Interesting... I asked o3 for help writing a flake so I could install the latest Webstorm on NixOS (since the one in the package repo is several months old), and it looks like it actually spun up a NixOS VM, downloaded the Webstorm package, wrote the Flake, calculated the SHA hash that NixOS needs, and wrote a test suite. The test suite indicates that it even did GUI testing- not sure whether that is a hallucination…
https://xcancel.com/TransluceAI/status/1912552046269771985 / https://news.ycombinator.com/item?id=43713502 is a discussion of these hallucinations.
As for the hash, could it have simply found a listing for the package with hashes provided and used that hash?