---
title: HTPC — magic4pc (LG Magic Remote)
created: '2026-05-28'
updated: '2026-05-29'
type: tech
namespace: family
tags: [htpc, how-to, pitfalls]
sources:
  - family/how-to/htpc-magic4pc.md
  - family/how-to/magic4pc-webos.md
confidence: medium
related:
  - "[[htpc-bazzite-proton]]"
  - "[[tech/htpc-steam-emulators]]"
  - "[[tech/tv-luna-send]]"
---

# HTPC — magic4pc (LG Magic Remote)

Go-client for using the LG Magic Remote (webOS TV app) as HTPC
mouse/keyboard input. Fork: `mallexxx/magic4pc_altclient` branch
`bazzite-linux`.

LG TV: `192.168.1.75`, HTPC: `192.168.1.86`.

## Architecture

- **TV server**: webOS app on LG TV → sends UDP to fixed source
  port **9106**
- **HTPC client**: `/usr/local/bin/magic4pc`, UDP listener
- **xdotool**: single persistent process via stdin pipe (mouse +
  keyboard)
- **ydotool**: gamescope-specific keys (Ctrl+1, Ctrl+2) via
  `/run/user/1000/.ydotool_socket`

Session detection:
- `isGamescopeSession()` — scans `/proc/*/cmdline` for `kwin_wayland`;
  if absent → gamescope (Steam Big Picture mode)
- `activeDisplay()` — KDE uses Xwayland display from kwin args; gamescope
  uses `:1` (game) if visible windows present, else `:0` (Steam BP)

## Button Mapping

| Button | Keycode | Gamescope | KDE Desktop |
|--------|---------|-----------|-------------|
| Red | 403 | Ctrl+1 (Steam menu) | Super |
| Green | 404 | Escape | Escape |
| Yellow | 405 | Ctrl+2 (Steam QAM) | Middle click |
| Blue | 406 | Right click | Right click |
| Back | 461 | Mouse X1 | Mouse X1 |
| D-pad | 37-40 | Arrow keys | Arrow keys |
| Ch+/Ch- | 33/34 | PageUp/Down | PageUp/Down |
| Play/Stop/Pause | 415/413/19 | XF86Audio* | XF86Audio* |
| Touch (swipe) | — | mousemove (scaled) | mousemove |
| Tap | — | Left click | Left click |

## Mouse Coordinate Mapping

TV sends coordinates in 0–1920 × 0–1080 space.

**In gamescope:** uses letterbox algorithm.
1. Find active window: (a) under cursor via `getmouselocation`, or
   (b) largest bounding-box window (non-popup, highest ID)
2. Compute 16:9 letterbox viewport from window width:
   `lb_h = win_w * 9/16`
3. Compute offset: `off_y = -(lb_h - win_h) / 2`
4. Map: `x11_x = tv_x * scale + off_x`; clip negatives to 0

**In KDE:** `getdisplaygeometry` → scale = display / 1920×1080.

## Key Pitfalls

| Problem | Fix |
|---------|-----|
| TV "service error" / won't reconnect | Fixed source UDP port 9106 |
| TV stuck "waiting for client" | Server keepalive timeout 10s |
| KDE XTest prompt on every click | Single persistent xdotool process |
| KDE XTest prompt after xdotool restart | `XwaylandEisNoPrompt=true` in kwinrc |
| Wrong mouse coordinates | Dynamic scale via `xdotool getdisplaygeometry` |
| Binary lost after `rpm-ostree upgrade` | Rebuild and redeploy |

## Deploy

```bash
# Build on Mac
cd ~/Developer/magic4pc_altclient
GOOS=linux GOARCH=amd64 go build -o magic4pc .

# Copy + restart on HTPC
scp magic4pc htpc:/home/bazzite/magic4pc/magic4pc
echo bazzite | sudo -S systemctl stop magic4pc.service
echo bazzite | sudo -S cp /home/bazzite/magic4pc/magic4pc \
  /usr/local/bin/magic4pc
echo bazzite | sudo -S systemctl start magic4pc.service
```

Sudoers rule (no-password systemctl):
```
bazzite ALL=(ALL) NOPASSWD: /usr/bin/systemctl
```

## WebOS TV App — Build & Deploy

The TV-side is a React/Enact WebOS app + Node.js service bundled into
an IPK. Sources: `~/Developer/magic4pc/webos/`.

### Build

```bash
cd ~/Developer/magic4pc/webos
NODE_OPTIONS=--openssl-legacy-provider npm run build
```

**Pitfall:** `--openssl-legacy-provider` is required — the old webpack
is incompatible with Node.js 25+.

### Package IPK

```bash
/Users/admin/webOS_TV_SDK/CLI/bin/ares-package dist/ service/ --outdir .
```

**Pitfall:** both `dist/` and `service/` arguments are required —
omitting `service/` excludes the Node.js service from the IPK.  
**Pitfall:** `npm run package` = `ares-package -n` (unsigned) — TV
rejects unsigned packages. Use the SDK command directly.

### Deploy (deploy.sh)

```bash
cd ~/Developer/magic4pc/webos && ./deploy.sh
```

Script flow: build → package → scp → close → remove → install → launch.
Uses [[tech/tv-luna-send]] wrapper for close/remove/launch.
For install (subscribe mode) — direct `ssh+script` with polling on
`"state":"installed"`.

**Pitfall:** `ares-install` / `ares-launch` are unreliable — they don't
wait for completion. Use `luna-send dev/install` via `script` wrapper.

### Version in UI

Displayed as `1.1.0 (YYYY-MM-DD HH:MM)` — injected by webpack at
build time via `process.env.BUILD_DATE`.

## Auto-launch on Boot/Wake

Magic4pc launches a configured app when the TV boots or wakes.

| File | Location | Purpose |
|------|----------|---------|
| `magic4pc-settings` | PERSISTENT_DIR | Selected app ID |
| `magic4pc-last-app` | PERSISTENT_DIR | Last foreground app |
| `magic4pc-run-state` | `/tmp/` | `running` after first launch |

`PERSISTENT_DIR = /media/developer/apps/usr/palm/services/me.wouterdek.magic4pc.service`

Logic:
- **Boot/wake:** `/tmp` is cleared → no `run-state` → `freshStart=true`
  → launches configured app
- **Manual launch:** `run-state=running` already present → skips auto-launch

The `init.d` script on TV (`/var/lib/webosbrew/init.d/magic4pc`) removes
`run-state` on suspend so wake triggers fresh launch. Always edit in
repo (`tv-scripts/init.d-magic4pc.sh`), never directly on TV.

## WebOS Back Key + System Keyboard

When the system keyboard is open, **Back #1** is consumed by the OS
(closes keyboard) — the `keydown` DOM event and `onButtonDown` are
**not** fired. **Back #2** arrives normally.

Fix used in `MainPanel.js` (`_kbWasOpen` flag):

```js
// Input.onActivate:
this._kbWasOpen = true;

// onButtonDown on Back:
if (this.state.wolMacActive || this._kbWasOpen) {
    this._kbWasOpen = false;
    return; // suppress panel close
}
```

Approaches that don't work: `Popup.noAutoDismiss`, timeout heuristic,
polling `document.activeElement` (keyboard is a system overlay, focus
never moves to INPUT).

## See Also

- [[htpc-bazzite-proton]] — Proton game compatibility on this HTPC
- [[tech/htpc-steam-emulators]] — Steam, emulators, gamepad config
- [[tech/tv-luna-send]] — luna-send SSH wrapper for WebOS TV commands