r9p adds remote filesystem synchronization support to replican-sync with the Plan9 filesystem protocol.
9P is used to implement fs.BlockStore, which is a suitable match & patch endpoint for replican-sync.
r9p is not serving the remote files directly over 9P. Instead, the server indexes locally, and serves up the metadata and raw block access in a custom filesystem structure.
This pre-indexing and fetching of only the delta follows a similar synchronization pattern as zsync (pull, rather than push).