nix/doc/manual/rl-next/better-flake-git-errors.md

synopsis	issues	prs
Improve error message for untracked files in git-based flakes		12870

If Nix cannot access a file in a flake because it is not tracked by Git, it now provides clear instructions to resolve the issue:

error: The path 'foo/bar' in the repository "/path/to/repo" is not tracked by Git.

       To make it accessible to Nix, you need to add it to Git by running:

       git -C "/path/to/repo" add "foo/bar"