Diagrams should get rendered to an output folder below resources/_gen/images. Otherwise one needs to add content/**/*.png|jpg|svg|... to the .gitignore file to avoid Git changes in the worktree which need to get reverted after each site build.

Currently if one is working with workingFolderCurrent: true the images are generated besides their origin *.adoc files. This is required when you want to have working relative AsciiDoc cross references and AsciiDoc includes. But it would be totally fine to have generated images in resources/_gen/images, as they are combined in Hugo's union file system. It would just be necessary that the folder structure under content would be reflected so that image references are fine. Also for permalinks of course.

Maybe there is a way to achieve this with the current AsciiDoctor integration.

I think the imagesoutdir attribute would need to be configured per file in a way that resources/_gen/images is used as prefix and content/path/to/image/origin/file.adoc is converted to path/to/image/origin/ and concatenated with the prefix.

resources/_gen/images/path/to/image/origin/

@jmooring What do you think?