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Open-source AI functionality provided by the Copilot Chat extension #249031

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Description

@kieferrm

Our blog post outlines our motivation to open-source the client-side code of our AI features in VS Code. We also compiled FAQs.

Goals

  1. Open source is only useful, if you can participate in the development process of the AI features. We need a development story that allows you to make code changes and debug AI interactions end-to-end. You need to be able to run the AI tests suites. Since all AI features are powered by models, you need to have access to models during development.
  2. Once open source, we re-evaluate how we split the functionality between VS Code Core, built-in extension(s), and the Chat extension. We want to improve the user experience and simplify our architecture and build processes.

Approach

We'll first open-source the GitHub Copilot Chat extension. To do so we need:

  1. Ensure code compliance
  2. Define the strategy for service access
  3. Define how to run tests
  4. Define OSS builds
  5. Issue management

Note: Today, NES functionality is separate from code completions. NES is implemented in the Chat extension, while completions are implemented in the GitHub Copilot completions extension. We have concrete plans to bring NES and completions together in the Chat extension. Therefore, at the moment, we don't have concrete plans to open-source the Copilot completions extension.

Compliance Review

  • We need to review every file in the Copilot Chat extension for compliance. This includes adding copyrights and removing references to internal processes, IP, and issues. This is particularly important for our test suite that contains test cases created with information from private issues.
  • After the review, we'll move the Chat extension code to a new repository without history avoiding the need to review thousands of commits.

Service Access

  • The Chat extension is powered by the GitHub Copilot service. The GitHub Copilot service provides access to general purpose and custom models, embeddings computation, and semantic code search of GitHub repositories.
  • To talk to the GitHub Copilot service, the Chat extension uses CAPI (the GitHub Copilot API). Just like our other production services, for example the settings sync service, the Copilot service will remain closed source, and its usage will continue to be regulated by its service license.
  • For debug AI interactions, you need to be able to run Code-OSS with the Chat extension installed. Normally, Code-OSS does not have access to production services. This is not a handicap for non-AI features, but AI features are useless without model access. Our current thinking is that we'll provide a closed-source, licensed npm module providing CAPI access that you can choose to install into the codebase before launching Code-OSS. Or you can use BYOK without CAPI for limited scenarios.

Tests

  • We built a test infrastructure that deals with the stochastic nature of LLMs and makes heavy use of caching LLM responses for given prompts. If you make a change in the code that results in a prompt change for a specific scenario, you want to only issue LLM requests for the changed prompts and use the cached LLM responses in all other cases. The cache is implemented using Redis. We need to allow read-only access to the Redis cache which in MS terminology makes the Redis cache a production service. We therefore need to go through the motions of creating a new production service.
  • We need to investigate if we can use PR submissions for cache baseline updates.

Builds

  • We'll need to define what PR builds look like for the Chat extension.

Issues

  • Today, issues for AI features are in three different repositories: microsoft/vscode, microsoft/vscode-copilot-release, and the private repository we use(d) for developing the Chat extension.
  • Going forward, all client issues should be in microsoft/vscode.
  • We'll move only select issues from the private repo into the public repo.
  • We'll archive/lock the microsoft/vscode-copilot-release repo, so that no new issues can be created there and existing issues are locked. The issues will continue to be accessible.
  • We need a clearer separation of client issues from service issues. We have a large number of service issues, particularly in the microsoft/vscode-copilot-release repo that are not actionable and have no clear path to being closeable.

Activity

  1. locked and limited conversation to collaborators on May 15, 2025
  2. changed the title [-]Re-evaluate split of functionality between VS Code and the Copilot Chat extension[/-] [+]Open-source AI functionality provided by the Copilot Chat extension[/+] on May 19, 2025
  3. unlocked this conversation on May 19, 2025
  4. ups216 commented on May 19, 2025

    @ups216

    Kai Maetzel (@kieferrm) is agent mode also part of the open source plan?

  5. dengyakui commented on May 19, 2025

    @dengyakui

    Kai Maetzel (@kieferrm) : Is the Visual Studio 2022 Github Copilot also be open sourced?

  6. iwangbowen commented on May 20, 2025

    @iwangbowen

    Great work

  7. kieferrm commented on May 20, 2025

    @kieferrm
    MemberAuthor

    About #249031 (comment). Lei Xu (@ups216) yes, everything but ghost text completions. See the note in the issue description.

  8. elongl commented on May 20, 2025

    @elongl

    Out of curiosity, as I'm not proficient in VSCode's architecture, what's the value in moving Copilot from being an extension to being part of the core codebase as opposed to a built-in extension as mentioned here?

    In fact, many core features of VS Code are built as extensions and use the same Extension API.

  9. NaokiS28 commented on May 20, 2025

    @NaokiS28

    Is there going to be an option to be opted-out by default or outright disable the AI features for people who do not wish to use it? Thats currently something I prefer with the extension and I'm sure a great deal more would like. My experience with copilot was subpar and I would certainly not want to use it even if it was integrated.

  10. htahir1 commented on May 20, 2025

    @htahir1

    Can users skip using CAPI and just bring their own models or API services that the Chat can talk to?

  11. hu-qi commented on May 21, 2025

    @hu-qi

    Great!Support any LLMs that comply with the OpenAI specifications?

  12. trancethehuman commented on May 21, 2025

    @trancethehuman

    Looking forward to this!

  13. 2 remaining items

  14. kirkilj commented on Jun 7, 2025

    @kirkilj

    This will only give it more customization and other extensions that cannot be used, allowing more people to help you maintain this github copilot closed ai service. The function should be opened to extensions and then github copilot extensions is called, instead of putting github copilot into vscode. This is fake open source, which uses the ability of vscode not to open to extension to suppress other ai extensions.

    How might this affect products like Windsurf and Cursor that are built on VS-Code and are competitors to GitHub CoPilot?

  15. LakshmanKishore commented on Jun 18, 2025

    @LakshmanKishore

    Waiting for this update.

  16. kdlslyv commented on Jun 27, 2025

    @kdlslyv

    it will open in 2049

  17. tekumara commented on Jun 28, 2025

    @tekumara
  18. kdlslyv commented on Jun 28, 2025

    @kdlslyv

    Without InlineCompletionItem this might as well be a glorified vibecoded webview chatwindow

  19. ritamariavermelho06 commented on Jul 1, 2025

    @ritamariavermelho06

    Without InlineCompletionItem this might as well be a glorified vibecoded webview chatwindow

    The InlineCompletion will be merged to the chat plugin, is on the roadmap.

  20. trivikr commented on Jul 1, 2025

    @trivikr

    Should this issue be closed since first milestone is achieved?

  21. pai4451 commented on Jul 12, 2025

    @pai4451

    SyfyCoder (@ritamariavermelho06) Will the inline completion feature open-source released in GitHub Copilot Chat completely the same as in closed source GitHub Copilot?

  22. locked and limited conversation to collaborators on Aug 27, 2025
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