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docs(env): stop teaching the compositor pin + uid-1000 anchors in starters
Field triage (Nobara, Discord): the kde.md starter host.env told desktop
users to set PUNKTFUNK_COMPOSITOR=kwin, which PINS the backend — detect()
short-circuits and the capture-loss rebuild never re-detects — so a
mid-stream switch to Game Mode killed the stream instead of following it.
A follow-up hardcoded XDG_RUNTIME_DIR=/run/user/1000 anchor broke PipeWire
for any non-1000 uid (pw audio connect: Creation failed).

Revamp across every starter/example/reference:
- Desktop starters (kde/gnome/hyprland/sway) shrink to
  PUNKTFUNK_VIDEO_SOURCE=virtual + an explicit warning that pinning
  disables session-following; forcing a backend is CI/appliance-only.
- host.env.example: rewritten around auto-detection; anchors demoted to a
  commented ssh/cron-only block with the uid trap spelled out; the
  gamescope ATTACH/MANAGED knobs documented (previously missing);
  case-sensitivity called out.
- packaging/bazzite/host.env + README: drop the uid-1000 anchors (a
  systemctl --user service inherits/derives them); README's stale
  PUNKTFUNK_COMPOSITOR=gamescope-era template synced to the real one.
- packaging/kde/host.env: loud APPLIANCE-ONLY header (it pins on purpose).
- configuration.md: session-anchors section inverted to "leave unset",
  compositor row states the pin consequence, case-sensitivity note.
- troubleshooting.md: new "session fails right after editing host.env"
  section (case, wrong-uid anchors, stale pin, restart-to-apply).
- gamescope.md/bazzite.md: attach/managed descriptions match current
  behavior (managed is the infra-detected default; attach re-modes a
  box-owned session to the client's resolution).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-23 22:42:59 +02:00

124 lines
5.4 KiB
Markdown

---
title: KDE Plasma (KWin)
description: Configure a punktfunk host for KDE — host.env, quirks, and a headless KWin session.
---
Configure a punktfunk host on **KDE Plasma**. The host uses KDE's KWin compositor to create a
per-client virtual display, captured zero-copy on NVIDIA. This page assumes the package is already
installed — see [Ubuntu](/docs/ubuntu), [Fedora](/docs/fedora), [Arch](/docs/arch), or the
[Bazzite](/docs/bazzite) appliance.
> 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.
## host.env
The host auto-detects your KWin session on every connect — including a box that switches between
the Plasma desktop and Steam Game Mode — so the starter `~/.config/punktfunk/host.env` is one line:
```ini
# ~/.config/punktfunk/host.env (keys are case-sensitive)
PUNKTFUNK_VIDEO_SOURCE=virtual
# GPU zero-copy (dmabuf → CUDA → NVENC) is ON by default; auto-falls back to CPU. Set =0 to force CPU.
```
> **Don't set `PUNKTFUNK_COMPOSITOR`, `WAYLAND_DISPLAY`, or `XDG_CURRENT_DESKTOP` here.** Pinning
> the compositor turns auto-detection **off** — per connect *and* mid-stream — so a switch to Game
> Mode then kills the stream instead of being followed, and stale session values point the host at
> dead sockets. Forcing a backend is for CI and dedicated appliances (the
> [headless session](#headless-session) below ships a `host.env.kde` that pins on purpose).
If the box switches between the desktop and Game Mode, also enable lingering — the host is a user
service, and without linger the logout moment of a session switch tears it (and PipeWire) down
mid-stream:
```sh
sudo loginctl enable-linger "$USER"
```
See the [Configuration reference](/docs/configuration) for every option.
## Use a Wayland session
KDE must run on **Wayland**, not X11 — pick the Wayland session from the picker on the login screen.
The virtual-display path is Wayland-only and will not come up under X11.
KWin must be **6.5.6 or newer** (virtual outputs land there). Check with:
```sh
kwin_wayland --version
```
## Streaming the interactive desktop
To stream a logged-in Plasma desktop (rather than a headless session, below), KWin has to hand the
host its restricted screencast protocol. The host package ships an `io.unom.Punktfunk.Host.desktop`
file whose `X-KDE-Wayland-Interfaces` grants exactly that on a normal interactive session
(least-privilege, the same mechanism krfb/krdp use). After a **fresh install, log out and back into
the Desktop session once** so KWin re-reads the grant.
A normal KDE login still lacks the RemoteDesktop grant that **input** injection needs — without it the
host pops an "Allow remote control?" dialog no headless box can answer. **Fedora and Bazzite** ship a
one-shot helper that seeds it (run once as the streaming user, no root):
```sh
bash /usr/share/punktfunk/bazzite/kde-desktop-setup.sh # Fedora / Bazzite
```
The `.deb` and Arch packages don't include that wrapper. Seed the grant by hand instead — copy the
shipped `kde-authorized` file into the portal store (the share dir is `/usr/share/punktfunk-host` on
Debian/Ubuntu, `/usr/share/punktfunk` on Arch), then log out and back in:
```sh
mkdir -p ~/.local/share/flatpak/db
cp /usr/share/punktfunk*/headless/kde-authorized ~/.local/share/flatpak/db/kde-authorized
```
A login-less appliance skips all of this — its headless session (below) needs none of these grants.
## Start the host
With `host.env` in place, start the host from **inside your Plasma session**:
```sh
systemctl --user enable --now punktfunk-host
journalctl --user -u punktfunk-host -f # watch it come up and print its identity fingerprint
```
Then bring up [The Web Console](/docs/web-console) to arm pairing and connect a
[client](/docs/clients). To start at boot — including fully headless — see the
[headless session](#headless-session) below or [Running as a Service](/docs/running-as-a-service).
## Persistent per-client scaling
KWin round-trips per-client display scale: it names each session's virtual output per client, so a
scale you set for one client (150 %, 125 %, …) is reapplied on that client's next connect. See
[Virtual displays](/docs/virtual-displays).
## Headless session
For a login-less appliance — a box that streams at boot with no graphical login — the host brings up a
**dedicated headless KWin session** rather than relying on an interactive one. It runs its own
`kwin --virtual` session (shipped as the `punktfunk-kde-session.service` unit) with permission checks
relaxed, so it needs none of the interactive grants above.
```sh
mkdir -p ~/.config/punktfunk
cp /usr/share/punktfunk/host.env.kde ~/.config/punktfunk/host.env # Debian/Ubuntu: /usr/share/punktfunk-host/host.env.kde
systemctl --user daemon-reload
systemctl --user enable --now punktfunk-kde-session punktfunk-host
sudo loginctl enable-linger "$USER"
```
The session unit brings up headless KWin; the host unit follows it and starts listening. See
[Running as a Service](/docs/running-as-a-service) for the full headless setup.
## Troubleshooting
- **KWin too old:** virtual outputs need KWin **≥ 6.5.6**. Check with `kwin_wayland --version`.
- **Black screen / no picture:** confirm you're on a Wayland session (not X11) and the NVIDIA GL
userspace is installed. More in [Troubleshooting](/docs/troubleshooting).
To bring the console up and pair, see [The Web Console](/docs/web-console).