How to use GPT-5.6

Hey folks,

OpenAI finally released the GPT-5.6 models to everyone, with many product changes. ChatGPT’s macOS app and the Codex app are now merged, with a new mode called . You can update your Codex app and get the new combined app. Codex and Work look similar, with the details fine-tuned for coding-related vs non-coding-related work. There’s a new plugin called “ChatGPT Sites” that lets you build hosted websites with an optional “Login with ChatGPT” feature. It’s nice for sharing but kept annoying me by making everything that I ask on ChatGPT Sites, so I turned it off.

GPT-5.6 series has three models: Luna, Terra and Sol. Each of them comes with 5 thinking levels - light, medium, high, xhigh, max, and a new mode: Ultra mode. Ultra mode basically allows these models to go haywire with subagents.

Now… these models eat up your usage limits much faster when used at higher thinking levels. So don’t rip ultra; first time I’ve ever been nearly out of usage in Codex. I’m defaulting to sol medium for most building/creativity, background agents for harder tasks and day-to-day productivity using luna xhigh.

Some general patterns I’ve noticed:

• Sol is pretty good at UI, but it’s even better once you give it some references. Sol at Max thinking has really good writing, and it’s fun to chat with.

• Terra feels like a replacement for 5.5 with minor improvements in UI and writing skills. It also feels more steerable, so skills would be useful with it.

• Luna has a bit of a mini model smell, like sometimes it doesn’t “get” what you meant in ambiguous prompts. But it doesn’t fail at tasks you clearly defin

Over the weekend, OpenAI reset usage 4-5 times while they were fixing bugs introduced during the app merge, and they have temporarily removed the 5h limit on your usage. Take note of that because you might end up using up your weekly limits in one go.

These models in the Codex app are really good at Computer Use, i.e., self-driving your cursor so it can open apps, click buttons, and use them by looking at the screen. You should definitely try this with Sol medium/high for some small task to see it in action.

Further reading:

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