ChatGPT 5.1 Codex Max - by Zvi Mowshowitz

It scores 77.9% on SWE-bench-verified, 79.9% on SWE-Lancer-IC SWE and 58.1% on Terminal-Bench 2.0, all substantial gains over GPT-5.1-Codex. It’s triggering OpenAI to prepare for being high level in cybersecurity threats. There’s a 27 page system card. One could call this the secret ‘real’ GPT-5.1 that matters. They even finally trained it to use Windows, somehow this is a new idea. My goal is for my review of Opus 4.5 to start on Friday, as it takes a few days to sort through new releases. This post was written before Anthropic revealed Opus 4.5, and we don’t yet know how big an upgrade Opus 4.5 will prove to be. As always, try all your various options and choose what is best for you. GPT-5.1-Codex-Max is a new high on the METR graph. METR’s thread is here. Prinz: METR (50% accuracy): GPT-5.1-Codex-Max = 2 hours, 42 minutes This is 25 minutes longer than GPT-5. Samuel Albanie: a data point for that ai 2027 graph That’s in between the two lines, looking closer to linear progress. Fin

It scores 77.9% on SWE-bench-verified, 79.9% on SWE-Lancer-IC SWE and 58.1% on Terminal-Bench 2.0, all substantial gains over GPT-5.1-Codex. It’s triggering OpenAI to prepare for being high level in cybersecurity threats. There’s a 27 page system card. One could call this the secret ‘real’ GPT-5.1 that matters. They even finally trained it to use Windows, somehow this is a new idea. My goal is for my review of Opus 4.5 to start on Friday, as it takes a few days to sort through new releases. This post was written before Anthropic revealed Opus 4.5, and we don’t yet know how big an upgrade Opus