fix: correctly pass in userDataDir to chrome launcher (#1462)

# why
Stagehand's `userDataDir` was ignored b/c of `chrome-launcher`'s default
automatic `--user-data-flag`. Fixes #1377

# what changed
Directly pass in `userDataDir` via `launch()` options

# test plan
Tested that Chrome now correctly uses the custom `userDataDir`







<!-- This is an auto-generated description by cubic. -->
---
## Summary by cubic
Fix Chrome launch to respect the provided userDataDir by passing it
directly to chrome-launcher via launch options. Previously, the flag was
ignored due to chrome-launcher’s default user-data-dir.

<sup>Written for commit dfc55fa.
Summary will update automatically on new commits.</sup>

<!-- End of auto-generated description by cubic. -->

Author: shrey150

.changeset/tall-icons-type.md

@@ -0,0 +1,5 @@
+---
+"@browserbasehq/stagehand": patch
+---
+
+fix: correctly pass userDataDir to chrome launcher

packages/core/lib/v3/launch/local.ts

@@ -20,13 +20,13 @@ export async function launchLocalChrome(
     "--no-default-browser-check",
     "--disable-dev-shm-usage",
     "--site-per-process",
-    opts.userDataDir ? `--user-data-dir=${opts.userDataDir}` : undefined,
     ...(opts.chromeFlags ?? []),
   ].filter((f): f is string => typeof f === "string");
 
   const chrome = await launch({
     chromePath: opts.chromePath,
     chromeFlags,
+    userDataDir: opts.userDataDir,
   });
 
   const ws = await waitForWebSocketDebuggerUrl(

packages/core/lib/v3/tests/user-data-dir.spec.ts

@@ -0,0 +1,48 @@
+import { test, expect } from "@playwright/test";
+import { V3 } from "../v3";
+import { v3TestConfig } from "./v3.config";
+import * as fs from "fs";
+import * as path from "path";
+import * as os from "os";
+
+test.describe("userDataDir persistence", () => {
+  let v3: V3;
+  let testDir: string;
+
+  test.beforeEach(() => {
+    testDir = fs.mkdtempSync(
+      path.join(os.tmpdir(), "stagehand-userdata-test-"),
+    );
+  });
+
+  test.afterEach(async () => {
+    await v3?.close?.().catch(() => {});
+    if (testDir && fs.existsSync(testDir)) {
+      fs.rmSync(testDir, { recursive: true, force: true });
+    }
+  });
+
+  test("Chrome uses the specified userDataDir", async () => {
+    v3 = new V3({
+      ...v3TestConfig,
+      localBrowserLaunchOptions: {
+        ...v3TestConfig.localBrowserLaunchOptions,
+        userDataDir: testDir,
+        preserveUserDataDir: true,
+      },
+    });
+
+    await v3.init();
+
+    const page = v3.context.pages()[0];
+    await page.goto("about:blank");
+
+    await expect
+      .poll(() => fs.existsSync(path.join(testDir, "Default")), {
+        timeout: 10_000,
+      })
+      .toBe(true);
+
+    expect(fs.existsSync(path.join(testDir, "Local State"))).toBe(true);
+  });
+});