As part of the Section Translation process (T243495), users can pick a suggested article to expand with a new section. In order to support this, we need a service that finds articles that exists in both source and target languages for which there are some sections available for translation.

The purpose of this ticket is to provide a basic approach that can complement the more advanced approach from the Research team (T224234). This would work as a fall-back and as an initial version until the later is ready. Since the more advanced approach may not cover all languages or topics, the basic approach is expected to coexist with it. So it is worth considering how the new approach will be integrated into the system when designing the current one.

Some strategies that can be considered to find articles to suggest:

• Previous translations. Articles the user published using Content Translation and some of their sections have not been translated. This can work as a logical next step (e.g., the user translates Ukelele, and is suggested to expand with some more sections later to improve it).
• Relevant articles for the user without sections in the target language. We can search for article recently edited (and those connected through Wikidata with those edits) and filter those cases where the article exist in both languages, has one or more sections in the source languages, and has no sections in the target one. Alternatively, we could select those were the number of sections in the source is higher than the number of sections in the target (so at least one section is likely to be missing in the target according to the pigeonhole principle), but we need to be confident on the mapping service (T243430).
• General articles without sections in the target language. Similar to the previous case, but making a more general selection which can be based on the featured status of an article and/or the number of visits. Since this criteria is not based on previous edits it can be applied to newcomers (without previous editing experience) but is likely to provide less relevant results.

Note that we want to expose only articles where we can provide a mapping for. So the basic suggestion service should consider the capabilities of the basic mapping service (T243430). In addition, note that the number of sections that can be translated is surfaced from the suggestions view.