Plasma Task Manager Notifications

Taskbar badge notifications for KDE Plasma 6. Dynamically discovers running applications via KWin, monitors desktop notifications via D-Bus, and sets badge counts on taskbar icons using the Unity Launcher API.

How it works

1. Discovers apps dynamically by querying KWin via D-Bus — enumerates open windows using WindowsRunner.Match, then calls KWin.getWindowInfo for each to get the desktopFile property. Rediscovers every 30 seconds in a background thread.
2. Runs an unfiltered dbus-monitor --session subprocess (unfiltered is required to capture method return messages which contain the assigned notification ID).
3. Parses the dbus-monitor output as a stream, tracking three message types:
   • method_call with member=Notify — extract the app_name and message serial
   • method_return with matching reply_serial — extract the notification ID
   • signal with member=NotificationClosed — notification was dismissed
4. Matches app_name (case-insensitive) against the dynamically discovered app map. Also supports Flatpak apps via desktop-entry hints.
5. Emits com.canonical.Unity.LauncherEntry.Update signals via gdbus emit to set/clear badge counts and the urgent flag on the corresponding taskbar icon.
6. On shutdown (SIGINT/SIGTERM), clears all badges.

Requirements

• KDE Plasma 6 with KWin and Task Manager
• dbus-monitor (from dbus-tools, typically pre-installed)
• gdbus (from glib2, typically pre-installed)
• Rust toolchain (to build)

Install

git clone ssh://git@git.nmm.ee/asko/plasma-task-manager-notifications.git
cd plasma-task-manager-notifications
make install

This installs the binary to ~/.local/bin/ and the systemd service to ~/.config/systemd/user/.

Enable at login

systemctl --user enable --now plasma-task-manager-notifications.service

Check status

systemctl --user status plasma-task-manager-notifications.service
journalctl --user -u plasma-task-manager-notifications.service -f

Uninstall

make uninstall

Usage

Run manually (logs to stderr):

plasma-task-manager-notifications

Test with a sample notification:

notify-send --app-name=firefox "Test" "Badge should appear"

Development

cargo test        # run all tests
cargo build       # debug build
make build        # release build

Architecture

The crate is split into four modules:

Module	Purpose
parser	Streaming parser for dbus-monitor text output
app_map	Tracks discovered apps, pending notifications, and active badge counts
discovery	Queries KWin D-Bus interfaces to discover running apps and their desktop file IDs
badge	Emits Unity LauncherEntry Update signals via gdbus

All modules are designed for testability — external D-Bus calls are injected as function parameters in tests.

Known limitations

• Processes all session bus traffic (unfiltered monitor). Lightweight in practice but could theoretically be optimized with BecomeMonitor D-Bus API.
• Only badges apps that currently have an open window. Pinned taskbar icons without a running instance won't be badged.
• If two apps share the same last dot-segment in their desktop file ID, they would collide in the match map. Unlikely in practice.
• Firefox web app notifications all badge under the single Firefox icon.
• Notifications that expire via timeout also emit NotificationClosed, so badges clear when notifications auto-dismiss.

License

MIT