Things Rain Paharia Has Said on Podcasts

“I think personally that agents actually like JJ more than they like Git. Not to anthropomorphize it too much, but what I mean specifically is that I have seen agents screw up and then use undo.” — Rain Paharia, Fallthrough

Paharia is describing using coding agents with Jujutsu (JJ), a version control system that snapshots and logs every operation. Because of that log, an agent can undo its own mistakes and see what changes a human made in the meantime.

Fallthrough · 2026-10-17 Permalink → Listen →

Fallthrough Around 21:04 into the episode

Rain Paharia

…real expertise and mastery in it. And, um, and you know, I think I guess a lot of people these days don't even use version control, they just use agents to do their version control. I am still pretty old school, I do my version control by hand for the most part. I do have is that old school now?

Matthew Sanabria

Is that what the definition of old school has updated to now?

Rain Paharia

You know, like I, I, uh, the, the one thing, the one source control operation I do use uh, uh, it for uh agents for is resolving merge conflicts, by the way. Uh, so if folks are, um, you know, that that's the thing that I do use it for. Um, I have found that JJ, you can just tell your agent to use JJ whenever it needs to do, say, read-only operation or something like that. And then it just uses JJ consistently. And what that means is that with JJ, and I think personally, that agents actually like JJ more than they like Git. Not to anthropomorphize it too much, but what I mean specifically is that I have seen agents screw up and then use undo. Or, for example, I have made local changes, right? And so, you know, I'll have an agent window and then I will make a local change to it. And then I will go back to the agent window and it'll be like, okay, well, you know, resume from here. And then the agent knows like clawed code or whatever, knows how to look at the operation log in JJ…

Matthew Sanabria

You hear that, Chris? This is for you. Okay. We're going to convert you over to JJ. It's happening. You're not holding out on us anymore. I think Chris and I have spoken about it in the past, especially since we've had Steve on and we chat a little bit about it too. And I think Chris is still in…

Kris Brandow

Steve on is an understatement. Yeah, Steve's been

Matthew Sanabria

on a lot.

Speaker names from our own diarization · position estimated from where the line sits in the episode

“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.” — Rain Paharia, Fallthrough

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.

Fallthrough · 2026-10-17 Permalink → Listen →

Fallthrough Around 31:14 into the episode

Kris Brandow

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.

Matthew Sanabria

…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.

Rain Paharia

…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…

Kris Brandow

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…

Rain Paharia

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…

Matthew Sanabria

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…

Speaker names from our own diarization · position estimated from where the line sits in the episode

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