Besides converting wikitext to HTML, Parsoid has the ability to convert HTML to wikitext. This opens up the possibility of taking HTML from different applications and converting them to wikitext.
Examples:
# converting phabricator output to wikitext
# converting mardown to wikitext
# converting google doc output to wikitext
For #2, there is https://gerrit.wikimedia.org/r/#/c/225253/.
Strictly speaking Parsoid is not required, but Parsoid could provide a simpler / unified interface for this.
So, the goals of this project would be to:
(a) develop a webservice that provides these conversion utilities in a single place.
(b) talks to Parsoid under the hood to do these necessary conversions
(c) does any necessarily HTML cleanup / normalization to nudge Parsoid to provide clean wikitext
(d) tweak Parsoid's HTML to wikitext code to better enable these transformations
An example of (d) is T127207
@Arlolra is interesting in mentoring this project. The rest of us on the parsing team will be the backups.