The Eclipse Theia Community Release 2025-11

We are happy to announce the twelfth Eclipse Theia community release, “2025-11,” incorporating the latest advances from Theia releases 1.65 and 1.66.

New to Eclipse Theia? It is the next-generation platform for building IDEs and tools for the web or desktop, based on modern web technologies. With Theia AI, you can build AI-powered tools and IDEs with ease. Visit the Theia website for more info.

The Theia project also delivers a product: the Theia IDE, a modern, AI-powered, and open IDE for cloud and desktop environments. The Theia IDE is based on Theia and includes advanced AI-powered features. See the Theia IDE website or download the latest release for a hands-on experience!

Community releases are provided quarterly and serve as stable anchors for downstream adopters. Each combines features, fixes, and hardening from monthly releases. Learn more about the advantages of the community release, or visit Theia’s releases page.

Before diving into the release highlights, we’re excited to share that TheiaCon 2025 took place in October and was a fantastic success! The conference brought together the Theia community to share insights, showcase innovations, and discuss the future of cloud and desktop IDE development. If you missed it, all session recordings are available on our YouTube playlist. Check out the project update keynote for a comprehensive overview of Theia’s remarkable progress over the past year—including over 1,167 merged pull requests!

Now let’s explore the key highlights from this twelfth Theia community release!

Highlights of the Theia 2025-11 Community Release

This community release ships cumulative improvements from releases 1.65 and 1.66, in total 156 improvements. For a comprehensive list of changes, please see the individual announcements. Here are some top highlights:

Native Claude Code IDE Integration

The headline feature of this release is the first open-source, native Claude Code IDE integration. This delivers a truly integrated AI-in-the-IDE experience that goes far beyond terminal wrappers and basic extensions. Claude Code now has deep awareness of your IDE’s current context, open files, and editor selections—creating a seamless experience where powerful AI assistance meets rich IDE functionality.

Key capabilities include native chat sessions without webview limitations, integrated code editing with all changes tracked in Theia’s diff editor, full slash command support, and inline AI assistance directly from editors and terminal with Ctrl+I. Perhaps most importantly, Claude Code becomes part of Theia’s extensible multi-agent ecosystem—combine it with other AI agents to create sophisticated, domain-specific workflows. Read more in our detailed blog post.

Chat Session Persistence & Enhanced Chat Experience

One of the most requested features for Theia AI has arrived: chat session persistence. Chat sessions are now automatically stored to disk, allowing you to seamlessly continue AI conversations even after restarting the IDE. The system maintains up to 25 sessions, stores the full chat tree including message alternatives and branches, and even preserves changesets with fully functional apply, revert, and open operations.

The chat experience is further enhanced with slash commands—a more intuitive way to invoke pre-defined prompt templates. Simply type /commandname arguments instead of the more technical syntax. Commands support argument substitution, autocomplete in the chat input, and can be scoped to specific agents. In the Theia IDE, users can create their own custom commands for repetitive workflows.

New AI Agents: GitHub & Project Info

This release introduces two powerful new agents. The GitHub Agent enables natural language interaction with GitHub repositories—query repository information, create issues, manage pull requests, or review code simply by chatting. The agent leverages MCP to communicate with GitHub’s API and includes built-in setup support.

The Project Info Agent helps developers create and maintain project context artifacts. It auto-discovers relevant project artifacts and consolidates existing documentation from sources like .copilot-instructions.md or Claude.md files into a unified format. This centralized documentation helps other AI agents like Theia Coder provide more accurate, contextually relevant assistance.

Agent Mode Support

Theia AI 1.66 adds optional mode support for chat agents, allowing them to define different operational modes that users can select. This enables agents to adjust their behavior based on user preferences—for example, switching between “edit” and “agent” modes for coding, or “plan” versus “act” approaches. A mode selector appears in the chat UI when supported, and users can cycle through modes using Shift+Tab.

MCP Server Support: Theia as Both Client and Server

While Theia AI has supported connecting to MCP (Model Context Protocol) servers since MCP’s inception, this release expands that support by enabling Theia-based applications to also act as MCP servers. External AI agents and tools can now connect to Theia applications and access their exposed functions via MCP. This bidirectional support creates a powerful ecosystem where Theia can both consume and provide AI-powered services through the standard MCP protocol, opening new possibilities for tool interoperability and AI-assisted workflows.

Platform Improvements & Browser-Only Enhancements

Backend Preferences Support enables server-side components to access configuration values directly—particularly valuable for tools that need to work both with and without a frontend interface, such as CLI tools or headless services sharing the same codebase as their GUI counterparts.

The browser-only version of Theia received substantial improvements, making it more robust for real development work without backend infrastructure. Safari compatibility issues have been fixed, file system watching is now implemented (detecting changes from other browser tabs), and full upload/download support has been added with memory-efficient streaming. The “Search in Workspace” functionality is now available in browser-only mode, respecting .gitignore patterns for consistency with the desktop version.

Debugging & UI Improvements

Debugging capabilities have been enhanced with “Run to Cursor” and “Run to Line” commands, accessible through the command palette, editor context menu, and line number context menu. These features use temporary breakpoints that are automatically cleaned up and intelligently adjust target positions when exact locations aren’t valid.

Secondary window management has improved: widgets now automatically restore to their original location in the main window when a secondary window is closed. Context menu performance has been optimized, and the debugging reveal position behavior is now smoother, preventing unnecessary document jumping during debug steps.

Additional Highlights

This release includes many more improvements: VS Code Extension API compatibility upgraded to version 1.105.0, Electron updated to 38.4.0, proxy configuration support for LLMs behind corporate firewalls, terminal command suggestions where AI agents can insert commands for user review before execution, an improved code editing strategy for the Coder agent, and symbol icons in breadcrumbs and outline views now include theme-adaptive default colors.

For a comprehensive breakdown, please read the in-depth release news:

• Eclipse Theia 1.65 announcement
• Eclipse Theia 1.66 announcement

Build or Extend Your Own IDE or Tool with Eclipse Theia

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 and IDEs, for Tools or extensions based on VS Code as well as for web-based tools in general. We also provide a Eclipse Theia online training that you can take anytime for a running start with Theia extension development. If you want to extend Theia with features or bug fixes, EclipseSource provides sponsored development for Theia, too. Finally, for cloud deployments we offer consulting and support for web-based tools.

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