Platform support

Matrix

Feature	Windows 10/11	GNOME 42+	KDE Plasma 5/6	XFCE	Hyprland	Sway	Generic X11
Theme detection	✅	✅	✅	✅	⚠️	⚠️	⚠️
Accent colour	✅	✅	⚠️	⚠️	❌	❌	❌
Wallpaper	✅	✅	✅	✅	✅	✅	✅
Notification	✅¹	✅	✅	✅	⚠️	⚠️	⚠️
Notification icon	✅	✅	✅	✅	✅	✅	✅
Notification actions	⚠️²	✅	✅	✅	✅	✅	✅
Wake lock	✅	✅	✅	✅	⚠️	⚠️	⚠️
System tray	✅	✅	✅	⚠️	✅	✅	✅
Media control	✅	✅	✅	✅	✅	✅	✅
Session lock	✅	✅	✅	✅	✅	✅	✅
Session logout	✅	✅	✅	⚠️	⚠️	⚠️	⚠️
Suspend / hibernate	✅	✅	✅	✅	✅	✅	✅
Reboot / shutdown	✅	✅	✅	✅	✅	✅	✅

✅ verified against the real backend · ⚠️ best-effort, or needs an extra component · ❌ the platform has no such concept.

What ⚠️ means in practice

The symbols are only a static hint. The real answer at runtime always comes from capabilities() / support_level() — never assume from this table:

Entry	What the fallback does	Reported as
Theme detection on Hyprland / Sway / X11	No system-wide colour scheme; reads GSettings if a GTK app has written a value	`Theme::Unknown` when every probe comes up empty
Notifications on tilers / X11	`org.freedesktop.Notifications` works, but actions and images depend on the installed daemon	actions render only if the daemon supports them
Wake lock on tilers / X11	The call fails outright when the ScreenSaver service is absent	a `UdaError` (connection failure); this module has no graded report
Tray on XFCE	SNI works through the AppIndicator-compatible watcher, but there is no native double-click event	`DoubleClick` reports `SupportLevel::None`

Reporting from a host application

use uda_core::capability::SupportLevel;
use uda_core::tray::{TrayFeature, TrayManager};

let manager = uda_platform_linux::LinuxTrayManager::new();
let level = manager.support_level(TrayFeature::DoubleClick);

match level {
    SupportLevel::Full => { /* draw the double-click action */ }
    SupportLevel::Partial(reason) => { warn!("double click is degraded on this backend: {reason}") }
    SupportLevel::None => { /* hide it */ }
}

From a C host the same information is available through uda_session_capabilities and the module capabilities() functions.

Backend used per cell

Theme detection

Environment	Backend
Windows	Registry `AppsUseLightTheme`
GNOME	Portal `org.freedesktop.appearance` → `gsettings color-scheme`
KDE	`kreadconfig6/5` reads `Colors:Scheme`
XFCE	`xfconf-query -c xsettings`
Wayland tiling WM	⚠️ cannot be determined reliably; returns `UNKNOWN`

Wallpaper

The wallpaper backend does not use the XDG Desktop Portal: org.freedesktop.portal.Wallpaper exists but is never called.

Environment	Mechanism
GNOME	the `gsettings` CLI, writing `picture-uri` and `picture-uri-dark` as a pair
KDE	D-Bus `org.kde.plasmashell` → `/PlasmaShell` → `evaluateScript`
Hyprland	the `hyprpaper` CLI, falling back to `swww`
Sway	the `swww` CLI
Generic X11	the `feh` CLI, falling back to `nitrogen`
Windows	`SystemParametersInfoW(SPI_SETDESKWALLPAPER)`

Notifications

Environment	Backend	Icon	Actions
Any Linux DE	`org.freedesktop.Notifications`	✅	✅
Windows	WinRT `ToastNotificationManager`	✅	⚠️²

A Wayland tiling WM needs a notification daemon running (mako, swaync, dunst, …), otherwise the Notify call fails with ServiceUnknown.

System tray

Environment	Backend	Note
Linux	`org.kde.StatusNotifierItem` + `com.canonical.dbusmenu`	GNOME needs the AppIndicator extension
Windows	`Shell_NotifyIconW` (`NOTIFYICON_VERSION_4`)	dedicated worker thread + message pump

Media control

Environment	Backend
Linux	MPRIS v2 over session D-Bus
Windows	WinRT SMTC

Session and power

Action	Linux	Windows
Lock	ScreenSaver `Lock` → `loginctl lock-session`	`LockWorkStation()`
Logout	GNOME/KDE D-Bus methods	`ExitWindowsEx(EWX_LOGOFF)`
Suspend / hibernate	logind `Suspend` / `Hibernate`	`SetSuspendState`
Reboot / shutdown	logind `Reboot` / `PowerOff`	`ExitWindowsEx` + `SeShutdownPrivilege`

The Linux side of logout depends on the DE providing a D-Bus method; on an unrecognised desktop the capability bit for that action is false.

Cases that are not `Full`

SupportLevel has exactly three variants: Full, Partial(reason) and None. Partial must carry its reason — a host that wants to explain a degradation to the user should not have to guess why.

Feature × environment	Level	Reason
Theme detection × Wayland tiling	`Partial`	no standard query path; every probe comes up empty
Accent colour × KDE/XFCE	`None`	no system-level accent colour
Notification actions × Windows unpackaged	`Partial`	needs an MSIX-registered COM activator
Tray × XFCE	`None`	SNI has no double-click event, so the feature is not reported
Wake lock × Wayland tiling	`None`	the call fails outright when ScreenSaver is absent; there is no CLI fallback

Version requirements

Environment	Minimum version
Windows	10 (toasts are complete on 10/11)
GNOME	42
KDE Plasma	5
XFCE	4.14+
Rust	1.70
Python	3.9
Node.js	16

Not yet covered (Phase 3)

Global shortcuts, the multi-format clipboard with change listening, audio endpoint routing and display brightness are in progress — see plans/phase3_plan.md.