exhale-app

exhale is a calming full-screen overlay that paces your breathing with a
tunable inhale/exhale/hold rhythm. Runs as a menu-bar / system-tray app
with customisable colours, shapes, and cadence, and optional reminder
notifications.

Controls live in the system tray: Start/Stop animation, toggle pause,
reset to defaults, open preferences. The overlay itself is click-through
so it never interrupts whatever you're doing.