Yes they are not part of your source code

I see. The file add/remove is used only to force VS intellisense to connect arduino code. In previous tests we found that VS does not refresh its intellisense without this mechanism but it is due for re-test since so many microsoft vs changes of the past year.

If I recall there is a "tools>options>don't re-add header" option which hasn't been discussed for a long time but should work. In this case if intellisense doesn't function correctly after adding libraries or changing board etc. then close and re-open the project or delete the vs-intllisense.h file in the _vm folder then build.

I will try to do some testing over the next week or so.

I Have had a look into both xml files to check the differences.

In both, the <Board> tag is marked as different. But comparing the text, they seem to be identically, cannot see any differences. The git compare tool mark them as deleted and added again.

As I wrote in my first post, I've tried already to exclude __vm from git without success.

But one more (may be silly) idea.
The lines in those xml files with the <Board> tag are extremly large. And as I wrote, they are recognized as changed allthough if there are no changes. Could it simply be, that git comparation (which uses hash values) cannot handle such large lines?

Just an idea.