Stream Management (XEP-0189)
There seems to be basic support in libpurple now (https://bitbucket.org/pidgin/main/pull-requests/309/xep-0198-stream-management/diff) and the MR has by @bwildenhain that somebody is working on resumption support.
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information