GPT-6.2 Astra and Claude Mythos 5.5 Leaks: What We Know

Two of the biggest AI labs appear to have tipped their next models on the same weekend. On November 1, developers noticed a model called gpt-6.2-astra showing up inside OpenAI's Codex, and a "Claude Mythos 5.5" label appeared in the page source of Anthropic's Mythos page. Neither company has announced anything. Here is what is actually verified, what is rumour, and what it could mean for you.

• GPT-6.2 Astra: spotted in Codex usage data and API responses for some Pro users. Not announced.
• Claude Mythos 5.5: named in the HTML of Anthropic's Mythos page, then removed. Not announced.
• Fable 5.5: a second Anthropic name mentioned in secondary reports. Unverified.
• Pricing and release dates: none confirmed for any of them.

What was spotted in OpenAI's Codex?

On the evening of November 1, developer Salio reportedly noticed that while the Codex interface still said GPT-6 Astra, the API response identified the model as gpt-6.2-astra. Several Pro subscribers then posted usage-dashboard screenshots with the same label. Chinese outlets QbitAI and 36Kr report that roughly one in five Astra requests for some users, and in at least one case all of them, were routed to the new model, which points to a staged "gray" rollout rather than a one-account glitch. The roughly 20% share comes from user screenshots and has not been confirmed by OpenAI.

One caution: a screenshot circulating from Codex CLI showed an "unsupported model" error before a /review task still completed, so these images show some users have access but do not prove the model is ready. OpenAI's public model catalogue does not list GPT-6.2 Astra.

Why did OpenAI skip GPT-6.1 Astra?

Chinese-language reports claim a planned GPT-6.1 Astra was pulled after failing safety testing, and that OpenAI spent about a month reworking it before jumping to 6.2. That is rumour from secondary sources, not an OpenAI statement. What is public is that OpenAI shipped GPT-6.1 Terra on October 26 at $1 per million input tokens and $5 per million output tokens, covered in our GPT-6.1 Terra guide.

What is the Claude Mythos 5.5 sighting?

Late on November 1, X user kimmonismus posted that "Mythos 5.5" was in the HTML of Anthropic's Mythos page, crediting an anonymous tipster. TestingCatalog noted a hidden mention beside the line "Our most capable model class for cybersecurity and biology research." Artificial Watch read the page source directly at about 15:30 UTC and found the string "Claude Mythos 5.5" six times, all in the header and wordmark alt text, while the availability and pricing text still described Mythos 5.1. By 17:30 UTC the name had been removed and the header read Mythos 5.1 again. Anthropic has said nothing.

Some reports add that a Fable 5.5 model with a 1M-token context window exists alongside Mythos, and that a repository claiming to hold leaked Mythos weights appeared on Hugging Face. QbitAI itself calls the weights claim unlikely to be genuine, and we have not seen verification of the Fable details, so ignore both until Anthropic speaks.

How does this fit the current AI race?

Google's Gemini 4 Carbon reclaimed the top ranking only days ago, per our Gemini 4 Carbon explainer, and the new GDPx benchmark showed even the best model solving only a small share of hard real-world tasks. Frontier release cycles are now measured in weeks.

Can you use GPT-6.2 Astra or Mythos 5.5 in India?

Not officially. Mythos models have been aimed at vetted cybersecurity and research users, and the Astra reports mention only a small group of Pro-tier Codex users. Expect an announcement to spell out access, pricing and regions. Until then, existing models such as GPT-6 Astra, Claude Opus 5.5 and Gemini 4 Carbon remain the ones you can actually rely on.

What to watch for next

• An OpenAI post or model-catalogue entry for GPT-6.2 Astra, with API pricing.
• An Anthropic announcement that restores the Mythos 5.5 name to its page.
• Independent benchmark runs from Artificial Analysis or SemiAnalysis.

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