(In reply to MZMcBride from comment #0)

When a page has been occupied by the Flow extension, the standard delete
action no longer functions. This should be fixed.

Sorry, I should've been clearer here: by "standard delete action" I mean index.php?action=delete.

It's unclear what the right behavior here is, and it may change depending on how we enable Flow on pages in the future.

If Flow is enabled on some page, visiting it shows the Flow header and topics for that page. The wikitext of the page isn't shown, so whether it's deleted or changed (which you can currently still do through the API) has no effect. Behind the scenes Flow calls ensureFlowRevision(), which creates a dummy "This talk page has been taken over by a [https://www.mediawiki.org/wiki/Special:MyLanguage/Flow_Portal Flow board]" revision, but users won't see this text until Flow is disabled on that page.

This might have been resolved for Flow boards that aren't in wgFlowOccupyPages list by gerrit 175574 (towards T76778).

To test, try ?action=delete on a Flow board that someone created through the new-topic or edit-header API, e.g. https://test.wikipedia.org/wiki/User_talk:SPage_%28WMF%29/New_Board_from_new-topic_4

In T63730#956330, @Spage wrote:

This might have been resolved for Flow boardds that aren't in wgFlowOccupyPages list by gerrit 175574 (towards T76778).

To test, try ?action=delete on a Flow board that someone created through the new-topic or edit-header API, e.g. https://test.wikipedia.org/wiki/User_talk:SPage_%28WMF%29/New_Board_from_new-topic_4

Confirmed: hacking the URL to use &action=delete does work. I deleted the example you linked to (which was previously a normal Flow Board).

Doing a "Restore" action doesn't work though. It just results in a wikipage with this content:

{"flow-workflow":"s9c1puxfwguhvdwt"}

and that's all that was visible when viewing the deleted page, too.

(The 1 topic that was attached to the board, is Topic:S9c1puyfrauenodp)