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The Trace Has the Answer, Not the Alternative: Agentic-DPO for Offline Agent Training

TL;DR for operators Historical agent traces usually tell you what a successful operator or agent did. They do not tell you which plausible alternative the current model is most likely to choose incorrectly. That missing contrast is the problem Agentic-DPO targets.1 Instead of sending the student through full environment rollouts, Agentic-DPO pauses at states already present in expert trajectories, samples several one-step actions from the current student, and contrasts the expert action with a plausible different action the student actually favors. On StableToolBench with Qwen3.5-2B, plain SFT reaches 57.1% canonical accuracy while Agentic-DPO reaches 90.9%. ...

August 19, 2026 · 8 min · Zelina