handling
+
+### Payment Callbacks
+
+When you create an invoice with metadata, you'll receive that metadata back in the payment callback:
+
+```typescript
+// Creating invoice with metadata
+const invoice = await ctx.createInvoice(1000, {
+  metadata: {
+    extension: 'my-extension',
+    order_id: 'order-123'
+  }
+})
+
+// Handling payment
+ctx.onPaymentReceived(async (payment) => {
+  if (payment.metadata?.extension === 'my-extension') {
+    const orderId = payment.metadata.order_id
+    await this.handlePayment(orderId, payment)
+  }
+})
+```
+
+### Nostr Events
+
+Subscribe to Nostr events for your application:
+
+```typescript
+ctx.onNostrEvent(async (event, applicationId) => {
+  // Filter by event kind
+  if (event.kind === 4) {  // Encrypted DM
+    await this.handleDirectMessage(event, applicationId)
+  }
+})
+```
+
+---
+
+## Configuration
+
+### Loader Configuration
+
+```typescript
+interface ExtensionLoaderConfig {
+  extensionsDir: string         // Directory containing extensions
+  databaseDir: string           // Directory for extension databases
+  enabledExtensions?: string[]  // Whitelist (if set, only these load)
+  disabledExtensions?: string[] // Blacklist
+}
+```
+
+### Usage
+
+```typescript
+import { createExtensionLoader } from './extensions'
+
+const loader = createExtensionLoader({
+  extensionsDir: './src/extensions',
+  databaseDir: './data/extensions',
+  disabledExtensions: ['experimental-ext']
+}, mainHandler)
+
+await loader.loadAll()
+
+// Call extension methods
+const result = await loader.callMethod(
+  'marketplace.createStall',
+  { name: 'My Shop', currency: 'sat', shipping_zones: [] },
+  applicationId,
+  userPubkey
+)
+
+// Dispatch events
+loader.dispatchPaymentReceived(paymentData)
+loader.dispatchNostrEvent(event, applicationId)
+
+// Shutdown
+await loader.shutdown()
+```
+
+---
+
+## Examples
+
+### Example: Simple Counter Extension
+
+```typescript
+// src/extensions/counter/index.ts
+
+import { Extension, ExtensionInfo, ExtensionContext, ExtensionDatabase } from '../types.js'
+
+export default class CounterExtension implements Extension {
+  readonly info: ExtensionInfo = {
+    id: 'counter',
+    name: 'Simple Counter',
+    version: '1.0.0',
+    description: 'A simple counter for each application',
+    author: 'Example'
+  }
+
+  private db!: ExtensionDatabase
+
+  async initialize(ctx: ExtensionContext, db: ExtensionDatabase): Promise<void> {
+    this.db = db
+
+    await db.execute(`
+      CREATE TABLE IF NOT EXISTS counters (
+        application_id TEXT PRIMARY KEY,
+        count INTEGER NOT NULL DEFAULT 0
+      )
+    `)
+
+    ctx.registerMethod('counter.increment', async (req, appId) => {
+      await db.execute(
+        `INSERT INTO counters (application_id, count) VALUES (?, 1)
+         ON CONFLICT(application_id) DO UPDATE SET count = count + 1`,
+        [appId]
+      )
+      const result = await db.query<{ count: number }>(
+        'SELECT count FROM counters WHERE application_id = ?',
+        [appId]
+      )
+      return { count: result[0]?.count || 0 }
+    })
+
+    ctx.registerMethod('counter.get', async (req, appId) => {
+      const result = await db.query<{ count: number }>(
+        'SELECT count FROM counters WHERE application_id = ?',
+        [appId]
+      )
+      return { count: result[0]?.count || 0 }
+    })
+
+    ctx.registerMethod('counter.reset', async (req, appId) => {
+      await db.execute(
+        'UPDATE counters SET count = 0 WHERE application_id = ?',
+        [appId]
+      )
+      return { count: 0 }
+    })
+  }
+}
+```
+
+### Example: Payment-Triggered Extension
+
+```typescript
+// src/extensions/donations/index.ts
+
+import { Extension, ExtensionContext, ExtensionDatabase } from '../types.js'
+
+export default class DonationsExtension implements Extension {
+  readonly info = {
+    id: 'donations',
+    name: 'Donations',
+    version: '1.0.0',
+    description: 'Accept donations with thank-you messages',
+    author: 'Example'
+  }
+
+  private db!: ExtensionDatabase
+  private ctx!: ExtensionContext
+
+  async initialize(ctx: ExtensionContext, db: ExtensionDatabase): Promise<void> {
+    this.db = db
+    this.ctx = ctx
+
+    await db.execute(`
+      CREATE TABLE IF NOT EXISTS donations (
+        id TEXT PRIMARY KEY,
+        application_id TEXT NOT NULL,
+        amount_sats INTEGER NOT NULL,
+        donor_pubkey TEXT,
+        message TEXT,
+        created_at INTEGER NOT NULL
+      )
+    `)
+
+    // Create donation invoice
+    ctx.registerMethod('donations.createInvoice', async (req, appId) => {
+      const invoice = await ctx.createInvoice(req.amount_sats, {
+        memo: req.message || 'Donation',
+        metadata: {
+          extension: 'donations',
+          donor_pubkey: req.donor_pubkey,
+          message: req.message
+        }
+      })
+      return { invoice: invoice.paymentRequest }
+    })
+
+    // Handle successful payments
+    ctx.onPaymentReceived(async (payment) => {
+      if (payment.metadata?.extension !== 'donations') return
+
+      // Record donation
+      await db.execute(
+        `INSERT INTO donations (id, application_id, amount_sats, donor_pubkey, message, created_at)
+         VALUES (?, ?, ?, ?, ?, ?)`,
+        [
+          payment.paymentHash,
+          payment.metadata.application_id,
+          payment.amountSats,
+          payment.metadata.donor_pubkey,
+          payment.metadata.message,
+          Math.floor(Date.now() / 1000)
+        ]
+      )
+
+      // Send thank-you DM if donor has pubkey
+      if (payment.metadata.donor_pubkey) {
+        await ctx.sendEncryptedDM(
+          payment.metadata.application_id,
+          payment.metadata.donor_pubkey,
+          `Thank you for your donation of ${payment.amountSats} sats!`
+        )
+      }
+    })
+
+    // List donations
+    ctx.registerMethod('donations.list', async (req, appId) => {
+      const donations = await db.query(
+        `SELECT * FROM donations WHERE application_id = ? ORDER BY created_at DESC LIMIT ?`,
+        [appId, req.limit || 50]
+      )
+      return { donations }
+    })
+  }
+}
+```
+
+---
+
+## Best Practices
+
+1. **Namespace your methods**: Always prefix RPC methods with your extension ID
+2. **Use migrations**: Never modify existing migration files; create new ones
+3. **Handle errors gracefully**: Throw descriptive errors, don't return error objects
+4. **Clean up in shutdown**: Close connections, cancel timers, etc.
+5. **Log appropriately**: Use debug for verbose info, error for failures
+6. **Validate inputs**: Check request parameters before processing
+7. **Use transactions**: For multi-step database operations
+8. **Document your API**: Include types and descriptions for RPC methods
+
+---
+
+## Troubleshooting
+
+### Extension not loading
+
+1. Check that directory name matches `info.id`
+2. Verify `index.ts` has a default export
+3. Check for TypeScript/import errors in logs
+
+### Database errors
+
+1. Check migration syntax
+2. Verify column types match queries
+3. Look for migration version conflicts
+
+### RPC method not found
+
+1. Verify method is registered in `initialize()`
+2. Check method name includes extension prefix
+3. Ensure extension status is `ready`
+
+### Payment callbacks not firing
+
+1. Verify `metadata.extension` matches your extension ID
+2. Check that `onPaymentReceived` is registered in `initialize()`
+3. Confirm invoice was created through the extension

src/extensions/context.ts

@@ -0,0 +1,324 @@
+import {
+  ExtensionContext,
+  ExtensionDatabase,
+  ExtensionInfo,
+  ApplicationInfo,
+  CreateInvoiceOptions,
+  CreatedInvoice,
+  PaymentReceivedData,
+  NostrEvent,
+  UnsignedNostrEvent,
+  RpcMethodHandler,
+  LnurlPayInfo
+} from './types.js'
+
+/**
+ * Main Handler interface (from Lightning.Pub)
+ * This is a minimal interface - the actual MainHandler has more methods
+ */
+export interface MainHandlerInterface {
+  // Application management
+  applicationManager: {
+    getById(id: string): Promise<any>
+    PayAppUserInvoice(appId: string, req: {
+      amount: number
+      invoice: string
+      user_identifier: string
+      debit_npub?: string
+    }): Promise<{
+      preimage: string
+      amount_paid: number
+      network_fee: number
+      service_fee: number
+    }>
+  }
+
+  // Payment operations
+  paymentManager: {
+    createInvoice(params: {
+      applicationId: string
+      amountSats: number
+      memo?: string
+      expiry?: number
+      metadata?: Record<string, any>
+    }): Promise<{
+      id: string
+      paymentRequest: string
+      paymentHash: string
+      expiry: number
+    }>
+
+    payInvoice(params: {
+      applicationId: string
+      paymentRequest: string
+      maxFeeSats?: number
+      userPubkey?: string
+    }): Promise<{
+      paymentHash: string
+      feeSats: number
+    }>
+
+    /**
+     * Get LNURL-pay info for a user by their Nostr pubkey
+     * This enables Lightning Address (LUD-16) and zap (NIP-57) support
+     */
+    getLnurlPayInfoByPubkey(pubkeyHex: string, options?: {
+      metadata?: string
+      description?: string
+    }): Promise<LnurlPayInfo>
+  }
+
+  // Nostr operations
+  sendNostrEvent(event: any): Promise<string | null>
+  sendEncryptedDM(applicationId: string, recipientPubkey: string, content: string): Promise<string>
+}
+
+/**
+ * Callback registries for extension events
+ */
+interface CallbackRegistries {
+  paymentReceived: Array<(payment: PaymentReceivedData) => Promise<void>>
+  nostrEvent: Array<(event: NostrEvent, applicationId: string) => Promise<void>>
+}
+
+/**
+ * Registered RPC method
+ */
+interface RegisteredMethod {
+  extensionId: string
+  handler: RpcMethodHandler
+}
+
+/**
+ * Extension Context Implementation
+ *
+ * Provides the interface for extensions to interact with Lightning.Pub.
+ * Each extension gets its own context instance.
+ */
+export class ExtensionContextImpl implements ExtensionContext {
+  private callbacks: CallbackRegistries = {
+    paymentReceived: [],
+    nostrEvent: []
+  }
+
+  constructor(
+    private extensionInfo: ExtensionInfo,
+    private database: ExtensionDatabase,
+    private mainHandler: MainHandlerInterface,
+    private methodRegistry: Map<string, RegisteredMethod>
+  ) {}
+
+  /**
+   * Get information about an application
+   */
+  async getApplication(applicationId: string): Promise<ApplicationInfo | null> {
+    try {
+      const app = await this.mainHandler.applicationManager.getById(applicationId)
+      if (!app) return null
+
+      return {
+        id: app.id,
+        name: app.name,
+        nostr_public: app.nostr_public,
+        balance_sats: app.balance || 0
+      }
+    } catch (e) {
+      this.log('error', `Failed to get application ${applicationId}:`, e)
+      return null
+    }
+  }
+
+  /**
+   * Create a Lightning invoice
+   */
+  async createInvoice(amountSats: number, options: CreateInvoiceOptions = {}): Promise<CreatedInvoice> {
+    // Note: In practice, this needs an applicationId. Extensions typically
+    // get this from the RPC request context. For now, we'll need to handle
+    // this in the actual implementation.
+    throw new Error('createInvoice requires applicationId from request context')
+  }
+
+  /**
+   * Create invoice with explicit application ID
+   * This is the internal method used by extensions
+   */
+  async createInvoiceForApp(
+    applicationId: string,
+    amountSats: number,
+    options: CreateInvoiceOptions = {}
+  ): Promise<CreatedInvoice> {
+    const result = await this.mainHandler.paymentManager.createInvoice({
+      applicationId,
+      amountSats,
+      memo: options.memo,
+      expiry: options.expiry,
+      metadata: {
+        ...options.metadata,
+        extension: this.extensionInfo.id
+      }
+    })
+
+    return {
+      id: result.id,
+      paymentRequest: result.paymentRequest,
+      paymentHash: result.paymentHash,
+      expiry: result.expiry
+    }
+  }
+
+  /**
+   * Pay a Lightning invoice
+   * If userPubkey is provided, pays from that user's balance instead of app.owner
+   */
+  async payInvoice(
+    applicationId: string,
+    paymentRequest: string,
+    maxFeeSats?: number,
+    userPubkey?: string
+  ): Promise<{ paymentHash: string; feeSats: number }> {
+    return this.mainHandler.paymentManager.payInvoice({
+      applicationId,
+      paymentRequest,
+      maxFeeSats,
+      userPubkey
+    })
+  }
+
+  /**
+   * Send an encrypted DM via Nostr
+   */
+  async sendEncryptedDM(
+    applicationId: string,
+    recipientPubkey: string,
+    content: string
+  ): Promise<string> {
+    return this.mainHandler.sendEncryptedDM(applicationId, recipientPubkey, content)
+  }
+
+  /**
+   * Publish a Nostr event
+   */
+  async publishNostrEvent(event: UnsignedNostrEvent): Promise<string | null> {
+    return this.mainHandler.sendNostrEvent(event)
+  }
+
+  /**
+   * Get LNURL-pay info for a user by pubkey
+   * Enables Lightning Address and zap support
+   */
+  async getLnurlPayInfo(pubkeyHex: string, options?: {
+    metadata?: string
+    description?: string
+  }): Promise<LnurlPayInfo> {
+    return this.mainHandler.paymentManager.getLnurlPayInfoByPubkey(pubkeyHex, options)
+  }
+
+  /**
+   * Subscribe to payment received callbacks
+   */
+  onPaymentReceived(callback: (payment: PaymentReceivedData) => Promise<void>): void {
+    this.callbacks.paymentReceived.push(callback)
+  }
+
+  /**
+   * Subscribe to incoming Nostr events
+   */
+  onNostrEvent(callback: (event: NostrEvent, applicationId: string) => Promise<void>): void {
+    this.callbacks.nostrEvent.push(callback)
+  }
+
+  /**
+   * Register an RPC method
+   */
+  registerMethod(name: string, handler: RpcMethodHandler): void {
+    const fullName = name.startsWith(`${this.extensionInfo.id}.`)
+      ? name
+      : `${this.extensionInfo.id}.${name}`
+
+    if (this.methodRegistry.has(fullName)) {
+      throw new Error(`RPC method ${fullName} already registered`)
+    }
+
+    this.methodRegistry.set(fullName, {
+      extensionId: this.extensionInfo.id,
+      handler
+    })
+
+    this.log('debug', `Registered RPC method: ${fullName}`)
+  }
+
+  /**
+   * Get the extension's database
+   */
+  getDatabase(): ExtensionDatabase {
+    return this.database
+  }
+
+  /**
+   * Log a message
+   */
+  log(level: 'debug' | 'info' | 'warn' | 'error', message: string, ...args: any[]): void {
+    const prefix = `[Extension:${this.extensionInfo.id}]`
+    switch (level) {
+      case 'debug':
+        console.debug(prefix, message, ...args)
+        break
+      case 'info':
+        console.info(prefix, message, ...args)
+        break
+      case 'warn':
+        console.warn(prefix, message, ...args)
+        break
+      case 'error':
+        console.error(prefix, message, ...args)
+        break
+    }
+  }
+
+  // ===== Internal Methods (called by ExtensionLoader) =====
+
+  /**
+   * Dispatch payment received event to extension callbacks
+   */
+  async dispatchPaymentReceived(payment: PaymentReceivedData): Promise<void> {
+    for (const callback of this.callbacks.paymentReceived) {
+      try {
+        await callback(payment)
+      } catch (e) {
+        this.log('error', 'Error in payment callback:', e)
+      }
+    }
+  }
+
+  /**
+   * Dispatch Nostr event to extension callbacks
+   */
+  async dispatchNostrEvent(event: NostrEvent, applicationId: string): Promise<void> {
+    for (const callback of this.callbacks.nostrEvent) {
+      try {
+        await callback(event, applicationId)
+      } catch (e) {
+        this.log('error', 'Error in Nostr event callback:', e)
+      }
+    }
+  }
+
+  /**
+   * Get registered callbacks for external access
+   */
+  getCallbacks(): CallbackRegistries {
+    return this.callbacks
+  }
+}
+
+/**
+ * Create an extension context
+ */
+export function createExtensionContext(
+  extensionInfo: ExtensionInfo,
+  database: ExtensionDatabase,
+  mainHandler: MainHandlerInterface,
+  methodRegistry: Map<string, RegisteredMethod>
+): ExtensionContextImpl {
+  return new ExtensionContextImpl(extensionInfo, database, mainHandler, methodRegistry)
+}

