[wp-trac] [WordPress Trac] #65407: Proposal: Add support for the No-Vary-Search HTTP response header

[WordPress Trac]

#65407: Proposal: Add support for the No-Vary-Search HTTP response header
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 Reporter:  jonoaldersonwp  |       Owner:  (none)
     Type:  defect (bug)    |      Status:  new
 Priority:  lowest          |   Milestone:  Awaiting Review
Component:  General         |     Version:
 Severity:  normal          |  Resolution:
 Keywords:                  |     Focuses:  performance
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Comment (by jonoaldersonwp):

 For opt-in, I think we'd need to consider:
 - Scenarios where sites use server-side logic around capturing campaign
 parameters (e.g., "this session came from Facebook"); e.g., for passing
 through a lead-gen form into Salesfore/similar.*
 - A/B testing / marketing customization / personalisation stuff, which
 runs server-side - which is 'relatively' common. We'd need that kit to
 either disable the header, or opt their affected params into an allow
 list.

 Annoyingly, the breakage in both cases would be silent/invisible, as it'd
 be as if the parameter simply wasn't there. That makes debugging breakages
 naaaaasty.

 *I can't think of a reason why those kinds of systems couldn't/shouldn't
 be client-side (cookies, local storage, etc). Am I missing something,
 other than "doing it wrong"?

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Ticket URL: <https://core.trac.wordpress.org/ticket/65407#comment:6>
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