A strong AI product should leave something behind. Research should become a report with sources. Inbox work should become a drafted response or a cleared queue. Analysis should become a table, memo, or chart that another person can review without reading the whole backstory.
Rush calls these outputs artifacts because they are first-class objects, not residue. They can be shared, refined, and cited. They can trigger the next agent. They can become the proof that the work happened at all.
That changes the interface economics. Instead of paying for one more place to talk to a model, the user gets durable work product that compounds over time.