src/extensions/database.ts

@@ -0,0 +1,148 @@
+import Database from 'better-sqlite3'
+import path from 'path'
+import fs from 'fs'
+import { ExtensionDatabase } from './types.js'
+
+/**
+ * Extension Database Implementation
+ *
+ * Provides isolated SQLite database access for each extension.
+ * Uses better-sqlite3 for synchronous, high-performance access.
+ */
+export class ExtensionDatabaseImpl implements ExtensionDatabase {
+  private db: Database.Database
+  private extensionId: string
+
+  constructor(extensionId: string, databaseDir: string) {
+    this.extensionId = extensionId
+
+    // Ensure database directory exists
+    if (!fs.existsSync(databaseDir)) {
+      fs.mkdirSync(databaseDir, { recursive: true })
+    }
+
+    // Create database file for this extension
+    const dbPath = path.join(databaseDir, `${extensionId}.db`)
+    this.db = new Database(dbPath)
+
+    // Enable WAL mode for better concurrency
+    this.db.pragma('journal_mode = WAL')
+
+    // Enable foreign keys
+    this.db.pragma('foreign_keys = ON')
+
+    // Create metadata table for tracking migrations
+    this.db.exec(`
+      CREATE TABLE IF NOT EXISTS _extension_meta (
+        key TEXT PRIMARY KEY,
+        value TEXT NOT NULL
+      )
+    `)
+  }
+
+  /**
+   * Execute a write query (INSERT, UPDATE, DELETE, CREATE, etc.)
+   */
+  async execute(sql: string, params: any[] = []): Promise<{ changes?: number; lastId?: number }> {
+    try {
+      const stmt = this.db.prepare(sql)
+      const result = stmt.run(...params)
+
+      return {
+        changes: result.changes,
+        lastId: result.lastInsertRowid as number
+      }
+    } catch (e) {
+      console.error(`[Extension:${this.extensionId}] Database execute error:`, e)
+      throw e
+    }
+  }
+
+  /**
+   * Execute a read query (SELECT)
+   */
+  async query<T = any>(sql: string, params: any[] = []): Promise<T[]> {
+    try {
+      const stmt = this.db.prepare(sql)
+      return stmt.all(...params) as T[]
+    } catch (e) {
+      console.error(`[Extension:${this.extensionId}] Database query error:`, e)
+      throw e
+    }
+  }
+
+  /**
+   * Execute multiple statements in a transaction
+   */
+  async transaction<T>(fn: () => Promise<T>): Promise<T> {
+    const runTransaction = this.db.transaction(() => {
+      // Note: better-sqlite3 transactions are synchronous
+      // We wrap the async function but it executes synchronously
+      return fn()
+    })
+
+    return runTransaction() as T
+  }
+
+  /**
+   * Get a metadata value
+   */
+  async getMeta(key: string): Promise<string | null> {
+    const rows = await this.query<{ value: string }>(
+      'SELECT value FROM _extension_meta WHERE key = ?',
+      [key]
+    )
+    return rows.length > 0 ? rows[0].value : null
+  }
+
+  /**
+   * Set a metadata value
+   */
+  async setMeta(key: string, value: string): Promise<void> {
+    await this.execute(
+      `INSERT INTO _extension_meta (key, value) VALUES (?, ?)
+       ON CONFLICT(key) DO UPDATE SET value = excluded.value`,
+      [key, value]
+    )
+  }
+
+  /**
+   * Get current migration version
+   */
+  async getMigrationVersion(): Promise<number> {
+    const version = await this.getMeta('migration_version')
+    return version ? parseInt(version, 10) : 0
+  }
+
+  /**
+   * Set migration version
+   */
+  async setMigrationVersion(version: number): Promise<void> {
+    await this.setMeta('migration_version', String(version))
+  }
+
+  /**
+   * Close the database connection
+   */
+  close(): void {
+    this.db.close()
+  }
+
+  /**
+   * Get the underlying database for advanced operations
+   * (Use with caution - bypasses isolation)
+   */
+  getUnderlyingDb(): Database.Database {
+    return this.db
+  }
+}
+
+/**
+ * Create an extension database instance
+ */
+export function createExtensionDatabase(
+  extensionId: string,
+  databaseDir: string
+): ExtensionDatabaseImpl {
+  return new ExtensionDatabaseImpl(extensionId, databaseDir)
+}

src/extensions/index.ts

@@ -0,0 +1,56 @@
+/**
+ * Lightning.Pub Extension System
+ *
+ * This module provides the extension infrastructure for Lightning.Pub.
+ * Extensions can add functionality like marketplaces, subscriptions,
+ * tipping, and more.
+ *
+ * Usage:
+ *
+ * ```typescript
+ * import { createExtensionLoader, ExtensionLoaderConfig } from './extensions'
+ *
+ * const config: ExtensionLoaderConfig = {
+ *   extensionsDir: './extensions',
+ *   databaseDir: './data/extensions'
+ * }
+ *
+ * const loader = createExtensionLoader(config, mainHandler)
+ * await loader.loadAll()
+ *
+ * // Call extension methods
+ * const result = await loader.callMethod(
+ *   'marketplace.createStall',
+ *   { name: 'My Shop', currency: 'sat', shipping_zones: [...] },
+ *   applicationId
+ * )
+ * ```
+ */
+
+// Export types
+export {
+  Extension,
+  ExtensionInfo,
+  ExtensionContext,
+  ExtensionDatabase,
+  ExtensionModule,
+  ExtensionConstructor,
+  LoadedExtension,
+  ExtensionLoaderConfig,
+  ApplicationInfo,
+  CreateInvoiceOptions,
+  CreatedInvoice,
+  PaymentReceivedData,
+  NostrEvent,
+  UnsignedNostrEvent,
+  RpcMethodHandler
+} from './types.js'
+
+// Export loader
+export { ExtensionLoader, createExtensionLoader } from './loader.js'
+
+// Export database utilities
+export { ExtensionDatabaseImpl, createExtensionDatabase } from './database.js'
+
+// Export context utilities
+export { ExtensionContextImpl, createExtensionContext, MainHandlerInterface } from './context.js'

