The rule. Use AI where the user cannot specify the action precisely; where they can (undo, sort, pay, toggle), give them a control that does the same thing every time.
Why. Google's People + AI Guidebook is blunt about it: "Often a rule or heuristic-based solution will work just as well, if not better, than an AI version," and "Sometimes the most valuable part of the core experience is its predictability, regardless of context or additional user input" (Google People + AI Research, n.d.). Nielsen, who called intent-based outcome specification the first new UI paradigm in 60 years, kept a seat for the old one in the same article: "Clicking or tapping things on a screen is an intuitive and essential aspect of user interaction that should not be overlooked," and the likely future is "a hybrid user interface that combines elements of both intent-based and command-based interfaces" (Nielsen, 2023). The Guidebook's test for the feature review is not whether AI can be added, but whether it solves the problem in a way nothing simpler can.
Seen in the wild. NN/g's most exciting generative UI development of 2026 is, by its own account, buttons and checkboxes inside AI chat, because they "allow the user to directly select specific options, rather than typing them out" (Moran, 2026).