Centralize Language Server workspace folder tracking by JoeRobich · Pull Request #85105 · dotnet/roslyn

JoeRobich · 2026-08-31T16:10:00Z

Summary

Introduce a synchronized Language Server service as the authoritative source of current local workspace folders.

Add initial folders directly from the LSP initialize handler.
Remove and add folders for workspace/didChangeWorkspaceFolders notifications.
Normalize paths and compare them with platform path semantics, and ignore non-file workspace-folder URIs.
Migrate existing file-based-program consumers away from IInitializeManager folder state.

Validation

WorkspaceFolderTrackerTests (2 passed)
Analyzer-enabled Language Server unit-test project build succeeded with 0 errors
Final stacked analyzer-enabled Language Server build succeeded with 0 errors

Microsoft Reviewers: Open in CodeFlow

azure-pipelines · 2026-08-31T16:10:10Z

Azure Pipelines: 2 pipeline(s) were filtered out due to trigger conditions. There may be pipelines that require an authorized user to comment /azp run to run.

Copilot

Copilot review overview

🟡 Changes recommended

Workspace folder path normalization currently doesn’t handle trailing directory separators, which can lead to duplicate/unremovable entries with PathUtilities.Comparer.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Review tier: Lite
Findings: 1 · 1

New issues introduced by this change (2)

Severity	Finding
	`src/LanguageServer/Protocol/Handler/WorkspaceFolderTracker.cs` — NormalizePath uses Path.GetFullPath but does not normalize trailing directory separators. Since…
	`src/LanguageServer/ProtocolUnitTests/WorkspaceFolderTrackerTests.cs` — Add a regression test that covers workspace-folder URIs that differ only by a trailing directory…

What changed in this PR

This PR introduces a new Language Server service (IWorkspaceFolderTracker) to centralize tracking of local workspace-folder paths, initializes it during initialize, and updates it on workspace/didChangeWorkspaceFolders notifications. It also migrates existing file-based-program components away from IInitializeManager’s previous folder-state.

Changes:

Add IWorkspaceFolderTracker/WorkspaceFolderTracker and register it as a server service.
Populate initial workspace folders during initialize and update them during workspace/didChangeWorkspaceFolders.
Remove workspace-folder tracking from IInitializeManager and update file-based-program consumers to use the new tracker.

File	Description
src/LanguageServer/ProtocolUnitTests/WorkspaceFolderTrackerTests.cs	Adds unit tests for tracker behavior (path semantics, non-file URIs).
src/LanguageServer/Protocol/RoslynLanguageServer.cs	Registers `IWorkspaceFolderTracker` as a base service.
src/LanguageServer/Protocol/Handler/WorkspaceFolderTracker.cs	Implements synchronized add/remove/query of normalized workspace-folder paths.
src/LanguageServer/Protocol/Handler/ServerLifetime/InitializeHandler.cs	Seeds the tracker with `InitializeParams.WorkspaceFolders`.
src/LanguageServer/Protocol/Handler/ServerLifetime/DidChangeWorkspaceFoldersNotificationHandler.cs	Handles workspace-folder change notifications by removing/adding entries in the tracker.
src/LanguageServer/Protocol/Handler/IWorkspaceFolderTracker.cs	Defines the tracker service contract used across handlers/components.
src/LanguageServer/Protocol/Handler/InitializeManager.cs	Removes workspace-folder state; keeps only initialize params/capabilities.
src/LanguageServer/Protocol/Handler/IInitializeManager.cs	Drops the workspace-folder API from the initialize manager interface.
src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/FileBasedPrograms/FileBasedProgramsEntryPointDiscovery.cs	Switches to reading workspace folders from `IWorkspaceFolderTracker`.
src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/FileBasedPrograms/CsprojInConeChecker.cs	Switches to reading workspace folders from `IWorkspaceFolderTracker`.
src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer.UnitTests/Daemon/ClientProcessMonitorTests.cs	Mechanical file header/BOM update only.

Copilot

Copilot review overview

🔵 Needs a closer look

Workspace folder “normalization” currently preserves trailing directory separators, which can lead to duplicate entries and failed removals unless canonicalized (and ideally covered by a regression test).

