where about's in the world are you?
I know we had a very similar wasp in Queensland in Australia and was always impressed watching them build their pots and stack them with spiders. Yes, usually they would just seal paralysed spiders in the pot, after laying her egg in the unfortunate arachnid's flesh.
That's how I remember them, but I haven't lived there for more than two decades. I may well be mistaken. Maybe they were caterpillars?
Good on you for raising awareness of these wonderful creatures.
big hugs
I'm in the San Antonio, TX area. I did read that the Potters wasp does also predate on spiders.