Anthropic stealth-tests mysterious 'Fable 5.1' checkpoint across Chat, Cowork and Claude Code
JasonBotterill · x · 2026-09-19
Users report Anthropic is stealth-testing a new checkpoint: Opus-Next is back for most (possibly all) paid accounts, now appearing across Chat, Cowork and Claude Code after being limited to Claude Code — a sign of an imminent launch or new variant. JasonBotterill quips the checkpoint self-identifies as "Fable 5.1," mocking the irony that after a week of Dario talking up transparency, the stealth test will lie to your face about its identity.
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