We use Madcap Flare for a large documentation set, with HTML output. (Flare source is a very HTML-y XML with some Flare-specific additions.) We use git for source control and new work is done on branches. This means that at the end we have a git pull request (PR) that can show a diff between the branch and the main (master) branch. This diff is very helpful for reviewing a PR, if you're comfortable reviewing by reading the raw XML.
Some of our reviewers would prefer to look at the changes in the HTML output. That's fine in one sense -- we can do a build from the branch, so reviewers can see what the documentation looks like. But that just gets you a build; reviewers still have to dig around to see what parts changed. We can give them a list of changed topics, but if a topic is long and the small-but-important change is those two paragraphs most of the way down, then either the writer has to construct detailed instructions for reviewers or reviewers have to scan everything looking for the change. I'm looking for a way to make the specific changes more visible in the HTML output.
We use Jenkins to manage our builds. Jenkins checks out the branch from git in order to do the build. Git knows where the diffs are on the branch. Is there a way to feed those git diffs into a Flare build (this probably involves preprocessing the source) so that in the output, diffs are highlighted? If showing deletions is hard, is there a way to at least mark, at the paragraph level, where there were changes? "Mark" can mean changebars, a font color change, an icon at the beginning of the paragraph -- I don't much care what the marker is, as it'll only ever be seen in these review builds.
This question is different from How can we make reviewing HTML documentation easier?. That question asks about ways to help reviewers attach their comments to specific changes; this question is about identifying those changes in the output.
The ideal answer to this question would describe an automated path (no human intervention after setting it up) from the git diffs to highlighted changes in the output HTML. A preprocessing step that locally modifies the XML source to, say, wrap font tags to change the color around changed parts before running the build would be fine. (This build never checks anything in, so it doesn't matter if it alters the Flare source after checking it out.) If that's hard, then we could work with a solution that shows, for each changed topic, the diff and a link to the right place in the output. Perhaps, based on comments, we might be able to use Flare index tags or bookmarks and git "export patch" to do that. It still has to be automatic, generated from the git diff, though; asking writers to manually mark changes isn't going to work.