Persistent goals, not one-shot prompts
An agent holds a stateful objective — "answer this complaint," "prepare for the deposition on the 18th," "close out the M&A due-diligence checklist" — and returns to it across days and turns. That is the single feature that separates an agent from a chat box: the work does not restart every time the tab closes. For a solo running twenty active matters, this is the difference between a tool that saves five minutes per prompt and a tool that saves five hours per matter.