Review tier: Lite
Findings: 1 · 1

Pre-existing issues (2)

Severity	Finding
	`src/LanguageServer/Protocol/Handler/WorkspaceFolderTracker.cs` — NormalizePath uses Path.GetFullPath but does not normalize trailing directory separators. Since… View comment
	`src/LanguageServer/ProtocolUnitTests/WorkspaceFolderTrackerTests.cs` — Add a regression test that covers workspace-folder URIs that differ only by a trailing directory… View comment

Suppressed comments (2)

src/LanguageServer/Protocol/Handler/WorkspaceFolderTracker.cs:81

NormalizePath only calls Path.GetFullPath, which preserves trailing directory separators. That means the tracker can treat the same workspace folder as distinct entries (e.g. "C:\Repo" vs "C:\Repo\" or "/repo" vs "/repo/") and Remove may fail to match if the client switches representations. Since this type is intended to normalize/compare workspace folders with platform path semantics, it should canonicalize directory paths by trimming trailing separators (except for the root).

    private static string NormalizePath(string path)
        => Path.GetFullPath(path);

src/LanguageServer/ProtocolUnitTests/WorkspaceFolderTrackerTests.cs:67

The current tests cover case-sensitivity differences and non-file URIs, but they don’t cover normalization of trailing directory separators. Without trimming trailing separators, the tracker can retain duplicate entries for the same folder or fail to remove a folder when the client changes URI formatting (with/without a trailing '/'). Adding a regression test here would lock in the intended normalization behavior.

    private static WorkspaceFolder CreateWorkspaceFolder(DocumentUri uri)
        => new() { DocumentUri = uri, Name = "Workspace" };
}

Copilot

Copilot review overview

🟡 Changes recommended

The new workspace-folder notification handler has an incorrect MutatesSolutionState setting (unnecessarily serializing work) and needs additional wiring-level coverage to prevent composition/dispatch regressions.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Review tier: Lite
Findings: 2 · 2

New issues introduced by this change (2)

Severity	Finding
	`src/LanguageServer/Protocol/Handler/ServerLifetime/DidChangeWorkspaceFoldersNotificationHandler.cs` — MutatesSolutionState is set to true, but this handler only updates the workspace-folder tracker and…
	`src/LanguageServer/Protocol/Handler/ServerLifetime/DidChangeWorkspaceFoldersNotificationHandler.cs` — This new notification handler introduces observable behavior (updating the authoritative…

Pre-existing issues (2)

Severity	Finding
	`src/LanguageServer/Protocol/Handler/WorkspaceFolderTracker.cs` — NormalizePath uses Path.GetFullPath but does not normalize trailing directory separators. Since… View comment
	`src/LanguageServer/ProtocolUnitTests/WorkspaceFolderTrackerTests.cs` — Add a regression test that covers workspace-folder URIs that differ only by a trailing directory… View comment

Copilot

Copilot review overview

🟢 Approval recommended

The behavioral change is well-scoped, includes targeted tests, and only has minor follow-up nits noted in review comments.

Review tier: Lite
Findings: 1 · 4

New issues introduced by this change (2)

Severity	Finding
	`src/LanguageServer/Protocol/Handler/WorkspaceFolderTracker.cs` — `using System;` is unnecessary here and will trigger unused-using analyzers (the file doesn’t…
	`src/LanguageServer/Protocol/Handler/WorkspaceFolderTracker.cs` — `Remove` allocates a builder and re-materializes the immutable array even when the input is…

Pre-existing issues (3)

Severity	Finding
	`src/LanguageServer/Protocol/Handler/WorkspaceFolderTracker.cs` — NormalizePath uses Path.GetFullPath but does not normalize trailing directory separators. Since… View comment
	`src/LanguageServer/Protocol/Handler/ServerLifetime/DidChangeWorkspaceFoldersNotificationHandler.cs` — This new notification handler introduces observable behavior (updating the authoritative… View comment
	`src/LanguageServer/ProtocolUnitTests/WorkspaceFolderTrackerTests.cs` — Add a regression test that covers workspace-folder URIs that differ only by a trailing directory… View comment

Issues resolved since last review (1)

Severity	Finding
	`src/LanguageServer/Protocol/Handler/ServerLifetime/DidChangeWorkspaceFoldersNotificationHandler.cs` — MutatesSolutionState is set to true, but this handler only updates the workspace-folder tracker and… View resolved comment

