SteamOS only ships /etc/xdg/menus/plasma-applications.menu; the nested
desktop sets XDG_MENU_PREFIX=plasma-, the Steam session doesn't, so KDE
apps started there (Dolphin from the "+" menu) built an empty app
database: "no installed application can open" every file.
session.applicationsMenu (module applications-menu, on by default) links
~/.config/menus/applications.menu to Plasma's menu. Flake check: the link
is generated by default and absent when disabled.
steamFrame.launchers.<desktop ID> takes the app's own entry (a Flatpak's
export, a Nix package's or a host file) and rewrites only its command lines
(hostEnv, env, flatpakArgs, args, wrappers) and the keys asked for
(mimeTypes, defaultFor, settings), so name, icon, translations and actions
stay the app's and follow its updates.
- Package entries are rewritten at build time; Flatpak/host file entries at
runtime by steam-frame-nix-launchers into
<session.runtimeDir>/steam-frame-nix/applications (tmpfs), on switch, at
login and when Flatpak installs/updates apps (path unit); the Home Manager
links point there.
- keyring.{enable,electron} replaces steamFrame.keyring.{flatpaks,programs}
(clean break: the old options fail with the new form).
- Firefox's launcher is the Flatpak's entry with the profile wrapper in
front (no --profile for the profile manager); Jellyfin's hardware
decoding sets flatpakArgs and env.
- cleanup --all removes the tmpfs entries.
- Check on copies of the real Element, KRDC, Firefox, gedit, Jellyfin and
Claude entries, quoting and generator behaviour.
Pierre Kisters