Solution
We developed several new data sources which we maintain (and especially for Transformative Agreements), and we built a comprehensive data gathering and caching system which pulls information from definitive scholarly information sources such as Crossref, DOAJ, ROR, and OA.Works. Then in close collaboration with our colleagues at the coalition, we developed a layered query algorithm that allows us to answer compliance questions with nuanced responses, references to additional information, and detailed information about how the result was deteremined. This system is then kept up-to-date with the current state of the data in those external systems, so the results are as timely and accurate as possible in the changing publishing landscape.