added a validation step to detect a profile mismatch

Author: Yasindu20

src/browser.ts

@@ -43,13 +43,21 @@ function makeTargetFilter() {
   };
 }
 
+//Extracts the profile directory name from a user data dir path. 
+function getProfileNameFromUserDataDir(userDataDir: string): string {
+  const normalized = userDataDir.replace(/\\/g, '/');
+  const parts = normalized.split('/');
+  return parts[parts.length - 1] || 'Default';
+}
+
 export async function ensureBrowserConnected(options: {
   browserURL?: string;
   wsEndpoint?: string;
   wsHeaders?: Record<string, string>;
   devtools: boolean;
   channel?: Channel;
   userDataDir?: string;
+  profileDirectory?: string;
 }) {
   const {channel} = options;
   if (browser?.connected) {
@@ -126,6 +134,36 @@ export async function ensureBrowserConnected(options: {
       },
     );
   }
+
+  if (options.profileDirectory && options.userDataDir) {
+    try {
+      const portPath = path.join(options.userDataDir, 'DevToolsActivatePort');
+      const fileContent = await fs.promises.readFile(portPath, 'utf8');
+      const lines = fileContent.split('\n').map(line => line.trim()).filter(line => line);
+
+      if (lines.length >= 2) {
+        const browserPath = lines[1];
+        const actualProfile = getProfileNameFromUserDataDir(browserPath);
+        const requestedProfile = options.profileDirectory;
+
+        if (actualProfile !== requestedProfile) {
+          await browser.disconnect();
+          throw new Error(
+            `Profile mismatch: Requested profile "${requestedProfile}" but Chrome is running with profile "${actualProfile}". ` +
+            `Please close Chrome and restart with the correct profile, or remove the --profile-directory flag.`
+          );
+        }
+
+        logger(`Successfully validated profile: ${actualProfile}`);
+      }
+    } catch (error) {
+      if ((error as Error).message.includes('Profile mismatch')) {
+        throw error;
+      }
+
+      logger('Could not validate profile directory: ', error);
+    }
+  }
   logger('Connected Puppeteer');
   return browser;
 }

src/cli.ts

@@ -200,10 +200,10 @@ export const cliOptions = {
   },
   profileDirectory: {
     type: 'string',
-    description:
-      'Specify which Chrome profile to use by specifying its directory name (e.g., "Profile 1", "Default") inside a chrome user data directory. Only works with --autoConnect or when launching Chrome via the Chrome DevTools MCP server.',
+    description: 'Specify which Chrome profile to use by specifying its directory name (e.g., "Profile 1", "Default") inside a chrome user data directory. Only works with --autoConnect or when launching Chrome via the Chrome DevTools MCP server.',
     alias: 'profile-dir',
     conflicts: ['browserUrl', 'wsEndpoint'],
+  },
   usageStatistics: {
     type: 'boolean',
     // Marked as `false` until the feature is ready to be enabled by default.

src/main.ts

@@ -72,6 +72,7 @@ async function getContext(): Promise<McpContext> {
           channel: args.autoConnect ? (args.channel as Channel) : undefined,
           userDataDir: args.userDataDir,
           devtools,
+          profileDirectory: args.profileDirectory,
         })
       : await ensureBrowserLaunched({
           headless: args.headless,