clawdbot/docs/gateway/bridge-protocol.md

summary, read_when

summary	read_when
Bridge protocol (legacy nodes): TCP JSONL, pairing, scoped RPC	Building or debugging node clients (iOS/Android/macOS node mode) Investigating pairing or bridge auth failures Auditing the node surface exposed by the gateway

Bridge protocol (legacy node transport)

The Bridge protocol is a legacy node transport (TCP JSONL). New node clients should use the unified Gateway WebSocket protocol instead.

If you are building an operator or node client, use the Gateway protocol.

Why we have both

• Security boundary: the bridge exposes a small allowlist instead of the full gateway API surface.
• Pairing + node identity: node admission is owned by the gateway and tied to a per-node token.
• Discovery UX: nodes can discover gateways via Bonjour on LAN, or connect directly over a tailnet.
• Loopback WS: the full WS control plane stays local unless tunneled via SSH.

Transport

• TCP, one JSON object per line (JSONL).
• Optional TLS (when bridge.tls.enabled is true).
• Gateway owns the listener (default 18790).

When TLS is enabled, discovery TXT records include bridgeTls=1 plus bridgeTlsSha256 so nodes can pin the certificate.

Handshake + pairing

1. Client sends hello with node metadata + token (if already paired).
2. If not paired, gateway replies error (NOT_PAIRED/UNAUTHORIZED).
3. Client sends pair-request.
4. Gateway waits for approval, then sends pair-ok and hello-ok.

hello-ok returns serverName and may include canvasHostUrl.

Frames

Client → Gateway:

• req / res: scoped gateway RPC (chat, sessions, config, health, voicewake, skills.bins)
• event: node signals (voice transcript, agent request, chat subscribe, exec lifecycle)

Gateway → Client:

• invoke / invoke-res: node commands (canvas.*, camera.*, screen.record, location.get, sms.send)
• event: chat updates for subscribed sessions
• ping / pong: keepalive

Exact allowlist is enforced in src/gateway/server-bridge.ts.

Exec lifecycle events

Nodes can emit exec.finished or exec.denied events to surface system.run activity. These are mapped to system events in the gateway. (Legacy nodes may still emit exec.started.)

Payload fields (all optional unless noted):

• sessionKey (required): agent session to receive the system event.
• runId: unique exec id for grouping.
• command: raw or formatted command string.
• exitCode, timedOut, success, output: completion details (finished only).
• reason: denial reason (denied only).

Tailnet usage

• Bind the bridge to a tailnet IP: bridge.bind: "tailnet" in ~/.clawdbot/clawdbot.json.
• Clients connect via MagicDNS name or tailnet IP.
• Bonjour does not cross networks; use manual host/port or wide-area DNS‑SD when needed.

Versioning

Bridge is currently implicit v1 (no min/max negotiation). Backward‑compat is expected; add a bridge protocol version field before any breaking changes.