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Theia AI and Theia IDE support o3-mini and o1
February 3, 2025 | 4 min ReadExciting news for developers and tool builders: Theia AI and the AI-powered Theia IDE now support the new o3-mini and o1 models right out of the box. These models can be used seamlessly without any update—simply add them to the list of OpenAI models (as shown below), and you’re ready to go.
In case you don’t know Theia AI or the AI-powered Theia IDE, visit the Theia AI introduction and the AI Theia IDE overview, or download the AI-powered Theia IDE here.
Add o1 and o3-mini to Theia AI
Theia AI, a framework for building AI-powered tools and IDEs, is designed to be fully extensible. It supports arbitrary LLMs from various providers including OpenAI, Anthropic or HuggingFace (see for example how it supports StarCoder).
The AI-powered Theia IDE is built on Theia AI and gives even end users complete control over their AI interactions. Therefore, in the Theia IDE, end users can easily add new models to work with. So let’s add the new models o3-mini and o1 (see screenshot below)!

With this simple setting, o3-mini will already work fine. For o1, we need to disable streaming (streaming is the assumed default for OpenAI models). We can do this with the following settings entry to add o1 as a custom model.
"ai-features.openAiCustom.customOpenAiModels": [
{
"model": "o1",
"url": "https://api.openai.com/v1",
"id": "openai-o1",
"apiKey": true,
"enableStreaming": false
}
],
Use o1 and o3-mini in the Theia IDE
Now we are fully set and can use OpenAI’s latest frontier reasoning models, o1 and o3-mini, with all agents in the Theia IDE. Of course you can also use both models now in any custom tool or IDE built on Theia AI and Theia.
Let’s test o3-mini with the new Theia Coder agent in the Theia IDE to complete a simple coding task. For fun, we use o3-mini to add itself to the default list of available models in the Theia IDE code base, so that future releases will provide it as an option even without users adding it manually to the settings (see following video). As you can see, o3-mini navigates the workspace to find the correct place and then suggests a valid change to add the two new models to the default list.
Conclusion
Theia AI and the AI-powered Theia IDE continue to push the boundaries of flexibility and openness in AI-powered development environments. With seamless support for OpenAI’s latest models, o3-mini and o1, developers and tool builders can work with cutting-edge reasoning models without friction.
Thanks to Theia AI’s extensibility, integrating new models is as simple as updating the configuration—whether you’re using Theia IDE or building a custom AI-powered tool. This ensures that both tool providers and end users remain in full control of their AI workflows, adapting quickly to new advancements while maintaining transparency and flexibility.
Of course, adopting new models may require adjustments, such as tweaking prompts, refining workflows, or adapting response parsing to achieve optimal results. However, Theia AI is designed to give you the flexibility to experiment and fine-tune your setup, making it easy to evaluate and integrate new models with minimal effort.
If you want to explore the full potential of Theia AI or optimize your setup for specific LLMs, now is the perfect time to dive in. Whether you’re looking to enhance your own AI-powered tool, extend Theia IDE, or contribute to the open-source ecosystem, Theia AI provides everything you need to get started.
For more details, check out our blog post: Introducing AI Support in Theia IDE and Introducing Theia AI (the underlying framework for tool builders).
If you are interested in building custom AI-powered Tools, EclipseSource provides consulting and implementation services backed by our extensive experience with successful AI tool projects. We also specialize in web- and cloud-based tools and support for popular platforms like Eclipse Theia and VS Code.
Get in touch with us to learn more.