During December 2024, Isabella Cai enhanced API error signaling and response consistency in the allenjzhang/typespec-e2e-demo repository. She focused on refining how NoContent and NotFound scenarios are handled, using TypeScript and TypeSpec to mark NoContentResponse and NotFoundResponse as error types with the @error decorator. This approach standardized delete and createAttachment responses, ensuring they align with the intended NoContentResponse and correcting previous model definitions. By clarifying error semantics and improving API typing, Isabella reduced ambiguity for clients during resource retrieval and deletion, resulting in more reliable client interactions and a clearer contract for API consumers.