`nix profile` broken after macOS upgrade

system details

issue

I recently upgraded to macOS 15.1, and now nix profile commands are completely broken. copied below is a description from another issue:

specifically running nix profile list produces the same list of installs I had before the upgrade/uninstall/reinstall, but none of them are accessible from PATH, and trying to make edits via nix commands like nix profile remove [PACKAGE] produces errors like:

error: filesystem error: in directory_iterator::directory_iterator(...): No such file or directory ["/nix/store/fgsrkvsa9mck3njnv0yz1f3d2yxd86nw-roc_cli-0.0.1"]

Not sure how to fix this.

edit: I followed some guides for changing my nix profile and now I don’t seem to be able to get my original profile back; all I see from ls -l /nix/var/nix/profiles/ is the default link and per-user, neither of which have my previous profile contents. and when trying to install “new” packages like nix profile install nixpkgs#git, I get an error like:

error: filesystem error: in create_symlink: Permission denied ["/nix/store/k7dcpp11x8j6vbpjh4nayfdinn79sf83-profile"] ["/nix/var/nix/profiles/default-1-link.tmp-1811-116806888"]