Quoting Romain Huet

Simon Willison's Blog / 4/25/2026

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Key Points

Romain Huet said that since GPT-5.4, OpenAI has unified Codex and the main model into a single system, removing the need for a separate coding line.
Huet claims GPT-5.5 further improves performance for agentic coding.
He also attributes GPT-5.5’s gains to better “computer use,” implying stronger capabilities for tasks performed on a computer.
Huet confirmed that OpenAI will not release a separate GPT-5.5-Codex model.
The post frames these updates as moving more coding and computer-execution functionality into one unified GPT system rather than specialized variants.

Simon Willison’s Weblog

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25th April 2026

Since GPT-5.4, we’ve unified Codex and the main model into a single system, so there’s no separate coding line anymore.

GPT-5.5 takes this further, with strong gains in agentic coding, computer use, and any task on a computer.

— Romain Huet, confirming OpenAI won't release a GPT-5.5-Codex model

Posted 25th April 2026 at 12:06 pm