Mitigating selective disclosure in recommender explanations via risk-aware memory and hierarchical planning
摘要
Large language models (LLMs) have improved the fluency of explanations in recommender systems. However, existing research largely focuses on mitigating factual hallucinations or preference misalignment, leaving a trust failure underexplored. In practice, these systems often exhibit a biased promoter persona: they generate explanations that are factually correct and preference-aligned, yet strategically incomplete by concealing item defects. We term this phenomenon Selective Disclosure, which produces true-but-incomplete explanations that erode long-term user trust. To address this, we propose STRATA, a risk-aware plan-and-generate framework that explicitly decouples disclosure decisions from language realization. Specifically, we introduce a Risk-Aware Preference Memory (RAPM) to distinguish between negotiable preferences and non-negotiable constraints. Guided by RAPM, a Strategic Plan Selector performs hierarchical disclosure planning by assigning attribute-level stances, while an Attribute-Grounded Generator translates these strategies into controlled natural language. An offline learning pipeline combining supervised warm-up and KL-regularized reinforcement learning optimizes the trade-off between disclosure sufficiency and evidence consistency. Experiments on three benchmark datasets show that STRATA reduces the selective disclosure of risk-relevant negatives and improves human-perceived trustworthiness and helpfulness over existing baselines. Our code is available at https://anonymous.4open.science/r/STRATA-C040.