Over the past several months, the .NET team has evaluated ways to evolve the .NET tooling ecosystem and incorporate more capabilities into VS Code. Currently, the C# experience in VS Code is powered by OmniSharp. This is thanks to the leadership of Filip Wojcieszyn, David Driscoll, Martin Björkström, and also, Jason Imison, who originally started the OmniSharp project over eight years ago. OmniSharp generated a lot of excitement by bringing the C# experience to VS Code, using the APIs and protocols that were available at that time. VS Code has since matured and today, the Language Server Protocol (LSP) has become the standard mechanism through which modern developer tools speak to one another. We believe that moving the C# extension to LSP will help us accomplish our goal of creating an extensible and flexible tooling environment which easily integrates new experiences into C# for VS Code.

As we move towards a more dynamic future for the C# experience in VS Code, we intend to switch the extension to communicate entirely using LSP and plan to update the existing OmniSharp component to communicate in this manner as well. Utilizing LSP will allow us to bring innovative new features to the C# for VS Code extension. This includes making advanced capabilities available and, in some cases, closed-source experiences, such as IntelliCode. We plan to create a new “LSP Tools Host” component (not an official name 😊), which integrates both open-source components, like Roslyn and Razor, with closed-source components, offering a wider array of tooling capabilities.

Once the “LSP Tools Host” is complete, this will become the default experience for the C# for VS Code extension. Existing users will be able to choose between the open-source OmniSharp powered system that exists today, or the new “'LSP Tools Host” which will provide access to additional experiences. The “LSP Tools Host” will not be open-sourced, but we plan to communicate with the community along the way to help guide our future plans.

We'd like to again thank everyone at OmniSharp and all the contributors to this project for doing such an incredible job in helping to bring the C# developer experience to VS Code. We have been collaborating with the OmniSharp team and will be working with them to ensure that this process is smooth, and plan to work with them, as well as the broader community, in order to drive forward this exciting new future for .NET tooling.

Next Steps (these will ideally be issues that will be trackable, timelines of these may vary)

• Update the C# for VS Code extension to communicate with OmniSharp Server via LSP by default.
• Switch the C# for VS Code extension to use the new “LSP Tools Host” by default and allow users to choose an alternative language server.
• Ship the C# for VS Code extension with these new defaults bundled with more features “out of the box”.
• Move the C# for VS Code extension from github.com/OmniSharp/omnisharp-vscode to github.com/dotnet/vscode-csharp and have Microsoft keep this up to date and ship it. This move will enable us to easily integrate and reuse the existing dotnet infrastructure assets, like our shared building, testing, and publishing system, and will reduce overall engineering costs.

UPDATE:
Thanks for the passionate feedback. I’d like to clarify a few things stated in the feedback that we failed to make clear.

The LSP implementations for Razor and C# will remain open-source (Roslyn and Razor) as they are today. The VS Code C# extension (ms-dotnettools.csharp) itself will also remain open-source. That which is open source today remains so and in active OSS development. This ensures that others outside of VS Code that use LSP continue to have access to C#.

This new host component is the bridge between open and closed source functionality letting us deliver both at the same time.