Add UnboundDirectiveAttributeAddUsingCodeActionProvider for directive attributes

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/Extensions/IServiceCollectionExtensions.cs

@@ -153,6 +153,7 @@ public static void AddCodeActionsServices(this IServiceCollection services)
         services.AddSingleton<IRazorCodeActionResolver, ExtractToComponentCodeActionResolver>();
         services.AddSingleton<IRazorCodeActionProvider, ComponentAccessibilityCodeActionProvider>();
         services.AddSingleton<IRazorCodeActionResolver, CreateComponentCodeActionResolver>();
+        services.AddSingleton<IRazorCodeActionProvider, UnboundDirectiveAttributeAddUsingCodeActionProvider>();
         services.AddSingleton<IRazorCodeActionResolver, AddUsingsCodeActionResolver>();
         services.AddSingleton<IRazorCodeActionProvider, GenerateMethodCodeActionProvider>();
         services.AddSingleton<IRazorCodeActionResolver, GenerateMethodCodeActionResolver>();

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/CodeActions/Razor/AddUsingsCodeActionResolver.cs

@@ -62,22 +62,26 @@ internal static bool TryCreateAddUsingResolutionParams(string fullyQualifiedName
             return false;
         }
 
+        resolutionParams = CreateAddUsingResolutionParams(@namespace, textDocument, additionalEdit, delegatedDocumentUri);
+        return true;
+    }
+
+    internal static RazorCodeActionResolutionParams CreateAddUsingResolutionParams(string @namespace, VSTextDocumentIdentifier textDocument, TextDocumentEdit? additionalEdit, Uri? delegatedDocumentUri)
+    {
         var actionParams = new AddUsingsCodeActionParams
         {
             Namespace = @namespace,
             AdditionalEdit = additionalEdit
         };
 
-        resolutionParams = new RazorCodeActionResolutionParams
+        return new RazorCodeActionResolutionParams
         {
             TextDocument = textDocument,
             Action = LanguageServerConstants.CodeActions.AddUsing,
             Language = RazorLanguageKind.Razor,
             DelegatedDocumentUri = delegatedDocumentUri,
             Data = actionParams,
         };
-
-        return true;
     }
 
     // Internal for testing

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/CodeActions/Razor/UnboundDirectiveAttributeAddUsingCodeActionProvider.cs

