fix: 🐛 Stop the GUI hanging on close and reconnect the BLE keyboard when its hidraw node changes

[sammyapoex]

Note: This pr was generated with Claude. I don't have any experience with this code base, so these changes should be reviewed thoroughly. But I can confirm that it fixed the issues with the app freezing that I was having.

Two independent hangs I ran into while using the app on Linux with a ZMK keyboard over Bluetooth.

1. GUI hangs on close (libs/gui.py)

updateLayer had its await asyncio.sleep(0.1) inside the try, so any exception skipped the loop's only yield point. Once the window starts closing every iteration raises (the Image widget is gone) and the coroutine spins without ever awaiting, starving the asyncio event loop — async_run() never finishes, the window stops answering the compositor, and the app has to be force-quit. The Kivy log shows Window: exiting mainloop and closing. followed by hundreds of --- Logging error --- lines and no exit.

• Move the sleep out of the try so an error can never skip the yield.
• Cancel the task in on_stop so the loop actually ends on shutdown.
• Bounds-check the layer index instead of indexing config.layers blind, so a layer with no configured image logs and is ignored.

2. Frozen layer image after a BLE drop (libs/keyboard_ble_hid.py)

A keyboard that drops its BLE link comes back on a different /dev/hidraw node:

09:02:01  hidraw5 (Kibard) disappears
09:02:06  Kibard returns as hidraw7

notify_changes only looked for the device again from inside its HIDException handler, and did so with self.hid = self.find_device() or self.hid. The keyboard is absent during the gap, so find_device() returns None and the or puts the dead handle straight back. Nothing ever enumerates again, and reads on that handle are quiet rather than fatal, so the app polls a device that is gone: window responsive, no error printed, CPU normal, layer image frozen for good.

• Track the hidraw node we opened and re-open when it disappears; a stat() per poll is cheap enough for the GUI loop, unlike enumerate().
• Never keep a handle we failed to re-find, and close the old one so repeated blips don't leak descriptors.
• Throttle reconnect attempts to 1s so hid.enumerate() can't stall the event loop while the keyboard is away.
• Reset current_layer on reconnect, so a keyboard returning on the layer already displayed still redraws instead of comparing equal.
• Drop the unbounded tenacity @retry: its wait_exponential called blocking time.sleep() on the Kivy event loop, freezing the window for 1, 2, 4, 8, 10... seconds forever. The GUI already re-polls every 100 ms, so returning None is simpler and non-blocking.

Only the BLE path is changed — libs/keyboard_hid.py (USB raw HID) has a different report shape and is untested here, so it is left alone. tenacity is still used by libs/client.py and libs/keyboard_hid.py, so it stays a dependency.

🤖 Generated with Claude Code

[maatthc]

Thanks for you contribution @sammyapoex ! I will go through the changes and get back to you.