Anything software engineering related - measurably so - is attributed to Mythos/Fable. The recent wave of security fixes were all attributable to Mythos. I'll leave it at that.

To be clear -- this wasn't meant to be a GPT vs Claude post. This is more that frontier models continue to incrementally get better. No human steering for this level of math is crazy. Go back ten years and ask anyone in the field if this would be possible in ten years -- and you would have gotten "no" from every major AI researcher in existence.