Maybe Herald could be configured to do this?
Or I was thinking it might make sense for the "Wikimedia pageviews API" to have a dedicated project/tag in Phabricator Maniphest, maybe.
(I'll just say again that I hate Phabricator's projects input field and I primarily rely on Cunningham's Law when using it.)
I agree that this would help find all the pageview api tasks in one place, but it would be problematic for the Analytics team to keep track of. Tagging everything with Analytics-Backlog ensures that we look at them and triage them during Backlog grooming. We have a bunch of other tags like Analytics, Analytics-Eventlogging, Analytics-Cluster that we don't actively look at, but are telling people to additionally tag the Backlog project so we would pay attention to it.
It would be okay if users who are reporting bugs tag both backlog and pageview-api projects, but I doubt that'll happen. I'm in support of making a parent task in phab, and in our triaging process adding api related bugs as a subtask.
@ggellerman just mentioned to me that there are Phabricator tags, that behave differently from projects and it won't be possible to add a tag but not a project, so may be that would be okay.
The admins can make a Herald rule that ensures a project like Analytics-Backlog is added to everything inside this new pageviews API project.
Looks like usage of this tag is impossible due to Herald: https://phabricator.wikimedia.org/T124314#2234426
yeah, we haven't figured out a way to fix this, we're waiting for Herald to get smarter.