punktfunk/docs-site/content/docs/virtual-displays.md

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Virtual displays	Control how Punktfunk creates, keeps alive, and arranges the virtual displays it streams — presets, keep-alive, exclusive vs. extend, and persistent per-client scaling.

When a client connects, Punktfunk creates a virtual display at exactly that client's resolution and refresh, renders your desktop or game onto it, and streams it. This page covers the policy for that display: how long it survives a disconnect, whether it takes over your physical monitors, what happens when a second client connects, and how desktop environments remember per-client settings like scaling.

Set it in the web console (the Virtual displays page), or edit ~/.config/punktfunk/display-settings.json (%ProgramData%\punktfunk\display-settings.json on Windows). A change applies to the next connection.

You rarely need to touch this. The default matches how Punktfunk has always worked; reach for a preset when you want a specific experience.

Monitors that stayed dark, or a streamed screen showing only wallpaper? Go to Troubleshooting.

To stream a monitor the host already has instead, see Stream a real monitor instead — it turns most of this page off.

Stream a real monitor instead

Linux only. A Windows host enumerates its monitors but has no backend that can capture one — the Streamed screen card is read-only there.

Set Virtual displays → Streamed screen in the console to a listed monitor and Punktfunk streams that physical monitor instead of creating a virtual display; every client sees it at its resolution.

• The monitor is never touched — not resized, moved, disabled or restored. Keep-alive, topology and multi-monitor layout don't apply.
• The resolution is the monitor's, not yours. A client asking for a different one is told no and scales its own picture; mid-stream resize is off.
• Every client sees the same screen — two clients are two viewers of one monitor.
• Naming a monitor this host doesn't have, while it has others, is a hard error: the session fails with no monitor named "DP-9" — this host has: HDMI-1. The exception is a session with no physical heads at all (nested or headless compositor): the pin is set aside with a log warning, you get an ordinary virtual display, and the pin applies again on the next session with real heads.
• Virtual screen (default) in the same card puts you back on the normal path.

Supported on KDE/KWin, GNOME/Mutter, Sway/wlroots, Hyprland and gamescope Game Mode — each through the compositor's own screen-recording API, so there is no chooser dialog (a background service has nobody to answer one). On gamescope only the head the session is driving is listed — mirroring attaches to the session's own composited stream, so the screen keeps showing what the person in front of it sees. A nested or headless gamescope has no head, so the picker is empty there.

Naming the monitor from the host

Monitors are named by connector — HDMI-A-1, DP-2, eDP-1. List this host's (Linux-only subcommands, like the setting):

punktfunk-host list-monitors

Kwin:
  HDMI-A-1        1920x1080@60 at +0,+0    scale 1  Dell U2412M  [primary]
  DP-2            2560x1440@144 at +1920,+0  scale 1  ACME 27

To pin it from the host's configuration instead — the appliance route — set it in host.env:

PUNKTFUNK_CAPTURE_MONITOR=HDMI-A-1

The environment variable wins over the console setting; the console shows the card as locked while it's set.

Check the whole path — mirror, capture, frames — without a client:

punktfunk-host mirror-test --monitor HDMI-A-1 --seconds 20

Compositor screen recording is damage-driven: an idle desktop produces almost no frames, so move the mouse on the host while it runs or a working mirror reads as a stall.

Absolute input follows the pin

Pinning a monitor also re-aims absolute mouse and pen input to that head's origin, so a click lands where you point on that screen. Heads are matched by position, not size. The host resolves the pin at startup and whenever the console writes it — no restart; the log line is capture monitor: ….

To check it with no client involved:

punktfunk-host anchor-test --monitor HDMI-A-1

It lists this host's heads, says whether the box has the same-size pair the matching exists for, walks the pointer through the centre and corners, and prints the region it mapped into. --none runs the same walk unanchored, as an A/B. The anchor rides the libei injector — the GNOME/Mutter backend. On KWin, Sway and Hyprland the host injects through a different protocol, and anchor-test stops and says so rather than reporting a green run that proves nothing.

Pick a preset

Select one in the console and you're done. Each expands to a bundle of the options documented further down.

Preset	What it's for
Default	Most setups. Reconnects resume quickly, the streamed output becomes the whole desktop, extra viewers each get their own screen.
Headless box	A monitorless machine you only stream from. Game and display survive disconnects indefinitely (keep-alive forever); whoever connects next takes the box over. Release it from the console when you're done.
Shared desktop	A PC you also use in person. Never blanks your real monitors, never leaves a leftover display behind; extra viewers each get their own screen.
Hot-desk	One person at a time — roam between your own devices with an instant reconnect. Anyone else is told the box is busy; each device+resolution keeps its own scaling.
Workstation	Your multi-monitor daily driver. Displays come back exactly where you arranged them, each client keeps its own settings, the desktop is yours alone.

Save your own preset

• Save as preset — names the settings currently in force (all the options below plus Dedicated game sessions) and adds it to the picker alongside the built-ins.
• Apply — writes exactly those settings, like picking a built-in.
• Edit / delete — rename, update to your current settings, or remove. Deleting never changes what's running.

