tl;dr: Anthropic launched Claude Fable 5, a "Mythos-class" frontier model claiming state-of-the-art performance in coding, vision, knowledge work, and long-horizon agentic tasks, priced at $10/$50 per million input/output tokens. The model ships with new classifiers that fall back to Opus 4.8 on cybersecurity, bio/chem, and distillation-related queries (triggering in under 5% of sessions), plus a mandatory 30-day data retention policy for safety monitoring. A less-restricted variant, Mythos 5, is available to vetted cyber defenders via Project Glasswing, with a biology trusted-access program coming soon.