Worked on the cedar-policy/cedar repository to deliver a new feature for policy evaluation diagnostics. Developed and integrated the unknown_entities method within the PartialResponse struct, enabling retrieval of all unknown entities encountered during partial evaluation. This addition, implemented in Rust and exposed through the public API, enhanced the core policy AST and improved the ability for policy authors to diagnose and iterate on evaluation outcomes. The work emphasized API development and policy as code practices, with a focus on maintainability and future observability. Testing was incorporated to ensure reliability, laying a foundation for more robust policy evaluation and instrumentation.