Byte array response bodies broken after compojure-api+muuntaja upgrade. Gettiing unexpected base64 content in ByteArrayInputStream instead of msgpack content.
And ... with clarity, resolution. :formats (m/create (-> m/default-options (m/install m.format.msgpack/format)))
appears to solve the problem. While I'm sure that was well understood by the Metosin authors, for those of us who spend less time eating and breathing all things compojure-api and muuntaja, the way to unbreak breaking changes isn't always obvious. Unfortunately it was days lost for me.
By the way, the reason the solution wasn't obvious to me is because I didn't see the need for it, because the "Default Options" on this page https://github.com/metosin/muuntaja/blob/master/doc/Configuration.md#loose-matching-on-content-type would suggest that msgpack stuff is built in, though at the same time the change log breaking changes says that msgpack is an optional module, so it's confusing.