ResearchResearch paperReinforcement Learning · Large Language Models · Robotics & Embodied AI2 sources · Oct 7, 2026

MIMESIS: Learning User Simulators as Training Environments for Interactive Agents

We introduce MIMESIS, a purpose-built user simulator trained on human conversations with explicit reasoning supervision and 13 realistic behavioral patterns derived from real user interactions.

Key points

  • Training and evaluating interactive language agents typically requires rich user interactions, yet collecting human feedback is expensive and difficult to scale.
  • Simulated users offer a scalable alternative, but they must both resemble real user behavior and provide useful learning experiences for agents.
  • Across eight environments, training with MIMESIS yields better agent performance than training with GPT-5.5 under all nine unseen user simulators, demonstrating stronger generalization to new user simulators.
  • Moreover, we propose Coached On-Policy Self-Distillation (CSD), which leverages simulator-generated private reasoning traces and subsequent utterances as feedback on how well the agent addresses user needs.

Sources (2)

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