Add reference assemblies dir parameter

src/Features/Core/Portable/SemanticSearch/IRemoteSemanticSearchService.cs

@@ -26,7 +26,7 @@ internal interface ICallback
         ValueTask ItemsCompletedAsync(RemoteServiceCallbackId callbackId, int itemCount, CancellationToken cancellationToken);
     }
 
-    ValueTask<CompileQueryResult> CompileQueryAsync(string query, CancellationToken cancellationToken);
+    ValueTask<CompileQueryResult> CompileQueryAsync(string query, string referenceAssembliesDir, CancellationToken cancellationToken);
     ValueTask<ExecuteQueryResult> ExecuteQueryAsync(Checksum solutionChecksum, RemoteServiceCallbackId callbackId, CompiledQueryId queryId, CancellationToken cancellationToken);
     ValueTask DiscardQueryAsync(CompiledQueryId queryId, CancellationToken cancellationToken);
 }
@@ -123,7 +123,7 @@ public async ValueTask<ClassificationOptions> GetClassificationOptionsAsync(stri
         }
 
         var result = await client.TryInvokeAsync<IRemoteSemanticSearchService, CompileQueryResult>(
-            (service, cancellationToken) => service.CompileQueryAsync(query, cancellationToken),
+            (service, cancellationToken) => service.CompileQueryAsync(query, SemanticSearchWorkspace.ReferenceAssembliesDirectory, cancellationToken),
             cancellationToken).ConfigureAwait(false);
 
         return result.Value;

src/Features/Core/Portable/SemanticSearch/ISemanticSearchQueryService.cs

@@ -15,9 +15,11 @@ internal interface ISemanticSearchQueryService
     /// Compiles a query. The query has to be executed or discarded.
     /// </summary>
     /// <param name="query">Query (top-level code).</param>
+    /// <param name="referenceAssembliesDir">Directory containing reference assemblies.</param>
     CompileQueryResult CompileQuery(
         SolutionServices services,
         string query,
+        string referenceAssembliesDir,
         TraceSource traceSource,
         CancellationToken cancellationToken);
 

src/Features/Core/Portable/SemanticSearch/SemanticSearchWorkspace.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.IO;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.Host;
@@ -13,6 +14,12 @@ namespace Microsoft.CodeAnalysis.SemanticSearch;
 internal abstract class SemanticSearchWorkspace(HostServices services, ISemanticSearchSolutionService solutionService)
     : Workspace(services, WorkspaceKind.SemanticSearch)
 {
+    /// <summary>
+    /// Location of the directory containing reference assemblies used for semantic search queries.
+    /// The assemblies are shared between design-time (in-proc workspace) and compile-time (OOP service).
+    /// </summary>
+    public static readonly string ReferenceAssembliesDirectory = Path.Combine(Path.GetDirectoryName(typeof(SemanticSearchWorkspace).Assembly.Location)!, "SemanticSearchRefs");
+
     public override bool CanOpenDocuments
         => true;
 

src/Features/ExternalAccess/Copilot/Internal/SemanticSearch/CopilotSemanticSearchQueryService.cs

@@ -42,11 +42,11 @@ public ValueTask OnUserCodeExceptionAsync(ICopilotSemanticSearchResultsObserver.
                 cancellationToken);
     }
 
-    public CompileQueryResult CompileQuery(SolutionServices services, string query, TraceSource traceSource, CancellationToken cancellationToken)
+    public CompileQueryResult CompileQuery(SolutionServices services, string query, string referenceAssembliesDir, TraceSource traceSource, CancellationToken cancellationToken)
     {
         Contract.ThrowIfNull(impl);
 