@@ -0,0 +1,138 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Collections.Immutable;
+using System.Diagnostics.CodeAnalysis;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Razor.Language;
+using Microsoft.AspNetCore.Razor.Language.Syntax;
+using Microsoft.AspNetCore.Razor.Threading;
+using Microsoft.CodeAnalysis.Razor.CodeActions.Models;
+using Microsoft.CodeAnalysis.Razor.CodeActions.Razor;
+using Microsoft.CodeAnalysis.Razor.Workspaces;
+
+namespace Microsoft.CodeAnalysis.Razor.CodeActions;
+
+internal class UnboundDirectiveAttributeAddUsingCodeActionProvider : IRazorCodeActionProvider
+{
+    public Task<ImmutableArray<RazorVSInternalCodeAction>> ProvideAsync(RazorCodeActionContext context, CancellationToken cancellationToken)
+    {
+        if (context.HasSelection)
+        {
+            return SpecializedTasks.EmptyImmutableArray<RazorVSInternalCodeAction>();
+        }
+
+        // Only work in component files
+        if (!FileKinds.IsComponent(context.CodeDocument.FileKind))
+        {
+            return SpecializedTasks.EmptyImmutableArray<RazorVSInternalCodeAction>();
+        }
+
+        if (!context.CodeDocument.TryGetSyntaxRoot(out var syntaxRoot))
+        {
+            return SpecializedTasks.EmptyImmutableArray<RazorVSInternalCodeAction>();
+        }
+
+        // Find the node at the cursor position
+        var owner = syntaxRoot.FindInnermostNode(context.StartAbsoluteIndex, includeWhitespace: false);
+        if (owner is null)
+        {
+            return SpecializedTasks.EmptyImmutableArray<RazorVSInternalCodeAction>();
+        }
+
+        // Find a regular markup attribute (not a tag helper attribute) that starts with '@'
+        // Unbound directive attributes are just regular attributes that happen to start with '@'
+        var attributeBlock = owner.FirstAncestorOrSelf<MarkupAttributeBlockSyntax>();
+        if (attributeBlock is null)
+        {
+            return SpecializedTasks.EmptyImmutableArray<RazorVSInternalCodeAction>();
+        }
+
+        // Make sure the cursor is actually on the name part, since the attribute block is the whole attribute, including
+        // value and even some whitespace
+        if (!attributeBlock.Name.Span.Contains(context.StartAbsoluteIndex))
+        {
+            return SpecializedTasks.EmptyImmutableArray<RazorVSInternalCodeAction>();
+        }
+
+        // Try to find the missing namespace for this directive attribute
+        if (!TryGetMissingDirectiveAttributeNamespace(context.CodeDocument, attributeBlock, out var missingNamespace))
+        {
+            return SpecializedTasks.EmptyImmutableArray<RazorVSInternalCodeAction>();
+        }
+
+        // Create the code action
+        var resolutionParams = AddUsingsCodeActionResolver.CreateAddUsingResolutionParams(
+            missingNamespace,
+            context.Request.TextDocument,
+            additionalEdit: null,
+            context.DelegatedDocumentUri);
+
+        var addUsingCodeAction = RazorCodeActionFactory.CreateAddComponentUsing(
+            missingNamespace,
+            newTagName: null,
+            resolutionParams);
+
+        return Task.FromResult<ImmutableArray<RazorVSInternalCodeAction>>([addUsingCodeAction]);
+    }
+
+    private static bool TryGetMissingDirectiveAttributeNamespace(
+        RazorCodeDocument codeDocument,
+        MarkupAttributeBlockSyntax attributeBlock,
+        [NotNullWhen(true)] out string? missingNamespace)
+    {
+        missingNamespace = null;
+
+        // Check if this is a directive attribute (starts with '@')
+        var attributeName = attributeBlock.Name.GetContent();
+        if (attributeName is not ['@', ..])
+        {
+            return false;
+        }
+
+        // Get all tag helpers, not just those in scope, since we want to suggest adding a using
+        var tagHelpers = codeDocument.GetTagHelpers();
+        if (tagHelpers is null)
+        {
+            return false;
+        }
+
+        // For attributes with parameters (e.g., @bind:after), extract just the base attribute name
+        var baseAttributeName = attributeName;
+        var colonIndex = attributeName.IndexOf(':');
+        if (colonIndex > 0)
+        {
+            baseAttributeName = attributeName[..colonIndex];
+        }
+
+        // Search for matching bound attribute descriptors in all available tag helpers
+        foreach (var tagHelper in tagHelpers)
+        {
+            if (!tagHelper.IsAttributeDescriptor())
+            {
+                continue;
+            }
+
+            foreach (var boundAttribute in tagHelper.BoundAttributes)
+            {
+                // No need to worry about multiple matches, because Razor syntax has no way to disambiguate anyway.
+                // Currently only compiler can create directive attribute tag helpers anyway.
+                if (boundAttribute.IsDirectiveAttribute &&
+                    boundAttribute.Name == baseAttributeName)
+                {
+                    if (boundAttribute.Parent.TypeNamespace is { } typeNamespace)
+                    {
+                        missingNamespace = typeNamespace;
+                        return true;
+                    }
+
+                    // This is unexpected, but if for some reason we can't find a namespace, there is no point looking further
+                    break;
+                }
+            }
+        }
+
+        return false;
+    }
+}

src/Razor/src/Microsoft.CodeAnalysis.Remote.Razor/CodeActions/RemoteServices.cs

@@ -56,6 +56,9 @@ internal sealed class OOPSimplifyFullyQualifiedComponentCodeActionProvider : Sim
 [method: ImportingConstructor]
 internal sealed class OOPComponentAccessibilityCodeActionProvider(IFileSystem fileSystem) : ComponentAccessibilityCodeActionProvider(fileSystem);
 
