``` A---B---C main \ D---E---F feature1 \ \---G---H feature2 \ \---I---J feature3 ```
(sorry about the formatting here. I guess you'll have to copy & paste it to read it)
What I'm saying is that if I want to fix something in D, I do `jj new D` to create a new commit on top of D. Then I make the fix, run tests, etc., and then I run `jj squash` to amend the changes into D. The descendant commits (E through J) then get automatically rebased and the feature bookmarks/branches get updated.
I didn't follow what you about it other changes needed for updating the ancestor. Can you explain in the context of this example?
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The other thing I am saying is that I don't really let features depend on each other, I let them specify the API between them first and then develop them independently. Otherwise it is easy to violate boundaries. So the ideal is that any of G,H and I,J works with D,E,F and vice versa. Of course that is tangential and it doesn't always work that way.