src/extensions/loader.ts

@@ -0,0 +1,406 @@
+import path from 'path'
+import fs from 'fs'
+import {
+  Extension,
+  ExtensionInfo,
+  ExtensionModule,
+  LoadedExtension,
+  ExtensionLoaderConfig,
+  RpcMethodHandler,
+  PaymentReceivedData,
+  NostrEvent
+} from './types.js'
+import { ExtensionDatabaseImpl, createExtensionDatabase } from './database.js'
+import { ExtensionContextImpl, createExtensionContext, MainHandlerInterface } from './context.js'
+
+/**
+ * Registered RPC method entry
+ */
+interface RegisteredMethod {
+  extensionId: string
+  handler: RpcMethodHandler
+}
+
+/**
+ * Extension Loader
+ *
+ * Discovers, loads, and manages Lightning.Pub extensions.
+ * Provides lifecycle management and event dispatching.
+ */
+export class ExtensionLoader {
+  private config: ExtensionLoaderConfig
+  private mainHandler: MainHandlerInterface
+  private extensions: Map<string, LoadedExtension> = new Map()
+  private contexts: Map<string, ExtensionContextImpl> = new Map()
+  private methodRegistry: Map<string, RegisteredMethod> = new Map()
+  private initialized = false
+
+  constructor(config: ExtensionLoaderConfig, mainHandler: MainHandlerInterface) {
+    this.config = config
+    this.mainHandler = mainHandler
+  }
+
+  /**
+   * Discover and load all extensions
+   */
+  async loadAll(): Promise<void> {
+    if (this.initialized) {
+      throw new Error('Extension loader already initialized')
+    }
+
+    console.log('[Extensions] Loading extensions from:', this.config.extensionsDir)
+
+    // Ensure directories exist
+    if (!fs.existsSync(this.config.extensionsDir)) {
+      console.log('[Extensions] Extensions directory does not exist, creating...')
+      fs.mkdirSync(this.config.extensionsDir, { recursive: true })
+      this.initialized = true
+      return
+    }
+
+    if (!fs.existsSync(this.config.databaseDir)) {
+      fs.mkdirSync(this.config.databaseDir, { recursive: true })
+    }
+
+    // Discover extensions
+    const extensionDirs = await this.discoverExtensions()
+    console.log(`[Extensions] Found ${extensionDirs.length} extension(s)`)
+
+    // Load extensions in dependency order
+    const loadOrder = await this.resolveDependencies(extensionDirs)
+
+    for (const extDir of loadOrder) {
+      try {
+        await this.loadExtension(extDir)
+      } catch (e) {
+        console.error(`[Extensions] Failed to load extension from ${extDir}:`, e)
+      }
+    }
+
+    this.initialized = true
+    console.log(`[Extensions] Loaded ${this.extensions.size} extension(s)`)
+  }
+
+  /**
+   * Discover extension directories
+   */
+  private async discoverExtensions(): Promise<string[]> {
+    const entries = fs.readdirSync(this.config.extensionsDir, { withFileTypes: true })
+    const extensionDirs: string[] = []
+
+    for (const entry of entries) {
+      if (!entry.isDirectory()) continue
+
+      const extDir = path.join(this.config.extensionsDir, entry.name)
+      const indexPath = path.join(extDir, 'index.ts')
+      const indexJsPath = path.join(extDir, 'index.js')
+
+      // Check for index file
+      if (fs.existsSync(indexPath) || fs.existsSync(indexJsPath)) {
+        // Check enabled/disabled lists
+        if (this.config.disabledExtensions?.includes(entry.name)) {
+          console.log(`[Extensions] Skipping disabled extension: ${entry.name}`)
+          continue
+        }
+
+        if (this.config.enabledExtensions &&
+            !this.config.enabledExtensions.includes(entry.name)) {
+          console.log(`[Extensions] Skipping non-enabled extension: ${entry.name}`)
+          continue
+        }
+
+        extensionDirs.push(extDir)
+      }
+    }
+
+    return extensionDirs
+  }
+
+  /**
+   * Resolve extension dependencies and return load order
+   */
+  private async resolveDependencies(extensionDirs: string[]): Promise<string[]> {
+    // For now, simple alphabetical order
+    // TODO: Implement proper dependency resolution with topological sort
+    return extensionDirs.sort()
+  }
+
+  /**
+   * Load a single extension
+   */
+  private async loadExtension(extensionDir: string): Promise<void> {
+    const dirName = path.basename(extensionDir)
+    console.log(`[Extensions] Loading extension: ${dirName}`)
+
+    // Determine index file path
+    let indexPath = path.join(extensionDir, 'index.js')
+    if (!fs.existsSync(indexPath)) {
+      indexPath = path.join(extensionDir, 'index.ts')
+    }
+
+    // Dynamic import
+    const moduleUrl = `file://${indexPath}`
+    const module = await import(moduleUrl) as ExtensionModule
+
+    if (!module.default) {
+      throw new Error(`Extension ${dirName} has no default export`)
+    }
+
+    // Instantiate extension
+    const ExtensionClass = module.default
+    const instance = new ExtensionClass() as Extension
+
+    if (!instance.info) {
+      throw new Error(`Extension ${dirName} has no info property`)
+    }
+
+    const info = instance.info
+
+    // Validate extension ID matches directory name
+    if (info.id !== dirName) {
+      console.warn(
+        `[Extensions] Extension ID '${info.id}' doesn't match directory '${dirName}'`
+      )
+    }
+
+    // Check for duplicate
+    if (this.extensions.has(info.id)) {
+      throw new Error(`Extension ${info.id} already loaded`)
+    }
+
+    // Create isolated database
+    const database = createExtensionDatabase(info.id, this.config.databaseDir)
+
+    // Create context
+    const context = createExtensionContext(
+      info,
+      database,
+      this.mainHandler,
+      this.methodRegistry
+    )
+
+    // Track as loading
+    const loaded: LoadedExtension = {
+      info,
+      instance,
+      database,
+      status: 'loading',
+      loadedAt: Date.now()
+    }
+    this.extensions.set(info.id, loaded)
+    this.contexts.set(info.id, context)
+
+    try {
+      // Initialize extension
+      await instance.initialize(context, database)
+
+      loaded.status = 'ready'
+      console.log(`[Extensions] Extension ${info.id} v${info.version} loaded successfully`)
+    } catch (e) {
+      loaded.status = 'error'
+      loaded.error = e as Error
+      console.error(`[Extensions] Extension ${info.id} initialization failed:`, e)
+      throw e
+    }
+  }
+
+  /**
+   * Unload a specific extension
+   */
+  async unloadExtension(extensionId: string): Promise<void> {
+    const loaded = this.extensions.get(extensionId)
+    if (!loaded) {
+      throw new Error(`Extension ${extensionId} not found`)
+    }
+
+    console.log(`[Extensions] Unloading extension: ${extensionId}`)
+
+    try {
+      // Call shutdown if available
+      if (loaded.instance.shutdown) {
+        await loaded.instance.shutdown()
+      }
+
+      loaded.status = 'stopped'
+    } catch (e) {
+      console.error(`[Extensions] Error during ${extensionId} shutdown:`, e)
+    }
+
+    // Close database
+    if (loaded.database instanceof ExtensionDatabaseImpl) {
+      loaded.database.close()
+    }
+
+    // Remove registered methods
+    for (const [name, method] of this.methodRegistry.entries()) {
+      if (method.extensionId === extensionId) {
+        this.methodRegistry.delete(name)
+      }
+    }
+
+    // Remove from maps
+    this.extensions.delete(extensionId)
+    this.contexts.delete(extensionId)
+  }
+
+  /**
+   * Shutdown all extensions
+   */
+  async shutdown(): Promise<void> {
+    console.log('[Extensions] Shutting down all extensions...')
+
+    for (const extensionId of this.extensions.keys()) {
+      try {
+        await this.unloadExtension(extensionId)
+      } catch (e) {
+        console.error(`[Extensions] Error unloading ${extensionId}:`, e)
+      }
+    }
+
+    console.log('[Extensions] All extensions shut down')
+  }
+
+  /**
+   * Get a loaded extension
+   */
+  getExtension(extensionId: string): LoadedExtension | undefined {
+    return this.extensions.get(extensionId)
+  }
+
+  /**
+   * Get all loaded extensions
+   */
+  getAllExtensions(): LoadedExtension[] {
+    return Array.from(this.extensions.values())
+  }
+
+  /**
+   * Check if an extension is loaded and ready
+   */
+  isReady(extensionId: string): boolean {
+    const ext = this.extensions.get(extensionId)
+    return ext?.status === 'ready'
+  }
+
+  /**
+   * Get all registered RPC methods
+   */
+  getRegisteredMethods(): Map<string, RegisteredMethod> {
+    return this.methodRegistry
+  }
+
+  /**
+   * Call an extension RPC method
+   */
+  async callMethod(
+    methodName: string,
+    request: any,
+    applicationId: string,
+    userPubkey?: string
+  ): Promise<any> {
+    const method = this.methodRegistry.get(methodName)
+    if (!method) {
+      throw new Error(`Unknown method: ${methodName}`)
+    }
+
+    const ext = this.extensions.get(method.extensionId)
+    if (!ext || ext.status !== 'ready') {
+      throw new Error(`Extension ${method.extensionId} not ready`)
+    }
+
+    return method.handler(request, applicationId, userPubkey)
+  }
+
+  /**
+   * Check if a method exists
+   */
+  hasMethod(methodName: string): boolean {
+    return this.methodRegistry.has(methodName)
+  }
+
+  /**
+   * Dispatch payment received event to all extensions
+   */
+  async dispatchPaymentReceived(payment: PaymentReceivedData): Promise<void> {
+    for (const context of this.contexts.values()) {
+      try {
+        await context.dispatchPaymentReceived(payment)
+      } catch (e) {
+        console.error('[Extensions] Error dispatching payment:', e)
+      }
+    }
+  }
+
+  /**
+   * Dispatch Nostr event to all extensions
+   */
+  async dispatchNostrEvent(event: NostrEvent, applicationId: string): Promise<void> {
+    for (const context of this.contexts.values()) {
+      try {
+        await context.dispatchNostrEvent(event, applicationId)
+      } catch (e) {
+        console.error('[Extensions] Error dispatching Nostr event:', e)
+      }
+    }
+  }
+
+  /**
+   * Run health checks on all extensions
+   */
+  async healthCheck(): Promise<Map<string, boolean>> {
+    const results = new Map<string, boolean>()
+
+    for (const [id, ext] of this.extensions.entries()) {
+      if (ext.status !== 'ready') {
+        results.set(id, false)
+        continue
+      }
+
+      try {
+        if (ext.instance.healthCheck) {
+          results.set(id, await ext.instance.healthCheck())
+        } else {
+          results.set(id, true)
+        }
+      } catch (e) {
+        results.set(id, false)
+      }
+    }
+
+    return results
+  }
+
+  /**
+   * Get extension status summary
+   */
+  getStatus(): {
+    total: number
+    ready: number
+    error: number
+    extensions: Array<{ id: string; name: string; version: string; status: string }>
+  } {
+    const extensions = this.getAllExtensions().map(ext => ({
+      id: ext.info.id,
+      name: ext.info.name,
+      version: ext.info.version,
+      status: ext.status
+    }))
+
+    return {
+      total: extensions.length,
+      ready: extensions.filter(e => e.status === 'ready').length,
+      error: extensions.filter(e => e.status === 'error').length,
+      extensions
+    }
+  }
+}
+
+/**
+ * Create an extension loader instance
+ */
+export function createExtensionLoader(
+  config: ExtensionLoaderConfig,
+  mainHandler: MainHandlerInterface
+): ExtensionLoader {
+  return new ExtensionLoader(config, mainHandler)
+}

src/extensions/mainHandlerAdapter.ts

@@ -0,0 +1,155 @@
+/**
+ * MainHandler Adapter for Extension System
+ *
+ * Wraps the Lightning.Pub mainHandler to provide the MainHandlerInterface
+ * required by the extension system.
+ */
+
+import { MainHandlerInterface } from './context.js'
+import { LnurlPayInfo } from './types.js'
+import type Main from '../services/main/index.js'
+
+/**
+ * Create an adapter that wraps mainHandler for extension use
+ */
+export function createMainHandlerAdapter(mainHandler: Main): MainHandlerInterface {
+  return {
+    applicationManager: {
+      async getById(id: string) {
+        // The applicationManager stores apps internally
+        // We need to access it through the storage layer
+        try {
+          const app = await mainHandler.storage.applicationStorage.GetApplication(id)
+          if (!app) return null
+
+          return {
+            id: app.app_id,
+            name: app.name,
+            nostr_public: app.nostr_public_key || '',
+            balance: app.owner?.balance_sats || 0
+          }
+        } catch (e) {
+          // GetApplication throws if not found
+          return null
+        }
+      },
+
+      async PayAppUserInvoice(appId, req) {
+        return mainHandler.applicationManager.PayAppUserInvoice(appId, req)
+      }
+    },
+
+    paymentManager: {
+      async createInvoice(params: {
+        applicationId: string
+        amountSats: number
+        memo?: string
+        expiry?: number
+        metadata?: Record<string, any>
+      }) {
+        // Get the app to find the user ID
+        const app = await mainHandler.storage.applicationStorage.GetApplication(params.applicationId)
+        if (!app) {
+          throw new Error(`Application not found: ${params.applicationId}`)
+        }
+
+        // Create invoice using the app owner's user ID
+        const result = await mainHandler.paymentManager.NewInvoice(
+          app.owner.user_id,
+          {
+            amountSats: params.amountSats,
+            memo: params.memo || ''
+          },
+          {
+            expiry: params.expiry || 3600
+          }
+        )
+
+        return {
+          id: result.invoice.split(':')[0] || result.invoice, // Extract ID if present
+          paymentRequest: result.invoice,
+          paymentHash: '', // Not directly available from NewInvoice response
+          expiry: Date.now() + (params.expiry || 3600) * 1000
+        }
+      },
+
+      async payInvoice(params: {
+        applicationId: string
+        paymentRequest: string
+        maxFeeSats?: number
+        userPubkey?: string
+      }) {
+        // Get the app to find the user ID and app reference
+        const app = await mainHandler.storage.applicationStorage.GetApplication(params.applicationId)
+        if (!app) {
+          throw new Error(`Application not found: ${params.applicationId}`)
+        }
+
+        if (params.userPubkey) {
+          // Resolve the Nostr user's ApplicationUser to get their identifier
+          const appUser = await mainHandler.storage.applicationStorage.GetOrCreateNostrAppUser(app, params.userPubkey)
+          console.log(`[MainHandlerAdapter] Paying via PayAppUserInvoice from Nostr user ${params.userPubkey.slice(0, 8)}... (identifier: ${appUser.identifier})`)
+
+          // Use applicationManager.PayAppUserInvoice so notifyAppUserPayment fires
+          // This sends LiveUserOperation events via Nostr for real-time balance updates
+          const result = await mainHandler.applicationManager.PayAppUserInvoice(
+            params.applicationId,
+            {
+              invoice: params.paymentRequest,
+              amount: 0, // Use invoice amount
+              user_identifier: appUser.identifier
+            }
+          )
+
+          return {
+            paymentHash: result.preimage || '',
+            feeSats: result.network_fee || 0
+          }
+        }
+
+        // Fallback: pay from app owner's balance (no Nostr user context)
+        const result = await mainHandler.paymentManager.PayInvoice(
+          app.owner.user_id,
+          {
+            invoice: params.paymentRequest,
+            amount: 0
+          },
+          app,
+          {}
+        )
+
+        return {
+          paymentHash: result.preimage || '',
+          feeSats: result.network_fee || 0
+        }
+      },
+
+      async getLnurlPayInfoByPubkey(pubkeyHex: string, options?: {
+        metadata?: string
+        description?: string
+      }): Promise<LnurlPayInfo> {
+        // This would need implementation based on how Lightning.Pub handles LNURL-pay
+        // For now, throw not implemented
+        throw new Error('getLnurlPayInfoByPubkey not yet implemented')
+      }
+    },
+
+    async sendNostrEvent(event: any): Promise<string | null> {
+      // The mainHandler doesn't directly expose nostrSend
+      // This would need to be implemented through the nostrMiddleware
+      // For now, return null (not implemented)
+      console.warn('[MainHandlerAdapter] sendNostrEvent not fully implemented')
+      return null
+    },
+
+    async sendEncryptedDM(
+      applicationId: string,
+      recipientPubkey: string,
+      content: string
+    ): Promise<string> {
+      // This would need implementation using NIP-44 encryption
+      // For now, throw not implemented
+      throw new Error('sendEncryptedDM not yet implemented')
+    }
+  }
+}

