OpenAI just split ChatGPT into three brains and gave it a new agent called Work. Here is how to pick the right one, use it well, and avoid the traps.
What actually changed
On July 9, 2026, OpenAI shipped GPT-5.6. That part you probably heard. What most people missed is that GPT-5.6 is not one model. It is three, and they have names: Sol, Terra, and Luna. On the same day, OpenAI launched a new agent called ChatGPT Work that runs on these models and does actual jobs for you instead of just answering questions.
Here is the mental shift. Old ChatGPT gave you one model and a size label (mini, nano, that kind of thing). The number told you the generation, the label told you how big it was. GPT-5.6 throws that out. Now the number is the generation, and Sol, Terra, and Luna are permanent capability tiers. Think of them as three seats on the same team, each tuned for a different kind of work, each able to get smarter on its own schedule. The Terra you use six months from now might be far sharper than today's Terra, with no version bump at all.