to
Rebuilds a GridGraph from this structural spec — the consume side of the round-trip (P5b/G2). A modeler who wants the layout to be authoritative for geometry loads the layout, looks up the spec (AnimationLayout.gridGeometry(name)), and builds the graph from it. Reproduces dims, topology, obstacles, and costs exactly; the physical placement fields (originX/originY/cellSize) are layout/render concerns and are not part of the graph.