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Main Authors: Long, Da, Fu, Lingyi, Rao, Diya Michelle, Carrera, Jasmine Ruales, Bai, Yang, Zhe, Shandian
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.07011
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author Long, Da
Fu, Lingyi
Rao, Diya Michelle
Carrera, Jasmine Ruales
Bai, Yang
Zhe, Shandian
author_facet Long, Da
Fu, Lingyi
Rao, Diya Michelle
Carrera, Jasmine Ruales
Bai, Yang
Zhe, Shandian
contents Motivational-interviewing-based health coaching is an effective approach for improving mental health and promoting healthy behavior change. However, the scarcity of trained human coaches and the high cost of coaching services make such support inaccessible to many people who could benefit from it. This motivates the development of AI health coaches that can provide scalable and affordable support. Existing methods typically optimize only one side of the interaction: they either train a dialogue agent against a fixed client environment or train a client simulator against a fixed assistant. This one-sided setup can limit exploration of the interaction space and may be inefficient at developing the capabilities required by the target agent and pushing its performance boundaries. In this paper, we propose a dual-agent framework that interactively co-trains both the health coach agent and the client simulator. The coach is optimized with DPO using Pareto-dominant response pairs identified by a multi-dimensional LLM judge. In turn, the client is trained adversarially by reversing these preferences, inducing an implicit adversarial training dynamic. We further show that this co-training process admits a natural stochastic-game interpretation. Extensive experiments demonstrate that our method effectively improves coaching quality across several important dimensions.
format Preprint
id arxiv_https___arxiv_org_abs_2605_07011
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Dual-Agent Co-Training for Health Coaching via Implicit Adversarial Preference Optimization
Long, Da
Fu, Lingyi
Rao, Diya Michelle
Carrera, Jasmine Ruales
Bai, Yang
Zhe, Shandian
Machine Learning
Motivational-interviewing-based health coaching is an effective approach for improving mental health and promoting healthy behavior change. However, the scarcity of trained human coaches and the high cost of coaching services make such support inaccessible to many people who could benefit from it. This motivates the development of AI health coaches that can provide scalable and affordable support. Existing methods typically optimize only one side of the interaction: they either train a dialogue agent against a fixed client environment or train a client simulator against a fixed assistant. This one-sided setup can limit exploration of the interaction space and may be inefficient at developing the capabilities required by the target agent and pushing its performance boundaries. In this paper, we propose a dual-agent framework that interactively co-trains both the health coach agent and the client simulator. The coach is optimized with DPO using Pareto-dominant response pairs identified by a multi-dimensional LLM judge. In turn, the client is trained adversarially by reversing these preferences, inducing an implicit adversarial training dynamic. We further show that this co-training process admits a natural stochastic-game interpretation. Extensive experiments demonstrate that our method effectively improves coaching quality across several important dimensions.
title Dual-Agent Co-Training for Health Coaching via Implicit Adversarial Preference Optimization
topic Machine Learning
url https://arxiv.org/abs/2605.07011