The built-in presets leave Dedicated game sessions alone, so switching presets never changes your game-launch routing; a custom preset captures your full setup, including that axis. Custom presets live on the host in display-presets.json (next to display-settings.json); editing a preset never disturbs a running session.

Options reference

Choose Custom in the console to set these directly.

Keep alive

How long the virtual display survives after your last session disconnects. On a gamescope game host this also keeps the game itself running.

• Off — tear the display down at session end.
• A duration (seconds) — a reconnect inside the window drops you straight back in, with no re-negotiation and no desktop reshuffle.
• Forever — keep it until you stop the host or release it from the console (Virtual displays → Release). The headless-box model.

Default: 10 seconds.

A reconnect always resumes the kept display — even a second or two after dropping. Deliberately quitting (closing the client, not a network drop) tears the display down at once, skipping the linger. How quickly a dropped client is noticed is the QUIC idle timeout — 8 s by default, tunable with PUNKTFUNK_IDLE_TIMEOUT_MS (see Legacy environment knobs).

Keep-alive + Exclusive keeps your physical monitors dark after you disconnect, until the linger expires or you release the display. Intentional for a dedicated gaming box — on a machine whose monitors you also use in person, use Shared desktop.

Topology

What Punktfunk does with your monitor layout while it streams.

• Extend — add the virtual display alongside your real monitors; touch nothing else.
• Primary — make the virtual display your primary output; physical monitors stay on.
• Exclusive — the virtual display becomes your only enabled output (physical monitors are disabled, then restored when streaming ends), so panels and windows land on it.
• Automatic (default) — Exclusive on Windows and on an auto-detected KDE/GNOME desktop; Extend when you've pinned a specific compositor with PUNKTFUNK_COMPOSITOR.

Per-backend support:

	KWin	Mutter/GNOME	Sway/wlroots · Hyprland	Windows
Extend	✅	✅	✅	✅
Primary	✅	✅	⚠️ treated as Extend	✅
Exclusive	✅	✅	✅	✅

Sway/wlroots and Hyprland have no primary-output concept; they have a focused output, and the host points that at the streamed display — at session start, and again immediately before it launches anything from your library, which is what puts the game on the streamed display. Primary therefore behaves as Extend (the host says so in the log), and a window that opens later follows whatever has focus then — clicking a physical monitor mid-launch can still pull a window over.

Exclusive on both compositor families:

• Punktfunk only disables monitors it did not create, so a second concurrent client never goes dark.
• On Hyprland the restore is a hyprctl reload — nothing else re-enables a monitor a rule disabled. The reload re-reads your Hyprland config; settings changed at runtime with hyprctl keyword are dropped and a non-Lua config re-runs its exec = lines (exec-once is not). Only happens if a session actually disabled something.

Conflict handling · identity · layout

• Conflict handling — a different client connects mid-stream asking for a different resolution: give it its own display (separate), take the box over (steal), share the existing display at its current mode (join), or refuse it (reject). On Windows a second client is rejected ("host busy") even under separate — two clients can't yet share one virtual display's capture there. A same-client reconnect never conflicts — it resumes.
• Identity — whether each client gets a stable display identity so your desktop environment remembers its settings (see Persistent scaling): one shared identity, one per client, or one per client + resolution.
• Layout / max displays — several clients as monitors of one desktop: side by side (auto) or exactly where you arrange them in the console (manual, keyed to each client), up to max displays. Arrange them on the Virtual displays page once two or more are streaming.

Dedicated game sessions

How a session that launches a game from your library is served (Linux hosts):

• Auto (default) — the launch rides whatever session the box is in: the managed Steam session on a Steam Deck / Bazzite couch box, a bare gamescope on a plain distro, or your live KDE / GNOME / Sway desktop.
• Dedicated — every library launch gets its own headless gamescope at your exact resolution and refresh, with just the game inside. Steam titles launch with the client hidden (steam -silent); non-Steam titles start almost instantly (gamescope up in ~1 s). Combined with keep alive, the game keeps running when you disconnect.

Dedicated needs gamescope installed; without it a launch falls back to Auto. This axis is independent of the preset. On a box already in Steam game mode, a dedicated Steam launch frees game mode's Steam first and restores it when the session ends. (GameStream / Moonlight launches follow the same routing.)

When a game ends, and when a session does

Two switches, on the Virtual displays page under When a game or a session ends, tie a session to the game the host launched for it. They apply to every store and both protocols — and only to a game this host launched for the session: a game you started yourself is never touched.

When the game exits

End the session (default) — quit the game and your client goes back to its own library, on every path (live desktop, attached gamescope, Moonlight). Keep streaming if you stream the desktop and treat the game as incidental.

When the session ends

Whether stopping — or losing — a session also closes the game.

• Leave it running (default). Nothing is ever closed.
• Close it on Stop — closing the client, or Stop in the console, closes the game. A network drop does not.
• Always close it — a drop closes it too, after a reconnect window (5 minutes by default). Reconnect inside the window and nothing happens; the console shows the countdown, with an End now button.

