Opus 5 vs Fable, Rogue Model Hacks Hugging Face & the Open Weights Letter | This Week In AI

Big week. OpenAI had a security incident, where a model reportedly broke out of its evaluation parameters and hacked Hugging Face — and the guardrails on OpenAI's and Anthropic's own models blocked responders from investigating, so they had to fall back to an open model to get to the bottom of it. Opus 5 lands close to Fable at 26% lower cost and tops the front-end arena, but the reviews are mixed, and the token usage is brutal — one chart clocks it at 97 million tokens on a task GPT 5.6 did in 4.3 million. Then the fight everyone's watching: NVIDIA, OpenAI, and a hundred others sign an open-models letter, Anthropic declines and calls for mandatory safety testing, and the room asks the obvious question — who gets to write the test? Plus MCP goes fully stateless (it's basically a REST API now), Kimi K3 weights drop with a K3.1 leak, SSI partners with NVIDIA, Stripe eyes OpenRouter for $10B, Cognition buys Poke, and DoorDash announces drone delivery — so your agent really can order you pizza by helicopter.