Enable LSP go-to-definition, find-all-references, and go-to-implementation with command handler precedence

src/EditorFeatures/Core/Extensibility/Commands/PredefinedCommandHandlerNames.cs

@@ -191,4 +191,19 @@ internal static class PredefinedCommandHandlerNames
     /// Command handler name for showing the Callstack Explorer tool window.
     /// </summary>
     public const string ShowCallstackExplorer = "Show Callstack Explorer";
+
+    /// <summary>
+    /// Command handler name for LSP Go To Definition.
+    /// </summary>
+    public const string LspGoToDefinition = "LSP GoToDefinitionCommandHandler";
+
+    /// <summary>
+    /// Command handler name for LSP Find References.
+    /// </summary>
+    public const string LspFindReferences = "LSP FindReferenceCommandHandler";
+
+    /// <summary>
+    /// Command handler name for LSP Go To Implementation.
+    /// </summary>
+    public const string LspGoToImplementation = "LSP GoToImplementationCommandHandler";
 }

src/EditorFeatures/Core/GoOrFind/FindReferences/FindReferencesCommandHandler.cs

@@ -15,6 +15,7 @@ namespace Microsoft.CodeAnalysis.FindReferences;
 [Export(typeof(ICommandHandler))]
 [ContentType(ContentTypeNames.RoslynContentType)]
 [Name(PredefinedCommandHandlerNames.FindReferences)]
+[Order(Before = PredefinedCommandHandlerNames.LspFindReferences)]
 [method: ImportingConstructor]
 [method: SuppressMessage("RoslynDiagnosticsReliability", "RS0033:Importing constructor should be [Obsolete]", Justification = "Used in test code: https://github.com/dotnet/roslyn/issues/42814")]
 internal sealed class FindReferencesCommandHandler(FindReferencesNavigationService navigationService)

src/EditorFeatures/Core/GoOrFind/GoToImplementation/GoToImplementationCommandHandler.cs

@@ -16,6 +16,7 @@ namespace Microsoft.CodeAnalysis.GoToImplementation;
 [Export(typeof(ICommandHandler))]
 [ContentType(ContentTypeNames.RoslynContentType)]
 [Name(PredefinedCommandHandlerNames.GoToImplementation)]
+[Order(Before = PredefinedCommandHandlerNames.LspGoToImplementation)]
 [method: ImportingConstructor]
 [method: Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
 internal sealed class GoToImplementationCommandHandler(GoToImplementationNavigationService navigationService)

src/EditorFeatures/Core/GoToDefinition/GoToDefinitionCommandHandler.cs

@@ -28,6 +28,7 @@ namespace Microsoft.CodeAnalysis.GoToDefinition;
 [Export(typeof(ICommandHandler))]
 [ContentType(ContentTypeNames.RoslynContentType)]
 [Name(PredefinedCommandHandlerNames.GoToDefinition)]
+[Order(Before = PredefinedCommandHandlerNames.LspGoToDefinition)]
 [method: ImportingConstructor]
 [method: SuppressMessage("RoslynDiagnosticsReliability", "RS0033:Importing constructor should be [Obsolete]", Justification = "Used in test code: https://github.com/dotnet/roslyn/issues/42814")]
 internal sealed class GoToDefinitionCommandHandler(

src/EditorFeatures/Core/LanguageServer/AlwaysActivateInProcLanguageClient.cs

@@ -118,6 +118,15 @@ public override ServerCapabilities GetCapabilities(ClientCapabilities clientCapa
 
         serverCapabilities.SpellCheckingProvider = true;
 
+        // Enable go to definition, find all references, and go to implementation capabilities for experimentation.
+        // These are enabled regardless of the LSP feature flag to allow clients to call these handlers.
+        serverCapabilities.DefinitionProvider = true;
+        serverCapabilities.ReferencesProvider = new ReferenceOptions
+        {
+            WorkDoneProgress = true,
+        };
+        serverCapabilities.ImplementationProvider = true;
+
         return serverCapabilities;
     }