src/extensions/types.ts

@@ -0,0 +1,255 @@
+/**
+ * Extension System Core Types
+ *
+ * These types define the contract between Lightning.Pub and extensions.
+ */
+
+/**
+ * Extension metadata
+ */
+export interface ExtensionInfo {
+  id: string                    // Unique identifier (lowercase, no spaces)
+  name: string                  // Display name
+  version: string               // Semver version
+  description: string           // Short description
+  author: string                // Author name or organization
+  minPubVersion?: string        // Minimum Lightning.Pub version required
+  dependencies?: string[]       // Other extension IDs this depends on
+}
+
+/**
+ * Extension database interface
+ * Provides isolated database access for each extension
+ */
+export interface ExtensionDatabase {
+  /**
+   * Execute a write query (INSERT, UPDATE, DELETE, CREATE, etc.)
+   */
+  execute(sql: string, params?: any[]): Promise<{ changes?: number; lastId?: number }>
+
+  /**
+   * Execute a read query (SELECT)
+   */
+  query<T = any>(sql: string, params?: any[]): Promise<T[]>
+
+  /**
+   * Execute multiple statements in a transaction
+   */
+  transaction<T>(fn: () => Promise<T>): Promise<T>
+}
+
+/**
+ * Application info provided to extensions
+ */
+export interface ApplicationInfo {
+  id: string
+  name: string
+  nostr_public: string          // Application's Nostr pubkey (hex)
+  balance_sats: number
+}
+
+/**
+ * Invoice creation options
+ */
+export interface CreateInvoiceOptions {
+  memo?: string
+  expiry?: number               // Seconds until expiry
+  metadata?: Record<string, any>  // Custom metadata for callbacks
+}
+
+/**
+ * Created invoice result
+ */
+export interface CreatedInvoice {
+  id: string                    // Internal invoice ID
+  paymentRequest: string        // BOLT11 invoice string
+  paymentHash: string           // Payment hash (hex)
+  expiry: number                // Expiry timestamp
+}
+
+/**
+ * Payment received callback data
+ */
+export interface PaymentReceivedData {
+  invoiceId: string
+  paymentHash: string
+  amountSats: number
+  metadata?: Record<string, any>
+}
+
+/**
+ * LNURL-pay info response (LUD-06/LUD-16)
+ * Used for Lightning Address and zap support
+ */
+export interface LnurlPayInfo {
+  tag: 'payRequest'
+  callback: string                // URL to call with amount
+  minSendable: number             // Minimum msats
+  maxSendable: number             // Maximum msats
+  metadata: string                // JSON-encoded metadata array
+  allowsNostr?: boolean           // Whether zaps are supported
+  nostrPubkey?: string            // Pubkey for zap receipts (hex)
+}
+
+/**
+ * Nostr event structure (minimal)
+ */
+export interface NostrEvent {
+  id: string
+  pubkey: string
+  created_at: number
+  kind: number
+  tags: string[][]
+  content: string
+  sig?: string
+}
+
+/**
+ * Unsigned Nostr event for publishing
+ */
+export interface UnsignedNostrEvent {
+  kind: number
+  pubkey: string
+  created_at: number
+  tags: string[][]
+  content: string
+}
+
+/**
+ * RPC method handler function
+ */
+export type RpcMethodHandler = (
+  request: any,
+  applicationId: string,
+  userPubkey?: string
+) => Promise<any>
+
+/**
+ * Extension context - interface provided to extensions for interacting with Lightning.Pub
+ */
+export interface ExtensionContext {
+  /**
+   * Get information about an application
+   */
+  getApplication(applicationId: string): Promise<ApplicationInfo | null>
+
+  /**
+   * Create a Lightning invoice
+   */
+  createInvoice(amountSats: number, options?: CreateInvoiceOptions): Promise<CreatedInvoice>
+
+  /**
+   * Pay a Lightning invoice (requires sufficient balance)
+   * If userPubkey is provided, pays from that user's balance instead of app.owner
+   */
+  payInvoice(applicationId: string, paymentRequest: string, maxFeeSats?: number, userPubkey?: string): Promise<{
+    paymentHash: string
+    feeSats: number
+  }>
+
+  /**
+   * Send an encrypted DM via Nostr (NIP-44)
+   */
+  sendEncryptedDM(applicationId: string, recipientPubkey: string, content: string): Promise<string>
+
+  /**
+   * Publish a Nostr event (signed by application's key)
+   */
+  publishNostrEvent(event: UnsignedNostrEvent): Promise<string | null>
+
+  /**
+   * Get LNURL-pay info for a user (by pubkey)
+   * Used to enable Lightning Address support (LUD-16) and zaps (NIP-57)
+   */
+  getLnurlPayInfo(pubkeyHex: string, options?: {
+    metadata?: string              // Custom metadata JSON
+    description?: string           // Human-readable description
+  }): Promise<LnurlPayInfo>
+
+  /**
+   * Subscribe to payment received callbacks
+   */
+  onPaymentReceived(callback: (payment: PaymentReceivedData) => Promise<void>): void
+
+  /**
+   * Subscribe to incoming Nostr events for the application
+   */
+  onNostrEvent(callback: (event: NostrEvent, applicationId: string) => Promise<void>): void
+
+  /**
+   * Register an RPC method
+   */
+  registerMethod(name: string, handler: RpcMethodHandler): void
+
+  /**
+   * Get the extension's isolated database
+   */
+  getDatabase(): ExtensionDatabase
+
+  /**
+   * Log a message (prefixed with extension ID)
+   */
+  log(level: 'debug' | 'info' | 'warn' | 'error', message: string, ...args: any[]): void
+}
+
+/**
+ * Extension interface - what extensions must implement
+ */
+export interface Extension {
+  /**
+   * Extension metadata
+   */
+  readonly info: ExtensionInfo
+
+  /**
+   * Initialize the extension
+   * Called once when the extension is loaded
+   */
+  initialize(ctx: ExtensionContext, db: ExtensionDatabase): Promise<void>
+
+  /**
+   * Shutdown the extension
+   * Called when Lightning.Pub is shutting down
+   */
+  shutdown?(): Promise<void>
+
+  /**
+   * Health check
+   * Return true if extension is healthy
+   */
+  healthCheck?(): Promise<boolean>
+}
+
+/**
+ * Extension constructor type
+ */
+export type ExtensionConstructor = new () => Extension
+
+/**
+ * Extension module default export
+ */
+export interface ExtensionModule {
+  default: ExtensionConstructor
+}
+
+/**
+ * Loaded extension state
+ */
+export interface LoadedExtension {
+  info: ExtensionInfo
+  instance: Extension
+  database: ExtensionDatabase
+  status: 'loading' | 'ready' | 'error' | 'stopped'
+  error?: Error
+  loadedAt: number
+}
+
+/**
+ * Extension loader configuration
+ */
+export interface ExtensionLoaderConfig {
+  extensionsDir: string         // Directory containing extensions
+  databaseDir: string           // Directory for extension databases
+  enabledExtensions?: string[]  // If set, only load these extensions
+  disabledExtensions?: string[] // Extensions to skip
+}

src/extensions/withdraw/index.ts

@@ -0,0 +1,383 @@
+/**
+ * LNURL-withdraw Extension for Lightning.Pub
+ *
+ * Implements LUD-03 (LNURL-withdraw) for creating withdraw links
+ * that allow anyone to pull funds from a Lightning wallet.
+ *
+ * Use cases:
+ * - Quick vouchers (batch single-use codes)
+ * - Faucets
+ * - Gift cards / prepaid cards
+ * - Tips / donations
+ */
+
+import {
+  Extension,
+  ExtensionInfo,
+  ExtensionContext,
+  ExtensionDatabase,
+  CreateWithdrawLinkRequest,
+  UpdateWithdrawLinkRequest,
+  HttpRoute,
+  HttpRequest,
+  HttpResponse
+} from './types.js'
+import { runMigrations } from './migrations.js'
+import { WithdrawManager } from './managers/withdrawManager.js'
+
+/**
+ * LNURL-withdraw Extension
+ */
+export default class WithdrawExtension implements Extension {
+  readonly info: ExtensionInfo = {
+    id: 'withdraw',
+    name: 'LNURL Withdraw',
+    version: '1.0.0',
+    description: 'Create withdraw links for vouchers, faucets, and gifts (LUD-03)',
+    author: 'Lightning.Pub',
+    minPubVersion: '1.0.0'
+  }
+
+  private manager!: WithdrawManager
+  private baseUrl: string = ''
+
+  /**
+   * Initialize the extension
+   */
+  async initialize(ctx: ExtensionContext, db: ExtensionDatabase): Promise<void> {
+    // Run migrations
+    await runMigrations(db)
+
+    // Initialize manager
+    this.manager = new WithdrawManager(db, ctx)
+
+    // Register RPC methods
+    this.registerRpcMethods(ctx)
+
+    // Register HTTP routes for LNURL protocol
+    this.registerHttpRoutes(ctx)
+
+    ctx.log('info', 'Extension initialized')
+  }
+
+  /**
+   * Shutdown the extension
+   */
+  async shutdown(): Promise<void> {
+    // Cleanup if needed
+  }
+
+  /**
+   * Set the base URL for LNURL generation
+   * This should be called by the main application after loading
+   */
+  setBaseUrl(url: string): void {
+    this.baseUrl = url
+    this.manager.setBaseUrl(url)
+  }
+
+  /**
+   * Get HTTP routes for this extension
+   * These need to be mounted by the main HTTP server
+   */
+  getHttpRoutes(): HttpRoute[] {
+    return [
+      // Create withdraw link (HTTP API for ATM/external integrations)
+      {
+        method: 'POST',
+        path: '/api/v1/withdraw/create',
+        handler: this.handleCreateWithdrawLink.bind(this)
+      },
+      // LNURL callback (user submits invoice) - MUST be before :unique_hash routes
+      {
+        method: 'GET',
+        path: '/api/v1/lnurl/cb/:unique_hash',
+        handler: this.handleLnurlCallback.bind(this)
+      },
+      // Initial LNURL request (unique link with use hash)
+      {
+        method: 'GET',
+        path: '/api/v1/lnurl/:unique_hash/:id_unique_hash',
+        handler: this.handleLnurlUniqueRequest.bind(this)
+      },
+      // Initial LNURL request (simple link) - MUST be last (catches all)
+      {
+        method: 'GET',
+        path: '/api/v1/lnurl/:unique_hash',
+        handler: this.handleLnurlRequest.bind(this)
+      }
+    ]
+  }
+
+  /**
+   * Register RPC methods with the extension context
+   */
+  private registerRpcMethods(ctx: ExtensionContext): void {
+    // Create withdraw link
+    ctx.registerMethod('withdraw.createLink', async (req, appId, userPubkey) => {
+      const link = await this.manager.create(appId, req as CreateWithdrawLinkRequest, userPubkey)
+      const stats = await this.manager.getWithdrawalStats(link.id)
+      return {
+        link,
+        total_withdrawn_sats: stats.total_sats,
+        withdrawals_count: stats.count
+      }
+    })
+
+    // Create quick vouchers
+    ctx.registerMethod('withdraw.createVouchers', async (req, appId) => {
+      const vouchers = await this.manager.createVouchers(
+        appId,
+        req.title,
+        req.amount,
+        req.count,
+        req.description
+      )
+      return {
+        vouchers,
+        total_amount_sats: req.amount * req.count
+      }
+    })
+
+    // Get withdraw link
+    ctx.registerMethod('withdraw.getLink', async (req, appId) => {
+      const link = await this.manager.get(req.id, appId)
+      if (!link) throw new Error('Withdraw link not found')
+      const stats = await this.manager.getWithdrawalStats(link.id)
+      return {
+        link,
+        total_withdrawn_sats: stats.total_sats,
+        withdrawals_count: stats.count
+      }
+    })
+
+    // List withdraw links
+    ctx.registerMethod('withdraw.listLinks', async (req, appId) => {
+      const links = await this.manager.list(
+        appId,
+        req.include_spent || false,
+        req.limit,
+        req.offset
+      )
+      return { links }
+    })
+
+    // Update withdraw link
+    ctx.registerMethod('withdraw.updateLink', async (req, appId) => {
+      const link = await this.manager.update(req.id, appId, req as UpdateWithdrawLinkRequest)
+      if (!link) throw new Error('Withdraw link not found')
+      const stats = await this.manager.getWithdrawalStats(link.id)
+      return {
+        link,
+        total_withdrawn_sats: stats.total_sats,
+        withdrawals_count: stats.count
+      }
+    })
+
+    // Delete withdraw link
+    ctx.registerMethod('withdraw.deleteLink', async (req, appId) => {
+      const success = await this.manager.delete(req.id, appId)
+      if (!success) throw new Error('Withdraw link not found')
+      return { success }
+    })
+
+    // List withdrawals
+    ctx.registerMethod('withdraw.listWithdrawals', async (req, appId) => {
+      const withdrawals = await this.manager.listWithdrawals(
+        appId,
+        req.link_id,
+        req.limit,
+        req.offset
+      )
+      return { withdrawals }
+    })
+
+    // Get withdrawal stats
+    ctx.registerMethod('withdraw.getStats', async (req, appId) => {
+      // Get all links to calculate total stats
+      const links = await this.manager.list(appId, true)
+
+      let totalLinks = links.length
+      let activeLinks = 0
+      let spentLinks = 0
+      let totalWithdrawn = 0
+      let totalWithdrawals = 0
+
+      for (const link of links) {
+        if (link.used >= link.uses) {
+          spentLinks++
+        } else {
+          activeLinks++
+        }
+        const stats = await this.manager.getWithdrawalStats(link.id)
+        totalWithdrawn += stats.total_sats
+        totalWithdrawals += stats.count
+      }
+
+      return {
+        total_links: totalLinks,
+        active_links: activeLinks,
+        spent_links: spentLinks,
+        total_withdrawn_sats: totalWithdrawn,
+        total_withdrawals: totalWithdrawals
+      }
+    })
+  }
+
+  /**
+   * Register HTTP routes (called by extension context)
+   */
+  private registerHttpRoutes(ctx: ExtensionContext): void {
+    // HTTP routes are exposed via getHttpRoutes()
+    // The main application is responsible for mounting them
+    ctx.log('debug', 'HTTP routes registered for LNURL protocol')
+  }
+
+  // =========================================================================
+  // HTTP Route Handlers
+  // =========================================================================
+
+  /**
+   * Handle create withdraw link request (HTTP API)
+   * POST /api/v1/withdraw/create
+   *
+   * Body: {
+   *   title: string
+   *   min_withdrawable: number (sats)
+   *   max_withdrawable: number (sats)
+   *   uses?: number (defaults to 1)
+   *   wait_time?: number (seconds between uses, defaults to 0)
+   * }
+   *
+   * Auth: Bearer token in Authorization header (app_<app_id>)
+   *
+   * Returns: {
+   *   link: { lnurl, unique_hash, id, ... }
+   * }
+   */
+  private async handleCreateWithdrawLink(req: HttpRequest): Promise<HttpResponse> {
+    try {
+      const { title, min_withdrawable, max_withdrawable, uses, wait_time } = req.body
+
+      // Extract app_id from Authorization header (Bearer app_<app_id>)
+      const authHeader = req.headers?.authorization || req.headers?.Authorization || ''
+      let app_id = 'default'
+      if (authHeader.startsWith('Bearer app_')) {
+        app_id = authHeader.replace('Bearer app_', '')
+      }
+
+      if (!title || !min_withdrawable) {
+        return {
+          status: 400,
+          body: { status: 'ERROR', reason: 'Missing required fields: title, min_withdrawable' },
+          headers: { 'Content-Type': 'application/json' }
+        }
+      }
+
+      const link = await this.manager.create(app_id, {
+        title,
+        min_withdrawable,
+        max_withdrawable: max_withdrawable || min_withdrawable,
+        uses: uses || 1,
+        wait_time: wait_time || 0,
+        is_unique: false // Simple single-use links for ATM
+      })
+
+      // Return in format expected by ATM client
+      return {
+        status: 200,
+        body: {
+          status: 'OK',
+          link: {
+            lnurl: link.lnurl,
+            unique_hash: link.unique_hash,
+            id: link.id,
+            title: link.title,
+            min_withdrawable: link.min_withdrawable,
+            max_withdrawable: link.max_withdrawable,
+            uses: link.uses,
+            used: link.used
+          }
+        },
+        headers: { 'Content-Type': 'application/json' }
+      }
+    } catch (error: any) {
+      return {
+        status: 500,
+        body: { status: 'ERROR', reason: error.message },
+        headers: { 'Content-Type': 'application/json' }
+      }
+    }
+  }
+
+  /**
+   * Handle initial LNURL request (simple link)
+   * GET /api/v1/lnurl/:unique_hash
+   */
+  private async handleLnurlRequest(req: HttpRequest): Promise<HttpResponse> {
+    const { unique_hash } = req.params
+
+    const result = await this.manager.handleLnurlRequest(unique_hash)
+
+    return {
+      status: 200,
+      body: result,
+      headers: {
+        'Content-Type': 'application/json'
+      }
+    }
+  }
+
+  /**
+   * Handle initial LNURL request (unique link)
+   * GET /api/v1/lnurl/:unique_hash/:id_unique_hash
+   */
+  private async handleLnurlUniqueRequest(req: HttpRequest): Promise<HttpResponse> {
+    const { unique_hash, id_unique_hash } = req.params
+
+    const result = await this.manager.handleLnurlRequest(unique_hash, id_unique_hash)
+
+    return {
+      status: 200,
+      body: result,
+      headers: {
+        'Content-Type': 'application/json'
+      }
+    }
+  }
+
+  /**
+   * Handle LNURL callback (user submits invoice)
+   * GET /api/v1/lnurl/cb/:unique_hash?k1=...&pr=...&id_unique_hash=...
+   */
+  private async handleLnurlCallback(req: HttpRequest): Promise<HttpResponse> {
+    const { unique_hash } = req.params
+    const { k1, pr, id_unique_hash } = req.query
+
+    if (!k1 || !pr) {
+      return {
+        status: 200,
+        body: { status: 'ERROR', reason: 'Missing k1 or pr parameter' },
+        headers: { 'Content-Type': 'application/json' }
+      }
+    }
+
+    const result = await this.manager.handleLnurlCallback(unique_hash, {
+      k1,
+      pr,
+      id_unique_hash
+    })
+
+    return {
+      status: 200,
+      body: result,
+      headers: {
+        'Content-Type': 'application/json'
+      }
+    }
+  }
+}
+
+// Export types for external use
+export * from './types.js'
+export { WithdrawManager } from './managers/withdrawManager.js'

