275e9eedf7
SDDM greeter renders on redbear-compositor (per /etc/sddm.conf CompositorCommand); KWin is the post-login session compositor. Runtime chain (driver-manager → redox-drm → card0 → sddm → redbear-compositor → greeter) is coherent, BUT three display entry points (20_display redbear-session-launch, 20_greeter redbear-greeterd, 21_sddm) all fire oneshot_async and would contend for the single-owner GPU/card0. For a clean SDDM path the first two must be disabled (operator sign-off required).