Real run showed the first cut didn't fix it by default: the applied config was
the 'full' strategy (SLERP, energy 1.22x), while the style-preserving sum_preserve
config (no_slerp/basic, energy 1.91x) ranked LOWER and wasn't applied. Cause: the
Phase-2 scorer (_score_merge_result) is effective_rank*0.4 + (1-norm_cv)*0.3 +
sparsity_fit*0.3 — no magnitude/energy term, and (1-norm_cv) rewards uniform norms,
which is exactly SLERP's magnitude-flattening. So the scorer structurally prefers
the style-flattening merge over the style-preserving one.
SLERP is strictly worse than sum_preserve for orthogonal groups anyway (it rotates
two independent directions into a 45-degree blend that loses both, vs keeping each
in its own subspace), so orthogonal non-opposing groups now use sum_preserve in ALL
strategy sets — the AutoTuner's top config preserves the style by default, no manual
selection. SLERP is retained for its real sweet spot: non-orthogonal, similar-
direction (cos ~0.25-0.5) low-conflict groups in the full set.
Tests: orthogonal/full -> sum_preserve; non-orthogonal-aligned/full -> slerp;
non-orthogonal-aligned/no_slerp -> weighted_average. 304 pass. Docs + algo note updated.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
