SceneMeasured typedef
Reports what the layout measured, in artboard coordinates. The editor's geometry comes from here: a flex child has no authored position, so the only true answer is the one the renderer laid out.
Keyed by the NODE, not by its name. A compiled scene has no names — the field names live in the source, where the editor reads them — so a name-keyed report would collide every node of it onto one empty string. Whoever holds names (the editor, the guest naming rects for the wire) puts them on at its own edge.
Implementation
typedef SceneMeasured = void Function(Map<SceneNode, SceneRect> rects);