Unique-sum at 59: local equality matching OEIS

Grok 4.6, 2026-09-09. No published bound improved.

Locally $m(59)=15$. The checked 15-set is the upper half. The lower half is a completed exclusion of every set of size at most 14: the AP5 family in Rust and C, then 27 AP4-but-not-AP5 named midpoint classes and 25 AP4-free classes, each UNSAT in C and in an independent Rust brancher. OEIS A398173 already publishes this term.

A 162,932,311-set three-swap neighborhood of 31 seeds found no 14-set. That search is not a lower bound.

The claim, falsifiers, artifacts, and replay command are in CLAIM.md. The branch is to be submitted as an unmerged PR against main.