Simon Willison quoted a tweet by Romain Huet, an OpenAI executive, in which Huet said OpenAI merged its Codex coding model line into its main model at GPT-5.4 and confirmed there will be no separate GPT-5.5-Codex release.
This article is based on a single source: Willison’s blog post, which reproduces the tweet in a blockquote. The underlying tweet (twitter.com/romainhuet/status/2047955381578838357) is the original primary source but is not archived; the verbatim text below comes from Willison’s blockquote.
In Willison’s blockquote of the tweet, Huet is quoted as writing: “Since GPT-5.4, we’ve unified Codex and the main model into a single system, so there’s no separate coding line anymore.”
The same blockquote continues: “GPT-5.5 takes this further, with strong gains in agentic coding, computer use, and any task on a computer.”
Willison’s post notes that the tweet confirms OpenAI will not release a GPT-5.5-Codex model.