With I2C access granted, the helper still found nothing: every connected
monitor was probed on the wrong bus.
A connector has two. The `ddc` symlink points at the classic I2C line
that carries EDID on HDMI and DVI. DisplayPort carries DDC/CI over the
AUX channel instead, which appears as a child directory of the
connector. Both exist on a DP connector and both resolve, so the wrong
choice looks entirely reasonable and simply finds no monitor: this
machine's DP-2 has ddc -> i2c-5, where ddcutil reports "No monitor
detected", while its AUX child i2c-9 answers VCP 0x10 immediately.
This is the guess the previous commit said was unverified, and it was
wrong in the way that mattered. Enumerating from sysfs is still right --
it gives the connector name Hyprland uses and skips empty connectors --
but it has to prefer the AUX child and fall back to the symlink.
The fixture now mirrors sysfs properly: /sys/class/drm/<connector> is a
SYMLINK to the real device directory, and `find` does not follow the
path it is given. A fixture built from plain directories passes whether
or not the code resolves the symlink first, which is a test that agrees
with itself rather than with the kernel.
Verified on hardware: the Kuycon P20 reports 100%, accepts 70 and
returns to 100, and the media keys move it through codex's OSD path.
Both bus-selection mistakes are now caught by the contract.
Claude-Session: https://claude.ai/code/session_01BRvzt4H8XXLPVH5MyYdk9L
Gabriel Brown
816ea68f9a