I cannot generate the requested digest about AI agents or agentic AI in healthcare based on the provided search results. The search results contain healthcare news from April 13-21, 2026, covering topics such as joint replacement payment models, vaccine policy changes in Maine, bilateral health agreements, and Medicare updates. However, none of these results contain information about AI agents or agentic AI, which is the specific focus you requested. The search results discuss traditional healthcare policy, hospital payment systems, and clinical services, but do not address artificial intelligence, AI agents, or autonomous AI systems in healthcare contexts. To provide an accurate digest on AI agents or agentic AI in healthcare, I would need search results that specifically cover topics such as AI-powered diagnostic tools, autonomous clinical decision systems, machine learning applications in healthcare delivery, or AI agent implementations in medical settings.