Loxel
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C#

Loxel highlights .cs and .csx files out of the box. Everything else comes from csharp-ls, which you install yourself and which runs on your own .NET. Loxel does not bundle or download either one.

What to install

csharp-ls needs a .NET 10 SDK to install and a .NET 10 runtime to run, whatever version your projects target:

  1. Install the .NET 10 SDK. It sits next to the SDKs you already have, and projects that pin an older one with global.json keep using it. They still need that older SDK installed.
  2. In a terminal, outside any repository that pins an older SDK, run dotnet tool install --global csharp-ls.

Loxel needs csharp-ls 0.24.0 or newer. To update, run dotnet tool update --global csharp-ls. Loxel looks for csharp-ls on your PATH and in ~/.dotnet/tools.

A repository that lists csharp-ls in its .config/dotnet-tools.json manifest uses that version instead, once you run dotnet tool restore.

What a project needs

Language features start for a repository when all of these are true:

  • You trust the repository, because loading a C# project runs the repository’s build files.
  • Its projects are restored: you have run dotnet restore, so project.assets.json exists. If you accepted the setup suggestion when adding the project, each new worktree runs it; you can remove that from the setup script.
  • .NET and csharp-ls are installed, as above.

A fresh clone therefore gets syntax highlighting only, and a notice tells you the next step: what to install or what to run, or the status bar’s Restricted item asks about trust. You don’t need to restart anything. Language features start by themselves after you trust the repository, install csharp-ls or run dotnet restore.

Opening a C# file never restores packages, installs tools or downloads anything, including with a nuget.config that names a feed. Trusting a repository doesn’t change that.

What you get

Hover, go-to-definition, references, rename across files, completion, signature help, document and workspace symbols, formatting, code actions and quick fixes, semantic highlighting, inlay hints, and compiler and analyzer diagnostics that follow your .editorconfig severities.

Completion lists what is already imported. For a type from a namespace you haven’t imported, use the quick fix that adds the using.

Which projects load

  • One solution at the repository’s root is what loads.
  • With several solutions and no single one at the root, csharp-ls loads the first by path and a notice names it. Files outside it get syntax highlighting only. Choose another to load it instead.
  • With no solution, csharp-ls loads exactly the projects Loxel discovered, and the projects those reference. Loxel discovers the repository’s own projects, tracked or not, and not those in git-ignored directories, submodules or other repositories inside it. $(SolutionDir) in these projects points at a directory of Loxel’s.
  • A project in what loads that isn’t restored still loads, and a notice names it: references to its packages show as errors until you run dotnet restore.
  • A project csharp-ls can’t load gets a notice naming it, and its files may have fewer features.
  • A project using an MSBuild SDK delivered through NuGet, such as MSTest.Sdk or Aspire.AppHost.Sdk, loads without that SDK, since loading it could download it. A notice names it, and its files show errors.

After a dotnet restore, or when obj goes away, the server restarts to pick up the change. A large solution takes a little while to load again. Stopping csharp-ls also stops its child processes.

A .cs file outside any loaded project, or in a repository with no project at all, gets syntax highlighting only.

Status bar

While a C# file is the active editor in a repository with a project, the status bar shows what is loaded, such as C#: Polly.sln, or the missing step, in the warning color: C#: Not trusted, C#: Not restored, C#: csharp-ls missing, C#: csharp-ls too old, C#: csharp-ls failed, C#: .NET missing or C#: Load failed. Hover it for the loaded solution and the .NET SDK version, or for what to do, including the command to run in a terminal. It updates by itself when you trust the repository, run dotnet restore or install csharp-ls.

Choosing a solution

Click the item, or run C#: Select Solution from the command palette (), to choose what loads:

  • Use automatic detection goes back to the rules above.
  • Any .sln, .slnx or .slnf in the worktree that git doesn’t ignore loads that solution or solution filter. A single .csproj can’t be chosen: a project that no solution lists loads only in a repository with no solution.

The choice applies right away, restarting the server. It’s saved per worktree, survives restarts and goes away with the worktree. If the chosen file disappears, automatic detection takes over and the item turns the warning color, until the file returns or you choose again.

Choosing doesn’t change what is needed: an untrusted repository still loads nothing, and the picker says so.

Scope

Go-to-definition reaches your own code. Going into the source of the .NET libraries or NuGet packages isn’t supported: hover still shows their signatures and documentation, and definition finds nothing for those symbols.

For format on save with CSharpier, see Formatter auto-detection.