-        var result = impl.CompileQuery(services, query, traceSource, cancellationToken);
+        var result = impl.CompileQuery(services, query, referenceAssembliesDir, traceSource, cancellationToken);
         return new(
             new(result.QueryId.Id),
             result.CompilationErrors.SelectAsArray(static e => new QueryCompilationError(e.Id, e.Message, e.Span)),

src/Features/ExternalAccess/Copilot/InternalAPI.Unshipped.txt

@@ -107,7 +107,7 @@ Microsoft.CodeAnalysis.ExternalAccess.Copilot.SemanticSearch.ICopilotSemanticSea
 Microsoft.CodeAnalysis.ExternalAccess.Copilot.SemanticSearch.ICopilotSemanticSearchQueryService.CompiledQueryId.Equals(Microsoft.CodeAnalysis.ExternalAccess.Copilot.SemanticSearch.ICopilotSemanticSearchQueryService.CompiledQueryId other) -> bool
 Microsoft.CodeAnalysis.ExternalAccess.Copilot.SemanticSearch.ICopilotSemanticSearchQueryService.CompiledQueryId.Id.get -> int
 Microsoft.CodeAnalysis.ExternalAccess.Copilot.SemanticSearch.ICopilotSemanticSearchQueryService.CompiledQueryId.Id.init -> void
-Microsoft.CodeAnalysis.ExternalAccess.Copilot.SemanticSearch.ICopilotSemanticSearchQueryService.CompileQuery(Microsoft.CodeAnalysis.Host.SolutionServices! services, string! query, System.Diagnostics.TraceSource! traceSource, System.Threading.CancellationToken cancellationToken) -> Microsoft.CodeAnalysis.ExternalAccess.Copilot.SemanticSearch.ICopilotSemanticSearchQueryService.CompileQueryResult
+Microsoft.CodeAnalysis.ExternalAccess.Copilot.SemanticSearch.ICopilotSemanticSearchQueryService.CompileQuery(Microsoft.CodeAnalysis.Host.SolutionServices! services, string! query, string! referenceAssembliesDir, System.Diagnostics.TraceSource! traceSource, System.Threading.CancellationToken cancellationToken) -> Microsoft.CodeAnalysis.ExternalAccess.Copilot.SemanticSearch.ICopilotSemanticSearchQueryService.CompileQueryResult
 Microsoft.CodeAnalysis.ExternalAccess.Copilot.SemanticSearch.ICopilotSemanticSearchQueryService.CompileQueryResult
 Microsoft.CodeAnalysis.ExternalAccess.Copilot.SemanticSearch.ICopilotSemanticSearchQueryService.CompileQueryResult.CompilationErrors.get -> System.Collections.Immutable.ImmutableArray<Microsoft.CodeAnalysis.ExternalAccess.Copilot.SemanticSearch.ICopilotSemanticSearchQueryService.QueryCompilationError>
 Microsoft.CodeAnalysis.ExternalAccess.Copilot.SemanticSearch.ICopilotSemanticSearchQueryService.CompileQueryResult.CompilationErrors.init -> void

src/Features/ExternalAccess/Copilot/SemanticSearch/ICopilotSemanticSearchQueryService.cs

@@ -17,6 +17,7 @@ internal interface ICopilotSemanticSearchQueryService
     CompileQueryResult CompileQuery(
         SolutionServices services,
         string query,
+        string referenceAssembliesDir,
         TraceSource traceSource,
         CancellationToken cancellationToken);
 

src/Workspaces/Remote/ServiceHub/Services/SemanticSearch/RemoteSemanticSearchService.cs

@@ -52,13 +52,14 @@ public ValueTask OnUserCodeExceptionAsync(UserCodeExceptionInfo exception, Cance
     /// </summary>
     public ValueTask<CompileQueryResult> CompileQueryAsync(
         string query,
+        string referenceAssembliesDir,
         CancellationToken cancellationToken)
     {
         return RunServiceAsync(cancellationToken =>
         {
             var services = GetWorkspaceServices();
             var service = GetRequiredService<ISemanticSearchQueryService>();
-            var result = service.CompileQuery(services, query, TraceLogger, cancellationToken);
+            var result = service.CompileQuery(services, query, referenceAssembliesDir, TraceLogger, cancellationToken);
 
             return ValueTask.FromResult(result);
         }, cancellationToken);