The Jacobi adjacency relaxation in collapse_global (94g) re-solves a linear
assignment each round holding neighbours' labels fixed from the previous
round, which can 2-cycle between labellings that satisfy zero adjacency
requirements even when a fully-satisfying permutation exists (proved by
test_two_opt_polish_escapes_jacobi_plateau on a minimal 4-cell chain).
Fitness._two_opt_adjacency_polish runs after the Jacobi fixpoint and tries
swapping the labels of every same-level pair of supply leaves, keeping a
swap only on strict improvement -- monotone by construction. Gated behind
collapse_global(local_search=...) / homemaker-collapse --local-search,
default off pending a broader sweep (homemaker-py-cdl). Swept the 11
harbor-house evolved-*/3m/materialised .dom files: 0 regressions, 1 real
improvement (evolved-anneal-3M.dom 21->19 fails).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Bruno Postle
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