feat: support --user-data-dir (#622)

Allow configuring Chrome's `--user-data-dir` to allow changing the
defaults to support discovery of running Chrome instances later on.

Author: OrKoN

README.md

@@ -343,9 +343,12 @@ The Chrome DevTools MCP server supports the following configuration option:
   - **Type:** string
 
 - **`--isolated`**
-  If specified, creates a temporary user-data-dir that is automatically cleaned up after the browser is closed.
+  If specified, creates a temporary user-data-dir that is automatically cleaned up after the browser is closed. Defaults to false.
   - **Type:** boolean
-  - **Default:** `false`
+
+- **`--userDataDir`**
+  Path to the user data directory for Chrome. Default is $HOME/.cache/chrome-devtools-mcp/chrome-profile$CHANNEL_SUFFIX_IF_NON_STABLE
+  - **Type:** string
 
 - **`--channel`**
   Specify a different Chrome channel that should be used. The default is the stable channel version.

src/cli.ts

@@ -88,8 +88,13 @@ export const cliOptions = {
   isolated: {
     type: 'boolean',
     description:
-      'If specified, creates a temporary user-data-dir that is automatically cleaned up after the browser is closed.',
-    default: false,
+      'If specified, creates a temporary user-data-dir that is automatically cleaned up after the browser is closed. Defaults to false.',
+  },
+  userDataDir: {
+    type: 'string',
+    description:
+      'Path to the user data directory for Chrome. Default is $HOME/.cache/chrome-devtools-mcp/chrome-profile$CHANNEL_SUFFIX_IF_NON_STABLE',
+    conflicts: ['browserUrl', 'wsEndpoint', 'isolated'],
   },
   channel: {
     type: 'string',
@@ -212,6 +217,10 @@ export function parseArguments(version: string, argv = process.argv) {
         'Disable tools in the performance category',
       ],
       ['$0 --no-category-network', 'Disable tools in the network category'],
+      [
+        '$0 --user-data-dir=/tmp/user-data-dir',
+        'Use a custom user data directory',
+      ],
     ]);
 
   return yargsInstance

src/main.ts

@@ -74,7 +74,8 @@ async function getContext(): Promise<McpContext> {
           headless: args.headless,
           executablePath: args.executablePath,
           channel: args.channel as Channel,
-          isolated: args.isolated,
+          isolated: args.isolated ?? false,
+          userDataDir: args.userDataDir,
           logFile,
           viewport: args.viewport,
           args: extraArgs,

tests/cli.test.ts

@@ -25,7 +25,6 @@ describe('cli args parsing', () => {
       ...defaultArgs,
       _: [],
       headless: false,
-      isolated: false,
       $0: 'npx chrome-devtools-mcp@latest',
       channel: 'stable',
     });
@@ -42,14 +41,31 @@ describe('cli args parsing', () => {
       ...defaultArgs,
       _: [],
       headless: false,
-      isolated: false,
       $0: 'npx chrome-devtools-mcp@latest',
       'browser-url': 'http://localhost:3000',
       browserUrl: 'http://localhost:3000',
       u: 'http://localhost:3000',
     });
   });
 
+  it('parses with user data dir', async () => {
+    const args = parseArguments('1.0.0', [
+      'node',
+      'main.js',
+      '--user-data-dir',
+      '/tmp/chrome-profile',
+    ]);
+    assert.deepStrictEqual(args, {
+      ...defaultArgs,
+      _: [],
+      headless: false,
+      $0: 'npx chrome-devtools-mcp@latest',
+      channel: 'stable',
+      'user-data-dir': '/tmp/chrome-profile',
+      userDataDir: '/tmp/chrome-profile',
+    });
+  });
+
   it('parses an empty browser url', async () => {
     const args = parseArguments('1.0.0', [
       'node',
@@ -61,7 +77,6 @@ describe('cli args parsing', () => {
       ...defaultArgs,
       _: [],
       headless: false,
-      isolated: false,
       $0: 'npx chrome-devtools-mcp@latest',
       'browser-url': undefined,
       browserUrl: undefined,
@@ -81,7 +96,6 @@ describe('cli args parsing', () => {
       ...defaultArgs,
       _: [],
       headless: false,
-      isolated: false,
       $0: 'npx chrome-devtools-mcp@latest',
       'executable-path': '/tmp/test 123/chrome',
       e: '/tmp/test 123/chrome',
@@ -100,7 +114,6 @@ describe('cli args parsing', () => {
       ...defaultArgs,
       _: [],
       headless: false,
-      isolated: false,
       $0: 'npx chrome-devtools-mcp@latest',
       channel: 'stable',
       viewport: {
@@ -121,7 +134,6 @@ describe('cli args parsing', () => {
       ...defaultArgs,
       _: [],
       headless: false,
-      isolated: false,
       $0: 'npx chrome-devtools-mcp@latest',
       channel: 'stable',
       'chrome-arg': ['--no-sandbox', '--disable-setuid-sandbox'],
@@ -140,7 +152,6 @@ describe('cli args parsing', () => {
       ...defaultArgs,
       _: [],
       headless: false,
-      isolated: false,
       $0: 'npx chrome-devtools-mcp@latest',
       'ws-endpoint': 'ws://127.0.0.1:9222/devtools/browser/abc123',
       wsEndpoint: 'ws://127.0.0.1:9222/devtools/browser/abc123',
@@ -159,7 +170,6 @@ describe('cli args parsing', () => {
       ...defaultArgs,
       _: [],
       headless: false,
-      isolated: false,
       $0: 'npx chrome-devtools-mcp@latest',
       'ws-endpoint': 'wss://example.com:9222/devtools/browser/abc123',
       wsEndpoint: 'wss://example.com:9222/devtools/browser/abc123',
@@ -192,7 +202,6 @@ describe('cli args parsing', () => {
       ...defaultArgs,
       _: [],
       headless: false,
-      isolated: false,
       $0: 'npx chrome-devtools-mcp@latest',
       channel: 'stable',
       'category-emulation': false,