Series position: The fourth article in the ReAct agent quadrant series. The quadrant names align with the previous articles and with the AAP repository . Premise — The Four Quadrants Again Recapping the four quadrants set up in the first article : (1) Script Quadrant — deterministic × definable. Handled by scripts and pipelines. (2) Algorithmic Search Quadrant — deterministic × exploratory. Classical AI / OR territory. (3) LLM Workflow Quadrant — semantic judgment × definable. Calls an LLM inside a predefined workflow. (4) Autonomous Agentic Loop Quadrant — semantic judgment × exploratory. An autonomous loop where the LLM itself decides the next action (= ReAct agent). Up to the previous article, I treated (3) and (4) as a dichotomy — "pick one based on the nature of the work." The second article pointed out that the industry has no settled vocabulary for (3); the third article framed the dichotomy along the business-system axis and introduced the Phase Separation between design phase and operation phase.…