test: cover the env-backed welcome actions with a seeded Python env

When a Python env is configured the welcome local-server actions become
enabled; pin that. The test seeds `app-data.json` with a `pythonPath` (the real
config seam the app reads) and asserts the "New notebook" action loses its
`disabled` class. Gated on JLAB_TEST_PYTHON_PATH (CI provisions a venv with
jupyterlab and sets it; skipped locally when absent) so the suite stays green
everywhere. Driving the JupyterLab content itself is left to a separate
plain-Playwright suite against the server URL (Phase 3).

Note: AI-assisted (Claude Code). Manually verified: passes locally with
JLAB_TEST_PYTHON_PATH set to a jupyterlab env; skips cleanly when unset.

Author: notluquis

test/e2e/python-env.test.ts

@@ -0,0 +1,30 @@
+import { expect, test } from '@playwright/test';
+import { cleanup, launchApp, pageByTitle } from './helpers';
+
+// These tests need a real Python env with jupyterlab. CI provisions one and
+// points JLAB_TEST_PYTHON_PATH at it; locally, set it to any python that has
+// jupyterlab installed. Skipped when absent so the suite stays green everywhere.
+const pythonPath = process.env.JLAB_TEST_PYTHON_PATH;
+
+test.describe('with a seeded Python environment', () => {
+  test.skip(
+    !pythonPath,
+    'set JLAB_TEST_PYTHON_PATH to a python with jupyterlab'
+  );
+
+  test('the welcome local-server actions are enabled', async () => {
+    const { app, userDataDir } = await launchApp({ pythonPath });
+    try {
+      const welcome = await pageByTitle(app, /welcome/i);
+      await welcome.waitForLoadState('domcontentloaded');
+      const newNotebook = welcome.locator('#new-notebook-link');
+      await expect(newNotebook).toBeVisible();
+      // The app validates the seeded env and emits EnableLocalServerActions,
+      // which removes the `disabled` class from the local-server actions.
+      await expect(newNotebook).not.toHaveClass(/disabled/, { timeout: 20000 });
+    } finally {
+      await app.close();
+      cleanup(userDataDir);
+    }
+  });
+});