[techapostle]

What changed

On a desktop with no built-in screen, Controls shows a "Built-in display" brightness fader in the Brightness drawer, and the bar brightness widget and the Kairos and Orpheus display pages count it as a display. Dragging it writes to a keyboard LED.

Cause. services/Devices.qml resolves the panel with ryoku-hw-backlight, which exits 1 and prints nothing when /sys/class/backlight is empty. ${BL:+-d "$BL"} then drops -d, and brightnessctl falls back to its first device of any class:

$ ryoku-hw-backlight
ryoku-hw-backlight: no backlight device under /sys/class/backlight
$ brightnessctl -m
input16::compose,leds,0,0%,1

The read parses 0, so backlightPct becomes 0 and backlightAvailable turns true. The comment on backlightPct says the reader should never set it on such a machine.

Fix. The read and the write in Devices.qml both pass -c backlight. With no backlight, brightnessctl exits 1 with no output (Failed to read any devices of class 'backlight'.), so backlightPct stays -1 and every consumer of backlightAvailable hides the fader. On a laptop the selector's device is already a backlight-class device, so -c backlight -d <it> resolves the same device as before. If the selector is missing, the class still keeps brightnessctl on a backlight.

Area

ryoku

How it was tested

Arch, Hyprland 0.57.0, desktop with no /sys/class/backlight device and two DDC monitors.

• The blRead command before the change prints 0; after it prints nothing.
• brightnessctl -c backlight -p set 50% exits 1 and leaves the LED untouched.
• -c and -d combine as expected: brightnessctl -c leds -d input16::compose -m finds the device.
• Live shell with the changed Devices.qml: before the change, Controls > Brightness drawer listed Built-in display, DP-1 and HDMI-A-1. After it, the drawer lists only DP-1 and HDMI-A-1, and the main Brightness slider still follows DP-1.
• The pre-commit QML binding check passes.

Not tested: a laptop with a real backlight. The argument rests on brightnessctl's class filter: -c backlight -d <name> resolves a device whose class is backlight, and ryoku-hw-backlight only ever prints entries from /sys/class/backlight.

Checklist

• One logical change, with a clear [area] scope: summary commit subject.
• Matching CHANGELOG.md updated in the area I touched.
• The git hooks pass locally; I did not use --no-verify.
• Lua parses (luac -p), shell scripts pass bash -n, and QML passes
  qmllint where applicable.
• No duplicated config, no dead code, no commented-out code, no em-dash.
• Docs updated if behavior or layout changed.