feat(browserContext): support maximized viewport by dcrousso · Pull Request #43363 · microsoft/playwright

Devin Rousso (dcrousso) · 2026-10-13T22:49:03Z

allow viewport: 'maximized' to maximize native browser windows without a default emulated viewport

keep native maximization independent of browser fullscreen and the web Fullscreen API

restore and resize the native window when page.setViewportSize() enables viewport emulation

Dmitry Gozman (dgozman) · 2026-10-14T09:52:14Z

+Use `null` to disable the consistent viewport emulation. Learn more about [viewport emulation](../emulation#viewport).
+Use `"maximized"` to disable viewport emulation and maximize each native browser window. This is only supported in headed mode and does not enter fullscreen mode or trigger the web Fullscreen API.
+
+Calling [`method: Page.setViewportSize`] overrides `"maximized"` for that page and resizes its native window.


I think this sentence is confusing rather than helping.

Dmitry Gozman (dgozman) · 2026-10-14T09:53:14Z

  if (options.userAgent)
    lines.push(`  .setUserAgent(${quote(options.userAgent)})`);
-  if (options.viewport)
+  if (options.viewport && options.viewport !== 'maximized')


Why suddenly a java-only change? I'd expect either all languages or none.

Dmitry Gozman (dgozman) · 2026-10-14T09:53:36Z

+tests non-deterministic.
+:::
+
+## java-context-option-viewport


Let's sketch out how this API looks for other languages right away.

Dmitry Gozman (dgozman) · 2026-10-14T09:55:29Z

      properties:
        width: int
        height: int
+    viewportMaximized: boolean?


I'd recommend an enum viewportMode instead of noDefaultViewport+viewportMaximized. Otherwise it's unclear what noDefaultViewport: true, viewportMaximized: true means.

Dmitry Gozman (dgozman) · 2026-10-14T09:57:28Z

+  it('should create context in maximized window without entering fullscreen', async ({ browser, browserName }) => {
+    const context = await browser.newContext({ viewport: 'maximized' });
+    const page = await context.newPage();
+    await expect.poll(() => windowIsMaximized(context, page, browserName)).toBe(true);


Why do we have to poll here? Shouldn't the newPage already be maximized right away? I'd expect that from the API.

Dmitry Gozman (dgozman) · 2026-10-14T10:04:00Z

    startAutomaticVideoRecording(this._page);
    await Promise.all(promises);
+    if (contextOptions.viewportMaximized) {
+      await this._browserContext._browser._browserSession.send('Playwright.maximizeWindow', {


Why is this not a part of _updateViewport() method? It seems to be either viewport or maximized, but not both.

Similarly, does setting viewport undo Playwright.maximizeWindow? If so, perhaps it should be the same webkit protocol method as well?

Dmitry Gozman (dgozman) · 2026-10-14T10:05:55Z

+    await context.close();
+  });
+
+  it('should override maximized viewport when resizing a page', async ({ browser, browserName }) => {


I'd expect a symmetric test as well: create a context with viewport=567x345, then call page.setViewportSize('maximized') after.

Dmitry Gozman (dgozman) · 2026-10-14T10:06:25Z

        },
      }));
    }
+    if (this._options.viewportMaximized) {


It feels like this should be a part of doUpdateDefaultViewport().

Dmitry Gozman (dgozman) · 2026-10-14T10:07:10Z


  async _initialize(hasUIWindow: boolean) {
    const browserOptions = this._crPage._browserContext._browser.options;
+    const options = this._crPage._browserContext._options;


nit: contextOptions

Dmitry Gozman (dgozman) · 2026-10-14T10:07:47Z

      }));
    }
    // Make sure that the viewport emulationis set after the embedder window resize.
    promises.push(this._client.send('Emulation.setDeviceMetricsOverride', metricsOverride));


I'd expect the new "maximized" option to affect metricsOverride somehow...

github-actions · 2026-11-02T18:35:22Z

🟢 The CI failure is a confirmed pre-existing flake

Hi, I'm the Playwright bot and I checked the latest CI reports. The failure is unlikely to be caused by this PR.

Details

The latest MCP report has one failure; the latest library/test-runner report has none. CI tested PR head afcd11266 as merge commit 3d11b41cf.

Pre-existing flake

[chromium] › mcp/sse.spec.ts:196 › sse transport browser lifecycle (persistent) on mcp-ubuntu-latest-chromium — after reconnecting, localStorage.a was undefined instead of "42" in the failed job.
The exact same test and assertion failed on main at de4a9068c and on #43781, independently of this PR. In the refreshed results database, this test on the same Ubuntu/Chromium bot passed 726 runs and failed 6 outside this PR, from October 6 through November 2.
This PR changes shared viewport setup, but this test uses the default headless viewport, not viewport: 'maximized'. The MCP connection and persistent-profile handling are unchanged. The matching failures elsewhere support a pre-existing flake, not a viewport regression.

_{Triaged by the Playwright bot - agent run}

Dmitry Gozman (dgozman) · 2026-10-30T14:16:37Z

+          this._browserContext._browser._browserSession.send('Playwright.maximizeWindow', {
+            pageProxyId: this._pageProxySession.sessionId,
+          }),
+          this._session.send('Page.setScreenSizeOverride', {}),


Shouldn't this also clear Emulation.setDeviceMetricsOverride?

