Thats the problem. Some developers want to avoid learning another programming language and use one for everything (including their technologies.)
Using TS, React here doesn’t make sense for stability in the long term. As you can see, even when they replaced Ink and built their own, the problem still exists.
There are other alternatives that are better than whatever Anthropic did such as Bubbletea (Go) or Ratatui (Rust) which both are better suited for this.
Maybe they were thinking more about job security with TypeScript over technical correctness and a robust implementation architecture and this shows the lack of it.
I’m a fan of Bubbletea, but it is significantly less ergonomic than React. Although I’d argue that if that starts to matter significantly, your TUI is probably too cluttered anyway and you should pare it down.