sRGB→linear alone lands cursor-white at 80 nits (scRGB 1.0) while DWM composes the surrounding SDR desktop at the user's SDR-brightness setting (~200+ nits by default) — the cursor read visibly dark on HDR. Scale by DISPLAYCONFIG_SDR_WHITE_LEVEL (new win_display::sdr_white_level_scale, queried on blend-scratch rebuilds — the CCD query stays off the per-frame path). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>