Jjinn

Jjinn is a script for nix projects that runs a program (such as a llm agent) sandboxed inside in an ephemeral jj workspace. It uses the contents of your project's devShells to construct the sandbox environment using bwrap.

Workflow

jjinn integrates nicely into a regular jj workflow. You simply run jjinn <revset> and it will make sure every change made in the ephemeral workspace is synced to a new revset before terminating. You can then jj describe, jj squash, jj merge, jj edit, etc to deal with the resulting revision.

$ jjinn
>>> Created workspace in "../../../../tmp/jjinn-GEgA"
>>> Working copy  (@) now at: ysoklwzx 35f06f33 (empty) (no description set)
>>> Parent commit (@-)      : twsyxytt 1610239f (no description set)
>>> Added 7 files, modified 0 files, removed 0 files

──────────────────────────────────────────────────────────────────────────────────────────
Jarvis, please create a agentic ai b2b saas company. Do not make mistakes.
──────────────────────────────────────────────────────────────────────────────────────────

 ...

Temporary workspace changes are now in:
>>> ○  ysoklwzx neil@rickastley.co.uk 2026-02-12 19:00:58 jjinn-GEgA@ 47b2de02
>>> │  (no description set)
>>> ~

$ jj squash -i --from yso --to @
Rebased 5 descendant commits
Working copy  (@) now at: twsyxytt e285b076 (no description set)
Parent commit (@-)      : vvzymmuy f94c44fb main | prefix jj output with >>>
Added 0 files, modified 1 files, removed 0 files

Installation

This project can be used as a flake from github:anglesideangle/jjinn. For example, nix profile add github:anglesideangle/jjinn#jjinn-opencode.

The default jjinn configuration uses pi-coding-agent. However, it is not tightly coupled to a specific tool, and you can create your own package using this flake's lib.makeJjinn wrapper. For example:

jjinn.lib.makeJjinn pkgs {
  executable = lib.getExe pkgs.claude-code;
  sandboxInputs = with pkgs; [
    claude-code
    nix
    coreutils
    curl
    which
    findutils
    diffutils
    gnupatch
    gnugrep
    ...etc
  ];
  homeBinds = [ ".claude" ];
}