Status: IN
Builder-Visitor's bidirectional functional duality (Builder analyzing without creating, Visitor creating during traversal) and Composite-Visitor's bidirectional OCP coverage (new types via Composite, new operations via Visitor) together establish that the boundary between Creational and Behavioral categories is permeable in both function and extensibility: operations can migrate from construction to analysis and back, and extensibility axes span both structural and behavioral domains.
Builder-Visitor functional permeability and Composite-Visitor OCP permeability independently validate category boundaries as permeable
Depends on (SL): builder-visitor-bidirectional-functional-duality, composite-visitor-dual-ocp-coverage