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Demo 65: Zero-Config Connectivity

Overview

VibeCody discovers peers and exposes its daemon without manual port-forwarding or config files. Two mechanisms work in tandem:

  • mDNS LAN discovery — broadcast _vibecli._tcp on the local network so other VibeCLI instances and the VibeUI desktop app find each other instantly
  • ngrok auto-detection — if ngrok is running, VibeCLI reads the tunnel URL from the ngrok API and announces it so remote collaborators can connect

mDNS LAN Discovery

# Start daemon with mDNS announcement (enabled by default)
vibecli --serve --port 7860

# Output:
# [vibecli] A2A protocol enabled on port 7860
# [mdns] Announced _vibecli._tcp → vibecli-macbook.local:7860
# [vibecli serve] Listening on http://127.0.0.1:7860

# Discover peers on your LAN (from any machine)
vibecli --discover

# Output:
# Peers on local network:
#   alice-mbp.local       → http://alice-mbp.local:7860
#   build-server.local    → http://build-server.local:7860

How it works

VibeCLI registers an mDNS service record via the mdns_announce module:

Service type : _vibecli._tcp.local.
Instance     : vibecli-<hostname>
Port         : 7860 (configurable)
TXT records  : version=<semver>, agent=<agent-name>

The VibeUI desktop app listens for these announcements and populates the “Local Peers” panel automatically.

ngrok Tunnel Auto-Detection

# 1. Start ngrok in another terminal (or as a background service)
ngrok http 7860

# 2. Start VibeCLI — it detects the active tunnel automatically
vibecli --serve

# Output:
# [ngrok] Detected tunnel: https://abc123.ngrok.io → 127.0.0.1:7860
# [ngrok] Public URL: https://abc123.ngrok.io
# [vibecli serve] Listening on http://127.0.0.1:7860

# Share the ngrok URL with a remote collaborator
vibecli --tunnel-url
# → https://abc123.ngrok.io

Detection mechanism

The ngrok module polls http://127.0.0.1:4040/api/tunnels (ngrok’s local API) every 5 seconds. When a https tunnel is found pointing to the configured daemon port, the URL is stored and broadcast via mDNS TXT record tunnel=<url>.

# Manually set a tunnel URL (useful with other tunnel providers)
vibecli --config set network.tunnel_url https://my-tunnel.example.com

# Disable auto-detection
vibecli --config set network.ngrok_autodetect false

Tailscale Integration

For persistent, authenticated connectivity use Tailscale Funnel:

# See Demo 55 for the full Tailscale walkthrough
vibecli --serve --tailscale
# [tailscale] Funnel URL: https://myhost.tail12345.ts.net/vibecli

The tailscale module integrates with mdns_announce — the Funnel URL is added as a TXT record alongside the ngrok URL so peers have both options.

VibeUI Auto-Connect

When the VibeUI desktop app starts, it:

  1. Listens for _vibecli._tcp mDNS announcements
  2. Checks the ngrok TXT record on discovered peers
  3. Connects to the first healthy peer (ping < 100ms)
  4. Falls back to http://127.0.0.1:7860 if no peers found

This means opening VibeUI on a machine where VibeCLI is already running connects them automatically — no configuration needed.

Configuration

# ~/.vibecli/config.toml
[network]
mdns_enabled       = true
mdns_service_name  = "vibecli"          # → _vibecli._tcp
mdns_port          = 7860
ngrok_autodetect   = true
ngrok_api_port     = 4040               # default ngrok local API port
tunnel_url         = ""                 # override: set manually if needed

Rust Modules

Module Purpose
mdns_announce mDNS/DNS-SD service registration and peer discovery
ngrok ngrok local API polling, tunnel URL extraction
tailscale Tailscale daemon integration, Funnel URL detection