In T266149#6758710, @cscott wrote:

WRT captions appearing in the error case:
The {MediaWiki DOM Spec](https://www.mediawiki.org/wiki/Specs/HTML/2.2.0#Images) says:

<figcaption (absent when inline)>...</figcaption>

and

The outer <figure> element needs to become a <span> element when the figure is rendered inline, since otherwise the HTML5 parser will interrupt a surrounding block context. The inner <figcaption> element is rendered as a data-mw attribute in this case (since block content in an invisible caption would otherwise break parsing).

So the issue here is a bit of ambiguity in what "when rendered inline" means, and we can be more precise about it. But probably "rendered inline" meaning "uses a span as the wrapper" and so if we decide to output the caption for broken error cases we should also change the outer wrapper from "span" to "figure". That might also cause rendering differences, but at least it would be self-consistent. Then we'd just need to clarify that media will be "rendered inline" only for non-error cases.

https://mw-expt-tests.wmflabs.org/diff/dewiki/Ingvar_Carlsson is an example where the image in the figcaption overflows, resulting in a rendering difference. This similar to T171761 but the word-break isn't going to work here

In T266149#6752543, @Arlolra wrote:

Also on https://mw-expt-tests.wmflabs.org/diff/enwiki/Diffusion, it appears that thumb at "Diffusion in the context of different disciplines" is clearing right, when it shouldn't be, since it's floating above the heading. That's a bug in the CSS that needs resolving.

In T270373#6758772, @cscott wrote:

What's the wikitext source?

Only thumbnails should get the margin-bottom: 0.5em; from,
https://github.com/wikimedia/mediawiki/blob/master/resources/src/mediawiki.skinning/content.less#L110

Also on https://mw-expt-tests.wmflabs.org/diff/enwiki/Diffusion, it appears that thumb at "Diffusion in the context of different disciplines" is clearing right, when it shouldn't be, since it's floating above the heading. That's a bug in the CSS that needs resolving.

https://mw-expt-tests.wmflabs.org/diff/enwiki/Diffusion shows that TimedMediaHandler isn't recognizing the new output. That should be handled in T272186

https://mw-expt-tests.wmflabs.org/diff/dewiki/Liste%20der%20preu%C3%9Fischen%20Handelsminister is an example of https://gerrit.wikimedia.org/r/c/mediawiki/core/+/507512/16/includes/Linker.php#b417

From the early results, https://mw-expt-tests.wmflabs.org/diff/enwiki/Anglo-Saxon%20settlement%20of%20Britain is an example of T169975#4176954

We might want to do a round of $wgParserOutputLegacyMediaDOM = true; vs HEAD^ to establish a baseline that nothing is broken.

A round of visual diff'ing is now running with the key "media-test", results at https://mw-expt-tests.wmflabs.org/

Maybe just mention T252246 or T262833 here so that we add coverage when doing those?

From @ssastry on irc,

For where this is used, see for example "Localisation" in the infobox on https://fr.wikipedia.org/wiki/Bratislava

See the tooltip issue in T108380

It looks like this is just waiting on QA in T268309 so I'm going to close it but please reopen if that proves problematic.

Parsoid started producing spans again in version 2.2.0 of its output.

Also related, T92999

But @Arlolra seems to have found the exception to that rule which we've all forgotten; I await with bated breath.

In T51097#6690931, @Arlolra wrote:

I said this because I think the place where the stylesheet is saying to hide the figcaption is misleading. Those are inline images where it isn't even emitted and the content is placed in the data-mw.

I think we should file individual tasks for these things so they can be researched more thoroughly.

In T51097#6690317, @Krinkle wrote:

@Arlolra @Jdlrobson The new selectors introduced here seem quite bad in terms of performance and stability. They seem very fragile, and I don't think we should use those on production page views.

Code in question at mediawiki.skinning/content.media.less.

T258719 is perhaps relevant for which selector to use, but orthogonal to the issue here.

It does use mw-content-$dir elsewhere, but see T258719

Parsoid sets mw-content-$dir based on the page language,
https://github.com/wikimedia/parsoid/blob/master/src/Wt2Html/DOMPostProcessor.php#L734

This exists as $wgUseNewMediaStructure now

This was deprecated in https://github.com/wikimedia/mediawiki/commit/8c43d758414925bae6e4442486f3c768102fecd1 as part of T254802

When I want to test this locally, I'll put in my LocalSettings.php,

@Arlolra had a more clever idea, which I'll let him relate.

T266143#6668090 starts on looking at the changes Mobile-Content-Service made in T177301

It looks like StructuredDiscussions is backwards compatible for T173972. The above patch in T266143#6667623 just updates the test suite.

After that's merged, I think this can be closed as a dupe of T162399

Registering a modulestyle with the extension seems like a pretty coarse grained api. The legacy parser only adds the styles/scripts if the tag is used on the page. We currently do that for places where we call the out to the legacy parser, with env->addOutputProperty

Looks like it's happening in https://es.wikipedia.org/w/load.php?lang=es&modules=mediawiki.page.gallery&only=scripts&raw=1&skin=vector&debug=true

The legacy output has the same dimensions height="120" as Parsoid,

In https://github.com/wikimedia/mediawiki/commit/16b76a486d774e31283a62c0a17cfc9f356ca106 we changed the figcaption from display: table-caption; to display: block; since the figcaption wasn't always present and we didn't want the bottom border to depend on it.

See T267282#6641741 where we're saying this is valid in the case where |link=| suppresses the anchor element around the image.