DWM presents a display only when something dirties it. On an idle desktop a
perfectly healthy session sat at E_PENDING: the driver attached but no
first frame ever landed, so wait_for_attach's 4 s gate failed the open (and
a mid-session ring recreate hit the same stall against the 3 s
recover-or-drop). A real client escaped only because its own input soon
dirtied the desktop; a headless probe / input-less connect never did.
kick_dwm_compose() injects two net-zero 1 px relative mouse moves via
SendInput — pf-vdisplay has no hardware-cursor plane, so a cursor move is
composited into the frame, a guaranteed real present onto the IDD
swap-chain (the mechanism --input-test always relied on; the pointer ends
where it started). Wired into wait_for_attach (first kick at 600 ms, then
every 800 ms) and, rate-limited, into the GB1 recovery window.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
enricobuehler
d4aba755b6