We need to investigate:
- What happens if the client user has not logged into the repo before?
- What are the possible reasons when centralauth doesn't log you in to the repo? (see for example T231209#5445076)
- What are possible ways out of these cases?
- What options do we have for recovery on the client after assertuser fails?
- What happens when sending an edit request without "having been" to wikidata before? Is the right user used then?
Timeboxing it to 1 person for 1 day.