A generative AI agent is tasked with planning a complex event. It first gathers initial requirements, then formulates a preliminary plan, then seeks feedback or additional information (perhaps using a tool), refines the plan based on this new input, and continues this cycle until a satisfactory plan is achieved or a constraint is met. This cyclical process of information gathering, internal processing, decision-making, and action, which repeats until a goal is met, is a key characteristic of what component in a generative AI agent?