[Raintree] PolicyStrata: Responsibility-Scoped Testing for Cross-Layer Policy Drift in LLM Data Agents

A policy-guided regression-testing and stack-audit framework for governed LLM data-agent stacks, with DataPolicyDriftBench, detector-frozen suites, clean controls, scanner traces, privacy and terms document checks, prompt-manifest audit coverage, minimized witnesses, baselines, ablations, and a brownfield case study over real application surfaces with synthetic fixture data.