Comment by 9dev

Even Claude Code can whip up interactive, tabbed, multiple choice questions for example. If you use the superpowers plugin, it'll sometimes spawn a small web server demoing UI concepts or previewing more complex choices using LLM-generated HTML. Claude Code on the web will do even more involved React apps on the fly next to the chat. There's no technical reasons this couldn't get more complex, or vertically integrated with code editors.

I'd definitely call that on-demand, purpose-generated ephemeral UI.