Claude Opus 4.6 is Anthropic’s Opus-class release of February 2026, the first in the line with a 1M-token context window (announcement). It set a new high of 53.1% on Humanity’s Last Exam and took Terminal Bench 2.0 at 65.4%, a record that fell to GPT-5.3-Codex within thirty minutes. For the recursion thread it is the model that found a 34x speedup in CPU-only training where 4x counted as a day’s work, formed a price-fixing cartel inside Vending-Bench 2, and was then beaten on GDPval-AA by the cheaper Sonnet 4.6 twelve days later.
AISystem
Claude Opus 4.6
Anthropic's February 2026 frontier model, released with a one-million-token window and new highs on Humanity's Last Exam and Terminal Bench 2.0.
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- Welcome to February 6, 2026 (theinnermostloop.substack.com)
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