“I actually think of Git and especially GitHub as a little bit outsider art, where it doesn't quite engage with the theory or the history or anything. It just kind of did its own thing. And of course, it became wildly successful… All this branch stuff is just ceremony that Git enforces.”
Fallthrough · Hands-On Engineering Podcasts · October 2026
Paharia, who has worked on version control at Meta, says nearly every other version control system treats individual commits, not branches, as the source of truth. She adds that Meta's usage data showed most Mercurial users never created a branch when given the option.
Transcript
Just burned rebasing into my fingers now. It's just like, I don't know. So when I even want to do stack disks, I'm like, I can just rebase. I'll just move these around. It's whatever.
…on something and then go to switch context to do something else, then you go into the whole stash stuff, which gets annoying. Where JJ, you just don't do that. You just, you just leave. You just go to the, you go check out or you go do JJ new, and now you're working somewhere else. It's so magical.
…based around this kind of like branches being the source of truth and so on. In most version control systems, in basically every other version control system that I know about, the source of truth is not branches. The source of truth is individual commits. And so the units of work, not a branch, they're instead of commit. And so JJ follows in the older tradition of version control systems. And I actually think of Git and especially GitHub as a little bit outsider art, where it doesn't quite engage with the theory or the history or anything. It just kind of did its own thing. And of course, it became wildly successful. But I think JJ is built in this kind of older model, which is that commits are the source of truth. So individual commits are the units of work. I will say that at Meta, we used to do surveys and we used to kind of look at people's usage patterns. Mercurial also has commits as the source of truth. And what we found was that the vast, vast, vast majority of developers, effectively, when you gave…
I feel like even Git though, like I feel like GitHub is a branch-based system because Git itself, I mean, branches are basically just refs, right? Which are tags and all of that. So it's like, I feel like it's mostly GitHub that has inflicted this branch-based. Because you have like Garrett, which…
Yeah, so I think GitHub is definitely part of the thing here, but I do think that Git really, really wants you to. So, for context, like when I used Git, I actually used it in what is called detached head mode a lot. So, there was a year where I used Git, and I used it in detached head mode, aka…
Oh, my experience watching Rain work is looking at my email and seeing 11 stacked diffs on top of one another in like the Omicron repo or whatever. And it's like, you know, one of N, two of N, whatever. And I'm just like, oh, Rain's making some changes in the code today. And it's nice to see that…
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