Push notification support is only enabled on wikis in the [[ https://noc.wikimedia.org/conf/highlight.php?file=dblists%2Fwikipedia.dblist | wikipedia ]] group at present. This is accomplished using the `EchoEnablePush` config setting provided by the Echo extension.
A few wikis had to be individually excluded yesterday to resolve a train blocker (T291128). This solution is brittle because the problem could reappear anytime a new private wiki is added to the `wikipedia` group. This task is to implement a more future-proof solution.
Potential solutions:
# Create the push tables in private wiki DBs, and enable the `push` notifier type universally. This would have the added benefit of allowing the `push` notifier type to be defined and configured in Echo like the `web` and `email` types rather than being special-cased in CommonSettings.php. The drawback is that this could potentially cause the users of the Wikipedia apps to receive notifications for wikis irrelevant to them, but this could be handled by the app clients (either by appropriate use of per-wiki filtering when requesting notification content, or post-hoc filtering of received notifications).
# Investigate options for updating configuration to be more future-proof, e.g., to exclude non-SUL wikis by group. (Would `$wgEchoEnablePush = [ 'default' => false, 'wikipedia' => true, 'special' => false ]` have the desired effect? Note that [[ https://www.php.net/manual/en/language.types.array.php | arrays in PHP are actually ordered maps ]], so if MediaWiki applies these rules in the order defined, it should work.)