[martinvonz]

> Do you want to educate us of the command?

Not sure that they had in mind but you can do `jj squash --from <oldest commit with unwanted file>:: --destination 'root()' <path to unwanted file>`. That will take the changes to the unwanted file from all those commits and move them into a new commit based on the root commit (the root commit is virtual commit that's the ancestor of every other commit).