CONSTRAINT / STACKING
Stacking
Stackability, stack counts, interlocking height and density limits shape a legal column. Density is checked at every level, not only the floor.
stackable · max_stacked_items · nesting_height · max_stack_densityWhy it exists
Identical dimensions do not imply identical stacking policy, and the rule that only holds on the floor is the rule that breaks in the middle of the load.
What a useful refusal looks like
The engine returns the rule that refused, the item it refused, and the measured value against the configured threshold. It also states how strongly that is backed: proven, observed, inferred, or unknown because a search limit was reached first.
See the fixtures for this rule ↗