src/extensions/withdraw/managers/withdrawManager.ts

@@ -0,0 +1,717 @@
+/**
+ * Withdraw Link Manager
+ *
+ * Handles CRUD operations for withdraw links and processes withdrawals
+ */
+
+import {
+  ExtensionContext,
+  ExtensionDatabase,
+  WithdrawLink,
+  Withdrawal,
+  CreateWithdrawLinkRequest,
+  UpdateWithdrawLinkRequest,
+  WithdrawLinkWithLnurl,
+  LnurlWithdrawResponse,
+  LnurlErrorResponse,
+  LnurlSuccessResponse,
+  LnurlCallbackParams
+} from '../types.js'
+import {
+  generateId,
+  generateK1,
+  generateUniqueHash,
+  generateUseHash,
+  verifyUseHash,
+  encodeLnurl,
+  buildLnurlUrl,
+  buildUniqueLnurlUrl,
+  buildCallbackUrl,
+  satsToMsats
+} from '../utils/lnurl.js'
+
+/**
+ * Database row types
+ */
+interface WithdrawLinkRow {
+  id: string
+  application_id: string
+  title: string
+  description: string | null
+  min_withdrawable: number
+  max_withdrawable: number
+  uses: number
+  used: number
+  wait_time: number
+  unique_hash: string
+  k1: string
+  is_unique: number
+  uses_csv: string
+  open_time: number
+  creator_pubkey: string | null
+  webhook_url: string | null
+  webhook_headers: string | null
+  webhook_body: string | null
+  created_at: number
+  updated_at: number
+}
+
+interface WithdrawalRow {
+  id: string
+  link_id: string
+  application_id: string
+  payment_hash: string
+  amount_sats: number
+  fee_sats: number
+  recipient_node: string | null
+  webhook_success: number | null
+  webhook_response: string | null
+  created_at: number
+}
+
+/**
+ * Convert row to WithdrawLink
+ */
+function rowToLink(row: WithdrawLinkRow): WithdrawLink {
+  return {
+    id: row.id,
+    application_id: row.application_id,
+    title: row.title,
+    description: row.description || undefined,
+    min_withdrawable: row.min_withdrawable,
+    max_withdrawable: row.max_withdrawable,
+    uses: row.uses,
+    used: row.used,
+    wait_time: row.wait_time,
+    unique_hash: row.unique_hash,
+    k1: row.k1,
+    is_unique: row.is_unique === 1,
+    uses_csv: row.uses_csv,
+    open_time: row.open_time,
+    creator_pubkey: row.creator_pubkey || undefined,
+    webhook_url: row.webhook_url || undefined,
+    webhook_headers: row.webhook_headers || undefined,
+    webhook_body: row.webhook_body || undefined,
+    created_at: row.created_at,
+    updated_at: row.updated_at
+  }
+}
+
+/**
+ * Convert row to Withdrawal
+ */
+function rowToWithdrawal(row: WithdrawalRow): Withdrawal {
+  return {
+    id: row.id,
+    link_id: row.link_id,
+    application_id: row.application_id,
+    payment_hash: row.payment_hash,
+    amount_sats: row.amount_sats,
+    fee_sats: row.fee_sats,
+    recipient_node: row.recipient_node || undefined,
+    webhook_success: row.webhook_success === null ? undefined : row.webhook_success === 1,
+    webhook_response: row.webhook_response || undefined,
+    created_at: row.created_at
+  }
+}
+
+/**
+ * WithdrawManager - Handles withdraw link operations
+ */
+export class WithdrawManager {
+  private baseUrl: string = ''
+
+  constructor(
+    private db: ExtensionDatabase,
+    private ctx: ExtensionContext
+  ) {}
+
+  /**
+   * Set the base URL for LNURL generation
+   */
+  setBaseUrl(url: string): void {
+    this.baseUrl = url.replace(/\/$/, '')
+  }
+
+  /**
+   * Add LNURL to a withdraw link
+   */
+  private addLnurl(link: WithdrawLink): WithdrawLinkWithLnurl {
+    const lnurlUrl = buildLnurlUrl(this.baseUrl, link.unique_hash)
+    return {
+      ...link,
+      lnurl: encodeLnurl(lnurlUrl),
+      lnurl_url: lnurlUrl
+    }
+  }
+
+  // =========================================================================
+  // CRUD Operations
+  // =========================================================================
+
+  /**
+   * Create a new withdraw link
+   */
+  async create(applicationId: string, req: CreateWithdrawLinkRequest, creatorPubkey?: string): Promise<WithdrawLinkWithLnurl> {
+    // Validation
+    if (req.uses < 1 || req.uses > 250) {
+      throw new Error('Uses must be between 1 and 250')
+    }
+    if (req.min_withdrawable < 1) {
+      throw new Error('Min withdrawable must be at least 1 sat')
+    }
+    if (req.max_withdrawable < req.min_withdrawable) {
+      throw new Error('Max withdrawable must be >= min withdrawable')
+    }
+    if (req.wait_time < 0) {
+      throw new Error('Wait time cannot be negative')
+    }
+
+    // Validate webhook JSON if provided
+    if (req.webhook_headers) {
+      try {
+        JSON.parse(req.webhook_headers)
+      } catch {
+        throw new Error('webhook_headers must be valid JSON')
+      }
+    }
+    if (req.webhook_body) {
+      try {
+        JSON.parse(req.webhook_body)
+      } catch {
+        throw new Error('webhook_body must be valid JSON')
+      }
+    }
+
+    const now = Math.floor(Date.now() / 1000)
+    const id = generateId()
+    const usesCsv = Array.from({ length: req.uses }, (_, i) => String(i)).join(',')
+
+    const link: WithdrawLink = {
+      id,
+      application_id: applicationId,
+      title: req.title.trim(),
+      description: req.description?.trim(),
+      min_withdrawable: req.min_withdrawable,
+      max_withdrawable: req.max_withdrawable,
+      uses: req.uses,
+      used: 0,
+      wait_time: req.wait_time,
+      unique_hash: generateUniqueHash(),
+      k1: generateK1(),
+      is_unique: req.is_unique || false,
+      uses_csv: usesCsv,
+      open_time: now,
+      creator_pubkey: creatorPubkey,
+      webhook_url: req.webhook_url,
+      webhook_headers: req.webhook_headers,
+      webhook_body: req.webhook_body,
+      created_at: now,
+      updated_at: now
+    }
+
+    await this.db.execute(
+      `INSERT INTO withdraw_links (
+        id, application_id, title, description,
+        min_withdrawable, max_withdrawable, uses, used, wait_time,
+        unique_hash, k1, is_unique, uses_csv, open_time,
+        creator_pubkey,
+        webhook_url, webhook_headers, webhook_body,
+        created_at, updated_at
+      ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
+      [
+        link.id, link.application_id, link.title, link.description || null,
+        link.min_withdrawable, link.max_withdrawable, link.uses, link.used, link.wait_time,
+        link.unique_hash, link.k1, link.is_unique ? 1 : 0, link.uses_csv, link.open_time,
+        link.creator_pubkey || null,
+        link.webhook_url || null, link.webhook_headers || null, link.webhook_body || null,
+        link.created_at, link.updated_at
+      ]
+    )
+
+    return this.addLnurl(link)
+  }
+
+  /**
+   * Create multiple vouchers (single-use withdraw links)
+   */
+  async createVouchers(
+    applicationId: string,
+    title: string,
+    amount: number,
+    count: number,
+    description?: string
+  ): Promise<WithdrawLinkWithLnurl[]> {
+    if (count < 1 || count > 100) {
+      throw new Error('Count must be between 1 and 100')
+    }
+    if (amount < 1) {
+      throw new Error('Amount must be at least 1 sat')
+    }
+
+    const vouchers: WithdrawLinkWithLnurl[] = []
+
+    for (let i = 0; i < count; i++) {
+      const voucher = await this.create(applicationId, {
+        title: `${title} #${i + 1}`,
+        description,
+        min_withdrawable: amount,
+        max_withdrawable: amount,
+        uses: 1,
+        wait_time: 0,
+        is_unique: false
+      })
+      vouchers.push(voucher)
+    }
+
+    return vouchers
+  }
+
+  /**
+   * Get a withdraw link by ID
+   */
+  async get(id: string, applicationId: string): Promise<WithdrawLinkWithLnurl | null> {
+    const rows = await this.db.query<WithdrawLinkRow>(
+      'SELECT * FROM withdraw_links WHERE id = ? AND application_id = ?',
+      [id, applicationId]
+    )
+
+    if (rows.length === 0) return null
+    return this.addLnurl(rowToLink(rows[0]))
+  }
+
+  /**
+   * Get a withdraw link by unique hash (for LNURL)
+   */
+  async getByHash(uniqueHash: string): Promise<WithdrawLink | null> {
+    const rows = await this.db.query<WithdrawLinkRow>(
+      'SELECT * FROM withdraw_links WHERE unique_hash = ?',
+      [uniqueHash]
+    )
+
+    if (rows.length === 0) return null
+    return rowToLink(rows[0])
+  }
+
+  /**
+   * List withdraw links for an application
+   */
+  async list(
+    applicationId: string,
+    includeSpent: boolean = false,
+    limit?: number,
+    offset?: number
+  ): Promise<WithdrawLinkWithLnurl[]> {
+    let sql = 'SELECT * FROM withdraw_links WHERE application_id = ?'
+    const params: any[] = [applicationId]
+
+    if (!includeSpent) {
+      sql += ' AND used < uses'
+    }
+
+    sql += ' ORDER BY created_at DESC'
+
+    if (limit) {
+      sql += ' LIMIT ?'
+      params.push(limit)
+      if (offset) {
+        sql += ' OFFSET ?'
+        params.push(offset)
+      }
+    }
+
+    const rows = await this.db.query<WithdrawLinkRow>(sql, params)
+    return rows.map(row => this.addLnurl(rowToLink(row)))
+  }
+
+  /**
+   * Update a withdraw link
+   */
+  async update(
+    id: string,
+    applicationId: string,
+    req: UpdateWithdrawLinkRequest
+  ): Promise<WithdrawLinkWithLnurl | null> {
+    const existing = await this.get(id, applicationId)
+    if (!existing) return null
+
+    // Validation
+    if (req.uses !== undefined) {
+      if (req.uses < 1 || req.uses > 250) {
+        throw new Error('Uses must be between 1 and 250')
+      }
+      if (req.uses < existing.used) {
+        throw new Error('Cannot reduce uses below current used count')
+      }
+    }
+
+    const minWith = req.min_withdrawable ?? existing.min_withdrawable
+    const maxWith = req.max_withdrawable ?? existing.max_withdrawable
+
+    if (minWith < 1) {
+      throw new Error('Min withdrawable must be at least 1 sat')
+    }
+    if (maxWith < minWith) {
+      throw new Error('Max withdrawable must be >= min withdrawable')
+    }
+
+    // Handle uses change
+    let usesCsv = existing.uses_csv
+    const newUses = req.uses ?? existing.uses
+    if (newUses !== existing.uses) {
+      const currentUses = usesCsv.split(',').filter(u => u !== '')
+      if (newUses > existing.uses) {
+        // Add more uses
+        const lastNum = currentUses.length > 0 ? parseInt(currentUses[currentUses.length - 1], 10) : -1
+        for (let i = lastNum + 1; currentUses.length < (newUses - existing.used); i++) {
