OptionalisThe injected quiescence predicate, TRI-STATE — see
OfflineCaptureStrategyHooks.isLODSettled for what each state means.
null and absent are identical: this scene has no lod_group to wait for,
so the whole drain is skipped, mandatory tick included.
False once the user has pressed Stop.
True once the session has been aborted (cancel / dispose / error).
One animation frame. Injected so tests can drive the clock.
What the drain needs from the capture session to know it may keep waiting.