Make Razor a built in feature of the Roslyn language server by davidwengier · Pull Request #83575 · dotnet/roslyn

davidwengier · 2026-05-06T00:17:49Z

Now that we're in the same repo, we can just reference the Razor bits directly and ship everything together in one happy package.

C# extension PR: dotnet/vscode-csharp#9277

Microsoft Reviewers: Open in CodeFlow

Local testing is not just one setting (dotnet.server.path) so simply enough to not need a skill IMO

Copilot

Pull request overview

This PR integrates the Razor VS Code component directly into the Roslyn language server so Razor functionality ships as part of the same tool/package, rather than being provided via externally-supplied component paths.

Changes:

Removes command-line/config plumbing for supplying Razor design-time inputs via arguments.
Adds the VS Code Razor extension project as a runtime dependency of the language server and ensures its entry assembly participates in the language server MEF catalog.
Updates project loading to always set RazorDesignTimeTargets based on the language server deployment layout.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/ServerConfigurationFactory.cs	Removes `RazorDesignTimePath` from `ServerConfiguration`.
src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/Program.cs	Removes Razor-related CLI options and stops flowing Razor design-time paths into configuration.
src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/Microsoft.CodeAnalysis.LanguageServer.csproj	Adds a project reference to `Microsoft.VisualStudioCode.RazorExtension` so it’s a runtime dependency.
src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/LanguageServerExportProviderBuilder.cs	Adds Razor extension assembly to MEF discovery and excludes specific Razor/remote assemblies from the main MEF catalog.
src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/HostWorkspace/LanguageServerProjectLoader.cs	Always sets `RazorDesignTimeTargets` to a path under `AppContext.BaseDirectory`.
src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer.UnitTests/Utilities/LanguageServerTestComposition.cs	Updates test server configuration construction to match the new `ServerConfiguration` shape.
.github/skills/run-vscode-local-testing/SKILL.md	Removes the local VS Code testing skill documentation.
.github/skills/run-vscode-local-testing/scripts/Start-LocalVsCode.ps1	Removes the helper script used by the deleted skill.

dibarbet

🥳

dibarbet · 2026-05-06T00:37:15Z

        Required = false
    };

-    var razorSourceGeneratorOption = new Option<string?>("--razorSourceGenerator")


Was this unused? Not seeing anything removed that actually touched this option

Yep, it was, the option value stopped getting passed to ServerConfiguration in #78852, and this either didn't get cleaned up, or left as an option so a coordinated change wasn't necessary.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Razor dynamic registration is sometimes coming into play when running multiple tests.

Copilot

Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (1)

src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/LanguageServerExportProviderBuilder.cs:73

The MEF exclusion list is only applied when enumerating assemblies in the base directory, but extension-provided assemblies are added unfiltered. If an older VS Code extension (or other host) still passes Razor/Remote.ServiceHub DLLs via ExtensionAssemblyPaths, they'll be reintroduced into the MEF catalog and can trigger the same export collisions this exclusion list is trying to prevent. Consider applying the same filtering to extensionManager.ExtensionAssemblyPaths (or explicitly skipping these known-conflicting DLL names) when adding extension assemblies to the catalog.

        assemblyPathsBuilder.AddRange(FilterFiles(baseDirectory, "Microsoft.CodeAnalysis*.dll"));
        assemblyPathsBuilder.AddRange(FilterFiles(baseDirectory, "Microsoft.ServiceHub*.dll"));

        // The Razor extension ships with Roslyn and so needs to be in our MEF composition
        assemblyPathsBuilder.Add(Path.Combine(baseDirectory, "Microsoft.VisualStudioCode.RazorExtension.dll"));

        // DevKit assemblies are not shipped in the main language server folder
        // and not included in ExtensionAssemblyPaths (they get loaded into the default ALC).
        // So manually add them to the MEF catalog here.
        if (devKitDependencyPath != null)
            assemblyPathsBuilder.Add(devKitDependencyPath);

        // Add the extension assemblies to the MEF catalog.
        assemblyPathsBuilder.AddRange(extensionManager.ExtensionAssemblyPaths);

davidwengier · 2026-05-06T05:13:13Z

Got a correctness failure for missing runtime identifiers, and while fixing that I realised we don't need to publish the razor package any more, so there have been a couple of smallish updates since last review, FYI

davidwengier · 2026-05-06T05:13:17Z

/pr-val

github-actions · 2026-05-06T05:13:51Z

View PR Validation Run triggered by @davidwengier

Parameters

Validation Type: pr-val
Pipeline ID: 8972
Pipeline Version: main
PR Number: 83575
Commit SHA: 333225ea9faac0463dbb5a27dae7b461a6398589
Source Branch: RazorInRoslynLSP
Target Branch: main
Build ID: 14025264

ToddGrun · 2026-05-06T20:00:35Z

+    {
+        foreach (var file in Directory.EnumerateFiles(baseDirectory, filter))
+        {
+            if (!s_dllsToExcludeFromMef.Contains(Path.GetFileName(file)))


if (!s_dllsToExcludeFromMef.Contains(Path.GetFileName(file)))

No case sensitivity concerns?

