The standing model carries every measured mesh top as an automatic
standing surface, including rooftops and skybox fragments far above the
floor. Dragging an agent across one lifted the eye by metres (Haven B site
had a surface 65 m up) and the cone became a bird's-eye view over every
wall. scripts/demote_unreachable_supports.py walks reachability from the
reference ground through touching supports with a 2.5 m climb, and demotes
mesh-derived tops that nothing reaches and that sit at least 5 m above the
ground everywhere. Reviewed floors are never touched: stairs inside
two-storey buildings are not in the data, so reachability cannot judge
them. Explicitly reviewed fixture cases such as Split's preserved roof
levels stay automatic.

The regional standing test now treats a demoted level as present but not
as the expected automatic answer; the measured level still has to exist.

tool/svg_height_flip_rank_test.dart ranks standing spots by how much the
cone changes between two models, which is how these were found.

Gate: all tests pass.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>