Anthropic opens Mythos-class AI with guardrails

Anthropic launched Claude Fable 5 publicly and Claude Mythos 5 for vetted cybersecurity partners on June 9, 2026. Both models share identical weights and pricing but carry a mandatory 30-day data-retention requirement, overriding prior zero-retention agreements. The company reported over 1,000 hours of external testing found no universal jailbreak.