What are the three GPT-5.6 models, and how do they differ?

The three models are Luna, Terra, and Sol. Sol is strong at UI design and writing (especially at Max thinking); Terra functions as a minor improvement over GPT-5.5 with better steerability; Luna works well for clearly-defined tasks but can struggle with ambiguous prompts.

How do the new thinking levels affect usage?

Each of the three models comes with five thinking levels (light, medium, high, xhigh, max) plus Ultra mode. Higher thinking levels consume usage limits much faster. OpenAI temporarily removed the 5-hour usage limit during weekend bug fixes, so users can deplete weekly allowances in a single go.

What new features are included in ChatGPT Work?

ChatGPT Work is the merged app combining the macOS ChatGPT app and Codex. It includes a new ChatGPT Sites plugin that lets users build hosted websites with an optional 'Login with ChatGPT' feature, and Computer Use capability that can self-drive the cursor to open apps, click buttons, and interact with screens.

Large Language ModelsBen's BitesJul 14, 2026Jul 15, 2026, 01:00 JST

OpenAI releases GPT-5.6 with three models, merges Codex into ChatGPT Work

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3 Key Points

What happened
OpenAI released GPT-5.6 models to all users, featuring three variants (Luna, Terra, Sol) each with five thinking levels (light, medium, high, xhigh, max) plus a new Ultra mode. The macOS ChatGPT app and Codex app have merged into a single unified application called ChatGPT Work, and a new ChatGPT Sites plugin enables building hosted websites with optional login integration.
Why it matters
The merge simplifies the user experience by combining coding and general-purpose tools into one app, while the expanded thinking-level options let users trade off speed and accuracy per task. However, higher thinking levels consume usage limits significantly faster—OpenAI even temporarily removed the 5-hour usage limit during weekend bug fixes, meaning users can deplete weekly allowances in a single session.
What to watch
Sol excels at UI design and writing at Max thinking; Terra offers minor improvements over GPT-5.5 with better steerability; Luna works best for clearly-defined tasks but struggles with ambiguous prompts. The models' Computer Use feature (self-driving cursor control) is available now, particularly effective at Sol medium/high thinking levels.

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Context & Analysis

OpenAI's GPT-5.6 release marks a significant consolidation of its product surface. By merging Codex and ChatGPT into a single ChatGPT Work application, the company is streamlining the user experience—though this integration required multiple usage resets during the weekend to fix bugs introduced by the app merge, and the temporary removal of usage limits suggests the transition was operationally complex. The introduction of three distinct models (Luna, Terra, Sol) with granular thinking-level control reflects a design philosophy that lets users optimize for their specific task and budget constraints rather than forcing all workloads through a single model. However, the body notes that higher thinking levels consume limits much faster, creating a practical tension: users who rely on Max or Ultra thinking may exhaust their allocations quickly, particularly if they default to expensive reasoning chains for routine tasks.

FAQ

What are the three GPT-5.6 models, and how do they differ?: The three models are Luna, Terra, and Sol. Sol is strong at UI design and writing (especially at Max thinking); Terra functions as a minor improvement over GPT-5.5 with better steerability; Luna works well for clearly-defined tasks but can struggle with ambiguous prompts.
How do the new thinking levels affect usage?: Each of the three models comes with five thinking levels (light, medium, high, xhigh, max) plus Ultra mode. Higher thinking levels consume usage limits much faster. OpenAI temporarily removed the 5-hour usage limit during weekend bug fixes, so users can deplete weekly allowances in a single go.
What new features are included in ChatGPT Work?: ChatGPT Work is the merged app combining the macOS ChatGPT app and Codex. It includes a new ChatGPT Sites plugin that lets users build hosted websites with an optional 'Login with ChatGPT' feature, and Computer Use capability that can self-drive the cursor to open apps, click buttons, and interact with screens.

Ben's BitesRead Original Article

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