feat: add browser configuration tool and fix STDIO mode

- Add browser_configure tool to change headless/headed mode, viewport, and user agent during session
- Fix STDIO entry point by preventing stdin close handlers in STDIO mode
- Fix headed mode default behavior when DISPLAY is available on Linux
- Add dynamic browser configuration update mechanism in Context class

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/tools/configure.ts

@@ -0,0 +1,87 @@
+/**
+ * Copyright (c) Microsoft Corporation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { z } from 'zod';
+import { defineTool } from './tool.js';
+import type { Context } from '../context.js';
+import type { Response } from '../response.js';
+
+const configureSchema = z.object({
+  headless: z.boolean().optional().describe('Whether to run the browser in headless mode'),
+  viewport: z.object({
+    width: z.number(),
+    height: z.number(),
+  }).optional().describe('Browser viewport size'),
+  userAgent: z.string().optional().describe('User agent string for the browser'),
+});
+
+export default [
+  defineTool({
+    capability: 'core',
+    schema: {
+      name: 'browser_configure',
+      title: 'Configure browser settings',
+      description: 'Change browser configuration settings like headless/headed mode, viewport size, or user agent for subsequent operations. This will close the current browser and restart it with new settings.',
+      inputSchema: configureSchema,
+      type: 'destructive',
+    },
+    handle: async (context: Context, params: z.output<typeof configureSchema>, response: Response) => {
+      try {
+        const currentConfig = context.config;
+        const changes: string[] = [];
+        
+        // Track what's changing
+        if (params.headless !== undefined) {
+          const currentHeadless = currentConfig.browser.launchOptions.headless;
+          if (params.headless !== currentHeadless) {
+            changes.push(`headless: ${currentHeadless} → ${params.headless}`);
+          }
+        }
+        
+        if (params.viewport) {
+          const currentViewport = currentConfig.browser.contextOptions.viewport;
+          if (!currentViewport || currentViewport.width !== params.viewport.width || currentViewport.height !== params.viewport.height) {
+            changes.push(`viewport: ${currentViewport?.width || 'default'}x${currentViewport?.height || 'default'} → ${params.viewport.width}x${params.viewport.height}`);
+          }
+        }
+        
+        if (params.userAgent) {
+          const currentUA = currentConfig.browser.contextOptions.userAgent;
+          if (params.userAgent !== currentUA) {
+            changes.push(`userAgent: ${currentUA || 'default'} → ${params.userAgent}`);
+          }
+        }
+        
+        if (changes.length === 0) {
+          response.addResult('No configuration changes detected. Current settings remain the same.');
+          return;
+        }
+        
+        // Apply the configuration changes
+        await context.updateBrowserConfig({
+          headless: params.headless,
+          viewport: params.viewport,
+          userAgent: params.userAgent,
+        });
+        
+        response.addResult(`Browser configuration updated successfully:\n${changes.map(c => `• ${c}`).join('\n')}\n\nThe browser has been restarted with the new settings.`);
+        
+      } catch (error) {
+        throw new Error(`Failed to update browser configuration: ${error}`);
+      }
+    },
+  }),
+];