Yeah, good catch, doesn't hurt to be a bit more forgiving here.

davidwengier · 2026-05-06T20:55:48Z

RPS and Speedometer are happy :)

jasonmalinowski · 2026-05-06T22:41:13Z


        // Get rid of the registration and it should be gone again
        watchedFile.Dispose();
+        context.Dispose();


Disposing this before the assert might be defeating the point this part of the test. Should line 90 just become a using context instead?

The missing dispose is something copilot noticed, but I did think the same thing. The test above already has the context.Dispose call, and it is before the wait and assert though, so I assumed it to be correct.

jasonmalinowski · 2026-05-06T22:44:23Z

    <Nullable>enable</Nullable>
-    <IsShippingPackage>true</IsShippingPackage>
+    <!-- This assembly ships inside roslyn-language-server, not as its own NuGet package. -->
+    <IsShippingAssembly>false</IsShippingAssembly>


What does IsShippingAssembly mean? I'd assume want this as true given the comment?

Shipping in this context means "create and push a package in CI", which we're not doing any more for this. It's in the roslyn package, but just brought in as a normal project reference.

jasonmalinowski · 2026-05-06T22:51:48Z

+        assemblyPathsBuilder.AddRange(FilterFiles(baseDirectory, "Microsoft.CodeAnalysis*.dll"));
+        assemblyPathsBuilder.AddRange(FilterFiles(baseDirectory, "Microsoft.ServiceHub*.dll"));


I wonder at what point it's just easier to list the files than keep adding fancier logic here.

Copilot

Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated no new comments.

davidwengier and others added 4 commits May 6, 2026 07:48

Remove local testing skill

7a6e3c0

Local testing is not just one setting (dotnet.server.path) so simply enough to not need a skill IMO

Package the Razor extension with the Roslyn language server package

9378ce0

Remove --razorSourceGenerator option. It wasn't used anyway

14edb00

Remove razorDesignTimeTargets option

451eb99

Copilot AI review requested due to automatic review settings May 6, 2026 00:17

davidwengier requested review from a team as code owners May 6, 2026 00:17

Copilot started reviewing on behalf of davidwengier May 6, 2026 00:18 View session

github-actions Bot added the Area-Infrastructure label May 6, 2026

dotnet-policy-service Bot added the VSCode label May 6, 2026

davidwengier mentioned this pull request May 6, 2026

Make Razor a built in feature of the Roslyn language server dotnet/vscode-csharp#9277

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Copilot AI reviewed May 6, 2026

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dibarbet approved these changes May 6, 2026

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davidwengier and others added 2 commits May 6, 2026 11:38

Expand Remote.Razor runtime identifiers

62288bf

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Stop publishing VSCode Razor extension package

28e314b

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

davidwengier requested a review from a team as a code owner May 6, 2026 01:51

dotnet-policy-service Bot added the Area-Razor label May 6, 2026

build-analysis Bot mentioned this pull request May 6, 2026

[Known Build Error] AssemblyLoading_MultipleVersions_AnalyzerDependency set difference #83286

Open

Strengthen test assertions

333225e

Razor dynamic registration is sometimes coming into play when running multiple tests.

Copilot AI review requested due to automatic review settings May 6, 2026 04:29

Copilot started reviewing on behalf of davidwengier May 6, 2026 04:29 View session

Copilot AI reviewed May 6, 2026

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dibarbet approved these changes May 6, 2026

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ToddGrun reviewed May 6, 2026

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JoeRobich approved these changes May 6, 2026

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Be case insensitive

2be36f9

jasonmalinowski approved these changes May 6, 2026

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Roslyn tests have no telemetry, but we're part of the MEF composition

1270ab9

Copilot AI review requested due to automatic review settings May 7, 2026 06:18

Copilot started reviewing on behalf of davidwengier May 7, 2026 06:18 View session

Copilot AI reviewed May 7, 2026

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		assemblyPathsBuilder.AddRange(FilterFiles(baseDirectory, "Microsoft.CodeAnalysis*.dll"));
		assemblyPathsBuilder.AddRange(FilterFiles(baseDirectory, "Microsoft.ServiceHub*.dll"));

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davidwengier commented May 6, 2026 •

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