LDK MCP Server

Instructions

Implementation Reference

• src/tools/backupState.ts:24-219 (handler)

  The main tool handler function (execute) that processes input arguments for 'backup' and 'restore' actions. For backup, it calls lightningService.backupState() and returns base64 data with size, timestamp, and extensive Swift iOS backup implementation example. For restore, it calls lightningService.restoreState() with provided backup data.

    execute: async (args: any): Promise<ToolResult> => {
      try {
        if (args.action === 'backup') {
          const backup = await lightningService.backupState();
          
          return {
            content: [{
              type: 'text',
              text: JSON.stringify({
                success: true,
                action: 'backup',
                backupData: backup,
                backupSize: Buffer.from(backup, 'base64').length,
                timestamp: new Date().toISOString(),
                swiftExample: `
  // Swift code for channel backup in your iOS app
  import LightningDevKit
  import Foundation
  
  class LDKBackupManager {
      private let fileManager = FileManager.default
      private let backupDirectory: URL
      
      init() throws {
          // Create backup directory in app's documents
          let documentsPath = fileManager.urls(for: .documentDirectory, 
                                             in: .userDomainMask).first!
          backupDirectory = documentsPath.appendingPathComponent("ldk_backups")
          
          try fileManager.createDirectory(at: backupDirectory, 
                                        withIntermediateDirectories: true)
      }
      
      // Backup channel state
      func backupChannels() throws {
          let channelManager = LDKManager.shared.channelManager
          let channels = channelManager.listChannels()
          
          // Serialize channel monitors
          var backupData: [String: Data] = [:]
          
          for channel in channels {
              let channelId = channel.getChannelId()
              let monitor = LDKManager.shared.getChannelMonitor(channelId: channelId)
              
              if let serialized = monitor?.write() {
                  backupData[channelId.toHex()] = Data(serialized)
              }
          }
          
          // Add channel manager state
          if let managerBytes = channelManager.write() {
              backupData["channel_manager"] = Data(managerBytes)
          }
          
          // Add network graph
          if let graphBytes = LDKManager.shared.networkGraph.write() {
              backupData["network_graph"] = Data(graphBytes)
          }
          
          // Create timestamped backup
          let timestamp = ISO8601DateFormatter().string(from: Date())
          let backupFile = backupDirectory
              .appendingPathComponent("backup_\\(timestamp).json")
          
          let jsonData = try JSONEncoder().encode(backupData)
          try jsonData.write(to: backupFile)
          
          // Also save to iCloud if available
          saveToICloud(data: jsonData, timestamp: timestamp)
          
          print("Backup saved: \\(backupFile.lastPathComponent)")
      }
      
      // Restore from backup
      func restoreFromBackup(backupFile: URL) throws {
          let jsonData = try Data(contentsOf: backupFile)
          let backupData = try JSONDecoder().decode([String: Data].self, from: jsonData)
          
          // Restore channel monitors first
          for (channelIdHex, monitorData) in backupData {
              if channelIdHex == "channel_manager" || channelIdHex == "network_graph" {
                  continue
              }
              
              let monitor = try ChannelMonitor.read(
                  ser: [UInt8](monitorData),
                  arg: LDKManager.shared.keysManager
              )
              
              // Persist restored monitor
              LDKManager.shared.persistChannelMonitor(monitor: monitor)
          }
          
          // Then restore channel manager
          if let managerData = backupData["channel_manager"] {
              // This requires rebuilding the channel manager with monitors
              try LDKManager.shared.restoreChannelManager(
                  serialized: [UInt8](managerData),
                  monitors: getRestoredMonitors()
              )
          }
          
          print("Restore completed successfully")
      }
      
      // Automatic backup on important events
      func setupAutomaticBackup() {
          // Backup after channel updates
          NotificationCenter.default.addObserver(
              self,
              selector: #selector(handleChannelUpdate),
              name: .ldkChannelUpdated,
              object: nil
          )
          
          // Backup periodically
          Timer.scheduledTimer(withTimeInterval: 3600, repeats: true) { _ in
              try? self.backupChannels()
          }
      }
      