+[Export(typeof(IRazorCodeActionProvider)), Shared]
+internal sealed class OOPUnboundDirectiveAttributeAddUsingCodeActionProvider : UnboundDirectiveAttributeAddUsingCodeActionProvider;
+
 [Export(typeof(IRazorCodeActionProvider)), Shared]
 internal sealed class OOPGenerateMethodCodeActionProvider : GenerateMethodCodeActionProvider;
 

src/Razor/test/Microsoft.AspNetCore.Razor.Test.Common.Cohosting/CohostTestBase.cs

@@ -152,7 +152,8 @@ protected abstract TextDocument CreateProjectAndRazorDocument(
         string? documentFilePath = null,
         (string fileName, string contents)[]? additionalFiles = null,
         bool inGlobalNamespace = false,
-        bool miscellaneousFile = false);
+        bool miscellaneousFile = false,
+        bool addDefaultImports = true);
 
     protected TextDocument CreateProjectAndRazorDocument(
         CodeAnalysis.Workspace remoteWorkspace,
@@ -161,7 +162,8 @@ protected TextDocument CreateProjectAndRazorDocument(
         string? documentFilePath = null,
         (string fileName, string contents)[]? additionalFiles = null,
         bool inGlobalNamespace = false,
-        bool miscellaneousFile = false)
+        bool miscellaneousFile = false,
+        bool addDefaultImports = true)
     {
         // Using IsLegacy means null == component, so easier for test authors
         var isComponent = fileKind != RazorFileKind.Legacy;
@@ -173,15 +175,15 @@ protected TextDocument CreateProjectAndRazorDocument(
         var projectId = ProjectId.CreateNewId(debugName: TestProjectData.SomeProject.DisplayName);
         var documentId = DocumentId.CreateNewId(projectId, debugName: documentFilePath);
 
-        return CreateProjectAndRazorDocument(remoteWorkspace, projectId, miscellaneousFile, documentId, documentFilePath, contents, additionalFiles, inGlobalNamespace);
+        return CreateProjectAndRazorDocument(remoteWorkspace, projectId, miscellaneousFile, documentId, documentFilePath, contents, additionalFiles, inGlobalNamespace, addDefaultImports);
     }
 
-    protected static TextDocument CreateProjectAndRazorDocument(CodeAnalysis.Workspace workspace, ProjectId projectId, bool miscellaneousFile, DocumentId documentId, string documentFilePath, string contents, (string fileName, string contents)[]? additionalFiles, bool inGlobalNamespace)
+    protected static TextDocument CreateProjectAndRazorDocument(CodeAnalysis.Workspace workspace, ProjectId projectId, bool miscellaneousFile, DocumentId documentId, string documentFilePath, string contents, (string fileName, string contents)[]? additionalFiles, bool inGlobalNamespace, bool addDefaultImports)
     {
-        return AddProjectAndRazorDocument(workspace.CurrentSolution, TestProjectData.SomeProject.FilePath, projectId, miscellaneousFile, documentId, documentFilePath, contents, additionalFiles, inGlobalNamespace);
+        return AddProjectAndRazorDocument(workspace.CurrentSolution, TestProjectData.SomeProject.FilePath, projectId, miscellaneousFile, documentId, documentFilePath, contents, additionalFiles, inGlobalNamespace, addDefaultImports);
     }
 
-    protected static TextDocument AddProjectAndRazorDocument(Solution solution, [DisallowNull] string? projectFilePath, ProjectId projectId, bool miscellaneousFile, DocumentId documentId, string documentFilePath, string contents, (string fileName, string contents)[]? additionalFiles, bool inGlobalNamespace)
+    protected static TextDocument AddProjectAndRazorDocument(Solution solution, [DisallowNull] string? projectFilePath, ProjectId projectId, bool miscellaneousFile, DocumentId documentId, string documentFilePath, string contents, (string fileName, string contents)[]? additionalFiles, bool inGlobalNamespace, bool addDefaultImports)
     {
         var builder = new RazorProjectBuilder(projectId);
 
