[IlliOnato]

For a long time I have been wishing that Git had a capability of "track this file locally, but don't transfer it when pushing or cloning". Such files would be listed using the same syntax as .gitignore, but in a different file, say .gitlocal or something.

Git kind of has some "local tracking" already: if I am not mistaken, lightweight tags behave like this. It would be cool if it could track files in the same way.

Under the hood it could be done via a separate database, stored not in .git but in .gitl directory or some such. The database in .git would behave as if both .gitignore and .gitlocal contribute to ignoring, and .gitl as if .gitlocal was .gitignore in reverse: it would ignore anything not covered in .gitlocal (and also ignore what's in .gitignore). Or something along these lines.

[mdaniel]

this may not help you, but JetBrains IDEs have "local history" which addresses many of those concerns, including applying tags to meaningful points in time: https://www.jetbrains.com/help/idea/local-history.html

[TylerE]

That has saved me so much time over the years. Makes quick experimentation totally painless.