a daily meter is already past SWEEP_START_FLOOR
the sweep's own share of the day is spent; it resumes at 00:00 UTC
the share of what is LEFT, which is what bounds one step rather than the day
one step queues at most one fill batch
the fill queue still has work, so the sweep yields to it
everything addressable is stored or queued
which bound stopped the sweep, so an operator knows which number to act on