@@ -202,7 +204,9 @@ protected static TextDocument AddProjectAndRazorDocument(Solution solution, [Dis
                 builder.RootNamespace = TestProjectData.SomeProject.RootNamespace;
             }
 
-            builder.AddAdditionalDocument(
+            if (addDefaultImports)
+            {
+                builder.AddAdditionalDocument(
                     filePath: TestProjectData.SomeProjectComponentImportFile1.FilePath,
                     text: SourceText.From("""
                         @using Microsoft.AspNetCore.Components
@@ -211,11 +215,12 @@ @using Microsoft.AspNetCore.Components.Forms
                         @using Microsoft.AspNetCore.Components.Routing
                         @using Microsoft.AspNetCore.Components.Web
                         """));
-            builder.AddAdditionalDocument(
+                builder.AddAdditionalDocument(
                     filePath: TestProjectData.SomeProjectImportFile.FilePath,
                     text: SourceText.From("""
                         @addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers
                         """));
+            }
 
             if (additionalFiles is not null)
             {

src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.Test/Cohost/CohostEndpointTestBase.cs

@@ -97,10 +97,11 @@ protected override TextDocument CreateProjectAndRazorDocument(
         string? documentFilePath = null,
         (string fileName, string contents)[]? additionalFiles = null,
         bool inGlobalNamespace = false,
-        bool miscellaneousFile = false)
+        bool miscellaneousFile = false,
+        bool addDefaultImports = true)
     {
         var remoteWorkspace = RemoteWorkspaceProvider.Instance.GetWorkspace();
-        var remoteDocument = base.CreateProjectAndRazorDocument(remoteWorkspace, contents, fileKind, documentFilePath, additionalFiles, inGlobalNamespace, miscellaneousFile);
+        var remoteDocument = base.CreateProjectAndRazorDocument(remoteWorkspace, contents, fileKind, documentFilePath, additionalFiles, inGlobalNamespace, miscellaneousFile, addDefaultImports);
 
         // In this project we simulate remote services running OOP by creating a different workspace with a different
         // set of services to represent the devenv Roslyn side of things. We don't have any actual solution syncing set
@@ -114,7 +115,8 @@ protected override TextDocument CreateProjectAndRazorDocument(
             remoteDocument.FilePath.AssumeNotNull(),
             contents,
             additionalFiles,
-            inGlobalNamespace);
+            inGlobalNamespace,
+            addDefaultImports);
     }
 
     private TextDocument CreateLocalProjectAndRazorDocument(
@@ -125,9 +127,10 @@ private TextDocument CreateLocalProjectAndRazorDocument(
         string documentFilePath,
         string contents,
         (string fileName, string contents)[]? additionalFiles,
-        bool inGlobalNamespace)
+        bool inGlobalNamespace,
+        bool addDefaultImports)
     {
-        var razorDocument = CreateProjectAndRazorDocument(LocalWorkspace, projectId, miscellaneousFile, documentId, documentFilePath, contents, additionalFiles, inGlobalNamespace);
+        var razorDocument = CreateProjectAndRazorDocument(LocalWorkspace, projectId, miscellaneousFile, documentId, documentFilePath, contents, additionalFiles, inGlobalNamespace, addDefaultImports);
 
         // If we're creating remote and local workspaces, then we'll return the local document, and have to allow
         // the remote service invoker to map from the local solution to the remote one.

src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.Test/Cohost/RetryProjectTest.cs

