Status: IN
Builder and Visitor achieve complete bidirectional functional duality: Builder can analyze without creating (CountingMazeBuilder demonstrates pure traversal-analysis), Visitor can create during traversal (discretionary glyphs demonstrate structure-modifying construction) — each pattern performing the other's primary function, validating that the construction-computation boundary is a concern axis rather than a fixed partition.
Builder's analysis capability and Visitor's construction capability complete the structural duality into a functional one
Depends on (SL): builder-visitor-dual-structure-traversal-patterns, discretionary-glyphs-validate-visitor-as-construction-mechanism