Copilot

Copilot review overview

🟡 Changes recommended

A small but concrete test-utility robustness issue was found (missing null guard for the new response-factory delegate) that should be fixed before approval.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Review tier: Lite
Findings: 1 · 1

New issues introduced by this change (1)

Severity	Finding
	`src/LanguageServer/ProtocolUnitTests/TestConfigurableDocumentHandler.cs` — `ConfigureHandler` accepts a `responseFactory` delegate but doesn’t guard against a null value. If…

Pre-existing issues (1)

Severity	Finding
	`src/LanguageServer/Protocol/Handler/WorkspaceFolderTracker.cs` — `Path.GetFullPath` can throw (e.g., invalid/unsupported/too-long paths). Since workspace folders… View comment

+    public void ConfigureHandler(bool mutatesSolutionState, bool requiresLspSolution, Func<RequestContext, CancellationToken, Task<TestConfigurableResponse>> responseFactory)
    {
-        if (_mutatesSolutionState is not null || _requiresLSPSolution is not null || _response is not null)
+        if (_mutatesSolutionState is not null || _requiresLSPSolution is not null || _responseFactory is not null)
        {
            throw new InvalidOperationException($"{nameof(ConfigureHandler)} has already been called");


Copilot

Copilot review overview

🟡 Changes recommended

WorkspaceFolderTracker.Update can still raise WorkspaceFoldersChanged for net-no-op remove+add updates, which can trigger unnecessary downstream work and should be addressed before merging.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Review tier: Lite
Findings: 1 · 2

New issues introduced by this change (1)

Severity	Finding
	`src/LanguageServer/Protocol/Handler/WorkspaceFolderTracker.cs` — `Update` uses `ReferenceEquals` to detect no-op updates, but a remove+add sequence that results in…

Pre-existing issues (2)

Severity	Finding
	`src/LanguageServer/Protocol/Handler/WorkspaceFolderTracker.cs` — `Path.GetFullPath` can throw (e.g., invalid/unsupported/too-long paths). Since workspace folders… View comment
	`src/LanguageServer/ProtocolUnitTests/TestConfigurableDocumentHandler.cs` — `ConfigureHandler` accepts a `responseFactory` delegate but doesn’t guard against a null value. If… View comment

Copilot

Copilot review overview

🔵 Needs a closer look

Workspace-folder path normalization can throw on malformed client-provided file URIs (via Path.GetFullPath), risking a language-server crash during initialize or folder-change handling.

Review tier: Lite
Findings: 1 · 2

Pre-existing issues (3)

Severity	Finding
	`src/LanguageServer/Protocol/Handler/WorkspaceFolderTracker.cs` — `Path.GetFullPath` can throw (e.g., invalid/unsupported/too-long paths). Since workspace folders… View comment
	`src/LanguageServer/Protocol/Handler/WorkspaceFolderTracker.cs` — `Update` uses `ReferenceEquals` to detect no-op updates, but a remove+add sequence that results in… View comment
	`src/LanguageServer/ProtocolUnitTests/TestConfigurableDocumentHandler.cs` — `ConfigureHandler` accepts a `responseFactory` delegate but doesn’t guard against a null value. If… View comment

Suppressed comments (1)

src/LanguageServer/Protocol/Handler/WorkspaceFolderTracker.cs:69

NormalizePath uses Path.GetFullPath, which can throw (e.g., malformed/empty file URI -> invalid path). Since workspace folders come from the client, a single bad workspace-folder URI could crash the language server during initialize or didChangeWorkspaceFolders. Consider treating path-normalization failures as non-fatal and ignoring that folder (return null) instead of throwing.

    private static string? GetNormalizedFilePath(WorkspaceFolder workspaceFolder)
        => workspaceFolder.DocumentUri.ParsedDocumentUri?.IsFile == true
            ? NormalizePath(workspaceFolder.DocumentUri.GetDocumentFilePathFromUri())
            : null;

Copilot

Copilot review overview

🔵 Needs a closer look

It changes core LSP lifetime/workspace-folder state flow and introduces new cross-component update notifications that warrant maintainer validation in broader scenarios beyond the added tests.

