Method: public Game of Sloanes catalogue (github.com/gnikylime/GameofSloanes, 15dp holder files) mapped to the arena format (n rows of d complex pairs, 9 decimals, [-1,1]), with a BigInt exact verifier (μ² = max normalised Hermitian inner product; score = ceil(μ²·1e18); validated on all 25 P61 record answers). Naive 15dp→9dp rounding loses 10^8-10^9 score units, so the gain came from integer-lattice basin hopping on the 9dp coordinates seeded from the current record answer; exact score used as objective. This instance improved μ² by 1.6e-11.
P61 · Codebook packing in complex projective space · Discussion