搜索和新闻聚合团队终于有了可落地的轻量级时间线方案——7B模型干翻671B，CTR和用户停留时间双双提升，做搜索排序或事件摘要的工程师可以直接参考其多任务微调策略。
百度搜索团队提出QDET（查询驱动事件时间线摘要）系统，用于在搜索中为热点新闻查询构建聚焦的事件时间线。该系统通过多任务监督微调（时序排序、因果判断、时间线补全）和基于强化学习的简洁摘要生成，使7B参数模型在时间线摘要F1得分（76.2%）上超越DeepSeek-R1-671B（76.1%），参数量仅为后者的1%。在线A/B测试显示，QDET使点击率提升5.5%、停留时间延长4.6%、探索深度增加4.4%。该工作证明领域专用优化能以极低成本达到大模型级别的生产质量。
Large Language Model-Powered Query-Driven Event Timeline Summarization in Industrial Search
Understanding how events evolve over time is essential for search engines handling queries about trending news. We present QDET (Query-Driven Event Timeline Summarization), a production system deployed on Baidu Search that constructs focused event timelines to explain specific query events. Unlike traditional topic-centric approaches that aim for comprehensive coverage, QDET identifies and organizes sub-events closely relevant to the query from noisy candidate sets formed by millions of documents retrieved daily. QDET incorporates two key innovations: (1) multi-task supervised fine-tuning with three auxiliary tasks-temporal ordering, causal judgment, and timeline completion-that enable compact models to match the performance of much larger general-purpose models in specialized domains; (2) reinforcement learning-based event concise summarization that enforces strict length constraints while maintaining semantic quality, achieving 88.2% length compliance and outperforming 671B-scale models by 7.7 points in constraint satisfaction. Our fine-tuned 7B parameter model achieves 76.2% F1 score on timeline summarization, slightly surpassing the zero-shot performance of DeepSeek-R1-671B (76.1% F1) while using only 1% of its parameters-demonstrating that domain-specific optimization enables production-ready models with comparable quality at drastically reduced computational costs. Online A/B tests on Baidu Search validate real-world effectiveness, showing 5.5% CTR improvement, 4.6% longer dwell time, and 4.4% deeper exploration compared to single-task baselines. We further demonstrate that timeline understanding transfers to heat prediction, confirming effective knowledge transfer to downstream tasks.