The latest public release of jj-vcs/jj is v0.46.0. Jujutsu is a version control system that copies the code of software projects, tracks changes and publishes them, and its command-line tool is named jj. The provided materials contain no change entries for v0.46.0, so what changed in this version cannot be confirmed.
jj uses Git repositories as its storage layer, so it stays compatible with existing Git-based tools. It automatically commits changes in the working copy, and its operation log and undo let you review or roll back the change history. Automatic committing is a model that records what you edit without a separate commit step. Automatic rebasing reapplies the related changes to their base and preserves that record when conflicts occur. This capability covers handling the working copy and commits, recording conflicts, and rewriting history, and it flows from there. Therefore jj is not simply a Git helper tool but an independent version control system that tracks and publishes code. The implementation language is Rust and the license is Apache-2.0.
That said, the README explains that what is stable is Git compatibility, while Jujutsu itself is experimental. Git submodule support is also not yet complete. So while it is clear that existing Git repositories and tools can be used, workflows that use submodules should consider the supported scope first.