No title attribute on oEmbed and REST API <link>s

[edent]

By default, WordPress adds three <link rel="alternate" ... to the <head> of every post.

These are missing the title="..." attribute. This means that some browsers will announce the links as "alternate" with no explanation of their destination - see screenshot attached.

The three links are:

<link rel="alternate" type="application/json" href="https://example.com/wp-json/wp/v2/posts/123" />
<link rel="alternate" type="application/json+oembed" href="https://sexample.com/wp-json/oembed/1.0/embed?url=https%3A%2F%2Fexample.com%2Fpost%2F" />
<link rel="alternate" type="text/xml+oembed" href="https://example.com/wp-json/oembed/1.0/embed?url=https%3A%2F%2Fexample.com%2Fpost%2F&#038;format=xml" />

Ideally, these would have title="JSON", title="oEmbed (JSON)", title="oEmbed (XML)" or similar.

[edent]

Lynx browser showing the "alternate" link.

[kadamwhite]

@TimothyBlynJacobs @rmccue Do you see any reason not to do this? I assume we'd want to translate the title strings

[TimothyBlynJacobs]

Yeah seems fine to add. I was unaware lynx was still a thing :)

This PR makes three changes:

• Adds the title attribute to <link rel="alternate"> tags for oEmbed and REST API endpoints
• Updates the oEmbed phpunit tests to reflect the above change
• Adds the title link-param to REST API Link: headers (verified as supported in RFC 8288 here: ​https://httpwg.org/specs/rfc8288.html#serialisation-defined-attributes)

Note: The Trac ticket referenced below does not include a consensus discussion around this change. Opening the PR as a proof of concept as part of familiarizing w/ the WP development process as a new contributor at WordCamp US 2023.

Trac ticket: https://core.trac.wordpress.org/ticket/59006

[kadamwhite]

@TimothyBlynJacobs Do you think these "title" strings should be translatable?

Maybe @SergeyBiryukov has some thoughts on localization. My inclination would be that we should still translate it.

I'm inclined to think these should be translated, although it does feel a little strange. At least in the case of oEmbed (XML), I think that the structure and order of the text could be variable by language, which is enough to justify it, to me.

[joedolson]

I think this is worth doing, even though it probably only applies in a very small number of cases. A little clarity doesn't hurt!

[audrasjb]

Yes these strings should be translatable: even if it's a edge case, as soon as the title is rendered in the user agent, any language change without information about the language of the string would be a compliance issue.

[swissspidy]

This is really more of an enhancement, so moving out of 6.5.

Not sure about the localization, but if we add it, it should use _x() with proper context.

[nhrrob]

We have reviewed this ticket in today's bug scrub. It still requires some changes on the PR.

Like #5080, this PR makes three changes:

• Adds the title attribute to <link rel="alternate"> tags for oEmbed and REST API endpoints
• Updates the oEmbed PHPUnit tests to reflect the above change
• Adds the title link-param to REST API Link: headers (verified as supported in ​RFC 8288)

In addition:

• The link names are translatable, with context.
• The printf and sprintf functions are on multiple lines for better readability with two placeholders.

Trac 59006

[oglekler]

@audrasjb can you take a look, please? It is simple enough to be able to get into 6.6.

[audrasjb]

In 58286:

Embeds: Add titles to alternate resource links for oEmbed and REST API.

This changeset makes the following changes:

• Adds the title attribute to <link rel="alternate"> tags for oEmbed and REST API endpoints
• Updates the oEmbed phpunit tests to reflect the above change
• Adds the title link-param to REST API Link: headers (verified as supported in RFC 8288 here: ​https://httpwg.org/specs/rfc8288.html#serialisation-defined-attributes)

Props edent, kadamwhite, TimothyBlynJacobs, joedolson, swissspidy, sabernhardt.
Fixes #59006.

Committed in https://core.trac.wordpress.org/changeset/58286

Closing as no longer needed due to #6703