Go all in on stdio and gate all the tools behind the launch tool (microsoft#264088)

* Removes HTTP logic
* enable/disables automation tools based on if app is opened
* kill and re-create the playwright server based on if app is opened

Author: TylerLeonhardt

test/mcp/README.md

@@ -27,28 +27,6 @@ That's it! It should automatically compile everything needed.
 
 Then you can use `/playwright` to ask specific questions.
 
-## Quick Start - HTTP
-
-Getting started with the MCP server is simple - just run the pre-configured Code - OSS task:
-
-1. Launch the MCP Server
-
-   In Code - OSS, open the Command Palette (`Ctrl+Shift+P` / `Cmd+Shift+P`) and run:
-
-   ```
-   Tasks: Run Task → Launch MCP Server
-   ```
-
-2. Start the MCP Server
-
-   Open the Command Palette and run:
-   ```
-   MCP: List Servers → vscode-playwright-mcp → Start Server
-   ```
-   or open [mcp.json](../../.vscode/mcp.json) and start it from there.
-
-That's it! Your AI assistant can now use browser automation capabilities through MCP.
-
 ## Arguments
 
 Open the [mcp.json](../../.vscode/mcp.json) and modify the `args`:
@@ -149,11 +127,6 @@ test/mcp/
 - Check that port 33418 is not already in use
 - Verify all dependencies are installed with `npm install`
 
-### Connection Issues
-- Confirm the server is running on `http://localhost:33418/mcp`
-- Check your AI assistant's MCP configuration
-- Look for CORS-related errors in browser console
-
 ### Browser Automation Issues
 - Ensure Code - OSS has been built and run at least once
 - Check the server logs for Playwright-related errors

test/mcp/package.json

@@ -9,7 +9,6 @@
     "watch-automation": "cd ../automation && npm run watch",
     "watch-mcp": "node ../../node_modules/typescript/bin/tsc --watch --preserveWatchOutput",
     "watch": "npm-run-all -lp watch-automation watch-mcp",
-    "start-http": "npm run -s compile && node ./out/main.js",
     "start-stdio": "npm run -s compile && node ./out/stdio.js"
   },
   "dependencies": {

test/mcp/src/application.ts

@@ -4,7 +4,7 @@
  *--------------------------------------------------------------------------------------------*/
 
 import * as playwright from 'playwright';
-import { getDevElectronPath, Quality, ConsoleLogger, FileLogger, Logger, MultiLogger, getBuildElectronPath, getBuildVersion, measureAndLog } from '../../automation';
+import { getDevElectronPath, Quality, ConsoleLogger, FileLogger, Logger, MultiLogger, getBuildElectronPath, getBuildVersion, measureAndLog, Application } from '../../automation';
 import * as path from 'path';
 import * as fs from 'fs';
 import * as os from 'os';
@@ -281,7 +281,6 @@ async function ensureStableCode(): Promise<void> {
 }
 
 async function setup(): Promise<void> {
-	logger.log('Test data path:', testDataPath);
 	logger.log('Preparing smoketest setup...');
 
 	if (!opts.web && !opts.remote && opts.build) {
@@ -329,3 +328,55 @@ export async function getApplication() {
 	});
 	return application;
 }
+
+export class ApplicationService {
+	private _application: Application | undefined;
+	private _closing: Promise<void> | undefined;
+	private _listeners: ((app: Application | undefined) => void)[] = [];
+
+	onApplicationChange(listener: (app: Application | undefined) => void): void {
+		this._listeners.push(listener);
+	}
+
+	removeApplicationChangeListener(listener: (app: Application | undefined) => void): void {
+		const index = this._listeners.indexOf(listener);
+		if (index >= 0) {
+			this._listeners.splice(index, 1);
+		}
+	}
+
+	get application(): Application | undefined {
+		return this._application;
+	}
+
+	async getOrCreateApplication(): Promise<Application> {
+		if (this._closing) {
+			await this._closing;
+		}
+		if (!this._application) {
+			this._application = await getApplication();
+			this._application.code.driver.browserContext.on('close', () => {
+				this._closing = (async () => {
+					if (this._application) {
+						this._application.code.driver.browserContext.removeAllListeners();
+						await this._application.stop();
+						this._application = undefined;
+						this._runAllListeners();
+					}
+				})();
+			});
+			this._runAllListeners();
+		}
+		return this._application;
+	}
+
+	private _runAllListeners() {
+		for (const listener of this._listeners) {
+			try {
+				listener(this._application);
+			} catch (error) {
+				console.error('Error occurred in application change listener:', error);
+			}
+		}
+	}
+}

test/mcp/src/automation.ts

@@ -4,25 +4,47 @@
  *--------------------------------------------------------------------------------------------*/
 
 import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
-import { getApplication } from './application';
+import { ApplicationService } from './application';
 import { applyAllTools } from './automationTools/index.js';
-import { Application } from '../../automation';
 import type { Server } from '@modelcontextprotocol/sdk/server/index.js';
 
-export async function getServer(app?: Application): Promise<Server> {
+export async function getServer(appService: ApplicationService): Promise<Server> {
 	const server = new McpServer({
 		name: 'VS Code Automation Server',
 		version: '1.0.0',
 		title: 'An MCP Server that can interact with a local build of VS Code. Used for verifying UI behavior.'
 	}, { capabilities: { logging: {} } });
 
