Mobile Mode

A third operating mode for your Steam Deck — touch-first, vertical, fully Linux.

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What is Mobile Mode?

Steam Deck has two built-in modes: Gaming and Desktop. Mobile Mode adds a third.

One tap in the Power Menu switches your Deck into a portrait-oriented, touch-first KDE session — no extra packages, no Plasma Mobile, no hacks. Everything needed is already in SteamOS 3.8.

Gaming Mode	Desktop Mode	Mobile Mode
Gamescope, controller	KDE landscape	KDE portrait · touch · Maliit keyboard
Games	Linux apps (mouse)	Linux apps (finger)
Steam UI	Full desktop	Vertical · thumb-friendly

What you get

• Portrait screen orientation (90° rotation via kscreen-doctor)
• Maliit virtual keyboard — auto-invokes on every text input
• Full Linux app access: browser, Telegram, media player, files
• "Switch to Mobile" button natively in the Steam Power Menu
• "Return to Gaming" one-tap button inside the KDE session
• Persistent across SteamOS updates (files reinstalled on every plugin load)

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Installation

Requires Decky Loader

From Decky Store (coming soon)

Search for "Mobile Mode" in the Decky plugin store.

Manual install

1. Download the latest release .zip from Releases
2. In Decky → Settings → Install plugin from zip

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How it works

Power Menu → "Switch to Mobile"
  └─ Decky backend (root) installs session files
  └─ steamosctl switches to mobile.desktop
  └─ KDE starts via plasma-dbus-run-session-if-needed
  └─ autostart: kscreen-doctor rotates screen · maliit-server starts
  └─ KDE in portrait mode ✓

KDE → "Return to Gaming"
  └─ kscreen-doctor restores landscape
  └─ steamosctl switch-to-game-mode

No extra packages required — KWin, maliit-keyboard, kscreen-doctor and steamosctl are all pre-installed in SteamOS 3.8.

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Architecture

decky-mobile-mode/
├── src/index.tsx              # Frontend: Power Menu patch · QAM panel
├── main.py                    # Backend (root): steamosctl · file management
└── assets/
    ├── mobile.desktop         # Wayland session descriptor
    ├── startplasma-mobile.sh  # KDE session launcher (Maliit env)
    ├── mobile-mode-init.sh    # Autostart: rotation + maliit-server
    ├── return-to-gaming.sh    # Switch back to Gaming Mode
    └── return-to-gaming.desktop

Power Menu patch

The "Switch to Mobile" button is injected into Steam's Power Menu at runtime. The approach is update-resistant — no hardcoded webpack module IDs, components are identified by stable content strings:

Target	Identified by
showContextMenu	CreateContextMenuInstance + GetContextMenuManagerFromWindow
Power Menu component	render source contains ShutdownPC + IN_GAMESCOPE

Research conducted via CEF DevTools on SteamOS 3.8.2 (Steam build Apr 11 2026). Full technical notes in .claude/CLAUDE.md.

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Development

Requirements

• Node.js ≥ 16.14
• pnpm v9+ (npm i -g pnpm@9)
• Steam Deck or SteamOS VM for testing

Build

pnpm i
pnpm run build    # → dist/index.js
pnpm run watch    # watch mode

Deploy to device

# Configure your device IP
echo 'DECK_IP=192.168.1.x' >> .vscode/config.sh

# Deploy via VSCode task or:
ssh deck@<IP> "..."

Debug

# Session log on device
cat ~/.config/mobile-mode/session.log

# Decky plugin logs
ssh deck@<IP> "journalctl -u plugin_loader -f"

# CEF DevTools (Power Menu research)
ssh -L 8080:localhost:8080 deck@<IP> -N
# → http://localhost:8080 → SharedJSContext

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Roadmap

• Phase 0 — Research (steamosctl, Maliit, kscreen-doctor verified)
• Phase 1 — MVP shell scripts (tested on device)
• Phase 2 — Decky plugin (current)
  • Power Menu patch — "Switch to Mobile"
  • Python backend
  • Return to Gaming
  • QAM mode indicator
  • On-device testing
• Phase 3 — UX polish (KWin rules, smooth transitions, gestures)
• Phase 4 — Decky Store submission

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Support

If Mobile Mode saves you from squinting at landscape apps — consider buying me a coffee ☕

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License

GPL-3.0-or-later © 2026 nord-winter

Plugin template originally by Steam Deck Homebrew — BSD-3-Clause.