Extension helper in the Editor namespace for resolving which ArchRoom a pillar belongs to. It provides a single extension method RoomStanding that returns the room hosting a given ArchPillarPart, optionally constrained by an ArchKinds table; columns on a porch return null per the comment.
namespace Sunless.Architecture;
public static class ArchPlanPillars
{
// Null for a column standing on a porch deck: it is filed there, not in a room.
public static ArchRoom RoomStanding( this ArchPlan plan, ArchPillarPart pillar, ArchKinds table = null ) =>
plan.HostOf<ArchRoom>( pillar, table );
}