punktfunk/docs-site/content/docs/gamescope.md

---
title: Steam / gamescope
description: Configure a gamescope/Steam host — attach vs managed, session following, and limits.
---

gamescope is the compositor behind Steam **Gaming Mode** — the couch/handheld game UI on Bazzite,
SteamOS, or any distro running a gamescope session. The host **auto-detects** gamescope from your
live session, so you rarely need to set anything here. It also **follows a Gaming ↔ Desktop switch
mid-stream** — flip between Gaming Mode and the desktop with Steam's normal UI and the host
re-targets whatever's running without a reconnect.

This page covers the gamescope-specific choices. To get a host running on an appliance box, start
from the install guide for your OS: [Bazzite](/docs/bazzite) or [SteamOS (Host)](/docs/steamos-host).

> New here? Read [Security & Safe Use](/docs/security) first — a streaming host is remote control of
> the machine, so keep it on a trusted LAN or VPN and require pairing.

## Attach vs managed

There are two mutually-exclusive models for a gamescope box; pick one. With **nothing set**, a box
that has gamescope session infrastructure (Bazzite, SteamOS, Nobara) gets **managed**; the
[Bazzite template](/docs/bazzite) ships with **attach** chosen instead.

- **Attach** (`PUNKTFUNK_GAMESCOPE_ATTACH=1`) — the **box** owns its gamescope session and decides
  Gaming vs Desktop via the normal Steam UI. Game Mode stays on the box's own (physical) display;
  the host attaches to whatever's live and never tears it down, so switching Desktop ↔ Game is
  rock-solid and disconnecting leaves the box where it was. When the box is **headless** (no
  display connected) and the session is its own autologin unit, the host restarts it at the
  **client's** resolution on a mismatch; a box driving a physical display — and any foreign or
  bare gamescope — is streamed at its own mode.
- **Managed** (the infra-detected default; force with `PUNKTFUNK_GAMESCOPE_MANAGED=1`) — the host
  takes the box's gamescope session over and relaunches it **headless** at the *client's* exact
  resolution and refresh — Game Mode runs on the virtual screen, physical displays drop out of it —
  restoring the box on idle after disconnect.

### Nobara and other autologin display managers

The managed takeover has to stop the box's Gaming Mode session to free Steam. How it does that
depends on the display manager driving the autologin:

- **SDDM** (Bazzite, SteamOS): handled automatically — no setup.
- **plasmalogin** (Nobara) and other display managers: the host must stop the display manager
  itself for the length of the stream and restart it afterwards, which needs privilege. Allow it
  with a polkit rule (adjust the unit and user names to your box):

  ```js
  // /etc/polkit-1/rules.d/49-punktfunk-dm.rules
  polkit.addRule(function(action, subject) {
      if (action.id == "org.freedesktop.systemd1.manage-units" &&
          action.lookup("unit") == "plasmalogin.service" &&
          subject.user == "YOUR_USER") {
          return polkit.Result.YES;
      }
  });
  ```

  Without the rule the host degrades safely: it **attaches** to the live Gaming Mode session
  instead (Game Mode stays on the box's display, mirrored to the client) rather than risk the
  display manager. If the display-manager restart ever loses its privilege mid-restore,
  `PUNKTFUNK_RECOVER_SESSION_CMD` (see [Configuration](/docs/configuration)) is fired as the
  fallback.

  With the rule in place the **in-stream session switch round-trips** in managed mode: Steam's
  "Switch to Desktop" inside the streamed Game Mode returns the box to its desktop session and the
  stream follows it there; the desktop's "Return to Gaming Mode" switches it forward again.

## Session following

`PUNKTFUNK_SESSION_WATCH` follows a Gaming ↔ Desktop switch **mid-stream** — the host rebuilds the
backend in place, with no reconnect. It is **on by default** on Bazzite/SteamOS; set `0` to disable.
One host service covers both faces of the box: it streams Gaming Mode over gamescope and the desktop
over its own compositor, and re-targets whichever is live on each switch.

## Start the host

On an appliance box (Bazzite, SteamOS) the install guide already enables the host service for you. On
any other distro running a gamescope session, just start it — the host auto-detects the live
gamescope session and picks the model for it:

```sh
systemctl --user enable --now punktfunk-host
```

Then bring up [The Web Console](/docs/web-console) to arm pairing.

## gamescope knobs

The gamescope-specific settings in `host.env`. Leave them unset to auto-detect; set one only to force
a model. See the full [Configuration reference](/docs/configuration) for every other knob.

| Setting | Values | Meaning |
|---|---|---|
| `PUNKTFUNK_GAMESCOPE_ATTACH` | `1` | **Attach** model: the box owns its gamescope session (on its own display); the host captures whatever's live and never tears it down. On a **headless** box the box-owned autologin session is restarted at the client's resolution on a mismatch; a box driving a physical display, and any foreign/bare gamescope, streams at its own mode. |
| `PUNKTFUNK_GAMESCOPE_MANAGED` | `1` | **Managed** model (the default where session infra is detected): the host takes the box's gamescope over and relaunches it headless at the client's exact mode, restoring on idle. |
| `PUNKTFUNK_GAMESCOPE_SESSION` | `steam` | The host owns a `gamescope-session-plus` (Steam) session at the client's mode — a headless appliance with no physical session running. |
| `PUNKTFUNK_GAMESCOPE_NODE` | `auto` · node id | Discover and capture a **running** gamescope's PipeWire node at a fixed mode. Do **not** combine with `SESSION`. |
| `PUNKTFUNK_GAMESCOPE_APP` | command | For an ad-hoc bare-gamescope session, the nested command to run (e.g. `vkcube`). |
| `PUNKTFUNK_SESSION_WATCH` | `1` · `0` | Follow a Gaming ↔ Desktop switch mid-stream (rebuild in place, no reconnect). On by default on Bazzite/SteamOS; set `0` to disable. |

## Known limits

These apply to the **Gaming Mode (gamescope)** path only; the desktop path is unaffected.

- **gamescope 3.16.22 or newer is required.** Older versions can deadlock during capture. Bazzite's
  and SteamOS's current gamescope is fine; this only bites if you've pinned an old one.
- **The mouse cursor isn't included in the captured image** — a gamescope limitation for now.
- **Touch arrives as a single-finger pointer.** gamescope's virtual input device has no
  touchscreen, so the host maps a client's touchscreen to an absolute pointer: taps click exactly
  where you touch and drags work, but multi-touch gestures (pinch) aren't available in Gaming
  Mode. The desktop path has full multi-touch.
- **HDR isn't supported on the gamescope path** — gamescope's capture output is 8-bit. SDR streams
  normally.

To stream the KDE Plasma desktop of a Steam box instead, see [KDE Plasma](/docs/kde). To bring up the
web console and pair a client, see [The Web Console](/docs/web-console).