I'm curious to dig a bit further in, but from the blog post I get the impression that they are also still cloning the full commit history, just not the full file trees attached to the commits and definitely not the full worktree of HEAD, leaving those to be lazily fetched. If that is the case, that sounds like an interesting compromise on the git model and something verging on some of the speculative ideas I've seen about using something like IPFS to back git's trees, to the point where maybe you could use something IPFS in tango with this and have a good DVCS solution.