Clicking the keyboard layout widget switches one device, chosen by
filtering the seat through UNTYPED_KEYBOARDS and then taking whichever
survivor sits furthest through the layout list. That filter has to
recognise every non-keyboard by name, and a laptop registers far more as
a keyboard than it lists.
On a Dell XPS 14, Hyprland reports ten keyboards and one of them is a
keyboard. The filter catches three of the other nine, leaving vendor
hotkey blocks (intel-hid-events, intel-hid-5-button-array,
dell-privacy-driver, dell-wmi-hotkeys) and two HID endpoints ahead of
at-translated-set-2-keyboard, which sorts last. Every click switches
hid-sdw:...-consumer-control instead, so the label cycles convincingly
while typing never changes. Device order is stable across polls, so it
is deterministic rather than a race, and needs no pre-existing bad state.
Switch every keyboard holding the same layout list instead, naming an
absolute index. "next" advances each device from wherever it sits, so a
seat that has already drifted apart stays drifted and merely inverts;
one index converges it in a single click, and a seat in lockstep leaves
the reading nothing to disagree about. Keyboards given their own
kb_layout hold a different list and are left alone, since an index into
this list would not mean the same layout to them.
The evdev KEY bitmap would separate these cleanly - the real keyboard
emits 167 keys, the pseudo-devices at most 19 - but hyprctl devices
reports no capability information, so the switch is taken out from
behind the name filter rather than the filter being lengthened.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
