Add support for running available commands prior to MCP servers loading (#15596)

packages/core/src/config/config.test.ts

@@ -274,6 +274,35 @@ describe('Server Config (config.ts)', () => {
       );
     });
 
+    it('should not await MCP initialization', async () => {
+      const config = new Config({
+        ...baseParams,
+        checkpointing: false,
+      });
+
+      const { McpClientManager } = await import(
+        '../tools/mcp-client-manager.js'
+      );
+      let mcpStarted = false;
+
+      (McpClientManager as unknown as Mock).mockImplementation(() => ({
+        startConfiguredMcpServers: vi.fn().mockImplementation(async () => {
+          await new Promise((resolve) => setTimeout(resolve, 50));
+          mcpStarted = true;
+        }),
+        getMcpInstructions: vi.fn(),
+      }));
+
+      await config.initialize();
+
+      // Should return immediately, before MCP finishes (50ms delay)
+      expect(mcpStarted).toBe(false);
+
+      // Wait for it to eventually finish to avoid open handles
+      await new Promise((resolve) => setTimeout(resolve, 60));
+      expect(mcpStarted).toBe(true);
+    });
+
     describe('getCompressionThreshold', () => {
       it('should return the local compression threshold if it is set', async () => {
         const config = new Config({

packages/core/src/config/config.ts

@@ -796,12 +796,14 @@ export class Config {
       this,
       this.eventEmitter,
     );
-    const initMcpHandle = startupProfiler.start('initialize_mcp_clients');
-    await Promise.all([
-      await this.mcpClientManager.startConfiguredMcpServers(),
-      await this.getExtensionLoader().start(this),
-    ]);
-    initMcpHandle?.end();
+    // We do not await this promise so that the CLI can start up even if
+    // MCP servers are slow to connect.
+    Promise.all([
+      this.mcpClientManager.startConfiguredMcpServers(),
+      this.getExtensionLoader().start(this),
+    ]).catch((error) => {
+      debugLogger.error('Error initializing MCP clients:', error);
+    });
 
     if (this.skillsSupport) {
       this.getSkillManager().setAdminSettings(this.adminSkillsEnabled);