They’re referring to the Jujutsu VCS https://docs.jj-vcs.dev/latest/

Jujutsu is a git-compatible version control system

oopsie; should have added links.

`jj` is a wrapper around git and offers a much better dev-ex for managing changes.

it has features like:

- conflicts are first class citizens

- `rebase` is the default mode; there is no need for an interactive rebase mode.

- all descendant changes automatically rebase

- a much more intuitive version of `git reflog`. in `jj`, we have `jj op log`

- cheap branching: branches in `jj` are just tags (or bookmarks) that can be moved around

jujutsu is a different version control system: https://www.jj-vcs.dev/