[twp]

> I know my way around emacs. vimdiff is a foreign country.

You don't have to use vimdiff. You can use any merge tool you want. See https://www.chezmoi.io/user-guide/tools/merge/.

> Often my changes are speculative or experimental. So I checkout, edit, apply and only then discover I’ve messed up. Or I can edit in place. Voila vimdiff!

> What’s the better way?

There are lots of options. See https://www.chezmoi.io/user-guide/frequently-asked-questions....

Personally, I tend to use `chezmoi edit` and then use git in my source directory to `git add -p . && git commit` the changes I want to keep and `git checkout` to discard the changes I don't want.