You’d probably have to say “port exactly as is without changing any assets and keeping the original structure of the code” or “port with using the exact same assets but write as if native JS but use good code structure principles for organizing”.

You have to be a lot more explicit but it’s hard to know a priori what decisions it’ll make. A good idea is to run it in plan mode so you can read those decisions before it sets out on a path and have an opportunity to make corrections.

What you've described is Claude's "secret sauce" and the reason some people love it and some people hate it. It's not really possible to turn off, you can try to prompt against it but it's not reliable, the solution is to use Claude when you want that behavior and other models when you don't.