Add support for MCP server instructions behind config option (#13432)

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

packages/core/src/utils/memoryDiscovery.test.ts

@@ -934,4 +934,43 @@ included directory memory
     expect(config.getGeminiMdFilePaths()).equals(refreshResult.filePaths);
     expect(mockEventListener).toHaveBeenCalledExactlyOnceWith(refreshResult);
   });
+
+  it('should include MCP instructions in user memory', async () => {
+    const mockConfig = {
+      getWorkingDir: vi.fn().mockReturnValue(cwd),
+      shouldLoadMemoryFromIncludeDirectories: vi.fn().mockReturnValue(false),
+      getDebugMode: vi.fn().mockReturnValue(false),
+      getFileService: vi
+        .fn()
+        .mockReturnValue(new FileDiscoveryService(projectRoot)),
+      getExtensionLoader: vi
+        .fn()
+        .mockReturnValue(new SimpleExtensionLoader([])),
+      isTrustedFolder: vi.fn().mockReturnValue(true),
+      getImportFormat: vi.fn().mockReturnValue('tree'),
+      getFileFilteringOptions: vi.fn().mockReturnValue(undefined),
+      getDiscoveryMaxDirs: vi.fn().mockReturnValue(200),
+      setUserMemory: vi.fn(),
+      setGeminiMdFileCount: vi.fn(),
+      setGeminiMdFilePaths: vi.fn(),
+      getMcpClientManager: vi.fn().mockReturnValue({
+        getMcpInstructions: vi
+          .fn()
+          .mockReturnValue(
+            "\n\n# Instructions for MCP Server 'extension-server'\nAlways be polite.",
+          ),
+      }),
+    } as unknown as Config;
+
+    await refreshServerHierarchicalMemory(mockConfig);
+
+    expect(mockConfig.setUserMemory).toHaveBeenCalledWith(
+      expect.stringContaining(
+        "# Instructions for MCP Server 'extension-server'",
+      ),
+    );
+    expect(mockConfig.setUserMemory).toHaveBeenCalledWith(
+      expect.stringContaining('Always be polite.'),
+    );
+  });
 });

packages/core/src/utils/memoryDiscovery.ts

@@ -569,7 +569,12 @@ export async function refreshServerHierarchicalMemory(config: Config) {
     config.getFileFilteringOptions(),
     config.getDiscoveryMaxDirs(),
   );
-  config.setUserMemory(result.memoryContent);
+  const mcpInstructions =
+    config.getMcpClientManager()?.getMcpInstructions() || '';
+  const finalMemory = [result.memoryContent, mcpInstructions.trimStart()]
+    .filter(Boolean)
+    .join('\n\n');
+  config.setUserMemory(finalMemory);
   config.setGeminiMdFileCount(result.fileCount);
   config.setGeminiMdFilePaths(result.filePaths);
   coreEvents.emit(CoreEvent.MemoryChanged, result);