Anthropic put GPU kernel optimization in the same Safeguards section as hacking and biology. WTF? It is in their launch post. During training they limited the skills that "could most directly accelerate AI development". "Accelerator kernel optimization." "Improving large language model architectures." There Fable 5.2 stays "at about the level of Opus 5.5". So making a model run faster on a cheap GPU is now a risk to be managed. You cannot see this one. There is no refusal and no warning. It was limited during training, before any user typed a word. Kernel work is how a used 3090 still runs new models. It is how open weights get to people who cannot pay $40 per 1M output tokens. What the hell? I genuinely wanted to say something nice, but now I can't. This completely broke me, I'm disappointed.
Claude Fable 5.2 and Claude Mythos 5.2 are available now: