Vim, Neovim

Using Vim as a diff tool

vimdiff comes as a pre-configured merge tool for jj and can be used with jj resolve out of the box. However, the default configuration for vimdiff as a diff editor (for jj split, etc.) is barely useable.

To more conveniently use Vim as a difftool for jj, try one of the following setups:

DirDiff plugin

1. Install the DirDiff Vim plugin.

2. Create a script in your PATH named vimdirdiff, with the following contents:

#!/bin/bash
# On Mac OS, you may need to replace `/bin/bash` with `/bin/zsh`.

# Shell-escape each path:
DIR1=$(printf '%q' "$1"); shift
DIR2=$(printf '%q' "$1"); shift
# Setting the colorscheme is optional
vim "$@" -c "colorscheme murphy" -c "DirDiff $DIR1 $DIR2"

3. Make that script executable: chmod +x vimdirdiff.
4. In your .jjconfig.toml, set ui.diff-editor="vimdirdiff".
5. (Optional) You can also create a similar gvimdirdiff script. The last line would need to include --nofork:

gvim --nofork "$@" -c "colorscheme murphy" -c "DirDiff $DIR1 $DIR2"

vimtabdiff.py script

1. Make sure you have Python installed. Optionally, check your Python version by running python --version.

2. Install vimtabdiff.py as described here. Use the command for python <3.10 if you are not sure what your version of Python is.

   Make sure it is in your PATH and that you ran chmod +x on it.

3. In your .jjconfig.toml, set ui.diff-editor="vimtabdiff.py".

Pros and cons of DirDiff/vimtabdiff.py

• The UI if DirDiff is better if you have many files to compare, while the vimtabdiff.py is better for fewer files
• vimtabdiff.py requires having Python installed, while DirDiff doesn't.
• DirDiff requires installing a Vim plugin, while vimtabdiff.py doesn't.

Syntax highlighting for editing commit descriptions

The vim-jjdescription Vim plugin provides highlighting of .jjdescription files that jj uses to edit commit messages.

Neovim

Using Neovim as editor

You can set Neovim to be your editor for describe and other commands with the following config:

ui.editor = "nvim"

This pairs well with vim-jjdescription Vim plugin as described above.

Using with flatten.nvim

flatten.nvim allows you to un-nest Neovim instances. For example, running jj describe in a :terminal will open in the parent Neovim instance.

jj expects the editor to wait until the file is closed to save. This can be achieved by using:

ui.editor = ["nvim", "--cmd", "let g:flatten_wait=1"]

Using Neovim as a diff editor (with existing git tooling)

The following merge-tool setup can be using to create a temporary parent and current git commit before invoking neovim, allowing you to use existing tooling like sindrets/diffviewiew.nvim, NeogitOrg/neogit, or tpope/vim-fugitive to edit and stage hunks during jj split -i, jj diffedit, etc.

config.toml:

[merge-tools.neovim]
program = "sh"
edit-args = [
  "-c",
  """
    set -eu
    rm -f "$right/JJ-INSTRUCTIONS"
    git -C "$left" init -q
    git -C "$left" add -A
    git -C "$left" commit -q -m baseline --allow-empty # create parent commit
    mv "$left/.git" "$right"
    git -C "$right" add --intent-to-add -A # create current working copy
    (cd "$right"; nvim)
    git -C "$right" diff-index --quiet --cached HEAD && { echo "No changes done, aborting split."; exit 1; }
    git -C "$right" commit -q -m split # create commit on top of parent including changes
    git -C "$right" restore . # undo changes in modified files
    git -C "$right" reset .   # undo --intent-to-add
    git -C "$right" clean -q -df # remove untracked files
  """
]

To use, run i.e. jj split -i --tool neovim, stage changes how you normally would in git, then quit neovim.

Plugins supporting jj

• jj-diffconflicts provides an interface to resolve merge conflicts. It can be configured to be invoked through jj resolve.

• vcsigns.nvim adds gutter signs and hunk operations for various version control systems, including dedicated support for jj.

• vcmarkers.nvim adds highlighting and operation for various conflict marker styles, but with specialized support for jj's conflict markers (e.g. cycling which side is shown as a snapshot).

• nvim-treesitter-jjconfig provides syntax highlighting (and other treesitter features) for revset and template expressions in jj configuration files.

Extensions

• zschreur/telescope-jj.nvim is a Neovim plugin to provide you with similar behavior to Telescope's builtin.git_files and builtin.git_status functions, as well listing conflicts.

• Cretezy/neo-tree-jj.nvim is a Neovim plugin to provide you with similar behavior to Neo-tree's git_status source. It can add a tab to Neo-tree to display the current status of a jj repo.

AstroNvim/AstroCommunity

You can use AstroCommunity (even without using AstroNvim) to configure several of these plugins at once. Import the jj pack in your Lazy.nvim config:

{
  "AstroNvim/astrocommunity",
  { import = "astrocommunity.pack.jj" },
}