Web privacy is experienced via two public artifacts: site utterances in policy texts, and the actions users are required to take during consent interfaces. In the extensive cross-section audits we've studied, there is a lack of longitudinal data detailing how these artifacts are changing together, and if interfaces are actually doing what they promise in policy. ConsentDiff provides that longitudinal view. We build a reproducible pipeline that snapshots sites every month, semantically aligns policy clauses to track clause-level churn, and classifies consent-UI patterns by pulling together DOM signals with cues provided by screenshots. We introduce a novel weighted claim-UI alignment score, connecting common policy claims to observable predicates, and enabling comparisons over time, regions, and verticals. Our measurements suggest continued policy churn, systematic changes to eliminate a higher-friction banner design, and significantly higher alignment where rejecting is visible and lower friction.

翻译：网络隐私通过两种公开产物被用户感知：政策文本中的站点表述，以及用户在同意界面上需执行的操作。在我们广泛研究的横截面审计中，缺乏关于这些产物如何共同演变、界面是否真正履行政策承诺的纵向数据。ConsentDiff提供了这一纵向视角。我们构建了一个可复现的流水线：每月对网站进行快照，语义对齐政策条款以追踪条款级变化，并通过整合DOM信号与截图提供的线索对同意-用户界面模式进行分类。我们引入了一种新颖的加权声明-用户界面对齐分数，将常见政策声明与可观察谓词关联起来，从而实现跨时间、区域和垂直领域的比较。我们的测量表明：政策持续变动、为消除更高摩擦的横幅设计而进行的系统性更改，以及在拒接操作可见且摩擦更低时，对齐程度显著提高。