Count aggregate: number of matched elements in this group combination.
Collision-free key — groupPathKey(path), matching the source ListGroup.key.
Group-by values, outermost first — one per active grouping level.
columnId -> summed numeric value, for the configured sum columns.
One row of the
schedulepresentation (issue #1790 round 2) — a single group-value tuple (a leaf group combination) carrying its Count and sums, projected from the LEAF entries ofListGroup[](seetoScheduleRows). UnlikeListGroup, a schedule row is never a parent: there is exactly one row per distinct combination of group-by values, matching Bonsai's "Building | Storey | Type | Count" schedule format.