Eea.facetednavigation: how to limit search to current folder?

Being new to eea.facetednavigation, I'm trying to configure a faceted navigation for a Folder, and I'm looking for an option to limit the search to this folder (and below). How?

I suspect that a TAL expression could do the trick, but I don't know where to start...

You could probably use the results filter widget: enter the TAL expression there and set the widget's hidden attribute.

Cant you just add s collection that has criteria 'this folder' ?

It works, but only with "Faceted items preview" ; with "Standard view", I get:

TypeError: ('Could not adapt', <generator object WidgetFilterBrains.__call__ at 0x7f9f8d0f1570>, <InterfaceClass>)

Also the site stops to accept any input (mouse clicks, keyboard events)

I need extra filters, so eea.facetednavigation is useful, and for some reason collective.collectionfilter does not work at all (as if installing it added no extra functionnalities).

Taken from memory, so I might remember wrongly:

one of the add-ons works on collections, the other works on folders

Seems like that could be a bug in eea.facetednavigation. Also see here for a related discussion: Faceted Navigation on Plone 5.2.1