[2026-05-28] htpc ecosystem, magic4pc, kodi layout, steam emulators, jellyfin, kraken, gitea, hermes, truenas, vault, reflect-skip, wiki curation

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+---
+title: HTPC — magic4pc (LG Magic Remote)
+created: '2026-05-28'
+updated: '2026-05-28'
+type: tech
+namespace: family
+tags: [htpc, how-to, pitfalls]
+sources: [family/how-to/htpc-magic4pc.md]
+confidence: medium
+related:
+  - "[[htpc-bazzite-proton]]"
+  - "[[tech/htpc-steam-emulators]]"
+---
+
+# 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
+```
+
+## See Also
+
+- [[htpc-bazzite-proton]] — Proton game compatibility on this HTPC
+- [[tech/htpc-steam-emulators]] — Steam, emulators, gamepad config