Installing graphviz package

General
1

I like to install graphviz package in my idx environment to be able to view AI models. I have include it in packages section of dev.nix:

  packages = [
    pkgs.p7zip
    pkgs.python311
    pkgs.python311Packages.pip
    pkgs.xxd
    pkgs.graphviz
  ];

However I cannot locate graphviz in the environment.
I reviewed messages created by onCreate hooks and don’t see any reference to graphviz. In fact I don’t see a reference to any of my installed packages there (including ones that are working).
Does anyone know if there is a log for installation of packages?