Keep HDR OFF for the DDA (secure-desktop) path rather than bailing to WGC: the DDA
capturer is SDR-only (BGRA8), so an HDR SudoVDA makes the Winlogon capture black.
On the secure transition, drop the monitor out of HDR and VERIFY it took (re-read
advanced_color_enabled, retry up to 6×200ms) before opening DDA — the CCD toggle can
transiently fail (rc=5) or lag. Restore HDR on return to the WGC normal-desktop leg.
Logs clearly if the drop can't be applied (e.g. denied on the Winlogon desktop).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
enricobuehler
69765bad93