I’ve done a few ports like this with Claude Code (but not with a while loop) and it did work amazingly well. The original codebase had a good test suite, so I had it port the test suite first, and gave it some code style guidance up front. Then the agent did remarkably well at doing a straight port from one imperative language to another. Then there’s some purely human work to get it really done — 80-90% done sounds about right.

What was your method of invoking Claude, out of curiosity?