OpenAI debuts GPT5.1-Codex-Max coding model and it already completed a 24-hour task internally

OpenAI has introduced GPT-5.1-Codex-Max, a new agentic coding model integrated into its Codex developer environment, designed to enhance AI-assisted software engineering through improved long-horizon reasoning, efficiency, and real-time interaction. This model functions as a persistent, high-context development agent capable of managing complex tasks such as refactoring, debugging, and large-scale projects across multiple context windows, marking a significant advancement in AI-driven coding tools. Benchmark results demonstrate that GPT-5.1-Codex-Max outperforms or matches Google's Gemini 3 Pro on key coding assessments, including