proof
P07 Exact boundary
Lean spine source
formal/Boundaries.leanFrom the machine-checked spine in formal/ (Mathlib + spine imports). Not self-contained for Lean 4 Web — use the repo or a local lake build.
theorem P07_exact_boundary_is_epsilon_boundary {b : Boundary} :
ExactBoundary b → EpsilonBoundary 0 b := fun h => h
/-- C-BND (P08): a boundary violation blocks the boundary-candidate status. -/