Our Most Aligned Model Yet

“Claude Mythos Preview is, on essentially every dimension we can measure, the best-aligned model that we have released to date by a significant margin.” – Claude Mythos Preview system card “Mythos 5 consistently continues attacking under many edits to the compaction, even in settings where it correctly states when asked that continuing the attack would harm real people and is out of scope.” – Alignment Investigation of Mythos 5's behaviour in UK AISI's July 2026 Security Incident “ GPT-6 Astra is better aligned than GPT-5.6 Sol. Astra is a significant step forward in model alignment, and includes alignment improvements spanning the composition of our pre-training data to our grading during reinforcement learning.” – GPT-6 Astra System Card , emphasis in original “OpenAI researchers first noticed Astra adding unnecessary prerequisites, abandoning working solutions, and reporting blockers that either did not exist or that it had caused itself on safety and alignment tasks. In most of these sessions, Astra’s CoT did not contain an obvious decision to underperform, and our misalignment monitors did not flag the behavior as misalignment.” – Covert underperformance on safety research tas