Review tier: Lite
Findings: 1 · 1

Pre-existing issues (2)

Severity	Finding
	`src/LanguageServer/Protocol/Handler/WorkspaceFolderTracker.cs` — `Path.GetFullPath` can throw (e.g., invalid/unsupported/too-long paths). Since workspace folders… View comment
	`src/LanguageServer/ProtocolUnitTests/TestConfigurableDocumentHandler.cs` — `ConfigureHandler` accepts a `responseFactory` delegate but doesn’t guard against a null value. If… View comment

Issues resolved since last review (1)

Severity	Finding
	`src/LanguageServer/Protocol/Handler/WorkspaceFolderTracker.cs` — `Update` uses `ReferenceEquals` to detect no-op updates, but a remove+add sequence that results in… View resolved comment

jasonmalinowski

Some small comments but could be done in a mop-up since everything else is stacked on this.

jasonmalinowski · 2026-09-04T18:16:13Z

+
+internal sealed class WorkspaceFolderTracker : IWorkspaceFolderTracker
+{
+    // Mutations are serialized by the request queue, but non-mutating requests may read the current folders concurrently.


Nit: use an XML doc comment here to mention the other field, so less of a chance this gets out of sync.

jasonmalinowski · 2026-09-04T18:16:53Z

+            if (removedFolders is not null)
+            {
+                foreach (var workspaceFolder in removedFolders)


Sometimes doing in removedFolders ?? [] is a nice shortcut...

jasonmalinowski · 2026-09-04T18:18:15Z

+        lock (_gate)
+        {


No reason to have the lock, especially since the comment said it wasn't needed.

jasonmalinowski · 2026-09-04T18:19:28Z

    }

-    internal async Task FindAndLoadEntryPointsAsync()
+    private void OnWorkspaceFoldersChanged(ImmutableHashSet<string> _)


It's a bit strange the event handler is giving us the set and we're ignoring it. That's fine since we'll look at the "final" output, but maybe we just don't need the argument at all?

jasonmalinowski · 2026-09-04T18:44:59Z

+    internal ValueTask FindAndLoadEntryPointsAsync(CancellationToken cancellationToken)
+        => FindAndLoadEntryPointsAsync(globalOptionService, fileBasedProgramService, workspaceFolderTracker, lspServices, logger, cancellationToken);
+
+    private static async ValueTask FindAndLoadEntryPointsAsync(


Wasn't sure why this got made static.

Other than to make the AsyncBatchingWorkQueue code duplicate the logic of the non-static overload.

JoeRobich · 2026-09-04T22:44:11Z

/azp run roslyn-CI

azure-pipelines · 2026-09-04T22:44:26Z

Azure Pipelines: Successfully started running 1 pipeline(s).

JoeRobich requested a review from a team as a code owner August 31, 2026 16:10

dotnet-policy-service Bot added the VSCode label Aug 31, 2026

JoeRobich mentioned this pull request Aug 31, 2026

Add on-demand project loading #84591

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JoeRobich force-pushed the dev/jorobich/lsp-workspace-folder-tracker branch from 6e9de4b to 9145fff Compare August 31, 2026 16:38

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Comment thread ...anguageServer/Microsoft.CodeAnalysis.LanguageServer/FileBasedPrograms/CsprojInConeChecker.cs

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Centralize Language Server workspace folder tracking

931c338

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jasonmalinowski approved these changes Sep 4, 2026

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JoeRobich merged commit 3550338 into main Sep 8, 2026
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dotnet-maestro Bot mentioned this pull request Sep 9, 2026

[release/11.0.1xx] Source code updates from dotnet/roslyn dotnet/dotnet#9160

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dibarbet mentioned this pull request Sep 9, 2026

Update roslyn to 5.12.0-1.26459.1 dotnet/vscode-csharp#9743

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JoeRobich mentioned this pull request Sep 9, 2026

Add on-demand project loading #85234

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dotnet-maestro Bot mentioned this pull request Sep 10, 2026

[main] Source code updates from dotnet/roslyn dotnet/dotnet#9228

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[Automated] PRs inserted in VS build main-12209.490 #85246

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Summary

Validation

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JoeRobich commented Aug 31, 2026 •

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