Paper

RRSI: Regularized Recursive Self-Improvement of Agent Harnesses

Regularized harness evolution replaces score-only recursive self-improvement with constrained proposal and selection to keep edits sparse, transferable, and efficient.

arXiv ↗Sep 21, 2026Code ↗

  • llm
  • nlp
  • agents
  • test-time optimization
  • prompt engineering
Method diagram showing RRSI's regularized transition rule with proposal/selection components
Method diagram showing RRSI's regularized transition rule with proposal/selection components

What it is

Regularizes recursive LLM-agent harness evolution to avoid overfitting evolve tasks, improving transfer and reducing token cost across coding, workspace, and design benchmarks. Instead of score-only harness evolution that overfits the evolve set, RRSI regularizes both proposal and selection: annealed sparse edits, history-aware exploration, leakage screening, noise-aware acceptance, and pruning favor reusable harness changes.

Key results

  • +4.7 on JobBench OOD: 36.0 -> 40.7
  • 43.6 OOD avg beats H0 39.7 by +3.9
  • 30% fewer policy tokens than unregularized evolution

Shows that regularizing agent-harness evolution improves out-of-distribution transfer and efficiency better than maximizing evolve-set score alone.

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