VecSeq (as produced by (seq (vector-of :int 1 2 3))) does not implements equals, hashCode, or hasheq and does not play with any other Clojure collections or sequences appropriately in this regard.
Approach: Implement Object.hashCode(), Object.equals(), and IHashEq.hasheq() in the primitive vector seq implementation. All of these leverage the prim vec seq itself rather than the underlying prim vec as it was quite a big simpler. The hasheq() impl calls Murmur3/hashOrdered, which takes an Iterable, so Iterable was also implemented using an iterator over the seq.
Some existing tests were expanded to include coverage of the primitive vec seq.