Racks are columns, slot 1 at the bottom. Racks the robot serves from one X position are grouped as a rack pair. The dotted route is priced leg by leg; pauses mark axis settles. During a rearrangement, a dashed outline is where a tray was picked up and a solid one where it was set down — both moves of a pair at once, because the pair is one decision.
The two objectives against their bounds
Every staging cost here is priced for the coming …-parcel run, held fixed for the whole timeline so that a loading run reopening the gap reads as the arrangement degrading rather than as the horizon shrinking under it. Neither bound is reachable — a tray footprint spans slots and every budget is finite — so the reading is the fraction of the gap closed.
What the locker has left
Front/rear and left/right weight imbalance are deliberately not shown: weight balance is a constraint neither rearrangement objective optimises, so here it would be noise competing with the signal.