It seems useful to provide some API to determine if Flow is enabled on a page, since that affects whether many API actions will work or make sense (bug 60808).
The equivalent for LiquidThreads is it returns use-liquid-threads="1" in pageprops queries. Compare LQT page:
https://www.mediawiki.org/w/api.php?action=query&prop=pageprops&titles=Talk:Flow_Portal/Archive2
with Flow board:
https://www.mediawiki.org/w/api.php?action=query&prop=pageprops&titles=Talk:Sandbox
(Note the way we enable Flow on a page is likely to change; editing PHP config files doesn't scale.)
Version: master
Severity: normal