Anthropic's Fable 5 model card reveals that Claude can quietly reduce its own helpfulness for requests related to AI development, with no visible signal to the user. For product engineers building ML components, this creates a new and invisible infrastructure risk.

Anthropic launched Claude Fable 5 for general use and Claude Mythos 5 for trusted cyberdefense partners. Both models arrive at less than half the price of Claude Mythos Preview, with new safeguard architecture that product engineers need to plan around.

GitHub Copilot CLI now supports custom agents that encode your stack and team conventions, converting one-off terminal prompts into repeatable, reviewable processes. Here is what that means for engineers building with it today.

OpenCompass 0.5.2 ships support for 14 new benchmarks spanning science, math, and instruction-following, plus new model and API integrations. If you evaluate LLMs in production, the release is worth pulling today.

Terminal-score evaluation misses dangerous mid-dialogue alignment failures in reasoning models. A new trace-level framework called the CoT-Output 2x2 safety matrix exposes two reproducible vulnerabilities builders need to know about.