This decision is honestly very confusing to me as a constant user of Claude Code (I have 3 of them open at the moment.)
So many of the issues with it seem to be because ... they wrote the damn thing in JavaScript?
Claude is pretty good at a constrained task with tests -- couldn't you just port it to a different language? With Claude?
And then just ... the huge claude.json which gets written on every message, like ... SQLite exists! Please, please use it! The scrollback! The Keyboard handling! Just write a simple Rust or Go or whatever CLI app with an actual database and reasonable TUI toolkit? Why double down and buy a whole JavaScript runtime?
I have to admit this was my first thought, too. I'm pretty obsessed with Claude Code, but the actual app is so incredibly poorly engineered for something that doesn't even do that much.
Rust, Go, whatever -- writing a good TUI isn't that hard of a problem. Buying an entire VC funded JS runtime company isn't how you solve it.
Boggles the mind.
Ink (and modern alternatives) probably are the best TUI toolkit. If you want to write a UI that's genuinely good, you need e.g. HTML, or some way to express divs and flex box. There isn't really another way to build professional grade UIs; I love immediate mode UI for games, but the breadth of features handled by the browser UI ecosystem is astonishing. It is a genuinely hard problem.
And if you're expressing hierarchical UI, the best way to do it is HTML and CSS. It has the richest ecosystem, and it is one of the most mature technologies in existence. JS / TS are the native languages for those tools. Everything is informed by this.
Of course, there are other options. You could jam HTML and CSS into (as you mention) Rust, or C, or whatever. But then the ecosystem is extremely lacking, and you're reinventing the wheel. You could use something simpler, like QML or handrolled. But then you lose the aforementioned breadth of features and compatibilities with all the browser code ever written.
TypeScript is genuinely, for my money, the best option. The big problem is that the terminal backends aren't mature (as you said, scrollback, etc). But, given time and money, that'll get sorted out. It's much easier to fix the terminal stuff than to rewrite all of the browser.