I've quickly read through your RFC, and since I've recently added support for Content-Range to LibreS3[0] that is the first thing I looked for, and sure enough you support it.
Although it is not clear to me why you need to use webfinger to announce Content-Range support.
There is Accept-Ranges header, or you can detect that you get a 200 instead of a 206 reply on a Range request for GET.
For PUT RFC7233 says "A server MUST ignore a Range header field received with a request method other than GET." so I'm not sure how that would work there, can you give an example?
I should have probably made it a bit more clear that I'm only working WITH remoteStorage on one of my side projects, and am not one of its developers. =)
Although it is not clear to me why you need to use webfinger to announce Content-Range support. There is Accept-Ranges header, or you can detect that you get a 200 instead of a 206 reply on a Range request for GET.
For PUT RFC7233 says "A server MUST ignore a Range header field received with a request method other than GET." so I'm not sure how that would work there, can you give an example?
[0] http://blog.skylable.com/2015/01/build-your-own-cdn-with-sky...