AI agents are evolving to require more than just models and prompts, but a runtime with a dynamic lifecycle to operate effectively. This evolution is driven by the need for flexibility, scalability, security, and state management in AI applications. The new definition of an AI agent breaks it down into four core components: model, instructions, tools, and runtime, which must work together seamlessly. A dynamic runtime supports the operational environment for complex systems like AI agents, enabling them to adapt to varying conditions, requirements, and feedback. This requires intelligent resource management, adaptive lifecycle management, and a comprehensive integration framework. As AI agents grow more sophisticated, their infrastructure needs will continue to evolve, with trends such as composable environments, cross-agent communication, and ethical guardrails emerging in the future.