ChatGPT hit 900 million weekly active users in February 2026. It does not have Cmd+Z.
Undo is not a feature. It is 50 years of accumulated design consensus. Larry Tesler built the foundation at Xerox PARC in the mid-1970s with the Gypsy editor, the first modeless text editor. Modeless editing made a coherent action history possible. Apple codified Edit > Undo as a system primitive in its 1987 Human Interface Guidelines. Don Norman named the underlying principle in The Design of Everyday Things in 1988: action should not equal commitment. Jakob Nielsen made it Heuristic 3 in 1994 and has reaffirmed it every decade since. AI products, the most heavily funded software category since mobile, inherited none of this. Press Cmd+Z in ChatGPT, Claude, or Gemini and nothing happens. Regenerate is a forward operation. Branching history is a filing system. Neither is undo.
The author runs browser extensions that wrap major AI chat products, a commercial conflict he discloses plainly, and that vantage point produced something worth reading: real user behavior data showing how people cope without undo. Power users copy all output to clipboard before every next action. Less technical users take screenshots of responses because they do not trust the interface to preserve their work. One-star reviews quote users comparing these products unfavorably to Notepad from 1995. The full article traces the complete lineage from Tesler to Norman to Nielsen to Bret Victor, then turns that history into a precise, four-property definition of undo that current AI products fail entirely. Read it for the argument, not just the conclusion.
[READ ORIGINAL →]