Eclipse Theia 1.59 Release: News and Noteworthy

We are happy to announce the Eclipse Theia 1.59 release! The release contains in total 95 merged pull requests. In this article, we will highlight some selected improvements and provide an overview of the latest news around Theia.

For those new to Eclipse Theia, it is the next-generation platform for building IDEs and tools for the web or desktop, based on modern state-of-the-art web technologies. With Theia AI, part of the Theia platform, you can also build AI-powered tools and IDEs with ease. For more details about Eclipse Theia, please refer to this article and visit the Theia website.

Current Theia project stats, more on Open Hub.

Important note for Mac users: We got very recent reports that the current Theia IDE version (currently only built for X86) runs with poor performance on Arm architectures. We are working on providing a signed Arm native build as soon as possible to resolve this, check our download page for updates!!

The Theia project also releases a product, the Theia IDE. The Eclipse Theia IDE is a modern, AI-powered, and open IDE for cloud and desktop environments, aimed at end users. The Theia IDE is based on the Theia platform and also includes AI powered assistants. For more details, see the Theia IDE website.

If you are looking for a simple way to check out the new release, please download and install the Theia IDE, which is based on Theia 1.59.

Eclipse Theia 1.59: Selected features and improvements

In the following, we will highlight some selected improvements in the new release. As usual, we cannot mention all 95 improvements, however we will focus on the most notable changes as well as changes visible to end users. The corresponding pull requests are linked under the respective heading when applicable.

Theia AI: Chat Context Management

Theia AI and the AI-powered Theia IDE now support chat context management, allowing users to attach relevant context elements—such as files, symbols, or domain-specific components—directly to their AI chat requests. This feature improves response accuracy while reducing the need for complex, time-consuming context retrieval mechanisms. Users can specify context by dragging items from custom editors, selecting from guided suggestions, or receiving smart auto-completions as they type.

All existing agents in the AI-powered Theia IDE are integrated with the new context feature, see the following screenshot for an example how to use it with Theia Coder (more details in the following section and the Theia Coder documentation)

By integrating chat context variables, tool builders gain fine-grained control over how context is selected, displayed, and processed. Theia AI provides several mechanisms to support user-friendly context selection, including drag-and-drop support, quick pick dialogs, and auto-completion suggestions. Once attached, context elements are accessible through Theia AI’s request model, enabling agents to process them flexibly—whether by summarization, dynamic context management, or on-demand retrieval using dedicated tool functions. For more details on this feature refer to this article on

👉 How to enhance your tools with chat context in Theia AI.

Along with the new context feature, we have also consolidated the variables available in the chat. See our documentation for more details or use the auto completion feature in the chat (press “#”) to see a list of available variables.

AI-Powered Coding with Theia Coder

With Theia 1.58, we have introduced Theia Coder (preview), an AI-powered coding agent designed to assist developers with structured code modifications directly within the Theia IDE. Theia Coder can browse the workspace, retrieve relevant context, and propose code changes that users can review and apply seamlessly. With the current 1.59 release, we have significantly improved and refined Theia Coder based on the great community feedback!

We again encourage users to test it and provide feedback, this will make it even better!

To summarize the current state, we recommend reading this article:

👉 Introducing Theia Coder - the open AI coding agent with full control

For more details on how to use Theia Coder, including specifying context, reviewing changes, and optimizing AI-driven development, also refer to the Theia Coder documentation.

Theia Coder in action

The 1.59 release specifically contains the following improvements for Theia Coder:

• Context integration: Theia Coder integrates with the new Theia AI context feature described in the previous section. You can now very easily point Theia Coder to files and other artifacts of interest. (#14787 and others)
• Changeset Handling: We worked a lot on improving the handling of proposed changes. Users can now review and apply the changes suggested by Coder much easier and without any delay. (#14910, #14904 and others)
• Prompt improvements: Based on community feedback, we improved Coder’s prompt and functions to improve the performance, the workspace navigation, the context navigation and to fix several issues. Specifically, Coder can now replace only specific parts of a file instead of rewriting files, which boosts the speed of generating file change suggestions a lot. (#14887, #14934, #14870 and others)
• SCANOSS integration: Any changes that are generated by Coder can now be automatically scanned using the SCANOSS service. This feature aims to identify potential licensing issues that may arise when incorporating AI-generated code snippets into your projects. For more details, check the SCANOSS documentation. We will provide more details about this feature soon, follow us on LinkedIn to stay up-to-date.

Keep in mind that Theia Coder is built on Theia AI, a flexible framework for AI-powered tools and IDEs, allowing easy customization and extension.

👉 More Details: Introducing Theia Coder - the open AI coding agent with full control

Try it out today, provide feedback and contribute your ideas and refinements!

LLM compatibility

Theia 1.59 improves the general compatibility of Theia AI and the AI-powered Theia IDE with various large language models (LLMs) and hosting providers. We also updated the list of default LLMs in the Theia IDE. As you might know, you can connect Theia AI to any LLM using any provider, ensuring maximum flexibility in AI integration. This means Theia AI is not limited to a predefined set of models but allows tool builders and users of the Theia IDE to configure and switch between different LLMs dynamically. Examples of LLMs and providers supported out-of-the-box include Azure, DeepSeek, o3-mini, Sonnet 3-7 and GPT-4.5,  among others.

Please note that in 1.59, we refined the system message settings to improve compatibility, so this might require a settings change for people using self-hosted models. See the Readme for more information.

