TL;DR: OpenAI released GPT-5.4 Thinking and GPT-5.4 Pro on March 5, 2026. GPT-5.4 Pro is likely the best model in the world for many catastrophic risk-relevant tasks, including biological research R&D, orchestrating cyberoffense operations, and computer use. GPT-5.4 Pro has no system card, only GPT-5.4 Thinking, and, to our best knowledge, Pro has been released without any safety evals. We argue this has occurred at least once before, with GPT-5.2 Pro, and provide recommendations for how a team could conduct fast, independent risk assessments of models post-deployment.
IMPORTANT EDIT: This problem, where Pro models don't have a safety card, has existed since at least o3-pro. Others have noticed this issue before (for o3 and GPT-5). Additionally,... (read 1227 more words →)
Anthropic summarizes their CoTs after Claude 4 models:
> With extended thinking enabled, the Messages API for Claude 4 models returns a summary of Claude's full thinking process. Summarized thinking provides the full intelligence benefits of extended thinking, while preventing misuse.
Source: https://platform.claude.com/docs/en/build-with-claude/extended-thinking
Although on the side note, it seems that frontier models suddenly solved the issue of alien languages in reasoning? In Apollo's paper, they mentioned that o3 often uses languages like "disclaim illusion watchers", but I haven't heard similar issues for their new models (or models of other labs). I'm very interested to know whether they just decided to train against the CoT to make it more legible, or is there some other method in creating legible CoT.