+          currentUses.push(String(i))
+        }
+      } else {
+        // Remove uses (keep first N)
+        usesCsv = currentUses.slice(0, newUses - existing.used).join(',')
+      }
+      usesCsv = currentUses.join(',')
+    }
+
+    const now = Math.floor(Date.now() / 1000)
+
+    await this.db.execute(
+      `UPDATE withdraw_links SET
+        title = ?, description = ?,
+        min_withdrawable = ?, max_withdrawable = ?,
+        uses = ?, wait_time = ?, is_unique = ?, uses_csv = ?,
+        webhook_url = ?, webhook_headers = ?, webhook_body = ?,
+        updated_at = ?
+      WHERE id = ? AND application_id = ?`,
+      [
+        req.title ?? existing.title,
+        req.description ?? existing.description ?? null,
+        minWith, maxWith,
+        newUses,
+        req.wait_time ?? existing.wait_time,
+        (req.is_unique ?? existing.is_unique) ? 1 : 0,
+        usesCsv,
+        req.webhook_url ?? existing.webhook_url ?? null,
+        req.webhook_headers ?? existing.webhook_headers ?? null,
+        req.webhook_body ?? existing.webhook_body ?? null,
+        now,
+        id, applicationId
+      ]
+    )
+
+    return this.get(id, applicationId)
+  }
+
+  /**
+   * Delete a withdraw link
+   */
+  async delete(id: string, applicationId: string): Promise<boolean> {
+    const result = await this.db.execute(
+      'DELETE FROM withdraw_links WHERE id = ? AND application_id = ?',
+      [id, applicationId]
+    )
+    return (result.changes || 0) > 0
+  }
+
+  // =========================================================================
+  // LNURL Protocol Handlers
+  // =========================================================================
+
+  /**
+   * Handle initial LNURL request (user scans QR)
+   * Returns withdraw parameters
+   */
+  async handleLnurlRequest(
+    uniqueHash: string,
+    idUniqueHash?: string
+  ): Promise<LnurlWithdrawResponse | LnurlErrorResponse> {
+    const link = await this.getByHash(uniqueHash)
+
+    if (!link) {
+      return { status: 'ERROR', reason: 'Withdraw link does not exist.' }
+    }
+
+    if (link.used >= link.uses) {
+      return { status: 'ERROR', reason: 'Withdraw link is spent.' }
+    }
+
+    // For unique links, require id_unique_hash
+    if (link.is_unique && !idUniqueHash) {
+      return { status: 'ERROR', reason: 'This link requires a unique hash.' }
+    }
+
+    // Verify unique hash if provided
+    if (idUniqueHash) {
+      const useNumber = verifyUseHash(link.id, link.unique_hash, link.uses_csv, idUniqueHash)
+      if (!useNumber) {
+        return { status: 'ERROR', reason: 'Invalid unique hash.' }
+      }
+    }
+
+    const callbackUrl = buildCallbackUrl(this.baseUrl, link.unique_hash)
+
+    return {
+      tag: 'withdrawRequest',
+      callback: idUniqueHash ? `${callbackUrl}?id_unique_hash=${idUniqueHash}` : callbackUrl,
+      k1: link.k1,
+      minWithdrawable: satsToMsats(link.min_withdrawable),
+      maxWithdrawable: satsToMsats(link.max_withdrawable),
+      defaultDescription: link.title
+    }
+  }
+
+  /**
+   * Handle LNURL callback (user submits invoice)
+   * Pays the invoice and records the withdrawal
+   */
+  async handleLnurlCallback(
+    uniqueHash: string,
+    params: LnurlCallbackParams
+  ): Promise<LnurlSuccessResponse | LnurlErrorResponse> {
+    const link = await this.getByHash(uniqueHash)
+
+    if (!link) {
+      return { status: 'ERROR', reason: 'Withdraw link not found.' }
+    }
+
+    if (link.used >= link.uses) {
+      return { status: 'ERROR', reason: 'Withdraw link is spent.' }
+    }
+
+    if (link.k1 !== params.k1) {
+      return { status: 'ERROR', reason: 'Invalid k1.' }
+    }
+
+    // Check wait time
+    const now = Math.floor(Date.now() / 1000)
+    if (now < link.open_time) {
+      const waitSecs = link.open_time - now
+      return { status: 'ERROR', reason: `Please wait ${waitSecs} seconds.` }
+    }
+
+    // For unique links, verify and consume the use hash
+    if (params.id_unique_hash) {
+      const useNumber = verifyUseHash(link.id, link.unique_hash, link.uses_csv, params.id_unique_hash)
+      if (!useNumber) {
+        return { status: 'ERROR', reason: 'Invalid unique hash.' }
+      }
+    } else if (link.is_unique) {
+      return { status: 'ERROR', reason: 'Unique hash required.' }
+    }
+
+    // Prevent double-spending with hash check
+    try {
+      await this.createHashCheck(params.id_unique_hash || uniqueHash, params.k1)
+    } catch {
+      return { status: 'ERROR', reason: 'Withdrawal already in progress.' }
+    }
+
+    try {
+      // Pay the invoice from the creator's balance (if created via Nostr RPC)
+      const payment = await this.ctx.payInvoice(
+        link.application_id,
+        params.pr,
+        link.max_withdrawable,
+        link.creator_pubkey
+      )
+
+      // Record the withdrawal
+      await this.recordWithdrawal(link, payment.paymentHash, link.max_withdrawable, payment.feeSats)
+
+      // Increment usage
+      await this.incrementUsage(link, params.id_unique_hash)
+
+      // Clean up hash check
+      await this.deleteHashCheck(params.id_unique_hash || uniqueHash)
+
+      // Dispatch webhook if configured
+      if (link.webhook_url) {
+        this.dispatchWebhook(link, payment.paymentHash, params.pr).catch(err => {
+          console.error('[Withdraw] Webhook error:', err)
+        })
+      }
+
+      return { status: 'OK' }
+    } catch (err: any) {
+      // Clean up hash check on failure
+      await this.deleteHashCheck(params.id_unique_hash || uniqueHash)
+      return { status: 'ERROR', reason: `Payment failed: ${err.message}` }
+    }
+  }
+
+  // =========================================================================
+  // Helper Methods
+  // =========================================================================
+
+  /**
+   * Increment link usage and update open_time
+   */
+  private async incrementUsage(link: WithdrawLink, idUniqueHash?: string): Promise<void> {
+    const now = Math.floor(Date.now() / 1000)
+    let usesCsv = link.uses_csv
+
+    // Remove used hash from uses_csv if unique
+    if (idUniqueHash) {
+      const uses = usesCsv.split(',').filter(u => {
+        const hash = generateUseHash(link.id, link.unique_hash, u.trim())
+        return hash !== idUniqueHash
+      })
+      usesCsv = uses.join(',')
+    }
+
+    await this.db.execute(
+      `UPDATE withdraw_links SET
+        used = used + 1,
+        open_time = ?,
+        uses_csv = ?,
+        updated_at = ?
+      WHERE id = ?`,
+      [now + link.wait_time, usesCsv, now, link.id]
+    )
+  }
+
+  /**
+   * Record a successful withdrawal
+   */
+  private async recordWithdrawal(
+    link: WithdrawLink,
+    paymentHash: string,
+    amountSats: number,
+    feeSats: number
+  ): Promise<void> {
+    const now = Math.floor(Date.now() / 1000)
+
+    await this.db.execute(
+      `INSERT INTO withdrawals (
+        id, link_id, application_id,
+        payment_hash, amount_sats, fee_sats,
+        created_at
+      ) VALUES (?, ?, ?, ?, ?, ?, ?)`,
+      [
+        generateId(),
+        link.id,
+        link.application_id,
+        paymentHash,
+        amountSats,
+        feeSats,
+        now
+      ]
+    )
+  }
+
+  /**
+   * Create hash check to prevent double-spending
+   */
+  private async createHashCheck(hash: string, k1: string): Promise<void> {
+    const now = Math.floor(Date.now() / 1000)
+    await this.db.execute(
+      'INSERT INTO hash_checks (hash, k1, created_at) VALUES (?, ?, ?)',
+      [hash, k1, now]
+    )
+  }
+
+  /**
+   * Delete hash check after completion
+   */
+  private async deleteHashCheck(hash: string): Promise<void> {
+    await this.db.execute('DELETE FROM hash_checks WHERE hash = ?', [hash])
+  }
+
+  /**
+   * List withdrawals
+   */
+  async listWithdrawals(
+    applicationId: string,
+    linkId?: string,
+    limit?: number,
+    offset?: number
+  ): Promise<Withdrawal[]> {
+    let sql = 'SELECT * FROM withdrawals WHERE application_id = ?'
+    const params: any[] = [applicationId]
+
+    if (linkId) {
+      sql += ' AND link_id = ?'
+      params.push(linkId)
+    }
+
+    sql += ' ORDER BY created_at DESC'
+
+    if (limit) {
+      sql += ' LIMIT ?'
+      params.push(limit)
+      if (offset) {
+        sql += ' OFFSET ?'
+        params.push(offset)
+      }
+    }
+
+    const rows = await this.db.query<WithdrawalRow>(sql, params)
+    return rows.map(rowToWithdrawal)
+  }
+
+  /**
+   * Get withdrawal stats for a link
+   */
+  async getWithdrawalStats(linkId: string): Promise<{ total_sats: number; count: number }> {
+    const result = await this.db.query<{ total: number; count: number }>(
+      `SELECT COALESCE(SUM(amount_sats), 0) as total, COUNT(*) as count
+       FROM withdrawals WHERE link_id = ?`,
+      [linkId]
+    )
+    return {
+      total_sats: result[0]?.total || 0,
+      count: result[0]?.count || 0
+    }
+  }
+
+  /**
+   * Dispatch webhook notification
+   */
+  private async dispatchWebhook(
+    link: WithdrawLink,
+    paymentHash: string,
+    paymentRequest: string
+  ): Promise<void> {
+    if (!link.webhook_url) return
+
+    try {
+      const headers: Record<string, string> = {
+        'Content-Type': 'application/json'
+      }
+
+      if (link.webhook_headers) {
+        Object.assign(headers, JSON.parse(link.webhook_headers))
+      }
+
+      const body = {
+        payment_hash: paymentHash,
+        payment_request: paymentRequest,
+        lnurlw: link.id,
+        body: link.webhook_body ? JSON.parse(link.webhook_body) : {}
+      }
+
+      const response = await fetch(link.webhook_url, {
+        method: 'POST',
+        headers,
+        body: JSON.stringify(body)
+      })
+
+      // Update withdrawal record with webhook result
+      await this.db.execute(
+        `UPDATE withdrawals SET
+          webhook_success = ?,
+          webhook_response = ?
+        WHERE payment_hash = ?`,
+        [response.ok ? 1 : 0, await response.text(), paymentHash]
+      )
+    } catch (err: any) {
+      await this.db.execute(
+        `UPDATE withdrawals SET
+          webhook_success = 0,
+          webhook_response = ?
+        WHERE payment_hash = ?`,
+        [err.message, paymentHash]
+      )
+    }
+  }
+}

