--- name: hd-networking description: > Port architecture, hostnames, and networking rules for Hydrogen Desktop. MUST READ before adding ports, exposing a service to your Windows 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, mirrored networking, 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 WSL2-runtime version (default). For the legacy Docker container > runtime (`HD_RUNTIME=docker`) see the docker/ bucket. ## Core Principle: WSL2 auto-forwards `0.0.0.0` listeners The HD workspace is a WSL2 distro (`Adom-Workspace`), not a Docker container. WSL2 has a built-in localhost-forwarding feature: **any service that binds `0.0.0.0:` inside the distro is automatically reachable at `127.0.0.1:` on Windows** — no Docker `-p` mapping, no proxy hop required. There is no port-mapping table to maintain; 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`.** WSL2 does NOT auto-forward a `127.0.0.1`-only listener — Windows can't see it. A distro 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 distro and is therefore reachable at `localhost:7380` on Windows automatically. Same for a dev server on `0.0.0.0:5173` → `localhost:5173`. ## In-distro services (no port mapping needed) | Distro Port | Service | Reachable on Windows at | |-------------|---------|-------------------------| | 7380 | code-server (VS Code) | `localhost:7380` (auto-forwarded) | | 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 Windows listeners) These ports run on the Windows host inside the HD Tauri process. They are native TCP listeners on Windows — not inside the distro. | 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, `/wsl/status`, `/port-forward` | | 47085 | WebView2 CDP | Chrome DevTools Protocol | These are configurable via `%APPDATA%\hydrogen-desktop\ports.json`. **Reaching a host service FROM the distro:** just use `127.0.0.1:`. WSL2 **mirrored networking** shares the loopback interface between the distro and the Windows host, so a Windows listener on `127.0.0.1:` is reachable at the same `127.0.0.1:` from inside the distro — no gateway IP, no firewall rule, no `0.0.0.0` requirement on the host side. (`host.docker.internal` is a Docker-ism HD does NOT use under WSL2 — inside the distro it resolves to a *different* interface, not where HD listens, so curls to it fail.) ## Hostnames — reach the host at `127.0.0.1` ### From inside the distro → host machine ``` 127.0.0.1 ``` WSL2 mirrored networking shares loopback with the Windows host, so `127.0.0.1` inside the distro reaches Windows host listeners directly. The distro's `/etc/hosts` also has `127.0.0.1 adom-host` (the non-Docker alias → loopback), but you generally don't need it — use `127.0.0.1`. Used for: - `ADOM_CARBON_URL=http://127.0.0.1:{proxy_port}` - `ADOM_HYDROGEN_URL=http://127.0.0.1:{proxy_port}` - Direct connect probe: `http://127.0.0.1:8770/health` - HD control API: the live URL in `~/.adom/hd-control-url` (`http://127.0.0.1:`) 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 → distro services (via proxy) ``` http://127.0.0.1:{code_server_port}/proxy/{distro_port}/ ws://127.0.0.1:{code_server_port}/proxy/{distro_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 distro services, because code-server itself is inside the distro and proxies to them locally. It is the preferred path for browser-facing HTTP/WS even though direct auto-forward 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 distro on ports 8765 (WebSocket) and 8766 (HTTP). It binds `0.0.0.0`, so it is reachable both via WSL2 auto-forward (`localhost:8765` / `localhost:8766` on Windows) and via the code-server proxy. The proxy path is preferred for connection stability: 1. **adom-desktop on Windows** 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 WSL", "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 distro, `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-distro command form The workspace is a WSL2 distro, so you reach it with `wsl`, NEVER `docker exec`: ```bash wsl -d Adom-Workspace -u adom -- # or, since the distro boots as root: wsl -d Adom-Workspace -- su - adom -c '' ``` ## NEVER Do These 1. **NEVER bind `127.0.0.1`-only** for a service that must be reachable from Windows. WSL2 won't auto-forward it. Bind `0.0.0.0`, or register it with the port-forward registry (see `hd-port-watcher`). 2. **NEVER use `host.docker.internal` for distro→host** communication — it's a Docker-ism HD doesn't use; inside the distro it resolves to the wrong interface. Reach the host at `127.0.0.1` (WSL2 mirrored networking shares loopback); read HD's live control URL from `~/.adom/hd-control-url`. 3. **NEVER assume you need a firewall rule or gateway IP to reach the host.** Under WSL2 mirrored networking the host's `127.0.0.1` listeners are shared with the distro's loopback — `127.0.0.1:` just works, no firewall allow needed. 4. **NEVER `docker exec` / `docker cp` against the workspace.** It's a WSL2 distro; use `wsl -d Adom-Workspace`. 5. **NEVER hardcode port numbers** in distro 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.