LarsenClose/OneEquation: v1.0.0

Structural consequences of the retraction equation on the classical carrier. Machine-checked in Lean 4 with Mathlib v4.28.0.

One equation on binary strings -- fold . unfold = id -- forces a canonical carrier architecture. The dual composition selfApp = unfold . fold is idempotent and classifies every fold/unfold geometry into three regimes.

On the classical carrier (headerLen > 0), three independent results exclude full closure:

fold shortens by headerLen
unfold lengthens by headerLen
headerLen > 0
────────────────────────────────
No map can commute with both.
FoldUnfoldSection → False
                                (six lines, omega)

selfApp([]) = header ≠ []       (selfApp ≠ id, pre-semantic)

selfApp factors through headerLen
drift = headerLen exactly        (tight, achieved)

A fourth result -- the super-polynomial counting gap -- establishes that the naming obstruction is intrinsic to the carrier's information geometry.

P and NP are defined on this carrier (rfl). The carrier's constraints are the carrier's, not the classes'. The obstruction is encoding-invariant.

21 source files, approximately 4,300 lines. Zero sorry. Zero custom axioms. Standard kernel axioms: propext, Classical.choice, Quot.sound.