I cannot provide the requested healthcare news digest focused on AI agents or agentic AI because the search results provided do not contain substantive information about these topics. While the search results cover various healthcare developments from April 20-28, 2026—including Grand Challenges Grant Opportunities that mention general AI applications, Medicaid automation in prior authorization, and policy updates—none of these sources specifically address agentic AI or AI agents in healthcare settings. To create an accurate digest meeting your requirements, I would need search results that specifically cover AI agent implementations, agentic AI research, or autonomous AI systems being deployed in healthcare contexts during this period.