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Longer Agent Traces Taught Persistence Past the Point of Use

A 12,000-token supervision horizon beat 16,000 tokens on Terminal-Bench while taking less training time.

Published Updated Story ID: mp-2026-10-06-014
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Summary

A 12,000-token supervision horizon beat 16,000 tokens on Terminal-Bench while taking less training time.

Imitating more of a teacher trajectory does not indefinitely improve a terminal agent. In the reported Terminal-Bench experiments, a 12,000-token horizon solved more tasks than a 16,000-token horizon while requiring 30% less training time. Short horizons encouraged premature stopping, intermediate ones supported error recovery and long ones produced over-persistence. The researchers then refined only continuations likely under a short-horizon warm start. At 16,000 tokens, that selective method increased successful attempts from 110 to 126 and improved results on two additional benchmarks; using half the long-horizon data still reduced training time by 23%. The useful lesson is selection, not sheer transcript length.

Why it matters

A 12,000-token supervision horizon beat 16,000 tokens on Terminal-Bench while taking less training time.

Limits and context

  • Imitating more of a teacher trajectory does not indefinitely improve a terminal agent.
  • The researchers then refined only continuations likely under a short-horizon warm start.
  • The useful lesson is selection, not sheer transcript length.

Key claims

  1. A 12,000-token supervision horizon beat 16,000 tokens on Terminal-Bench while taking less training time.

    Qualification: Imitating more of a teacher trajectory does not indefinitely improve a terminal agent.

    Evidence: source-2026-10-06-014

Sources

  1. arXiv preprint 2610.05831arXiv · primary research

Corrections

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