src/extensions/withdraw/migrations.ts

@@ -0,0 +1,164 @@
+/**
+ * LNURL-withdraw Extension Database Migrations
+ */
+
+import { ExtensionDatabase } from '../types.js'
+
+export interface Migration {
+  version: number
+  name: string
+  up: (db: ExtensionDatabase) => Promise<void>
+  down?: (db: ExtensionDatabase) => Promise<void>
+}
+
+export const migrations: Migration[] = [
+  {
+    version: 1,
+    name: 'create_withdraw_links_table',
+    up: async (db: ExtensionDatabase) => {
+      await db.execute(`
+        CREATE TABLE IF NOT EXISTS withdraw_links (
+          id TEXT PRIMARY KEY,
+          application_id TEXT NOT NULL,
+
+          -- Display
+          title TEXT NOT NULL,
+          description TEXT,
+
+          -- Amounts (sats)
+          min_withdrawable INTEGER NOT NULL,
+          max_withdrawable INTEGER NOT NULL,
+
+          -- Usage limits
+          uses INTEGER NOT NULL DEFAULT 1,
+          used INTEGER NOT NULL DEFAULT 0,
+          wait_time INTEGER NOT NULL DEFAULT 0,
+
+          -- Security
+          unique_hash TEXT NOT NULL UNIQUE,
+          k1 TEXT NOT NULL,
+          is_unique INTEGER NOT NULL DEFAULT 0,
+          uses_csv TEXT NOT NULL DEFAULT '',
+
+          -- Rate limiting
+          open_time INTEGER NOT NULL DEFAULT 0,
+
+          -- Webhooks
+          webhook_url TEXT,
+          webhook_headers TEXT,
+          webhook_body TEXT,
+
+          -- Timestamps
+          created_at INTEGER NOT NULL,
+          updated_at INTEGER NOT NULL
+        )
+      `)
+
+      // Index for looking up by unique_hash (LNURL)
+      await db.execute(`
+        CREATE INDEX IF NOT EXISTS idx_withdraw_links_unique_hash
+        ON withdraw_links(unique_hash)
+      `)
+
+      // Index for listing by application
+      await db.execute(`
+        CREATE INDEX IF NOT EXISTS idx_withdraw_links_application
+        ON withdraw_links(application_id, created_at DESC)
+      `)
+    }
+  },
+  {
+    version: 2,
+    name: 'create_withdrawals_table',
+    up: async (db: ExtensionDatabase) => {
+      await db.execute(`
+        CREATE TABLE IF NOT EXISTS withdrawals (
+          id TEXT PRIMARY KEY,
+          link_id TEXT NOT NULL,
+          application_id TEXT NOT NULL,
+
+          -- Payment details
+          payment_hash TEXT NOT NULL,
+          amount_sats INTEGER NOT NULL,
+          fee_sats INTEGER NOT NULL DEFAULT 0,
+
+          -- Recipient
+          recipient_node TEXT,
+
+          -- Webhook result
+          webhook_success INTEGER,
+          webhook_response TEXT,
+
+          -- Timestamp
+          created_at INTEGER NOT NULL,
+
+          FOREIGN KEY (link_id) REFERENCES withdraw_links(id) ON DELETE CASCADE
+        )
+      `)
+
+      // Index for listing withdrawals by link
+      await db.execute(`
+        CREATE INDEX IF NOT EXISTS idx_withdrawals_link
+        ON withdrawals(link_id, created_at DESC)
+      `)
+
+      // Index for looking up by payment hash
+      await db.execute(`
+        CREATE INDEX IF NOT EXISTS idx_withdrawals_payment_hash
+        ON withdrawals(payment_hash)
+      `)
+    }
+  },
+  {
+    version: 3,
+    name: 'create_hash_checks_table',
+    up: async (db: ExtensionDatabase) => {
+      // Temporary table to prevent double-spending during payment processing
+      await db.execute(`
+        CREATE TABLE IF NOT EXISTS hash_checks (
+          hash TEXT PRIMARY KEY,
+          k1 TEXT NOT NULL,
+          created_at INTEGER NOT NULL
+        )
+      `)
+    }
+  },
+  {
+    version: 4,
+    name: 'add_creator_pubkey_column',
+    up: async (db: ExtensionDatabase) => {
+      // Store the Nostr pubkey of the user who created the withdraw link
+      // so that when the LNURL callback fires, we debit the correct user's balance
+      await db.execute(`
+        ALTER TABLE withdraw_links ADD COLUMN creator_pubkey TEXT
+      `)
+    }
+  }
+]
+
+/**
+ * Run all pending migrations
+ */
+export async function runMigrations(db: ExtensionDatabase): Promise<void> {
+  // Get current version
+  const versionResult = await db.query<{ value: string }>(
+    `SELECT value FROM _extension_meta WHERE key = 'migration_version'`
+  ).catch(() => [])
+
+  const currentVersion = versionResult.length > 0 ? parseInt(versionResult[0].value, 10) : 0
+
+  // Run pending migrations
+  for (const migration of migrations) {
+    if (migration.version > currentVersion) {
+      console.log(`[Withdraw] Running migration ${migration.version}: ${migration.name}`)
+      await migration.up(db)
+
+      // Update version
+      await db.execute(
+        `INSERT INTO _extension_meta (key, value) VALUES ('migration_version', ?)
+         ON CONFLICT(key) DO UPDATE SET value = excluded.value`,
+        [String(migration.version)]
+      )
+    }
+  }
+}

src/extensions/withdraw/types.ts

@@ -0,0 +1,264 @@
+/**
+ * LNURL-withdraw Extension Types
+ * Implements LUD-03 (LNURL-withdraw) for Lightning.Pub
+ */
+
+// Re-export base extension types
+export {
+  Extension,
+  ExtensionInfo,
+  ExtensionContext,
+  ExtensionDatabase,
+  ApplicationInfo,
+  RpcMethodHandler
+} from '../types.js'
+
+// ============================================================================
+// Core Data Types
+// ============================================================================
+
+/**
+ * A withdraw link that can be used to pull funds
+ */
+export interface WithdrawLink {
+  id: string
+  application_id: string
+
+  // Display
+  title: string
+  description?: string
+
+  // Amounts (in sats)
+  min_withdrawable: number
+  max_withdrawable: number
+
+  // Usage limits
+  uses: number              // Total allowed uses
+  used: number              // Times used so far
+  wait_time: number         // Seconds between uses
+
+  // Security
+  unique_hash: string       // For LNURL URL
+  k1: string                // Challenge for callback
+  is_unique: boolean           // Generate unique code per use
+  uses_csv: string          // Comma-separated list of available use IDs
+
+  // Rate limiting
+  open_time: number         // Unix timestamp when next use is allowed
+
+  // Creator identity (for Nostr RPC-created links)
+  creator_pubkey?: string   // Nostr pubkey of the user who created this link
+
+  // Webhook notifications
+  webhook_url?: string
+  webhook_headers?: string  // JSON string
+  webhook_body?: string     // JSON string
+
+  // Timestamps
+  created_at: number
+  updated_at: number
+}
+
+/**
+ * Withdrawal record - tracks each successful withdrawal
+ */
+export interface Withdrawal {
+  id: string
+  link_id: string
+  application_id: string
+
+  // Payment details
+  payment_hash: string
+  amount_sats: number
+  fee_sats: number
+
+  // Recipient (if known)
+  recipient_node?: string
+
+  // Webhook result
+  webhook_success?: boolean
+  webhook_response?: string
+
+  // Timestamp
+  created_at: number
+}
+
+/**
+ * Hash check - prevents double-spending during payment
+ */
+export interface HashCheck {
+  hash: string
+  k1: string
+  created_at: number
+}
+
+// ============================================================================
+// LNURL Protocol Types (LUD-03)
+// ============================================================================
+
+/**
+ * LNURL-withdraw response (first call)
+ * Returned when user scans the QR code
+ */
+export interface LnurlWithdrawResponse {
+  tag: 'withdrawRequest'
+  callback: string          // URL to call with invoice
+  k1: string                // Challenge
+  minWithdrawable: number   // Millisats
+  maxWithdrawable: number   // Millisats
+  defaultDescription: string
+}
+
+/**
+ * LNURL error response
+ */
+export interface LnurlErrorResponse {
+  status: 'ERROR'
+  reason: string
+}
+
+/**
+ * LNURL success response
+ */
+export interface LnurlSuccessResponse {
+  status: 'OK'
+}
+
+// ============================================================================
+// RPC Request/Response Types
+// ============================================================================
+
+/**
+ * Create a new withdraw link
+ */
+export interface CreateWithdrawLinkRequest {
+  title: string
+  description?: string
+  min_withdrawable: number  // sats
+  max_withdrawable: number  // sats
+  uses: number              // 1-250
+  wait_time: number         // seconds between uses
+  is_unique?: boolean       // generate unique code per use
+  webhook_url?: string
+  webhook_headers?: string  // JSON
+  webhook_body?: string     // JSON
+}
+
+/**
+ * Update an existing withdraw link
+ */
+export interface UpdateWithdrawLinkRequest {
+  id: string
+  title?: string
+  description?: string
+  min_withdrawable?: number
+  max_withdrawable?: number
+  uses?: number
+  wait_time?: number
+  is_unique?: boolean
+  webhook_url?: string
+  webhook_headers?: string
+  webhook_body?: string
+}
+
+/**
+ * Get withdraw link by ID
+ */
+export interface GetWithdrawLinkRequest {
+  id: string
+}
+
+/**
+ * List withdraw links
+ */
+export interface ListWithdrawLinksRequest {
+  include_spent?: boolean   // Include fully used links
+  limit?: number
+  offset?: number
+}
+
+/**
+ * Delete withdraw link
+ */
+export interface DeleteWithdrawLinkRequest {
+  id: string
+}
+
+/**
+ * Create quick vouchers (batch of single-use links)
+ */
+export interface CreateVouchersRequest {
+  title: string
+  amount: number            // sats per voucher
+  count: number             // number of vouchers (1-100)
+  description?: string
+}
+
+/**
+ * Get withdraw link with LNURL
+ */
+export interface WithdrawLinkWithLnurl extends WithdrawLink {
+  lnurl: string             // bech32 encoded LNURL
+  lnurl_url: string         // raw callback URL
+}
+
+/**
+ * List withdrawals for a link
+ */
+export interface ListWithdrawalsRequest {
+  link_id?: string
+  limit?: number
+  offset?: number
+}
+
+/**
+ * Withdraw link response with stats
+ */
+export interface WithdrawLinkResponse {
+  link: WithdrawLinkWithLnurl
+  total_withdrawn_sats: number
+  withdrawals_count: number
+}
+
+/**
+ * Vouchers response
+ */
+export interface VouchersResponse {
+  vouchers: WithdrawLinkWithLnurl[]
+  total_amount_sats: number
+}
+
+// ============================================================================
+// HTTP Handler Types
+// ============================================================================
+
+/**
+ * LNURL callback parameters
+ */
+export interface LnurlCallbackParams {
+  k1: string                // Challenge from initial response
+  pr: string                // Payment request (BOLT11 invoice)
+  id_unique_hash?: string   // For unique links
+}
+
+/**
+ * HTTP route handler
+ */
+export interface HttpRoute {
+  method: 'GET' | 'POST'
+  path: string
+  handler: (req: HttpRequest) => Promise<HttpResponse>
+}
+
+export interface HttpRequest {
+  params: Record<string, string>
+  query: Record<string, string>
+  body?: any
+  headers: Record<string, string>
+}
+
+export interface HttpResponse {
+  status: number
+  body: any
+  headers?: Record<string, string>
+}

