MILO co-evolves agent harnesses and their search strategy, reaching 86.1% on Terminal-Bench 2.1 above the official leaderboard top and tightening three mathematical bounds
MILO (Meta-evolutionary Island Orchestration) co-evolves an agent harness together with the strategy that discovers it: a hierarchical island-based lineage memory treats rejected mutations as negative evidence, per-island mutator agents rewrite complete harnesses, and an orchestrator adapts the search through lineage grafting, speciation, mutator reassignment, and curriculum revision; across Terminal-Bench 2.1, PaperBench, and DeepSWE it improves resolution over its initial harness by 12.0%, 28.3%, and 10.3% with Opus 4.8 (versus best prior-search gains of 4.5%, 18.3%, and 0%), reaches 86.1±2.0% on Terminal-Bench 2.1 (official leaderboard top 83.8±2.