Region
One region: a group of modules treated as a unit when the project is too large to draw module by module.
Parameters
Stable identifier, used as a node id in the aggregated graph.
Display name.
Module paths in this region, sorted.
Production edges with both ends inside the region.
Production edges with exactly one end inside it.
internal / (internal + external), in [0, 1]. High cohesion means the region is a real boundary; low cohesion means the grouping cuts across how the code actually depends.
Sub-groups, present only when the region is too large to read as one list. A declared layer can legitimately hold hundreds of modules - a :feature:** layer over 120 features - and collapsing that to a single card says nothing. Splitting it one level deeper turns the region map into a drill-down: project → region → sub-region → module.