src/extensions/withdraw/utils/lnurl.ts

@@ -0,0 +1,131 @@
+/**
+ * LNURL Encoding Utilities
+ *
+ * LNURL is a bech32-encoded URL with hrp "lnurl"
+ * See: https://github.com/lnurl/luds
+ */
+
+import { bech32 } from 'bech32'
+import crypto from 'crypto'
+
+/**
+ * Encode a URL as LNURL (bech32)
+ */
+export function encodeLnurl(url: string): string {
+  const words = bech32.toWords(Buffer.from(url, 'utf8'))
+  return bech32.encode('lnurl', words, 2000)  // 2000 char limit for URLs
+}
+
+/**
+ * Decode an LNURL to a URL
+ */
+export function decodeLnurl(lnurl: string): string {
+  const { prefix, words } = bech32.decode(lnurl, 2000)
+  if (prefix !== 'lnurl') {
+    throw new Error('Invalid LNURL prefix')
+  }
+  return Buffer.from(bech32.fromWords(words)).toString('utf8')
+}
+
+/**
+ * Generate a URL-safe random ID
+ */
+export function generateId(length: number = 22): string {
+  const bytes = crypto.randomBytes(Math.ceil(length * 3 / 4))
+  return bytes.toString('base64url').slice(0, length)
+}
+
+/**
+ * Generate a k1 challenge (32 bytes hex)
+ */
+export function generateK1(): string {
+  return crypto.randomBytes(32).toString('hex')
+}
+
+/**
+ * Generate a unique hash for a link
+ */
+export function generateUniqueHash(): string {
+  return generateId(32)
+}
+
+/**
+ * Generate a unique hash for a specific use of a link
+ * This creates a deterministic hash based on link ID, unique_hash, and use number
+ */
+export function generateUseHash(linkId: string, uniqueHash: string, useNumber: string): string {
+  const data = `${linkId}${uniqueHash}${useNumber}`
+  return crypto.createHash('sha256').update(data).digest('hex').slice(0, 32)
+}
+
+/**
+ * Verify a use hash matches one of the available uses
+ */
+export function verifyUseHash(
+  linkId: string,
+  uniqueHash: string,
+  usesCsv: string,
+  providedHash: string
+): string | null {
+  const uses = usesCsv.split(',').filter(u => u.trim() !== '')
+
+  for (const useNumber of uses) {
+    const expectedHash = generateUseHash(linkId, uniqueHash, useNumber.trim())
+    if (expectedHash === providedHash) {
+      return useNumber.trim()
+    }
+  }
+
+  return null
+}
+
+/**
+ * Build the LNURL callback URL for a withdraw link
+ */
+export function buildLnurlUrl(baseUrl: string, uniqueHash: string): string {
+  // Remove trailing slash from baseUrl
+  const base = baseUrl.replace(/\/$/, '')
+  return `${base}/api/v1/lnurl/${uniqueHash}`
+}
+
+/**
+ * Build the LNURL callback URL for a unique withdraw link
+ */
+export function buildUniqueLnurlUrl(
+  baseUrl: string,
+  uniqueHash: string,
+  useHash: string
+): string {
+  const base = baseUrl.replace(/\/$/, '')
+  return `${base}/api/v1/lnurl/${uniqueHash}/${useHash}`
+}
+
+/**
+ * Build the callback URL for the second step (where user sends invoice)
+ */
+export function buildCallbackUrl(baseUrl: string, uniqueHash: string): string {
+  const base = baseUrl.replace(/\/$/, '')
+  return `${base}/api/v1/lnurl/cb/${uniqueHash}`
+}
+
+/**
+ * Sats to millisats
+ */
+export function satsToMsats(sats: number): number {
+  return sats * 1000
+}
+
+/**
+ * Millisats to sats
+ */
+export function msatsToSats(msats: number): number {
+  return Math.floor(msats / 1000)
+}
+
+/**
+ * Validate a BOLT11 invoice (basic check)
+ */
+export function isValidBolt11(invoice: string): boolean {
+  const lower = invoice.toLowerCase()
+  return lower.startsWith('lnbc') || lower.startsWith('lntb') || lower.startsWith('lnbcrt')
+}

src/index.ts

@@ -1,4 +1,8 @@
 import 'dotenv/config'
+import express from 'express'
+import cors from 'cors'
+import path from 'path'
+import { fileURLToPath } from 'url'
 import NewServer from '../proto/autogenerated/ts/express_server.js'
 import GetServerMethods from './services/serverMethods/index.js'
 import serverOptions from './auth.js';
@@ -8,9 +12,15 @@ import { initMainHandler, initSettings } from './services/main/init.js';
 import { nip19 } from 'nostr-tools'
 import { LoadStorageSettingsFromEnv } from './services/storage/index.js';
 import { AppInfo } from './services/nostr/nostrPool.js';
+import { createExtensionLoader, ExtensionLoader } from './extensions/loader.js'
+import { createMainHandlerAdapter } from './extensions/mainHandlerAdapter.js'
+import type { HttpRoute } from './extensions/withdraw/types.js'
 //@ts-ignore
 const { nprofileEncode } = nip19
 
+const __filename = fileURLToPath(import.meta.url)
+const __dirname = path.dirname(__filename)
+
 
 const start = async () => {
     const log = getLogger({})
@@ -25,6 +35,42 @@ const start = async () => {
 
     const { mainHandler, localProviderClient, wizard, adminManager } = keepOn
     const serverMethods = GetServerMethods(mainHandler)
+
+    // Initialize extension system BEFORE nostrMiddleware so RPC methods are available
+    let extensionLoader: ExtensionLoader | null = null
+    const mainPort = settingsManager.getSettings().serviceSettings.servicePort
+    const extensionPort = mainPort + 1
+
+    // Extension routes run on a separate port (main port + 1)
+    // SERVICE_URL for extensions should point to this port for LNURL to work
+    // In production, use a reverse proxy to route /api/v1/lnurl/* to extension port
+    const extensionServiceUrl = process.env.EXTENSION_SERVICE_URL || `http://localhost:${extensionPort}`
+
+    try {
+        log("initializing extension system")
+        const extensionsDir = path.join(__dirname, 'extensions')
+        const databaseDir = path.join(__dirname, '..', 'data', 'extensions')
+
+        const mainHandlerAdapter = createMainHandlerAdapter(mainHandler)
+        extensionLoader = createExtensionLoader(
+            { extensionsDir, databaseDir },
+            mainHandlerAdapter
+        )
+
+        await extensionLoader.loadAll()
+        log(`loaded ${extensionLoader.getAllExtensions().length} extension(s)`)
+
+        // Set base URL for LNURL generation on withdraw extension
+        const withdrawExt = extensionLoader.getExtension('withdraw')
+        if (withdrawExt && withdrawExt.instance && 'setBaseUrl' in withdrawExt.instance) {
+            (withdrawExt.instance as any).setBaseUrl(extensionServiceUrl)
+            log(`withdraw extension base URL set to ${extensionServiceUrl}`)
+        }
+    } catch (e) {
+        log(`extension system initialization failed: ${e}`)
+    }
+
+    // Initialize nostr middleware with extension loader for RPC routing
     log("initializing nostr middleware")
     const relays = settingsManager.getSettings().nostrRelaySettings.relays
     const maxEventContentLength = settingsManager.getSettings().nostrRelaySettings.maxEventContentLength
@@ -45,7 +91,8 @@ const start = async () => {
         {
             relays, maxEventContentLength, apps
         },
-        (e, p) => mainHandler.liquidityProvider.onEvent(e, p)
+        (e, p) => mainHandler.liquidityProvider.onEvent(e, p),
+        { extensionLoader: extensionLoader || undefined }
     )
     exitHandler(() => { Stop(); mainHandler.Stop() })
     log("starting server")
@@ -58,8 +105,58 @@ const start = async () => {
         wizard.AddConnectInfo(appNprofile, relays)
     }
     adminManager.setAppNprofile(appNprofile)
+
+    // Create Express app for extension HTTP routes
+    const extensionApp = express()
+    extensionApp.use(cors()) // Enable CORS for all origins (ATM apps, wallets, etc.)
+    extensionApp.use(express.json())
+
+    // Mount extension HTTP routes
+    if (extensionLoader) {
+        for (const ext of extensionLoader.getAllExtensions()) {
+            if (ext.status === 'ready' && 'getHttpRoutes' in ext.instance) {
+                const routes = (ext.instance as any).getHttpRoutes() as HttpRoute[]
+                for (const route of routes) {
+                    log(`mounting extension route: ${route.method} ${route.path}`)
+                    const handler = async (req: express.Request, res: express.Response) => {
+                        try {
+                            const httpReq = {
+                                params: req.params,
+                                query: req.query as Record<string, string>,
+                                body: req.body,
+                                headers: req.headers as Record<string, string>
+                            }
+                            const result = await route.handler(httpReq)
+                            res.status(result.status)
+                            if (result.headers) {
+                                for (const [key, value] of Object.entries(result.headers)) {
+                                    res.setHeader(key, value)
+                                }
+                            }
+                            res.json(result.body)
+                        } catch (e: any) {
+                            log(`extension route error: ${e.message}`)
+                            res.status(500).json({ status: 'ERROR', reason: e.message })
+                        }
+                    }
+                    if (route.method === 'GET') {
+                        extensionApp.get(route.path, handler)
+                    } else if (route.method === 'POST') {
+                        extensionApp.post(route.path, handler)
+                    }
+                }
+            }
+        }
+    }
+
+    // Start extension routes server
+    extensionApp.listen(extensionPort, () => {
+        log(`extension HTTP routes listening on port ${extensionPort}`)
+    })
+
+    // Start main proto server
     const Server = NewServer(serverMethods, serverOptions(mainHandler))
-    Server.Listen(settingsManager.getSettings().serviceSettings.servicePort)
+    Server.Listen(mainPort)
 }
 start()
 

src/nostrMiddleware.ts

@@ -5,9 +5,15 @@ import * as Types from '../proto/autogenerated/ts/types.js'
 import NewNostrTransport, { NostrRequest } from '../proto/autogenerated/ts/nostr_transport.js';
 import { ERROR, getLogger } from "./services/helpers/logger.js";
 import { NdebitData, NofferData, NmanageRequest } from "@shocknet/clink-sdk";
+import type { ExtensionLoader } from "./extensions/loader.js"
 type ExportedCalls = { Stop: () => void, Send: NostrSend, Ping: () => Promise<void>, Reset: (settings: NostrSettings) => void }
 type ClientEventCallback = (e: { requestId: string }, fromPub: string) => void
-export default (serverMethods: Types.ServerMethods, mainHandler: Main, nostrSettings: NostrSettings, onClientEvent: ClientEventCallback): ExportedCalls => {
+
+export type NostrMiddlewareOptions = {
+    extensionLoader?: ExtensionLoader
+}
+
+export default (serverMethods: Types.ServerMethods, mainHandler: Main, nostrSettings: NostrSettings, onClientEvent: ClientEventCallback, options?: NostrMiddlewareOptions): ExportedCalls => {
     const log = getLogger({})
     const nostrTransport = NewNostrTransport(serverMethods, {
         NostrUserAuthGuard: async (appId, pub) => {
@@ -95,6 +101,31 @@ export default (serverMethods: Types.ServerMethods, mainHandler: Main, nostrSett
             log(ERROR, "authIdentifier does not match", j.authIdentifier || "--", event.pub)
             return
         }
+
+        // Check if this is an extension RPC method
+        const extensionLoader = options?.extensionLoader
+        if (extensionLoader && j.rpcName && extensionLoader.hasMethod(j.rpcName)) {
+            // Route to extension
+            log(`[Nostr] Routing to extension method: ${j.rpcName}`)
+            extensionLoader.callMethod(j.rpcName, j.body || {}, event.appId, event.pub)
+                .then(result => {
+                    const response = { status: 'OK', requestId: j.requestId, ...result }
+                    nostr.Send(
+                        { type: 'app', appId: event.appId },
+                        { type: 'content', pub: event.pub, content: JSON.stringify(response) }
+                    )
+                })
+                .catch(err => {
+                    log(ERROR, `Extension method ${j.rpcName} failed:`, err.message)
+                    const response = { status: 'ERROR', requestId: j.requestId, reason: err.message }
+                    nostr.Send(
+                        { type: 'app', appId: event.appId },
+                        { type: 'content', pub: event.pub, content: JSON.stringify(response) }
+                    )
+                })
+            return
+        }
+
         nostrTransport({ ...j, appId: event.appId }, res => {
             nostr.Send({ type: 'app', appId: event.appId }, { type: 'content', pub: event.pub, content: JSON.stringify({ ...res, requestId: j.requestId }) })
         }, event.startAtNano, event.startAtMs)

src/services/lnd/payInvoiceReq.ts

@@ -9,7 +9,7 @@ export const PayInvoiceReq = (invoice: string, amount: number, feeLimit: number)
     maxParts: 3,
     timeoutSeconds: 50,
 
-    allowSelfPayment: false,
+    allowSelfPayment: true,
     amp: false,
     amtMsat: 0n,
     cltvLimit: 0,

src/services/main/applicationManager.ts

@@ -239,6 +239,8 @@ export default class {
             const paid = await this.paymentManager.PayInvoice(appUser.user.user_id, req, app, {
                 ack: pendingOp => { this.notifyAppUserPayment(appUser, pendingOp) }
             })
+            // Refresh appUser balance from DB so notification has accurate latest_balance
+            appUser.user.balance_sats = paid.latest_balance
             this.notifyAppUserPayment(appUser, paid.operation)
             getLogger({ appName: app.name })(appUser.identifier, "invoice paid", paid.amount_paid, "sats")
             return paid

src/services/nostr/nip44v1.ts

@@ -1,14 +1,14 @@
-import { base64 } from "@scure/base";
+import { base64, hex } from "@scure/base";
 import { randomBytes } from "@noble/hashes/utils";
 import { streamXOR as xchacha20 } from "@stablelib/xchacha20";
-import { secp256k1 } from "@noble/curves/secp256k1";
+import { secp256k1 } from "@noble/curves/secp256k1.js";
 import { sha256 } from "@noble/hashes/sha256";
 export type EncryptedData = {
     ciphertext: Uint8Array;
     nonce: Uint8Array;
 }
 export const getSharedSecret = (privateKey: string, publicKey: string) => {
-    const key = secp256k1.getSharedSecret(privateKey, "02" + publicKey);
+    const key = secp256k1.getSharedSecret(hex.decode(privateKey), hex.decode("02" + publicKey));
     return sha256(key.slice(1, 33));
 }