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Bonjour / mDNS discovery

Clawdbot uses Bonjour (mDNS / DNS‑SD) as a LAN‑only convenience to discover an active Gateway bridge. It is best‑effort and does not replace SSH or Tailnet-based connectivity.

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Wide‑area Bonjour (Unicast DNS‑SD) over Tailscale

If the node and gateway are on different networks, multicast mDNS won’t cross the boundary. You can keep the same discovery UX by switching to unicast DNS‑SD (“Wide‑Area Bonjour”) over Tailscale. High‑level steps:
  1. Run a DNS server on the gateway host (reachable over Tailnet).
  2. Publish DNS‑SD records for _clawdbot-bridge._tcp under a dedicated zone (example: clawdbot.internal.).
  3. Configure Tailscale split DNS so clawdbot.internal resolves via that DNS server for clients (including iOS).
Clawdbot standardizes on clawdbot.internal. for this mode. iOS/Android nodes browse both local. and clawdbot.internal. automatically. 
{
  bridge: { bind: "tailnet" }, // tailnet-only (recommended)
  discovery: { wideArea: { enabled: true } } // enables clawdbot.internal DNS-SD publishing
}

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One‑time DNS server setup (gateway host)

clawdbot dns setup --apply
This installs CoreDNS and configures it to:
  • listen on port 53 only on the gateway’s Tailscale interfaces
  • serve clawdbot.internal. from ~/.clawdbot/dns/clawdbot.internal.db
Validate from a tailnet‑connected machine: 
dns-sd -B _clawdbot-bridge._tcp clawdbot.internal.
dig @<TAILNET_IPV4> -p 53 _clawdbot-bridge._tcp.clawdbot.internal PTR +short

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Tailscale DNS settings

In the Tailscale admin console:
  • Add a nameserver pointing at the gateway’s tailnet IP (UDP/TCP 53).
  • Add split DNS so the domain clawdbot.internal uses that nameserver.
Once clients accept tailnet DNS, iOS nodes can browse _clawdbot-bridge._tcp in clawdbot.internal. without multicast. The bridge port (default 18790) is a plain TCP service. By default it binds to 0.0.0.0, which makes it reachable from any interface on the gateway host. For tailnet‑only setups:
  • Set bridge.bind: "tailnet" in ~/.clawdbot/clawdbot.json.
  • Restart the Gateway (or restart the macOS menubar app).

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What advertises

Only the Gateway (when the bridge is enabled) advertises _clawdbot-bridge._tcp.

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Service types

  • _clawdbot-bridge._tcp — bridge transport beacon (used by macOS/iOS/Android nodes).

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TXT keys (non‑secret hints)

The Gateway advertises small non‑secret hints to make UI flows convenient:
  • role=gateway
  • displayName=<friendly name>
  • lanHost=<hostname>.local
  • gatewayPort=<port> (informational; Gateway WS is usually loopback‑only)
  • bridgePort=<port> (only when bridge is enabled)
  • canvasPort=<port> (only when the canvas host is enabled; default 18793)
  • sshPort=<port> (defaults to 22 when not overridden)
  • transport=bridge
  • cliPath=<path> (optional; absolute path to a runnable clawdbot entrypoint)
  • tailnetDns=<magicdns> (optional hint when Tailnet is available)

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Debugging on macOS

Useful built‑in tools:
  • Browse instances: 
    dns-sd -B _clawdbot-bridge._tcp local.
  • Resolve one instance (replace <instance>): 
    dns-sd -L "<instance>" _clawdbot-bridge._tcp local.
If browsing works but resolving fails, you’re usually hitting a LAN policy or mDNS resolver issue.

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Debugging in Gateway logs

The Gateway writes a rolling log file (printed on startup as gateway log file: ...). Look for bonjour: lines, especially:
  • bonjour: advertise failed ...
  • bonjour: ... name conflict resolved / hostname conflict resolved
  • bonjour: watchdog detected non-announced service ...

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Debugging on iOS node

The iOS node uses NWBrowser to discover _clawdbot-bridge._tcp. To capture logs:
  • Settings → Bridge → Advanced → Discovery Debug Logs
  • Settings → Bridge → Advanced → Discovery Logs → reproduce → Copy
The log includes browser state transitions and result‑set changes.

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Common failure modes

  • Bonjour doesn’t cross networks: use Tailnet or SSH.
  • Multicast blocked: some Wi‑Fi networks disable mDNS.
  • Sleep / interface churn: macOS may temporarily drop mDNS results; retry.
  • Browse works but resolve fails: keep machine names simple (avoid emojis or punctuation), then restart the Gateway. The bridge instance name derives from the host name, so overly complex names can confuse some resolvers.

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Escaped instance names (\032)

Bonjour/DNS‑SD often escapes bytes in service instance names as decimal \DDD sequences (e.g. spaces become \032).
  • This is normal at the protocol level.
  • UIs should decode for display (iOS uses BonjourEscapes.decode).

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Disabling / configuration

  • CLAWDBOT_DISABLE_BONJOUR=1 disables advertising.
  • CLAWDBOT_BRIDGE_ENABLED=0 disables the bridge listener (and the bridge beacon).
  • bridge.bind / bridge.port in ~/.clawdbot/clawdbot.json control bridge bind/port.
  • CLAWDBOT_BRIDGE_HOST / CLAWDBOT_BRIDGE_PORT still work as back‑compat overrides.
  • CLAWDBOT_SSH_PORT overrides the SSH port advertised in TXT.
  • CLAWDBOT_TAILNET_DNS publishes a MagicDNS hint in TXT.
  • CLAWDBOT_CLI_PATH overrides the advertised CLI path.