Claude Fable 5.1 and Claude Mythos 5.1

**Anthropic** released **Claude Fable 5.1** and **Claude Mythos 5.1**, which share base weights but differ in safeguards and routing, showing improved coding performance and usability with a **75% cache-read price cut to $0.25/MTok**. Benchmarks highlight strong coding/science results, though Fable 5.1 costs about **20% more per task** than its predecessor. Adoption revealed aggressive safety triggers framed as **Enterprise Frontier Safeguards** for enterprise deployments. Meanwhile, **OpenAI** previewed **Astra**, its first model reaching the **Critical** cybersecurity preparedness level, demonstrating advanced cyber capabilities and employing a **recurrent depth/looped transformer architecture**, sparking debate on its impact on chain-of-thought reasoning and model transparency. **Sam Altman** noted safety work slowed Astra's deployment, indicating future models may prioritize safeguards over speed.