9fdc3c3246
ci / rust (push) Has been cancelled
Headless KDE startup was a chain of timing-sensitive handoffs gated by a blind `sleep 2`, the dominant source of black screens. Phase-1 fixes: - New `punktfunk-host probe-compositor` subcommand: exits 0 iff the detected compositor is up AND ready to create a virtual output now. KWin gets a real check (connect + registry roundtrip + the privileged zkde_screencast global must be advertised — what the backend needs); gamescope/Mutter/wlroots create on demand so the probe just confirms Linux. (vdisplay::probe dispatcher + kwin::probe; reuses kwin.rs's existing roundtrip path.) - run-headless-kde.sh: replace `sleep 2` with an active readiness wait (poll probe-compositor until ready, 30s deadline, and bail with kwin's log if kwin_wayland exits during init). Move the portal restart to AFTER readiness, and precede it with `systemctl --user import-environment` + `dbus-update-activation-environment` (the missing env import — the Sway script does this; without it a restarted portal inherits a stale/empty WAYLAND_DISPLAY, which is the "streams but eats no input/audio" failure). kwin's stderr → a log file. Validated: probe-compositor exits 0 "Kwin ready" against the live session, exit 1 with a clear diagnostic when the compositor is absent. 114 tests green, clippy/fmt clean. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>