GPT-5.1-Codex-Max, our most advanced agentic coding model to date, is now available in Codex. API availability is coming soon. It’s faster, more capable, and more token-efficient, with native long-running task support via a new built-in capability called compaction and a new extra-high reasoning effort option. The first Codex model trained in Windows environments, it now replaces GPT-5.1-Codex as the default model in Codex surfaces. Major speed + token efficiency gains: ⚡️️Matches GPT-5.1-Codex performance on SWE-Bench Verified with ~30% fewer thinking tokens ️⚡️️Real-world coding tasks show faster execution, fewer tool calls, and lower costs Long-running autonomy: ⏱️Compaction enables multi-hour reasoning without hitting context limits ⏱️Codex automatically manages context windows to sustain progress More details at link in comments.
More here: https://openai.com/index/gpt-5-1-codex-max/