Gate built-in agents behind experimental flag

Co-Authored-By: Paperclip <noreply@paperclip.ing>

packages/shared/src/validators/instance.ts

@@ -49,6 +49,7 @@ export const instanceExperimentalSettingsSchema = z.object({
   enableExperimentalFileViewer: z.boolean().default(false),
   enableCloudSync: z.boolean().default(false),
   enableExternalObjects: z.boolean().default(false),
+  enableBuiltInAgents: z.boolean().default(false),
   enableGoalsSidebarLink: z.boolean().default(false),
   enableServerInfoDebugView: z.boolean().default(false),
   autoRestartDevServerWhenIdle: z.boolean().default(false),