[teravor]

when doing rewrites like these, why isn't the first step to instrument the original code so that you would get very good automated test suites to point the LLM toward?

use both synthetic and real data to sample the internals of the original software to duplicate.

locate all the data transformation junctures, sample and then replicate the tranforms 1:1 in the rewrite.

[bluGill]

That forces you not only in not the intentional good decisions of the past but also copies too many bad ones.