More New AI Models! OpenAI Drops 5.1 Pro and Codex Pro

Quick Overview

OpenAI announced GPT-5.1-Codex-Max, a new frontier agentic coding model available in Codex, which is built upon GPT-5.1 and surpasses previous models like GPT-5.1-Codex, showing significant improvements in token efficiency and reasoning capabilities, particularly for long-running tasks via a new native compaction mechanism.

Key Points: OpenAI introduced GPT-5.1-Codex-Max, a new agentic coding model available in Codex, built on an update to the foundational GPT-5.1 reasoning model. GPT-5.1-Codex-Max is faster, more intelligent, and more token-efficient than GPT-5.1-Codex, achieving better performance using 30% fewer thinking tokens on SWE-Bench Verified tasks with 'medium' reasoning effort. The model introduces native 'compaction,' a mechanism that prunes and compresses the working session's history to preserve context over long horizons, enabling it to work on tasks for over 24 hours. Benchmark results on SWE-Lancer IC SWE showed GPT-5.1-Codex-Max achieving 79.9% accuracy compared to GPT-5.1-Codex's 68.3%, and on Terminal-Bench 2.0, it reached 68.7% accuracy compared to 62.8%. The release coincided with the announcement of GPT-5.1 Pro for all Pro users, described as a slow, heavy-weight reasoning model, which is still better than Gemini 3 on some complex tasks but suffers from interface limitations. The announcement was preceded by community discussion, including a tweet from Noam Brown noting the ability to work autonomously for more than a day, and a review from Matt Shumer calling 5.1 Pro an 'absolute monster' but noting interface friction. The improvements in long-horizon capabilities suggest OpenAI is pushing the frontier toward more general, reliable AI systems, as demonstrated by the METR chart showing tripled long-time horizon capability since early 2023.

Context: The video summarizes recent announcements and community reactions concerning OpenAI's new models, specifically GPT-5.1-Codex-Max and GPT-5.1 Pro, released around November 19, 2025. GPT-5.1-Codex-Max is positioned as a significant upgrade to the Codex ecosystem, focusing on enhanced coding capabilities, especially for long-running, complex tasks, achieved through a novel 'compaction' technique to manage context windows effectively. The context is set against the backdrop of perceived competition, particularly with Google's Gemini 3.