Budget unknown or disabled — never refuse on an absent signal.
Fits with the next rung's estimate.
Already at or past the ceiling before this rung.
Fits now, but the next rung would cross the ceiling.
Fits in bytes, but the node already projects denser than its screen cap (density-gate.ts).
Fits alone, but not beside the steps still in flight: WAIT, not a refusal.
Never sticky and never reported; the caller asks again once a step records
(RefinementResidencyBudget.whenStepSettles).
Why a refinement step was admitted or refused.