Class LanBeacon

src/utils/lanBeacon.ts:60–205

// ---------------------------------------------------------------------------

export class LanBeacon extends EventEmitter {
  private socket: DgramSocket | null = null
  private announceTimer: ReturnType<typeof setInterval> | null = null
  private cleanupTimer: ReturnType<typeof setInterval> | null = null
  private peers: Map<string, LanAnnounce> = new Map()
  private announce: LanAnnounce

  constructor(announce: Omit<LanAnnounce, 'proto' | 'ts'>) {
    super()
    this.announce = {
      ...announce,
      proto: 'claude-pipe-v1',
      ts: Date.now(),
    }
  }

  /**
   * Start broadcasting announcements and listening for peers.
   */
  start(): void {
    if (this.socket) return

    try {
      this.socket = createSocket({ type: 'udp4', reuseAddr: true })

      this.socket.on('error', err => {
        logError(err)
        // Non-fatal — multicast may not be supported on this network
      })

      this.socket.on('message', (buf, _rinfo) => {
        try {
          const msg = JSON.parse(buf.toString()) as LanAnnounce
          if (msg.proto !== 'claude-pipe-v1') return
          if (msg.pipeName === this.announce.pipeName) return // ignore self

          const isNew = !this.peers.has(msg.pipeName)
          this.peers.set(msg.pipeName, { ...msg, ts: Date.now() })

          if (isNew) {
            this.emit('peer-discovered', msg)
          }
        } catch {
          // Malformed packet — ignore
        }
      })

      this.socket.bind(MULTICAST_PORT, () => {
        try {
          // Specify the local LAN interface for multicast membership.
          // Without this, Windows may bind to a WSL/Docker virtual adapter
          // and multicast packets never reach the real LAN.
          const localIp = this.announce.ip
          this.socket!.addMembership(MULTICAST_GROUP, localIp)
          this.socket!.setMulticastInterface(localIp)
          this.socket!.setMulticastTTL(1) // link-local only
          this.socket!.setBroadcast(true)
        } catch (err) {