This enhancement ensures that both users and tool builders can integrate cloud-based, on-premise, and local AI models, avoiding vendor lock-in and enabling greater control over privacy and performance. For more details on why Theia AI supports any LLM, see:

👉 Why Theia supports any LLM!

MCP Improvements

The Model Context Protocol (MCP) in Theia AI and the AI-powered Theia IDE enables seamless integration of external tools and services, allowing AI agents to interact with various data sources, APIs, and workflows. With MCP, AI assistants can search the web, manage Git repositories, access databases, read and write files, communicate via Slack, and much more—all through a unified, extensible protocol.

The 1.59 release brings several improvements for Model Context Protocol (MCP) support in Theia AI and the AI-powered Theia IDE, including autostart for MCP servers (PR #14956) and better schema support for functions (PR #15012).

To explore the full potential of MCP in Theia AI, check out these in-depth articles:

👉 Let AI Commit (to) Your Work - With Theia AI, Git, and MCP: Discover how to create a custom Git Agent in Theia IDE that automates Git operations with simple natural-language prompts, making AI-assisted development more efficient (see also video below)

👉 Introducing Anthropics’s Model Context Protocol (MCP) for AI-Powered Tools in Theia AI and the Theia IDE: Learn how MCP enables seamless integration with external tools, bringing web search, GitHub access, database operations, and more to AI-powered development environments.

Agent “pinning” in the Chat View

The 1.59 release introduces an “agent pinning” feature to improve the user experience when working with chat agents. When a user mentions an agent in a prompt and no agent is currently pinned, the mentioned agent is automatically pinned. This removes the need to repeatedly reference the agent in subsequent prompts.

If a different agent is mentioned while another agent is already pinned, the pinned agent remains unchanged. The newly mentioned agent is used only for that specific prompt without affecting the pinned agent. Users can also manually unpin an agent through the chat interface if needed. Additionally, a new chat session can now be started directly with a pinned agent.

More Theia AI and IDE feature improvements

A big focus of the 1.59 release was improving Theia AI, the framework to build AI-powered tools and IDEs, as well as the AI-powered Theia IDE (built on Theia AI). Some bigger features were described in dedicated sections above, so let’s summarize some additional improvements

• AI-powered code completion: We iteratively improved the default prompt for the AI code completion and turned on automatic inline completion by default (you have to enable the general AI feature in the Theia IDE first). Please note that the default prompt works well with larger general purpose models, if you want to use a specialized model, you can adapt the prompt to your needs. See how Star Coder works in the Theia IDE as an example.
• Orchestrator improvements: If your tool consists of several agents, such as the AI-powered Theia IDE, the user can refer to agents using “@AgentName”. In case you do not do this in the Theia IDE, a default agent called “@Orchestrator” will investigate the user’s request and delegate to the most fitting agent automatically. In Theia 1.59, we have improved this process, so it is expected to work even more accurately in the new version.
• The AI Chat Window now opens to the right by default. You can of course decide to move it anywhere within Theia’s flexible workbench.
• “Plain prompt” for Universal Agent: As the Theia IDE now contains specialized agents for coding (“Theia Coder”), the purpose of the universal agent becomes to talk to the underlying LLMs as “plain” as possible. Therefore, we refactored its prompts:  The default prompt just includes the user context, the variant “universal-empty” provides an empty prompt to talk to the underlying LLM as from any other chat window without any context or additional information.
• Rename “Workspace” Agent to “Architect”: We renamed the existing workspace agent to Architect. In contrast to Coder, it cannot suggest direct code changes, but it can access the workspace. It is therefore a good choice to answer questions about a project and to plan changes, e.g. to be conducted with Coder later on.

Dev Container: Support for ContainerEnv

Dev containers in Theia allow software projects to define a Docker-based development environment, ensuring consistency and reliability across various setups. By using a devcontainer.json file, teams can provide a standardized, ready-to-use environment for all developers working on a project. This removes the complexity of local configuration and guarantees that every team member operates within the same setup.

With 1.59, the dev container support of Theia now allows setting environment variables that will be set once a dev container is launched. (see #14816 and #14821) (see the example configuration below setting two variables).

Streamline logging API

Theia 1.59 includes improvements to the logging API, making it easier to create named loggers dynamically. Previously, the binding logic for the @named decorator required additional effort to set up dedicated loggers. With this update, named loggers are generated on the fly, simplifying the process.  

Additionally, a new --log-file argument has been added to the CLI, allowing users to specify a file for log output directly. While similar functionality can be achieved through operating system features, this addition improves usability and discoverability.  

This release also fixes an issue where changes to a log configuration file were not being applied correctly. Users can now modify log levels in a configuration file, and Theia will update its logging behavior as expected.

As always, the 1.59 release contains much more than described in this article, e.g. the support for the VS Code extension API has been upgraded to support 1.97.1. All these features and improvements (in total 95) were the result of one month of intensive development. Eclipse Theia follows a monthly release schedule. We are looking forward to the next release due next month, stay tuned! To be notified about future releases, follow Theia on Twitter and subscribe to our mailing list.

If you are interested in building custom tools or IDEs based on Eclipse Theia, EclipseSource provides consulting and implementation services for Eclipse Theia, for AI-powered tools, as well as for web-based tools in general.

We also provide an Eclipse Theia online training that you can conduct anytime, anywhere. It provides you and your team with a jump start for the development of your own custom solutions based on Eclipse Theia extensions.

Furthermore, if you want to extend Theia with features such as the toolbar or the test framework, EclipseSource provides sponsored development for Theia, too. Finally, we provide consulting and support for hosting web-based tools in the cloud.

👉 Get in contact with us, to discuss your use case!