      @objc private func handleChannelUpdate() {
          // Debounce backups to avoid too frequent saves
          NSObject.cancelPreviousPerformRequests(
              withTarget: self,
              selector: #selector(performBackup),
              object: nil
          )
          
          perform(#selector(performBackup), with: nil, afterDelay: 5.0)
      }
      
      @objc private func performBackup() {
          try? backupChannels()
      }
      
      // iCloud backup
      private func saveToICloud(data: Data, timestamp: String) {
          guard let containerURL = FileManager.default.url(
              forUbiquityContainerIdentifier: nil
          ) else { return }
          
          let iCloudBackup = containerURL
              .appendingPathComponent("Documents")
              .appendingPathComponent("ldk_backup_\\(timestamp).json")
          
          do {
              try data.write(to: iCloudBackup)
              print("Backup saved to iCloud")
          } catch {
              print("iCloud backup failed: \\(error)")
          }
      }
  }
  
  // Extension for Notification.Name
  extension Notification.Name {
      static let ldkChannelUpdated = Notification.Name("ldkChannelUpdated")
  }`.trim()
              }, null, 2)
            }]
          };
        } else if (args.action === 'restore') {
          if (!args.backupData) {
            throw new Error('Backup data required for restore');
          }
          
          const success = await lightningService.restoreState(args.backupData);
          
          return {
            content: [{
              type: 'text',
              text: JSON.stringify({
                success,
                action: 'restore',
                message: success ? 'State restored successfully' : 'Restore failed'
              }, null, 2)
            }]
          };
        } else {
          throw new Error('Invalid action. Use "backup" or "restore"');
        }
      } catch (error) {
        return {
          content: [{
            type: 'text',
            text: JSON.stringify({
              success: false,
              error: error instanceof Error ? error.message : 'Unknown error'
            }, null, 2)
          }],
          isError: true
        };
      }
    }

• src/tools/backupState.ts:9-23 (schema)

  Tool input schema: object with 'action' (enum: 'backup', 'restore', required) and optional 'backupData' (string, base64 for restore).

  inputSchema: {
    type: 'object',
    properties: {
      action: {
        type: 'string',
        enum: ['backup', 'restore'],
        description: 'Action to perform'
      },
      backupData: {
        type: 'string',
        description: 'Base64 encoded backup data (required for restore)'
      }
    },
    required: ['action']
  },

• src/index.ts:38-62 (registration)

  Registration in the central tools array used by MCP server for listing and executing tools. backupStateTool is included at line 43. The array is used in setRequestHandler for ListToolsRequestSchema and CallToolRequestSchema.

  const tools = [
    generateInvoiceTool,
    payInvoiceTool,
    getChannelStatusTool,
    getNodeInfoTool,
    backupStateTool,
    keychainTestTool,
    backgroundTestTool,
    pushNotificationTool,
    biometricAuthTool,
    createChannelTool,
    closeChannelTool,
    getBalanceTool,
    decodeInvoiceTool,
    listPaymentsTool,
    estimateFeeTool,
    generateMnemonicTool,
    deriveAddressTool,
    getSwiftCodeTool,
    getArchitectureTool,
    testScenarioTool,
    networkGraphTool,
    eventHandlingTool,
    chainSyncTool,
  ];

• src/services/lightningService.ts:228-249 (helper)

  Supporting methods in LightningService: backupState() serializes nodeInfo, channels, payments to JSON base64; restoreState() deserializes and restores the mock LDK state.

  async backupState(): Promise<string> {
    const state = {
      nodeInfo: this.nodeInfo,
      channels: Array.from(this.channels.entries()),
      payments: Array.from(this.payments.entries()),
      timestamp: Date.now()
    };
    
    return Buffer.from(JSON.stringify(state)).toString('base64');
  }
  
  async restoreState(backup: string): Promise<boolean> {
    try {
      const state = JSON.parse(Buffer.from(backup, 'base64').toString());
      this.nodeInfo = state.nodeInfo;
      this.channels = new Map(state.channels);
      this.payments = new Map(state.payments);
      return true;
    } catch (error) {
      throw new Error(`Failed to restore state: ${error}`);
    }
  }