I have built a pretty full version of that idea in rust (codex tui2). There's a while tonne of downsides that make it basically impossible to really get to 100% good on this.

> Under the hood it's still a terminal app, but from the UI author's perspective you're not fighting terminfo, CSI sequences, or varying terminal support. You get proper cursor tracking, scroll regions, and editable text areas out of the box.

All that is not true. Take scrolling for example. Each terminal emulator implements this subtly differently (mouse/trackpad/speed etc.), scrolling will never feel native unless you push the control of it into the terminal emulator.

There's more than that, each and every point on this becomes something that you have a gap between native and the terminal emulator that you're building to run in the terminal.

See https://github.com/openai/codex/issues/8344 and https://github.com/openai/codex/pull/9640

Claude code and gemini have both had various versions of the same idea at times. I'm unsure where they ended up.