OpenAI’s new GPT-5.4 model is a big step toward autonomous agents | The Verge

I've been using Codex with GPT 5.4 a lot while building Elixir. I have been impressed. Since GPT 5.4 is a unified model, not a specific coding model, it seems to do a better job reasoning across the "product domain" with reasoning about what should something do, and the "coding domain" about how that could be created. It simultaneously has expertise in understanding the code and the solution. The result is better designs and debugging capabilities that extend to the logic of what it is doing and why that might matter.