fix(core): complete MCP discovery when configured servers are skipped (#18586)

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

packages/core/src/tools/mcp-client-manager.test.ts

@@ -103,6 +103,43 @@ describe('McpClientManager', () => {
     expect(manager.getDiscoveryState()).toBe(MCPDiscoveryState.COMPLETED);
   });
 
+  it('should mark discovery completed when all configured servers are user-disabled', async () => {
+    mockConfig.getMcpServers.mockReturnValue({
+      'test-server': {},
+    });
+    mockConfig.getMcpEnablementCallbacks.mockReturnValue({
+      isSessionDisabled: vi.fn().mockReturnValue(false),
+      isFileEnabled: vi.fn().mockResolvedValue(false),
+    });
+
+    const manager = new McpClientManager('0.0.1', toolRegistry, mockConfig);
+    const promise = manager.startConfiguredMcpServers();
+    expect(manager.getDiscoveryState()).toBe(MCPDiscoveryState.IN_PROGRESS);
+    await promise;
+
+    expect(manager.getDiscoveryState()).toBe(MCPDiscoveryState.COMPLETED);
+    expect(manager.getMcpServerCount()).toBe(0);
+    expect(mockedMcpClient.connect).not.toHaveBeenCalled();
+    expect(mockedMcpClient.discover).not.toHaveBeenCalled();
+  });
+
+  it('should mark discovery completed when all configured servers are blocked', async () => {
+    mockConfig.getMcpServers.mockReturnValue({
+      'test-server': {},
+    });
+    mockConfig.getBlockedMcpServers.mockReturnValue(['test-server']);
+
+    const manager = new McpClientManager('0.0.1', toolRegistry, mockConfig);
+    const promise = manager.startConfiguredMcpServers();
+    expect(manager.getDiscoveryState()).toBe(MCPDiscoveryState.IN_PROGRESS);
+    await promise;
+
+    expect(manager.getDiscoveryState()).toBe(MCPDiscoveryState.COMPLETED);
+    expect(manager.getMcpServerCount()).toBe(0);
+    expect(mockedMcpClient.connect).not.toHaveBeenCalled();
+    expect(mockedMcpClient.discover).not.toHaveBeenCalled();
+  });
+
   it('should not discover tools if folder is not trusted', async () => {
     mockConfig.getMcpServers.mockReturnValue({
       'test-server': {},

packages/core/src/tools/mcp-client-manager.ts

@@ -337,6 +337,15 @@ export class McpClientManager {
         this.maybeDiscoverMcpServer(name, config),
       ),
     );
+
+    // If every configured server was skipped (for example because all are
+    // disabled by user settings), no discovery promise is created. In that
+    // case we must still mark discovery complete or the UI will wait forever.
+    if (this.discoveryState === MCPDiscoveryState.IN_PROGRESS) {
+      this.discoveryState = MCPDiscoveryState.COMPLETED;
+      this.eventEmitter?.emit('mcp-client-update', this.clients);
+    }
+
     await this.cliConfig.refreshMcpContext();
   }