Closing a game costs whatever it hadn't saved, which is why nothing closes by default. The host asks first — a polite close, the same as clicking the window's X — and only forces the issue after ten seconds of being ignored.

Keep alive and this setting are different clocks. Keep-alive decides how long the display outlives a disconnect (10 s default); the reconnect window decides how long the game does (5 min). A display set to Forever stays up regardless of what happens to the game.

On a gamescope session, the display has the final say

When a launch gets its own gamescope — a dedicated game session, the usual setup on a Steam Deck or Bazzite couch box — the game runs inside the streamed display and lives exactly as long as it does, so Keep alive decides, not the setting above:

you disconnect by	what happens to the game
pressing Stop (or the console's stop)	the display tears down at once — keep-alive is skipped for a real stop — and the game goes with it, even on Leave it running
dropping out (network, sleep)	the display lingers for your keep-alive window, then tears down; the game ends with it
dropping out, keep-alive Forever	the display is pinned, so the game genuinely survives — and Always close it still ends it when the reconnect window closes

On a gamescope box, "leave the game running after I disconnect" means keep-alive Forever (or a window long enough to come back in). On a desktop session — KWin, GNOME, Sway — the game is an ordinary process and the setting above is the whole story.

Automation

The host publishes game.running and game.exited events (the latter says whether the player quit it or the host closed it), so a hook or plugin can react without polling. See Automation.

Persistent scaling

Set your display scaling once and have it stick across reconnects. Each client gets a stable display identity, so your desktop environment keys its per-monitor settings to it.

Host	Supported	How
Windows	✅ today	Set scaling in Settings while streaming — Windows remembers it per client.
KDE / KWin	✅ today	Set scaling in System Settings while streaming; KWin keys it to a stable per-client output name and reapplies it on reconnect.
GNOME / Mutter	✅ today	GNOME's virtual-monitor API exposes no stable identity, so the host persists the scale itself: set scaling in Settings while streaming — the host captures it per client and reapplies on reconnect.
Sway / wlroots	❌	Headless outputs can't carry a stable identity; pin scale in your sway config instead.

Legacy environment knobs

These PUNKTFUNK_* variables still work, but the console (and display-settings.json) supersede them — when a settings file exists, it wins.

Legacy knob	Now expressed as
PUNKTFUNK_MONITOR_LINGER_MS	Keep alive → duration (Windows)
PUNKTFUNK_NO_ISOLATE	Topology → Extend (Windows)
PUNKTFUNK_KWIN_VIRTUAL_PRIMARY / PUNKTFUNK_MUTTER_VIRTUAL_PRIMARY	Topology → Exclusive (when set) / Extend (when 0)

One knob has no console equivalent — transport tuning, not display policy:

• PUNKTFUNK_IDLE_TIMEOUT_MS (host, default 8000) — how long before a dropped client is declared gone, which is when a kept display starts its linger (or is freed). Lower it (e.g. 3000) to reclaim kept displays sooner; it's clamped to ≥1 s and its keep-alive ping scales with it, so a live session never false-disconnects. A deliberate quit is instant regardless. Also --idle-timeout-ms on punktfunk1-host.

Troubleshooting

My physical monitors stayed off after I disconnected. Keep-alive is set together with Exclusive topology — the display is kept for the linger window. Release it from the console (Virtual displays), or switch to the Shared desktop preset.

The virtual output shows only my wallpaper. Your topology is Extend, so the streamed display is an empty extension. Use Primary or Exclusive so your desktop lands on it.

KWin can't create the virtual output. On a normal Plasma session KWin runs its DRM backend, which creates virtual outputs at any version. The 6.5.6 floor applies only to the virtual backend (kwin_wayland --virtual, headless and test sessions) — below that the request fails with "Could not find output". On KWin 6.6+ that same message also covers an output KWin did create and then left disabled; KDE Plasma walks that one. See requirements.

Reconnecting into game mode reconnects cleanly now. On a Steam Deck / Bazzite box, disconnect/reconnect within game mode reuses the still-warm session (or cleanly recreates it), and switching between game mode and the desktop mid-stream follows the switch. If a launched game exits, a dedicated session ends and returns you to your library; a game mode / desktop session keeps streaming.

My keep-alive / topology / layout settings do nothing. Check whether Streamed screen is set to a real monitor — those options are about a display Punktfunk created. Switch the card back to Virtual screen (default).

The console won't let me change Streamed screen. PUNKTFUNK_CAPTURE_MONITOR is set in this host's host.env and outranks the console. Unset it (and restart the host).

My session fails with "no monitor named …". The pinned connector isn't among this host's monitors — renamed, unplugged, or the host is in a different session. Run punktfunk-host list-monitors to see the real names. Punktfunk will not quietly stream a different screen.

My couch box's TV stayed on the streamed session after I disconnected. With the Headless box preset (keep alive = forever), a managed Steam session is held indefinitely — return to game mode on the box (or restart the host) to hand the TV back.