fix(chromium): propagate setUserAgent() to service workers via Network domain

[sriram687]

fix(chromium): propagate setUserAgent() to service workers via Network domain

Resolves: (link your issue here)

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What

Closes the long-standing TODO in crBrowser.ts where browserContext.setUserAgent() silently skipped all active service workers with no warning to the developer.

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Why

Service workers do not expose the Emulation CDP domain, so Emulation.setUserAgentOverride — which pages use — cannot be called on their sessions. The fix uses Network.setUserAgentOverride, which is available on service worker sessions. This is the same domain already used by updateOffline(), updateHttpCredentials(), and updateExtraHTTPHeaders() for service workers.

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Changes

crServiceWorker.ts

• Added updateUserAgent() using Network.setUserAgentOverride with userAgent and acceptLanguage (locale) from browser context options
• Called during SW construction alongside existing network-level setup so newly registered workers immediately get the correct UA

crBrowser.ts

• setUserAgent() now loops over serviceWorkers() and calls updateUserAgent() on each — consistent with doUpdateOffline() and doSetHTTPCredentials()
• TODO comment removed

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Problem

Playwright tried to update the Service Worker's User-Agent using the page-only command: Emulation.setUserAgentOverride

But Service Workers do not support the Emulation category. As a result, Playwright skipped them, leaving service workers using the default user-agent while the web page used the overridden one.

The Fix

We updated the code to use the Network category command instead: Network.setUserAgentOverride

Since Service Workers already use the Network category to check offline modes and intercepts, this command works. We then updated crBrowser.ts to loop over all active service workers and call this update whenever the user-agent is changed.

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Testing

Existing tests in tests/library/chromium/extensions.spec.ts pass without modification.

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Checklist

• Follows the existing updateOffline / updateHttpCredentials pattern exactly
• No new dependencies introduced
• Errors swallowed with .catch(() => {}) — consistent with all sibling methods
• Works for both newly created and already-running service workers
• TODO comment removed

Resolves: #41070

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds support for propagating userAgent (and locale-derived acceptLanguage) overrides to Chromium service workers by using the Network domain (since Emulation isn’t available there).

Changes:

• Invoke service worker updateUserAgent() during initialization.
• Implement CRServiceWorker.updateUserAgent() via Network.setUserAgentOverride.
• Update CRBrowserContext.doUpdateUserAgent() to also apply updates to existing service workers.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
packages/playwright-core/src/server/chromium/crServiceWorker.ts	Adds a service worker user agent update method and calls it during session initialization.
packages/playwright-core/src/server/chromium/crBrowser.ts	Extends browser context UA updates to include service workers.

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