Intent to Prototype: Add bugfix version number to User-Agent string on Bling
Janice Liu
Contact emails
jani...@chromium.org, mike...@chromium.org
Explainer
None. This is a minor change and we are sharing it to provide transparency into changes that we are implementing.
Specification
https://www.rfc-editor.org/rfc/rfc9110#field.user-agent
Summary
User Agent (UA) strings in Chromium have been moving towards reducing or freezing information - but until WebKit allows us to implement UA client hints, we propose adding the bugfix number to the UA, for compatibility purposes.
Blink component
Motivation
The Chrome for iOS User-Agent header only includes the major and minor version numbers, while Safari and Firefox for iOS include the major, minor, and bugfix numbers. We have received a request from external partners to match this pattern, and are aware of at least one platform that relies on having an accurate bugfix version number to ensure the latest security updates are installed.
UA strings in Chromium have been moving towards reducing or freezing information - but until WebKit allows us to implement UA client hints, we propose adding the bugfix number to the UA, for compatibility purposes.
In practice:
Before this change: Mozilla/5.0 (iPhone; CPU iPhone OS 17_5 like Mac OS X)
AppleWebKit/602.1.50 (KHTML, like Gecko) CriOS/123.0.2924.75
Mobile/14E5239e Safari/602.1
After this change (note the additional “_1” in the OS version token): Mozilla/5.0 (iPhone; CPU iPhone OS 17_5_1 like Mac OS X)
AppleWebKit/602.1.50 (KHTML, like Gecko) CriOS/123.0.2924.75
Mobile/14E5239e Safari/602.1
Initial public proposal
None
TAG review
None
TAG review status
Not applicable
Risks
Interoperability and Compatibility
None
Gecko: No signal (Firefox on iOS already follows this pattern)
WebKit: No signal (mobile Safari already follows this pattern)
Web developers: We have received at least one external partner request for this change.
WebView application risks
Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications?
N/A (this is for iOS)
Debuggability
None
Is this feature fully tested by web-platform-tests?
No
Flag name on chrome://flags
None
Finch feature name
kAddBugFixNumber
Non-finch justification
None
Requires code in //chrome?
False
Tracking bug
https://issues.chromium.org/u/1/issues/350426233
Estimated milestones
No milestones specified
Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/5084885065400320?gate=5184007944536064