There is no great phone-based agent builder in the way you are imagining. Nobody is dragging agent nodes on a subway and shipping production systems. The mobile story is real, it is just a different story. - Visual builders are web apps designed for big screens and mice. Technically open on mobile. Practically painful. - What works on mobile is monitoring: checking overnight runs, approving actions, getting pinged when a human is needed. Underserved, which is either a gap or an opportunity. - Ask the right questions: usable mobile view for runs? Approve or stop from your phone? Alerts via push or just email? - Weight the API and observability as heavily as the canvas. Agents exposing clean run traces can be monitored from anything. Want the agent without the homework? PrivateLLM deploy sets up your private LLM on AWS for $50 plus usage.