Dmitry Gozman (dgozman) · 2026-10-30T14:19:16Z

+  it.skip(({ isBidi }) => isBidi, 'maximized viewport is not supported by BiDi');
+
+  async function windowIsMaximized(context: BrowserContext, page: Page, browserName: string) {
+    if (browserName === 'chromium') {


I wonder why use CDP instead of checking outerWidth/outerHeight like in other browsers?

Dmitry Gozman (dgozman) · 2026-10-30T14:22:17Z


  override async doUpdateDefaultViewport() {
+    if (this._options.viewportMode === 'maximized') {
+      await this._browser.session.send('Browser.setWindowMaximized', {


Since we control juggler, I'd prefer to use Browser.setDefaultViewport with "maximized" option, because maximized vs viewport are mutually exclusive. Otherwise, it's unclear what juggler would do if you send both commands. WDYT?

Dmitry Gozman (dgozman) · 2026-11-03T15:03:48Z

      return;
    const promises = [];
    if (!preserveWindowBoundaries && this._windowId) {
+      if (options.viewportMode === 'maximized')


I think it is better to gate this by a local field this._windowState, similar to this._metricsOverride, which would mean "the last set window state".

Dmitry Gozman (dgozman) · 2026-11-03T15:06:18Z

+Use `viewport="maximized"` to disable viewport emulation and maximize native browser windows.  This is only supported in headed mode and does not enter fullscreen mode or trigger the web Fullscreen API.
+
+:::note
+The `no_viewport=True` and `viewport="maximized"` values opt out from the default presets and make viewport depend on the host window size defined by the operating system.  It makes the execution of the tests non-deterministic.


Seeing these two together shows the non-ideal api 😄

agreed

i kept the existing no_viewport option for compatibility rather than adding another flag for maximization

are we OK having a breaking change for this or do we need to keep it?

We have to keep it for sure.

Dmitry Gozman (dgozman) · 2026-11-03T15:08:35Z

+import { PythonLanguageGenerator } from '../../../packages/isomorphic/codegen/python';
 import { getAPIRequestCodeGen } from '../../../packages/trace-viewer/src/ui/codegen';

+test('CG-192 should generate maximized viewport context options', { annotation: { type: 'issue', description: 'https://github.com/microsoft/playwright/issues/1086' } }, () => {


I can't say I love this change detector test.

allow `viewport: 'maximized'` to maximize native browser windows without a default emulated viewport keep native maximization independent of browser fullscreen and the web Fullscreen API preserve the maximized outer window when `Page.setViewportSize()` enables viewport emulation

`noDefaultViewport` duplicates `viewportMode` use `viewportMode` as the only viewport mode setting

github-actions · 2026-11-04T01:08:03Z

Test results for "tests 1"

1 flaky

⚠️ [chromium-library] › library/video.spec.ts:762 › screencast › VI-030 should work with video+trace `@chromium-playwright-x64-ubuntu24-64-core-node22`

23594 passed, 725 skipped

Merge workflow run.

github-actions · 2026-11-04T01:16:54Z

Test results for "MCP"

5194 passed, 616 skipped

Merge workflow run.

Devin Rousso (dcrousso) mentioned this pull request Oct 13, 2026

feat(browserContext): support maximized viewport #42286

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Devin Rousso (dcrousso) requested review from Dmitry Gozman (dgozman) and Yury Semikhatsky (yury-s) October 13, 2026 22:51

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Dmitry Gozman (dgozman) reviewed Oct 14, 2026

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Devin Rousso (dcrousso) force-pushed the fix-1086 branch from 12ac87f to 86ffb77 Compare October 19, 2026 15:32

Devin Rousso (dcrousso) force-pushed the fix-1086 branch from 86ffb77 to d74f097 Compare October 28, 2026 18:36

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Devin Rousso (dcrousso) force-pushed the fix-1086 branch from d74f097 to b9b3719 Compare October 30, 2026 18:03

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Devin Rousso (dcrousso) force-pushed the fix-1086 branch from b9b3719 to afcd112 Compare November 2, 2026 17:50

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Devin Rousso (dcrousso) requested a review from Dmitry Gozman (dgozman) November 2, 2026 18:59

Pavel Feldman (pavelfeldman) added the milestone label Nov 2, 2026

Dmitry Gozman (dgozman) approved these changes Nov 3, 2026

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Devin Rousso (dcrousso) added 2 commits November 3, 2026 17:35

chore(protocol): remove noDefaultViewport

c6e835a

`noDefaultViewport` duplicates `viewportMode` use `viewportMode` as the only viewport mode setting

Devin Rousso (dcrousso) force-pushed the fix-1086 branch from afcd112 to c6e835a Compare November 4, 2026 00:35

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github-actions Bot commented Nov 2, 2026

🟢 The CI failure is a confirmed pre-existing flake

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github-actions Bot commented Nov 4, 2026

Test results for "tests 1"

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github-actions Bot commented Nov 4, 2026

Test results for "MCP"

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Devin Rousso (dcrousso) commented Oct 13, 2026 •

edited

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