and how do I make it show something? at the moment it's just a blank area

if I recall correctly, there was a :data param in that body

for vega-lite to actually be able to render something you’d need an actually valid vl spec. a tiny one would be this:

{:data
   {:values
    [{:a "A", :b 28}
     {:a "B", :b 55}
     {:a "C", :b 43}
     {:a "D", :b 91}
     {:a "E", :b 81}
     {:a "F", :b 53}]}
:mark "bar"
:encoding
 {:x
   {:field "a"
     :type "nominal"
     :axis {:labelAngle 0}}
    :y {:field "b", :type "quantitative"}}}

Does it make sense to automatically choose vega viewer when stuff under :data doesnt conform to vega lite spec?

my indentation was bad, sorry. the data can be basically map/vector thing, so its hard to spec. and in general vega-lite needs very little in it’s spec, which is why djblue changed it to be more forgiving on the clojure side. the main problem is: you can’t be certain that something is valid vega before passing it into vega, so you want to be relaxed, but then you get false positives, like your case. the best solution would be to a separate predicate for “allowed as viewer” and “default as viewer”, but that’s a project that hasn’t started yet

I think for now, the spec can still be more open but the inspector view could have a higher priority to avoid this issue

If people want to use the vega viewers by default, it can be done via metadata

Makes sense, :data is a pretty common keyword