Tonight I switched Claude Code to Fable 5.1 and asked it, with no web search, whether it knew Tibo, the reset guy. It did. It named Thibault Sottiaux at OpenAI, explained the running joke about him resetting Codex usage limits, and admitted it couldn't say where it had learned any of this. According to a post doing the rounds on X, that answer means I'd been quietly handed Fable 5.5, because 5.1 supposedly wouldn't know. The first reply underneath says 5.1 knows him perfectly well.

I'm siding with the reply. Anthropic lists the same June 2026 cutoff for all its current 5.x models, and BitsMinds couldn't establish when the nickname caught on, so a right answer can't tell the two models apart.

My hunch is that something is being tested anyway, mostly because the last release went this way. On 18 August an account called leo reported a Fable 5 successor running on some Claude accounts, and Fable 5.1 shipped fourteen days later. The date going round now is tomorrow, Tuesday 6 October, from a single post by an account with no earlier hits anyone could find. Tuesday is the safe guess regardless: Fable 5 and Fable 5.1 both shipped on one. An older thread put Haiku 5.5 first with Fable a week behind, and Haiku, promised since Opus 5.5 launched, still hasn't appeared. My guess is that tomorrow's Tuesday belongs to Haiku, which puts my money on Tuesday 13 October for Fable.

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