--- name: hd-networking description: > Port architecture, hostnames, and networking rules for Hydrogen Desktop. MUST READ before adding ports, exposing a service to your macOS host, referencing host URLs from inside the workspace, or wiring any service communication. Trigger words — HD port, HD network, port mapping, proxy, 127.0.0.1, loopback, adom-host gateway, hd-control-url, VSCODE_PROXY_URI, relay URL, code-server proxy, container networking, ADOM_CARBON_URL, ADOM_HYDROGEN_URL, direct connect, 8770, 7380. --- # Hydrogen Desktop — Networking & Port Architecture > This is the machine-runtime version (default). For the legacy Docker container > runtime (`HD_RUNTIME=docker`) see the docker/ bucket. ## Core Principle: expose `0.0.0.0` listeners to the Mac The HD workspace is the `Adom-Workspace` machine (a systemd-nspawn machine booted inside the `hd-builder` Lima VM), not a Docker container. macOS does **not** do WSL2-style magic loopback mirroring — vz does NOT mirror loopback. Instead, Lima exposes the machine's listeners to the Mac: **any service that binds `0.0.0.0:` inside the workspace machine is reachable at `127.0.0.1:` on the Mac** — no Docker `-p` mapping, no proxy hop required. The port number is the same on both sides. The two corollaries that drive everything below: - **Bind `0.0.0.0`, not `127.0.0.1`.** A `127.0.0.1`-only listener inside the machine is NOT exposed to the Mac — the Mac can't see it. A workspace service that binds loopback-only is invisible to the host until you route it explicitly (see `hd-port-watcher`). - **There are NO Docker port mappings.** code-server binds `0.0.0.0:7380` inside the machine and is therefore reachable at `localhost:7380` on the Mac automatically. Same for a dev server on `0.0.0.0:5173` → `localhost:5173`. ## In-machine services (no port mapping needed) | Machine Port | Service | Reachable on the Mac at | |--------------|---------|-------------------------| | 7380 | code-server (VS Code) | `localhost:7380` (exposed by Lima) | | 8765 | relay WS | bind `0.0.0.0` → `localhost:8765`, or `/proxy/8765/` | | 8766 | relay HTTP | bind `0.0.0.0` → `localhost:8766`, or `/proxy/8766/` | | 5173 | your dev server | bind `0.0.0.0` → `localhost:5173` | All of these are also reachable through code-server's `/proxy//` URL (see below), which remains the preferred path for browser-facing HTTP/WS. ## Host-Side Ports (Tauri app, native macOS listeners) These ports run on the macOS host inside the HD Tauri process. They are native TCP listeners on the Mac — not inside the workspace machine. | Port | Service | Notes | |------|---------|-------| | 1420 | Dev file server | Dev mode only, serves `build/` | | 8770 | adom-desktop direct connect | Owned by Adom Desktop, NOT HD | | 47080 | HD discovery server | | | 47083 | HD reverse proxy | Proxies to code-server | | 47084 | HD control API | Health, setup, eval, CDP, `/workspace/status`, `/port-forward` | | 47085 | WebView2 CDP | Chrome DevTools Protocol | These are configurable via `~/Library/Application Support/hydrogen-desktop/ports.json`. **Reaching a host service FROM the machine:** use the `adom-host` gateway, NOT `127.0.0.1`. macOS/vz does NOT mirror loopback, so a host listener on `127.0.0.1:` is not visible at the machine's own loopback. Instead the host binds `0.0.0.0`, and the machine reaches it via the `adom-host` gateway hostname: `adom-host:`. The machine's `/etc/hosts` maps `adom-host` to the gateway IP — no extra firewall rule needed. (`host.docker.internal` is a Docker-ism HD does NOT use — inside the machine it resolves to a *different* interface, not where HD listens, so curls to it fail; use `adom-host` instead.) ## Hostnames — reach the host at `adom-host` ### From inside the machine → host machine ``` adom-host ``` macOS/vz does NOT mirror loopback, so use the `adom-host` gateway alias to reach host listeners from inside the workspace machine. The machine's `/etc/hosts` maps `adom-host` to the gateway IP, so `adom-host:` reaches the Mac's host listeners directly (the host binds `0.0.0.0`). Used for: - `ADOM_CARBON_URL=http://adom-host:{proxy_port}` - `ADOM_HYDROGEN_URL=http://adom-host:{proxy_port}` - Direct connect probe: `http://adom-host:8770/health` - HD control API: the live URL in `~/.adom/hd-control-url` (`http://adom-host:`) The control port is **dynamic per launch** — read it from `~/.adom/hd-control-url` (your non-interactive Bash shells don't source `.bashrc`/`profile.d`, so the env var alone is unreliable): `BASE="$(cat ~/.adom/hd-control-url)"`. ### From the host → machine services (via proxy) ``` http://127.0.0.1:{code_server_port}/proxy/{machine_port}/ ws://127.0.0.1:{code_server_port}/proxy/{machine_port}/ ``` Example: relay health → `http://127.0.0.1:7380/proxy/8766/health` Example: relay WS → `ws://127.0.0.1:7380/proxy/8765/` This path always works for `0.0.0.0` AND `127.0.0.1`-bound machine services, because code-server itself is inside the machine and proxies to them locally. It is the preferred path for browser-facing HTTP/WS even though direct exposure also works for `0.0.0.0` listeners. ### From the host → host-side services ``` http://127.0.0.1:{port}/ ``` Control API → `http://127.0.0.1:47084/health` Direct connect → `http://127.0.0.1:8770/health` ## Relay Architecture The relay (`adom-desktop serve`) runs inside the machine on ports 8765 (WebSocket) and 8766 (HTTP). It binds `0.0.0.0`, so it is reachable both via Lima's port exposure (`localhost:8765` / `localhost:8766` on the Mac) and via the code-server proxy. The proxy path is preferred for connection stability: 1. **adom-desktop on the Mac** connects as a WS client via the code-server proxy: `ws://127.0.0.1:7380/proxy/8765/` 2. **Registration** happens via `server_add` on the direct connect API (port 8770): ```json { "name": "HD Local Machine", "url": "ws://127.0.0.1:7380/proxy/8765/", "autoConnect": true } ``` 3. **Health checks** use the proxy path: `http://127.0.0.1:7380/proxy/8766/health` This matches cloud containers where adom-desktop connects via `wss://.adom.cloud/proxy/8765/`. ## VSCODE_PROXY_URI Inside the machine, `VSCODE_PROXY_URI` is set by code-server: ``` https://.adom.cloud/proxy/{{port}}/ (cloud) http://localhost:7380/proxy/{{port}}/ (HD local, approximate) ``` Tools that build proxy URLs should use `VSCODE_PROXY_URI` when available, falling back to `http://127.0.0.1:{code_server}/proxy/{port}/`. ## In-machine command form The workspace is the `Adom-Workspace` machine inside the `hd-builder` Lima VM, so you reach it by entering its namespaces via `nsenter`, NEVER `docker exec` (`` is the machine's leader PID): ```bash limactl shell hd-builder -- sudo nsenter -t -a -S 1001 -G 1001 -- bash -lc '' # or the simpler form for a single command: limactl shell hd-builder -- sudo nsenter -t -a -S 1001 -G 1001 -- ``` ## NEVER Do These 1. **NEVER bind `127.0.0.1`-only** for a service that must be reachable from the Mac. macOS won't expose it (vz does NOT mirror loopback). Bind `0.0.0.0`, or register it with the port-forward registry (see `hd-port-watcher`). 2. **NEVER use `host.docker.internal` for machine→host** communication — it's a Docker-ism HD doesn't use; inside the machine it resolves to the wrong interface. Reach the host via the `adom-host` gateway (vz does NOT mirror loopback, so `127.0.0.1` does NOT reach the host); read HD's live control URL from `~/.adom/hd-control-url`. 3. **NEVER assume the host's `127.0.0.1` is reachable from inside the machine.** macOS/vz does NOT mirror loopback — use the `adom-host` gateway alias (`adom-host:`); the host binds `0.0.0.0` and the machine's `/etc/hosts` maps `adom-host` to the gateway. No firewall allow needed. 4. **NEVER `docker exec` / `docker cp` against the workspace.** It's the `Adom-Workspace` machine; enter it via `limactl shell hd-builder -- sudo nsenter -t -a -S 1001 -G 1001 --`. 5. **NEVER hardcode port numbers** in machine code. Read from env vars (`ADOM_CARBON_URL`, `ADOM_HYDROGEN_URL`) or discover via the direct connect API. 6. **NEVER assume adom-desktop direct connect (8770) is owned by HD.** It's owned by Adom Desktop. HD's direct-api thread binds to 8770 as a fallback but Adom Desktop takes priority when both are running.