Discovery & transports

OpenSoul has two distinct problems that look similar on the surface:

1. Operator remote control: the macOS menu bar app controlling a gateway running elsewhere.
2. Node pairing: iOS/Android (and future nodes) finding a gateway and pairing securely.

The design goal is to keep all network discovery/advertising in the Node Gateway (opensoul gateway) and keep clients (mac app, iOS) as consumers.

Terms

• Gateway: a single long-running gateway process that owns state (sessions, pairing, node registry) and runs channels. Most setups use one per host; isolated multi-gateway setups are possible.
• Gateway WS (control plane): the WebSocket endpoint on 127.0.0.1:18789 by default; can be bound to LAN/tailnet via gateway.bind.
• Direct WS transport: a LAN/tailnet-facing Gateway WS endpoint (no SSH).
• SSH transport (fallback): remote control by forwarding 127.0.0.1:18789 over SSH.
• Legacy TCP bridge (deprecated/removed): older node transport (see Bridge protocol); no longer advertised for discovery.

Protocol details:

• Gateway protocol
• Bridge protocol (legacy)

Why we keep both “direct” and SSH

• Direct WS is the best UX on the same network and within a tailnet:
  • auto-discovery on LAN via Bonjour
  • pairing tokens + ACLs owned by the gateway
  • no shell access required; protocol surface can stay tight and auditable
• SSH remains the universal fallback:
  • works anywhere you have SSH access (even across unrelated networks)
  • survives multicast/mDNS issues
  • requires no new inbound ports besides SSH

Discovery inputs (how clients learn where the gateway is)

1) Bonjour / mDNS (LAN only)

Bonjour is best-effort and does not cross networks. It is only used for “same LAN” convenience.

Target direction:

• The gateway advertises its WS endpoint via Bonjour.
• Clients browse and show a “pick a gateway” list, then store the chosen endpoint.

Troubleshooting and beacon details: Bonjour.

Service beacon details

• Service types:
  • _opensoul-gw._tcp (gateway transport beacon)
• TXT keys (non-secret):
  • role=gateway
  • lanHost=<hostname>.local
  • sshPort=22 (or whatever is advertised)
  • gatewayPort=18789 (Gateway WS + HTTP)
  • gatewayTls=1 (only when TLS is enabled)
  • gatewayTlsSha256=<sha256> (only when TLS is enabled and fingerprint is available)
  • canvasPort=18793 (default canvas host port; serves /__opensoul__/canvas/)
  • cliPath=<path> (optional; absolute path to a runnable opensoul entrypoint or binary)
  • tailnetDns=<magicdns> (optional hint; auto-detected when Tailscale is available)

Disable/override:

• OPENSOUL_DISABLE_BONJOUR=1 disables advertising.
• gateway.bind in ~/.opensoul/opensoul.json controls the Gateway bind mode.
• OPENSOUL_SSH_PORT overrides the SSH port advertised in TXT (defaults to 22).
• OPENSOUL_TAILNET_DNS publishes a tailnetDns hint (MagicDNS).
• OPENSOUL_CLI_PATH overrides the advertised CLI path.

2) Tailnet (cross-network)

For London/Vienna style setups, Bonjour won’t help. The recommended “direct” target is:

• Tailscale MagicDNS name (preferred) or a stable tailnet IP.

If the gateway can detect it is running under Tailscale, it publishes tailnetDns as an optional hint for clients (including wide-area beacons).

3) Manual / SSH target

When there is no direct route (or direct is disabled), clients can always connect via SSH by forwarding the loopback gateway port.

See Remote access.

Transport selection (client policy)

Recommended client behavior:

1. If a paired direct endpoint is configured and reachable, use it.
2. Else, if Bonjour finds a gateway on LAN, offer a one-tap “Use this gateway” choice and save it as the direct endpoint.
3. Else, if a tailnet DNS/IP is configured, try direct.
4. Else, fall back to SSH.

Pairing + auth (direct transport)

The gateway is the source of truth for node/client admission.

• Pairing requests are created/approved/rejected in the gateway (see Gateway pairing).
• The gateway enforces:
  • auth (token / keypair)
  • scopes/ACLs (the gateway is not a raw proxy to every method)
  • rate limits

Responsibilities by component

• Gateway: advertises discovery beacons, owns pairing decisions, and hosts the WS endpoint.
• macOS app: helps you pick a gateway, shows pairing prompts, and uses SSH only as a fallback.
• iOS/Android nodes: browse Bonjour as a convenience and connect to the paired Gateway WS.