Sundog

Sundog is Frostyard’s KDE Plasma desktop. It is a Debian Trixie bootc/composefs image for x86-64 machines with UEFI, built from the same Base as the other Frostyard images. Plasma on Wayland is the only desktop session it offers. Sundog ships only as a bootc image. You install it with Firn.

The system lives in a read-only /usr that updates as one piece, and you can roll back to the previous version. Image and system-extension applications live under /usr. Your homes, Flatpak data, containers, and update state live under /var. Sundog has its own core Flatpak set.

Install

Firn is the installer. It needs UEFI and erases the disk you pick. It works with or without Secure Boot, TPM 2.0, and disk encryption, and asks you about each one. Use a disk of at least 30 GiB, and more if you plan to keep Flatpaks, containers, and several updates. The installer runs from RAM and needs at least 4.5 GiB of memory.

Download the installer and its checksums:
Check the signing key’s fingerprint and the ISO, then write the ISO to a USB stick. The installation guide has the exact gpgv and sha256sum commands and the commands to write the stick. Read its warning on picking the right device.
Boot the stick. In Firn, pick the bootc Sundog product, review the recipe Firn builds, and confirm the exact target disk.
If Firn shows a recovery key, store it somewhere other than this disk before you continue.
If Secure Boot is on, enroll the MOK when asked. Without it, the MOK-signed boot stage is not trusted while Secure Boot is enforced.

The native in the ISO address is an old folder name. It does not mean an A/B install.

First boot

Sundog starts at the SDDM login screen with the Breeze theme. Log in with the user you created in Firn. Plasma on Wayland is the only session the image offers; it has no Plasma X11 session. Discover lists Flatpak applications only.

Firn can install the chosen core Flatpak set as part of the recipe; Sundog uses its own list. If yours included it, the apps are already there.

Check that the system is healthy:

systemctl is-system-running
sudo bootc status
sudo snosi-update-status --check
systemctl list-timers bootc-update-stage.timer

bootc status shows the booted and staged deployments, and names the image it follows. snosi-update-status --check tells you whether a newer image is published. The timer is listed with its next run.

Install applications as Flatpaks or as system extensions. Do not install APT packages into /usr: an image update does not keep them. The package lists in the build are not a package manager you can add to.

Updates and rollback

Updates are automatic. Every hour, bootc-update-stage.timer checks for a new image, pulls it with Podman, and stages it. The timer adds a random delay of up to 15 minutes. The new version starts at your next normal reboot. The stager does not force a reboot.

Enabled system extensions update on their own. A new version is staged and starts at the next boot. See Automatic updates.

The stager runs the bootc commands itself. You do not need to run them. On the first staged update, while the host does not yet follow the image from containers-storage, it runs bootc switch --transport containers-storage. From then on, in steady state, it runs bootc upgrade, because a second bootc switch to the same image would do nothing. Both paths verify the staged digest before they report success.

To go back to the previous version:

sudo bootc rollback
sudo systemctl reboot

Homes and container data in /var are shared by all versions, so a rollback keeps them. After a rollback, the updater does not stage the version you rolled back from again. It waits for the next published image.

Keep about twice the image size free in /var. The updater pulls each new image into /var before it stages it.

What ships

Sundog is Base plus the bootc runtime, the bootc security setup, the KDE composition, the backports kernel, and the image output format.

Layer	What you get
Base	Debian Trixie userspace, systemd, the hourly update stager, Updex, and the system-extension definitions
Bootc runtime	`bootc`, `libostree-1-1`, and the packages OCI bootc needs
Desktop	Plasma 6 on Wayland with `kde-plasma-desktop`, `kwin-wayland`, SDDM, and the KDE applications below
Kernel	`linux-image-amd64/forky` for now, with most firmware and Mesa from `trixie-backports`
Core Flatpak set	Gwenview, Haruna, KCalc, KCharSelect, Okular, Skanpage, Weather, Kontainer, Bazaar, MissionCenter, Elisa, Filelight, KRDC, and KClock
Containers	Podman, Distrobox, and Buildah, plus `systemd-container` and the Frostyard Intune integration

The image carries its Flatpak list at /usr/share/frostyard/sundog.core-flatpaks.json.

