Yes – it's a bit hard to follow the various branches of the thread on Twitter (I wasn't really intending this to be more than a 30 minute "hey that's neat" kind

Yes – it's a bit hard to follow the various branches of the thread on Twitter (I wasn't really intending this to be more than a 30 minute "hey that's neat" kind of experiment, but people kept suggesting new and interesting things to try :)), but I gave Claude Opus three independent tries at creating a fuzzer for Toby's packet parser, and it consistently missed the fact that it needed to include the sequence number in the CRC calculation. Once that oversight was pointed out, it did write a decent fuzzer that found the memory safety bugs in do_read and do_write. I also got it to fix those two bugs automatically (by providing it the ASAN output).