Add a notification setting for likes, reposts and quotes

[pfefferle]

Fixes #3578

Proposed changes:

• Likes, reposts and quotes are stored as comments, so they trigger WordPress's normal "new comment" email to the post author. That email is separate from the ActivityPub notification settings, so until now there was no way to turn it off without also silencing real comments and replies.
• This adds a "Likes, Reposts and Quotes" toggle to the notification settings. It defaults to on, so nothing changes for existing users until they turn it off. When it is off, the author no longer gets an email for reaction comments, while real replies still notify as before.

Other information:

• Have you written new tests for your changes, if applicable?

Testing instructions:

• Go to Users > Profile and find the ActivityPub notification settings. Confirm the new "Likes, Reposts and Quotes" checkbox is there and checked by default.
• With it checked, receive (or insert) a like or repost comment on one of your posts. You get the usual "new comment" email.
• Uncheck the box and save. A new like, repost or quote no longer emails you.
• A real reply still emails you, whether the box is checked or not.

Changelog entry

The changelog entry is already included in the branch (.github/changelog/add-reaction-email-setting), so the auto-create box below is left unchecked.

Changelog Entry Details

Significance

• Minor

Type

• Added - for new features

Message

Add a notification setting to turn off emails about likes and reposts without silencing real comments and replies.

[Copilot]

Pull request overview

Adds a per-user notification toggle to suppress WordPress “new comment” emails for ActivityPub reaction comments (likes/reposts/quotes) while leaving normal replies unaffected, addressing #3578.

Changes:

• Introduces a new user option (activitypub_mailer_new_reaction) with a default “on” behavior.
• Adds a new checkbox in the user’s ActivityPub “Email Notifications” settings and persists it on save.
• Updates comment-notification suppression logic and adds PHPUnit coverage for the new behavior.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
includes/class-mailer.php	Applies the new per-user setting when deciding whether to send comment-notification emails.
includes/class-activitypub.php	Registers the new user meta and default behavior via get_user_option_* filter.
includes/wp-admin/class-user-settings-fields.php	Adds the “Likes, Reposts and Quotes” checkbox to the profile notification settings UI.
includes/wp-admin/class-admin.php	Persists the new user option on settings save.
tests/phpunit/tests/includes/class-test-mailer.php	Adds a unit test for the new reaction notification behavior.
.github/changelog/add-reaction-email-setting	Documents the new notification setting in the changelog.

[pfefferle]

Thanks, all three are addressed in 1b06ab0:

• The reaction opt-out is now its own filter on notify_post_author only, so it no longer affects the moderator notification.
• It matches the plugin's own reaction comment types via Comment::get_comment_type_slugs() instead of "not a plain comment", so pingbacks and trackbacks keep notifying, and any reaction type we register later is covered automatically.
• Added a repost case to the test, plus a check that the moderator notification is not gated by the author's preference.
• Updated the changelog to mention quotes.

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated no new comments.