Kadence — the native desktop app

Not Electron. PyQt6 + QML with Qt Quick Controls' Material style: the window is a native Wayland/X11 surface drawn by Qt, using the session's own fonts, scaling and colour scheme. The only dependency is PyQt6, which on Arch is the system package python-pyqt6; everything else — HTTP, config, process scanning — is the Python standard library.

It is also the piece that enforces things, because it is the only part running on your machine.

sudo pacman -S --needed python-pyqt6 qt6-declarative     # Arch
./packaging/install-desktop.sh                            # menu entry, icon, launcher
sudo ./helper/install.sh                                  # privileged helper (website blocking)
kadence-desktop

Run it straight from the checkout instead: python3 -m kadence_desktop.

What "native" buys you

Feature	How
Tray icon that is the timer	`QSystemTrayIcon` (a StatusNotifierItem on KDE). The icon is painted at runtime: a ring that drains as the interval runs, tinted by focus / break / idle, with a pause glyph when held. Middle-click toggles the timer.
Real notifications with buttons	`org.freedesktop.Notifications` over D-Bus, with actions: Start break · Another pomodoro · +5 min. Replaced in place, so a day of pomodoros never stacks a column of toasts.
Scriptable over D-Bus	`org.kadence.Desktop` exports `StartWork`, `Toggle`, `Pause`, `Complete`, `Extend`, `Interrupt`, `Status`, `SendReport`, `Raise`. Bind any of them to a global shortcut in System Settings — no key-grabbing hacks.
Screen stays awake	`org.freedesktop.ScreenSaver.Inhibit` while you focus, released the moment the interval ends.
Do Not Disturb	Other apps' banners are suppressed during focus (Plasma's `Notifications.Inhibit`; on GNOME the `show-banners` gsetting, put back afterwards).
Your music pauses	Any MPRIS player (Spotify, VLC, mpv, browsers) is paused when focus starts, and only the ones we paused resume on the break.
Taskbar progress	`com.canonical.Unity.LauncherEntry` — a progress bar under the dock icon and a badge with today's count.
Knows when you walked away	logind `Lock`/`Unlock` and `PrepareForSleep` pause and resume the timer; optional idle-pause uses KDE's or Mutter's idle monitor.
Starts with the session	XDG autostart entry, or a systemd user unit that restarts on failure and logs to the journal.
Single instance	Owning the D-Bus name is the lock; a second launch raises the first window and exits.
Launcher actions	Right-click the icon: Start a pomodoro, Start a break, Start / pause, Send today's report.

Every one of these degrades to a no-op where the desktop does not provide it, so the same build runs on KDE, GNOME or a bare window manager.

Blocking

The rules (which sites, which apps, when) live on the backend so the web app can edit them and a second machine obeys the same list. This app enforces them:

Websites — the managed region of /etc/hosts is kept in sync with the policy. Writing it needs root, which a desktop app must not have, so it calls kadence-helper through pkexec.
Applications — /proc is scanned every few seconds for your own processes matching the list; they are terminated (SIGTERM, then SIGKILL) or merely reported, and every attempt is sent to the backend for the evening report.
Everything is released when the interval ends — and on exit, including a crash, because shutdown() clears the block and the inhibits.

The privileged helper

helper/kadence-helper is the entire privileged surface, and it is deliberately dull:

every hostname must match a strict pattern, the redirect must parse as an IP;
only the region between its own markers is rewritten — your own entries above and below survive byte for byte;
the input list is opened O_NOFOLLOW and must be a regular file;
the write is atomic (temp file + rename), and the first run backs up /etc/hosts to /etc/hosts.kadence-backup;
localhost can never be blocked.

sudo ./helper/install.sh                  # polkit asks once per session
sudo ./helper/install.sh --passwordless   # or never, for your user only
sudo ./helper/install.sh --uninstall      # unblocks first, then removes itself

Global shortcuts

System Settings → Shortcuts → Custom Shortcuts → New → D-Bus command:

Field	Value
Service	`org.kadence.Desktop`
Path	`/Timer`
Method	`org.kadence.Timer.Toggle`

Or bind a command: kadence-desktop --toggle. The verbs talk to the running instance instead of starting a second one:

kadence-desktop --toggle      # start → pause → resume
kadence-desktop --start       # start a focus interval
kadence-desktop --break
kadence-desktop --complete
kadence-desktop --status      # "Focus 18:42 · Write the docs · 3/8 today"
kadence-desktop --report      # send today's report to Telegram

In-window shortcuts: Space start/pause · Ctrl+Enter finish · Ctrl+E +5 min · Ctrl+R refresh sources · Ctrl+1…5 pages · Ctrl+W hide to tray.

Configuration

~/.config/kadence/desktop.json holds only what is about this machine — the backend URL and token, and which integrations this box may use. Timer lengths, task sources, block lists and Telegram all live on the server, so they are the same everywhere. The Settings page edits both, clearly separated.

Layout

kadence_desktop/
  app.py                 # QApplication, QML engine, tray, D-Bus, single instance
  controller.py          # the object QML binds to; wires transitions to integrations
  worker.py              # the network thread (every HTTP call happens here)
  api.py                 # stdlib HTTP client for the backend
  config.py              # ~/.config/kadence/desktop.json
  tray.py                # the painted countdown icon and its menu
  integrations/          # notifications, inhibit/DND, MPRIS, launcher, logind, D-Bus, autostart
  blocking/              # hosts file, /proc scanning, and the manager that syncs policy
  qml/                   # Material UI: Timer, Tasks, Blocker, Report, Settings
helper/                  # the privileged helper + polkit action + installer
packaging/               # .desktop entry, icon, user installer

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