Desktop packages

The image carries these KDE packages:

Plasma and the session: kde-plasma-desktop, kwin-wayland, sddm, sddm-theme-breeze, plasma-nm, plasma-pa, kscreen, powerdevil, polkit-kde-agent-1, libpam-kwallet5, xdg-desktop-portal-kde, and qt6-wayland.
Applications: dolphin, dolphin-plugins, kio-extras, kio-fuse, ark, kate, konsole, kde-spectacle, kdeconnect, and khelpcenter.
System tools: plasma-systemmonitor, ksystemstats, kinfocenter, plasma-thunderbolt, kwalletmanager, kmenuedit, keditbookmarks, and kde-config-screenlocker.
Appearance, input, and previews: breeze-gtk-theme, kde-config-gtk-style, xsettingsd, sonnet6-plugins, hunspell-en-us, fcitx5, kde-config-fcitx5, fcitx5-frontend-gtk3, fcitx5-frontend-gtk4, fcitx5-frontend-qt6, ffmpegthumbs, kdegraphics-thumbnailers, qt6-image-formats-plugins, and kimageformat6-plugins.
Flatpak: flatpak, plasma-discover-backend-flatpak, and kde-config-flatpak.
Printing and scanning: cups, print-manager, system-config-printer-udev, and libsane1.
Hardware and power: pipewire, pipewire-audio, bluez, bluedevil, bolt, tuned, tuned-ppd, upower, and switcheroo-control.
Boot: plymouth, plymouth-label, and plymouth-theme-breeze.

Gwenview, Okular, KCalc, and Skanpage are Flatpaks, not packages in the image.

Services and settings

sddm.service is the display manager. The image links /usr/lib/systemd/system/display-manager.service to it, so SDDM starts on every boot.
/etc/sddm.conf.d/10-sundog.conf sets the Breeze theme and RememberLastSession=true.
/etc/plymouth/plymouthd.conf sets the Breeze Plymouth theme, ShowDelay=0, and DeviceTimeout=8.
The user preset 90-sundog.preset disables bazaar.service and podman.service. The Podman API socket stays available.
tmpfiles rules create /var/lib/sddm with mode 0750 for user sddm, and /var/lib/tuned.
The image removes the Plasma X11 session descriptor, so Plasma on Wayland is the only session.
Discover has only its Flatpak backend. The build removes the PackageKit backend plugin, and fails if the plugin is not there.
Flathub is configured as on Snow, from the same repository descriptor.
Sundog reuses the shared tree that Floe carries. That adds the Homebrew setup and update units and the presets that turn off the APT daily timers. The image removes /usr/share/floe. Base supplies the persistent journal and the zram swap, as on every image.

Choose Sundog

Choose Sundog for a KDE Plasma desktop on Wayland. For GNOME, use Snow. The other products are:

Snow: the general-purpose GNOME desktop.
Snowfield: GNOME for Microsoft Surface devices. It is untested on representative Surface hardware; its hardware gate was waived for catalog inclusion.
Floe: a headless server.

Base is the shared foundation, not a fifth installer choice. Sundog has the Trixie userspace with a newer kernel.

Troubleshooting

Symptom	Check	Fix
No update is staged	`systemctl list-timers bootc-update-stage.timer` and `journalctl -u bootc-update-stage.service`	Wait for the hourly run. Check the network and the free space in `/var`.
Staging fails for lack of space	Compare the free space in `/var` with the image size	Free space or grow the disk. The updater needs room for the download, the new version, and the previous one.
Discover shows no system packages	That is how Sundog ships: Discover has only its Flatpak backend	Install Flatpaks from Discover, or install host software as a system extension.
A KDE application you expect is missing	The core Flatpak set	Install it as a Flatpak. Gwenview, Okular, KCalc, and Skanpage are Flatpaks.
Secure Boot or TPM does not behave as you expect	`bootc status` and the firmware settings	Check the firmware settings, then read the Bootc Secure Operations runbook. Secure Boot is not production-ready yet.

Sources

Reviewed 2026-10-27 against snosi commit b2858ca0222814c395cf8248db98f3e096d57dc9.