86 lines
3.2 KiB
Markdown
86 lines
3.2 KiB
Markdown
---
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summary: "Bridge protocol (legacy nodes): TCP JSONL, pairing, scoped RPC"
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read_when:
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- Building or debugging node clients (iOS/Android/macOS node mode)
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- Investigating pairing or bridge auth failures
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- Auditing the node surface exposed by the gateway
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---
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# Bridge protocol (legacy node transport)
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The Bridge protocol is a **legacy** node transport (TCP JSONL). New node clients
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should use the unified Gateway WebSocket protocol instead.
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If you are building an operator or node client, use the
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[Gateway protocol](/gateway/protocol).
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**Note:** Current Clawdbot builds no longer ship the TCP bridge listener; this document is kept for historical reference.
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Legacy `bridge.*` config keys are no longer part of the config schema.
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## Why we have both
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- **Security boundary**: the bridge exposes a small allowlist instead of the
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full gateway API surface.
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- **Pairing + node identity**: node admission is owned by the gateway and tied
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to a per-node token.
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- **Discovery UX**: nodes can discover gateways via Bonjour on LAN, or connect
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directly over a tailnet.
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- **Loopback WS**: the full WS control plane stays local unless tunneled via SSH.
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## Transport
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- TCP, one JSON object per line (JSONL).
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- Optional TLS (when `bridge.tls.enabled` is true).
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- Legacy default listener port was `18790` (current builds do not start a TCP bridge).
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When TLS is enabled, discovery TXT records include `bridgeTls=1` plus
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`bridgeTlsSha256` so nodes can pin the certificate.
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## Handshake + pairing
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1) Client sends `hello` with node metadata + token (if already paired).
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2) If not paired, gateway replies `error` (`NOT_PAIRED`/`UNAUTHORIZED`).
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3) Client sends `pair-request`.
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4) Gateway waits for approval, then sends `pair-ok` and `hello-ok`.
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`hello-ok` returns `serverName` and may include `canvasHostUrl`.
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## Frames
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Client → Gateway:
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- `req` / `res`: scoped gateway RPC (chat, sessions, config, health, voicewake, skills.bins)
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- `event`: node signals (voice transcript, agent request, chat subscribe, exec lifecycle)
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Gateway → Client:
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- `invoke` / `invoke-res`: node commands (`canvas.*`, `camera.*`, `screen.record`,
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`location.get`, `sms.send`)
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- `event`: chat updates for subscribed sessions
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- `ping` / `pong`: keepalive
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Legacy allowlist enforcement lived in `src/gateway/server-bridge.ts` (removed).
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## Exec lifecycle events
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Nodes can emit `exec.finished` or `exec.denied` events to surface system.run activity.
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These are mapped to system events in the gateway. (Legacy nodes may still emit `exec.started`.)
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Payload fields (all optional unless noted):
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- `sessionKey` (required): agent session to receive the system event.
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- `runId`: unique exec id for grouping.
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- `command`: raw or formatted command string.
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- `exitCode`, `timedOut`, `success`, `output`: completion details (finished only).
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- `reason`: denial reason (denied only).
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## Tailnet usage
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- Bind the bridge to a tailnet IP: `bridge.bind: "tailnet"` in
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`~/.clawdbot/clawdbot.json`.
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- Clients connect via MagicDNS name or tailnet IP.
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- Bonjour does **not** cross networks; use manual host/port or wide-area DNS‑SD
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when needed.
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## Versioning
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Bridge is currently **implicit v1** (no min/max negotiation). Backward‑compat
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is expected; add a bridge protocol version field before any breaking changes.
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