Avoid large layout shifts while page loading on mobile
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	aklapper
	Fri, May 16, 07:38

Description

Phorge first trying to check a User Agent string (which seems a bad idea in 2025, plus things did change) in PhabricatorStandardPageView.php by setting $device_guess. See also related CSS docs in https://we.phorge.it/source/phorge/browse/master/src/docs/contributor/css_coding_standards.diviner. Again, this seems a bad idea in 2025.

Then Phorge applies some CSS rules sometimes based on that check and/or sometimes based on viewport width.

Screenshots of Firefox 138 on an Android 10 system:

Screenshots of Firefox 91 on a Sailfish system:

Chromium on Android also seems affected (though the User-Agent regex still seemed to match) but I didn't receive screenshots from folks.

rP Phorge
	Needs Review	D26021 Make User-Agent regex detect Firefox on Android

Per https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/User-Agent/Firefox (and other pages like https://www.whatismybrowser.com/guides/the-latest-user-agent/firefox ), the current regex check in Phorge requiring the string Chrome won't even try to match Firefox browsers on mobile (e.g. Mozilla/5.0 (Android 15; Mobile; rv:138.0) Gecko/138.0 Firefox/138.0).

valerio.bozzolan triaged this task as Normal priority.Fri, May 16, 13:19

	F4286129: Screenshot_20250510-phorge-rerender-2b.png
	Fri, May 16, 07:38

	F4286128: Screenshot_20250510-phorge-rerender-2a.png
	Fri, May 16, 07:38

	F4286115: Screenshot_20250510-phorge-rerender-1b.png
	Fri, May 16, 07:38

	F4286114: Screenshot_20250510-phorge-rerender-1a.png
	Fri, May 16, 07:38