@@ -72,7 +72,7 @@ public async Task HoverRequest_MultipleProjects_ReturnsResults()
         var projectId = ProjectId.CreateNewId(debugName: TestProjectData.SomeProject.DisplayName);
         var documentFilePath = TestProjectData.AnotherProjectComponentFile1.FilePath;
         var documentId = DocumentId.CreateNewId(projectId, debugName: documentFilePath);
-        var otherDocument = AddProjectAndRazorDocument(document.Project.Solution, TestProjectData.AnotherProject.FilePath, projectId, miscellaneousFile: false, documentId, documentFilePath, otherInput.Text, additionalFiles: null, inGlobalNamespace: false);
+        var otherDocument = AddProjectAndRazorDocument(document.Project.Solution, TestProjectData.AnotherProject.FilePath, projectId, miscellaneousFile: false, documentId, documentFilePath, otherInput.Text, additionalFiles: null, inGlobalNamespace: false, addDefaultImports: true);
 
         // Make sure we have the document from our new fork
         document = otherDocument.Project.Solution.GetAdditionalDocument(document.Id).AssumeNotNull();

src/Razor/test/Microsoft.VisualStudioCode.RazorExtension.Test/CohostEndpointTestBase.cs

@@ -87,8 +87,9 @@ protected override TextDocument CreateProjectAndRazorDocument(
         string? documentFilePath = null,
         (string fileName, string contents)[]? additionalFiles = null,
         bool inGlobalNamespace = false,
-        bool miscellaneousFile = false)
+        bool miscellaneousFile = false,
+        bool addDefaultImports = true)
     {
-        return CreateProjectAndRazorDocument(LocalWorkspace, contents, fileKind, documentFilePath, additionalFiles, inGlobalNamespace, miscellaneousFile);
+        return CreateProjectAndRazorDocument(LocalWorkspace, contents, fileKind, documentFilePath, additionalFiles, inGlobalNamespace, miscellaneousFile, addDefaultImports);
     }
 }

src/Razor/test/Microsoft.VisualStudioCode.RazorExtension.Test/Endpoints/Shared/CodeActions/CohostCodeActionsEndpointTestBase.cs

@@ -36,9 +36,10 @@ private protected async Task VerifyCodeActionAsync(
         RazorFileKind? fileKind = null,
         string? documentFilePath = null,
         (string filePath, string contents)[]? additionalFiles = null,
-        (Uri fileUri, string contents)[]? additionalExpectedFiles = null)
+        (Uri fileUri, string contents)[]? additionalExpectedFiles = null,
+        bool addDefaultImports = true)
     {
-        var document = CreateRazorDocument(input, fileKind, documentFilePath, additionalFiles);
+        var document = CreateRazorDocument(input, fileKind, documentFilePath, additionalFiles, addDefaultImports: addDefaultImports);
 
         var codeAction = await VerifyCodeActionRequestAsync(document, input, codeActionName, childActionIndex, expectOffer: expected is not null);
 
@@ -55,7 +56,7 @@ private protected async Task VerifyCodeActionAsync(
         await VerifyCodeActionResultAsync(document, workspaceEdit, expected, additionalExpectedFiles);
     }
 
-    private protected TextDocument CreateRazorDocument(TestCode input, RazorFileKind? fileKind = null, string? documentFilePath = null, (string filePath, string contents)[]? additionalFiles = null)
+    private protected TextDocument CreateRazorDocument(TestCode input, RazorFileKind? fileKind = null, string? documentFilePath = null, (string filePath, string contents)[]? additionalFiles = null, bool addDefaultImports = true)
     {
         var fileSystem = (RemoteFileSystem)OOPExportProvider.GetExportedValue<IFileSystem>();
         fileSystem.GetTestAccessor().SetFileSystem(new TestFileSystem(additionalFiles));
@@ -73,7 +74,7 @@ private protected TextDocument CreateRazorDocument(TestCode input, RazorFileKind
             return options;
         });
 
-        return CreateProjectAndRazorDocument(input.Text, fileKind, documentFilePath, additionalFiles: additionalFiles);
+        return CreateProjectAndRazorDocument(input.Text, fileKind, documentFilePath, additionalFiles: additionalFiles, addDefaultImports: addDefaultImports);
     }
 
     private async Task<CodeAction?> VerifyCodeActionRequestAsync(TextDocument document, TestCode input, string codeActionName, int childActionIndex, bool expectOffer)