-	const application = app ?? await getApplication();
+	server.tool(
+		'vscode_automation_start',
+		'Start VS Code Build',
+		{},
+		async () => {
+			const app = await appService.getOrCreateApplication();
+			return {
+				content: [{
+					type: 'text' as const,
+					text: app ? `VS Code started successfully` : `Failed to start VS Code`
+				}]
+			};
+		}
+	);
 
 	// Apply all VS Code automation tools using the modular structure
-	applyAllTools(server, application);
+	const registeredTools = applyAllTools(server, appService);
+	const app = appService.application;
+	if (app) {
+		registeredTools.forEach(t => t.enable());
+	} else {
+		registeredTools.forEach(t => t.disable());
+	}
 
-	application.code.driver.browserContext.on('close', async () => {
-		await server.close();
+	appService.onApplicationChange(app => {
+		if (app) {
+			registeredTools.forEach(t => t.enable());
+		} else {
+			registeredTools.forEach(t => t.disable());
+		}
 	});
 
 	return server.server;

test/mcp/src/automationTools/activityBar.ts

@@ -3,13 +3,15 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
-import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
-import { Application } from '../../../automation';
+import { McpServer, RegisteredTool } from '@modelcontextprotocol/sdk/server/mcp.js';
+import { ApplicationService } from '../application';
 
 /**
  * Activity Bar Tools
  */
-export function applyActivityBarTools(server: McpServer, app: Application) {
+export function applyActivityBarTools(server: McpServer, appService: ApplicationService): RegisteredTool[] {
+	const tools: RegisteredTool[] = [];
+
 	// Doesn't seem particularly useful
 	// server.tool(
 	// 	'vscode_automation_activitybar_wait_for_position',
@@ -29,4 +31,6 @@ export function applyActivityBarTools(server: McpServer, app: Application) {
 	// 		};
 	// 	}
 	// );
+
+	return tools;
 }

test/mcp/src/automationTools/core.ts

@@ -3,27 +3,15 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
-import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
-import { Application } from '../../../automation';
+import { McpServer, RegisteredTool } from '@modelcontextprotocol/sdk/server/mcp.js';
+import { ApplicationService } from '../application';
 
 /**
  * Core Application Management Tools
  */
-export function applyCoreTools(server: McpServer, app: Application) {
-	// A dummy start tool just so that the model has something to hold on to.
-	server.tool(
-		'vscode_automation_start',
-		'Start VS Code Build',
-		{},
-		async () => {
-			return {
-				content: [{
-					type: 'text' as const,
-					text: `VS Code started successfully`
-				}]
-			};
-		}
-	);
+export function applyCoreTools(server: McpServer, appService: ApplicationService): RegisteredTool[] {
+	const tools: RegisteredTool[] = [];
+
 	// Playwright keeps using this as a start... maybe it needs some massaging
 	// server.tool(
 	// 	'vscode_automation_restart',
@@ -166,4 +154,6 @@ export function applyCoreTools(server: McpServer, app: Application) {
 	// 		};
 	// 	}
 	// );
+
+	return tools;
 }

test/mcp/src/automationTools/debug.ts

@@ -3,18 +3,20 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
-import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
-import { Application } from '../../../automation';
+import { McpServer, RegisteredTool } from '@modelcontextprotocol/sdk/server/mcp.js';
+import { ApplicationService } from '../application';
 import { z } from 'zod';
 
 /**
  * Debug Tools
  */
-export function applyDebugTools(server: McpServer, app: Application) {
-	server.tool(
+export function applyDebugTools(server: McpServer, appService: ApplicationService): RegisteredTool[] {
+	const tools: RegisteredTool[] = [];
+	tools.push(server.tool(
 		'vscode_automation_debug_open',
 		'Open the debug viewlet',
 		async () => {
+			const app = await appService.getOrCreateApplication();
 			await app.workbench.debug.openDebugViewlet();
 			return {
 				content: [{
@@ -23,16 +25,17 @@ export function applyDebugTools(server: McpServer, app: Application) {
 				}]
 			};
 		}
-	);
+	));
 
-	server.tool(
+	tools.push(server.tool(
 		'vscode_automation_debug_set_breakpoint',
 		'Set a breakpoint on a specific line',
 		{
 			lineNumber: z.number().describe('Line number to set breakpoint on')
 		},
 		async (args) => {
 			const { lineNumber } = args;
+			const app = await appService.getOrCreateApplication();
 			await app.workbench.debug.setBreakpointOnLine(lineNumber);
 			return {
 				content: [{
@@ -41,12 +44,13 @@ export function applyDebugTools(server: McpServer, app: Application) {
 				}]
 			};
 		}
-	);
+	));
 
-	server.tool(
+	tools.push(server.tool(
 		'vscode_automation_debug_start',
 		'Start debugging',
 		async () => {
+			const app = await appService.getOrCreateApplication();
 			const result = await app.workbench.debug.startDebugging();
 			return {
 				content: [{
@@ -55,7 +59,7 @@ export function applyDebugTools(server: McpServer, app: Application) {
 				}]
 			};
 		}
-	);
+	));
 
 	// Playwright can probably figure this out
 	// server.tool(
@@ -131,4 +135,6 @@ export function applyDebugTools(server: McpServer, app: Application) {
 	// 		};
 	// 	}
 	// );
+
+	return tools;
 }