@evan if you want the simplest mechanism to upload media, why bother with multipart request bodies? Just do what I do in BOX->ONI, use a data URI for encoding the binary, either as Object.Content or Object.URL.
Can you tell me what's the difference between a request containing JSON with a data URI property and a multipart request body?
As far as I can tell the binary data is in both cases base64 encoded, so you're not saving on size, it can be malformed for both cases (but for multipart you now you need an extra check to not save the JSON-LD object if the bin-data is broken), etc...
(this suggestion is not entirely serious, but...)
etc...@hongminhee