[Bug]: "setExtraHTTPHeaders" and "route" methods don't work for <a> download links

[DeniDoman]

Version

1.43.1

Steps to reproduce

1. Clone my repo at https://github.com/denis-domanskii/playwright-download-intercept-issue
2. npm install
3. npm run test

Expected behavior

Two GET requests are intercepted, interceptionsCount variable equal 2

Actual behavior

Only one GET request is intercepted, interceptionsCount variable equal 1

Additional context

I want to test a web service protected by a token-based auth, so all requests must have an "X-Auth" header with a secret value.

Recently we added ability to download files, so I wrote an e2e test and it failed because when Playwright clicks on the <a href="/artifact.zip" download>Download link</a> link - it doesn't add the header, so server responds with 403 Forbidden and the test fails. I expect that the both setExtraHTTPHeaders and route methods should handle all requests, including download ones.

In my example repo, I am trying to intercept an archive download request:

test('Download intercept issue', async ({ page, context }) => {
  let interceptionsCount = 0;

  await context.route('https://denis-domanskii.github.io/playwright-download-intercept-issue/archive.zip', async route => {
    interceptionsCount++;
    await route.continue();
  });

  await page.goto('https://denis-domanskii.github.io/playwright-download-intercept-issue/');

  // FAIL: <a> tag with download is invisible for DevTools and Playwright intercept
  const downloadPromise1 = page.waitForEvent('download');
  await page.getByText("Download (with 'download' attr)").click();
  await downloadPromise1;

  // SUCCESS: <a> tag with download is visible for DevTools and Playwright intercept
  const downloadPromise2 = page.waitForEvent('download');
  await page.getByText("Download (without 'download' attr)").click();
  await downloadPromise2;

  expect(interceptionsCount).toBe(2);
});

As I can't provide logs from the server side with a proof that there were no the 'X-Auth' header, I added the interceptionsCount variable incrementing each time when a request to the zip archive is intercepted. So, it intercepted 1 times instead of 2 and the test fails.

context.setExtraHTTPHeaders() also doesn't work, I checked it using logs of my server - there were no added header too.

Environment

os: MacOS 14.2.1 (23C71)
npm: 10.2.4
node: v21.6.2
@playwright/test: 1.43.1

[DeniDoman]

Ok, probably it's a Chrome issue, because I see the that even Chrome DevTools ignores the request having the download attribute:

1. Visit the page https://denis-domanskii.github.io/playwright-download-intercept-issue/
2. Open Chrome DevTools "Network" tab (make sure that you capturing all requests)
3. Click the first button
4. Click the second button

Expected: Two requests are shown in the Network tab
Observed: Only one request is shown in the Network tab

So, could you please confirm that it's a Chrome issue and there is no way to handle it on Playwright side?
Chromium issue is raised too: https://issues.chromium.org/issues/338842124