I don't see that it takes JSON, looking at the form.

That's how I have the value set and it still expands by default files whose
path matches one of those regexes.

Oh, it wasn't really clear. I thought you were saying it worked, but the config page was different/confusing.

D13885 is a test I ran, at least on this instance regex's are working fine with @^webroot/rsrc/image/autosprite\.png$@

I can't reproduce this. Here's what I did:

I configured differential.generated-paths like your example:

I made some changes locally:

$ git status
On branch master
Your branch is up-to-date with 'origin/master'.
Changes to be committed:
  (use "git reset HEAD <file>..." to unstage)

	new file:   Gemfile.lock
	new file:   something-with-compiled.js
	new file:   vendor/example.c

I arc diff'd these changes, and got hits on two rules:

The third rule doesn't hit because it requires a leading /. I modified the rule into:

#(^|/)vendor/#

Then ran arc diff again and got hits on all three rules:

Note that these rules are evaluated the first time a changeset is rendered, not each time we re-render a changeset. If you're reloading existing diffs, they won't re-evaluate the rules. I'm going to assume that's the issue here and fix this with a documentation change.

I had this same issue because it wasn't clear to me from the example regex's that #/vendor/# wouldn't match a vendor folder that's at the root. Would it make sense to change that 2nd example value (#/autobuilt/#) to something like the modified rule from your comment? #(^|/)autobuilt/#