jj and icdiff
Since it wasn't that obvious 1 from the website that you need to define a merge-tools section to get a diff tool up and running for jj, this is what you need in .config/jj/config.toml
[merge-tools.icdiff]
diff-args = [ "$left", "$right", "-r"]
then you can do jj diff --tool icdiff
https://jj-vcs.github.io/jj/latest/config/#generating-diffs-by-external-command - its' very obvious when you search for diff.tool instead of diff-tool.↩