Change #1238295 had a related patch set uploaded (by Samwilson; author: Samwilson):

[mediawiki/core@master] Special:EditWatchlist: Add labels to both subject and talk pages

https://gerrit.wikimedia.org/r/1238295

Change #1238295 merged by jenkins-bot:

[mediawiki/core@master] Special:EditWatchlist: Add labels to both subject and talk pages

https://gerrit.wikimedia.org/r/1238295

Should you also check the case when the content page does not exist?

Should you also check the case when the content page does not exist?

I'm not sure I understand. Do you mean when you label a watched non-existing page, and then that page is later created? That works, as far as I can see, with the current set-up. A page and its talk page are given the label, regardless of if either exist yet.

(Moving back to in-development because there's still a maintenance script to write here to backfill the missing talk pages.)

@Samwilson Confirmed when a page has a label assigned, edits to its corresponding talk page are labelled, as seen in the screenshot/video below. I will mark this as Resolved. Thanks for all your work!

Test Result - Beta

Status: ✅ PASS
Environment: Beta
OS: macOS Tahoe 26.2
Browser: Chrome 143
Device: MBA
Emulated Device: NA

Test Artifact(s):

https://en.wikipedia.beta.wmcloud.org/w/index.php?title=Special:Watchlist&days=30&hideWikibase=1&hidecategorization=1&hidepreviousrevisions=1&limit=500&urlversion=2&wllabel=52

Test Steps

Test Case 1: Ensure edits to labeled page appear when filtering by label

1. Watch a page (e.g., Foo).
2. Assign a label to the watched page.
3. Make an edit to Foo.
4. Navigate to Special:Watchlist.
5. Apply a filter for the assigned label.
6. ✅ AC1: The edit to Foo appears in the filtered watchlist results.

Test Case 2: Ensure edits to corresponding talk page also appear when filtering by label

1. With the same labeled page (Foo), make an edit to Talk:Foo.
2. Navigate to Special:Watchlist.
3. Apply a filter for the same assigned label.
4. Observe the filtered results.
5. ✅ AC2: The edit to Talk:Foo appears in the filtered watchlist results when filtering by the page’s label.

In T416147#11609470, @Samwilson wrote:

Should you also check the case when the content page does not exist?

I'm not sure I understand. Do you mean when you label a watched non-existing page, and then that page is later created? That works, as far as I can see, with the current set-up. A page and its talk page are given the label, regardless of if either exist yet.

(Moving back to in-development because there's still a maintenance script to write here to backfill the missing talk pages.)

No, not that. I'm curious if this scenario should be checked by its own:

1. Some page does not exist.
2. Its talk page exists.
3. The page gets a label.
4. Check if the talk page edits include this label.

Don't know how the mechanism is build, so not sure if it should a case different from the rest.

Change #1239562 had a related patch set uploaded (by Samwilson; author: Samwilson):

[mediawiki/core@master] Add cleanupWatchlistLabelMember maintenance script

https://gerrit.wikimedia.org/r/1239562

The plan here is basically to run the following insert statement:

INSERT INTO watchlist_label_member (wlm_label, wlm_item)
SELECT DISTINCT wlm_subject.wlm_label, wl_talk.wl_id
FROM watchlist wl_subject
JOIN watchlist wl_talk 
    ON wl_subject.wl_user = wl_talk.wl_user 
    AND wl_subject.wl_namespace + 1 = wl_talk.wl_namespace
    AND wl_subject.wl_title = wl_talk.wl_title
    AND wl_subject.wl_id != wl_talk.wl_id
JOIN watchlist_label_member wlm_subject
    ON wlm_subject.wlm_item = wl_subject.wl_id
LEFT JOIN watchlist_label_member wlm_talk
    ON wlm_talk.wlm_item = wl_talk.wl_id
    AND wlm_talk.wlm_label = wlm_subject.wlm_label
WHERE wlm_talk.wlm_item IS NULL

I've started work on a maintenance script to do this, which will also be run as part of update.php.

Change #1239562 merged by jenkins-bot:

[mediawiki/core@master] Add cleanupWatchlistLabelMember maintenance script

https://gerrit.wikimedia.org/r/1239562

Confirmed with @Samwilson that this can be run at any time now - I've created T420328: Run cleanupWatchlistLabelMember maintenance script for the run