I need is_in_stock to be exposed as an attribute for which I can set "Use in layered navigation" to "Filterable (with results".
I can't seem to find a way to do this? I can't find an extension which does this? Does anyone have any ideas?
To clarify: I'm using ElasticSearch as my search backend, and ElasticSearch takes over layered navigation by using it's own facets which mirror the attribute settings for Layered Navigation - so that's why I need a stock attribute.