@matmarex @Zabe As consultants/reviewers of the original implementation at T151682, do you have any insights to inform which choice we should make or otherwise have a preference for one approach vs another?

Summary of audit

The feature is used on 4 wikis: enwiki, hrwiki, thwiki, dewiki

• ✅ enwiki: varies cleanly by content model, unused on wikitext or NS0 pages.
• ❌ hrwiki: used on one namspace (Draft, NS 118) which is wikitext. Unclear why because enwiki has a different solution already which predates this one.
• ✅ thwiki: varies cleanly by content model unused on wikitext or NS0 pages.
• ✅ dewiki: varies cleanly by content model unused on wikitext or NS0 pages.

Audit details

https://global-search.toolforge.org/?q=.*&regex=1&namespaces=8&title=Subjectpageheader

enwiki usage: https://en.wikipedia.org/wiki/MediaWiki:Subjectpageheader calls https://en.wikipedia.org/wiki/Module:Subject_page_header which is basically:

if title.contentModel == 'json' and  ..:
  ...
elseif title.contentModel == 'SecurePoll' and ..:
  ...
else
  return ""

https://hr.wikipedia.org/wiki/MediaWiki:Subjectpageheader

{{Zaštićen}}<!--
-->{{#switch:{{NAMESPACENUMBER}}|
|118={{Nacrt}}
}}

• NS 118 is the Draft namespace. This unconditionally prepends a message above all such pages. Other wikis solve this by adding the template directly as part of the wizard that creates the draft, with possibly an AbuseFilter rule to prevent removal. That might be preferred, given these are wikitext, which is not what the feature was developed for.
• Padlock icon on protected articles. Parsed on all articles, and if it's protected, it tries to add a page status indicator. This doesn't appear to work, because it requires page metadata to be merged, which we purposefully don't, because it would break caching and fall out of sync with link tables. Other wikis solve this with a gadget, or with a template on the page (added to at least all protected by convention or bot, and naturally no-ops after protection expires or is removed). I checked https://hr.wikipedia.org/wiki/Special:Log/protect for articles that are recently fully/admin protected such as https://hr.wikipedia.org/wiki/Ivan_Anušić and indeed this doesn't actually work. EDIT: It does work in terms of showing the icon, but not in terms of categories or link tables. I mistakenly thought it didn't work because my account is set to English and this feature parses MediaWiki:Subjectpageheader in the interface langauge instead of the content language, and so was actually parsing MediaWiki:Subjectpageheader/en. It works at https://hr.wikipedia.org/wiki/Ivan_Anu%C5%A1i%C4%87?useskin=vector&safemode=on&uselang=hr

https://th.wikipedia.org/wiki/MediaWiki:Subjectpageheader -> https://th.wikipedia.org/wiki/Module:Subject_page_header. This was copied from enwiki and does the same thing.

if title.contentModel == 'json' and  ..:
  ...
elseif title.contentModel == 'SecurePoll' and ..:
  ...
else
  return ""

https://de.wikipedia.org/wiki/MediaWiki:Subjectpageheader

Splits cleanly by content model and namespace. Either approach works. If we split by one, then they switch by the other. Or vice versa.

{{#switch: {{NAMESPACENUMBER}}
  |2|4|8|10|100|828 = {{#switch: {{#contentmodel:canonical}}
    |css
    |javascript
    |json
    |sanitized-css=…
    |text=…
  }}
}}

Change #1324806 had a related patch set uploaded (by Jforrester; author: Jforrester):

[mediawiki/core@master] Article:showNamespaceHeader: Disable in miser mode for non-talk pages

https://gerrit.wikimedia.org/r/1324806

See https://gerrit.wikimedia.org/r/c/mediawiki/core/+/1239204/3#message-dbd8338b0aeb9d6405a38b1d96e767bd55915cc6 for similar case in footer (and T138652#3186564)

Change #1326351 had a related patch set uploaded (by Krinkle; author: Krinkle):

[mediawiki/core@master] Article: Split subjectpageheader by model and disable for wikitext

https://gerrit.wikimedia.org/r/1326351

In T432882#12209151, @Krinkle wrote:

@matmarex @Zabe As consultants/reviewers of the original implementation at T151682, do you have any insights to inform which choice we should make or otherwise have a preference for one approach vs another?

It makes sense to me to split the message based on content model (or by namespace ID). We handle 'editnotice-...' messages similarly for similar reasons.

Change #1326351 merged by jenkins-bot:

[mediawiki/core@master] Article: Split subjectpageheader by model and disable for wikitext

https://gerrit.wikimedia.org/r/1326351

I've migrated the 3 wikis using this (audit at T432882#12209205) and these are now ready for the above change to rollout:

• enwiki: https://en.wikipedia.org/wiki/MediaWiki:Subjectpageheader
  • Created https://en.wikipedia.org/wiki/MediaWiki:Subjectpageheader-json
  • Created https://en.wikipedia.org/wiki/MediaWiki:Subjectpageheader-SecurePoll.
  • Test case: https://en.wikipedia.org/wiki/MediaWiki:SecurePoll/831.
  • I noticed the JSON message conflicts with another interface message, reported at Template_talk:Script_doc_auto.
• thwiki: Created https://th.wikipedia.org/wiki/MediaWiki:Subjectpageheader-json. (The wiki copied enwiki's Lua module, which includes a SecurePoll branch, but the wiki has no such pages in the MediaWiki-namespace.)
• dewiki: https://de.wikipedia.org/wiki/MediaWiki:Subjectpageheader
  • Created https://de.wikipedia.org/wiki/MediaWiki:Subjectpageheader-sanitized-css, https://de.wikipedia.org/wiki/MediaWiki:Subjectpageheader-css, https://de.wikipedia.org/wiki/MediaWiki:Subjectpageheader-json, https://de.wikipedia.org/wiki/MediaWiki:Subjectpageheader-javascript
    • Test case https://de.wikipedia.org/wiki/Vorlage:Tabellenstile/styles.css?uselang=de
  • Created https://de.wikipedia.org/wiki/MediaWiki:Subjectpageheader-text
    • Test case https://de.wikipedia.org/wiki/MediaWiki:Robots.txt?uselang=de

For hrwiki, I've reached out at T408264#12232754 and proposed alternatives that work on other wikis already.