Geometry and the single exchange

The finite implementation certifies a discrete event in a fixed family. All moving-patch transitions are pure gauge in one flat development. The example does not test support containing a particle or nontrivial monodromy. It supplies neither a complete transition catalogue nor a canonical constraint algebra for a full polygon implementation.

The compact collar is essential. An unbounded maximum graph without boundary matching would not establish a move attached to the same fixed conical exterior.