Custom systemd service failed at boot - Reason: Unit rollback.service not found

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I am trying to set up impermanence on a fresh NixOS install, but my rollback systemd service always fails during boot. Interestingly, I have tested adding files to /, /etc, /var, and /var/lib and they do get deleted after rebooting. Here is the output of systemctl status rollback:

rollback.service
    Loaded: not-found (Reason: Unit rollback.service not found.)
    Active: failed (Result: exit-code) since Mon 2025-06-16 13:15:12 PDT; 9min ago
Invocation: 7051293d90134aa49b2be6o1e46c987
  Main PID: 686 (code=exited, status=127)
  Mem peak: 2.3M
       CPU: 7ms

This is my configuration.nix:

{ config, lib, pkgs, ... }:

{
  imports = [
    ./hardware-configuration.nix
  ];

  # Use the systemd-boot EFI boot loader.
  boot.loader.systemd-boot.enable = true;
  boot.loader.efi.canTouchEfiVariables = true;
  boot.kernelPackages = pkgs.linuxPackages_6_14;

  # Flakes
  nix.settings = {
    experimental-features = [
      "nix-command"
      "flakes"
    ];
  };

  # Impermanence
  boot.initrd.systemd.services.rollback = {
    description = "Rollback ZFS datasets to a blank snapshot taken immediately after disko formatting.";
    wantedBy = [
      "initrd.target"
    ]; 
    after = [
      "zfs-import-zroot.service"
    ];
    before = [ 
      "sysroot.mount"
    ];
    path = with pkgs; [
      zfs
    ];
    unitConfig.DefaultDependencies = "no";
    serviceConfig.Type = "oneshot";
    script = ''
      zfs rollback -r zroot/root@blank && echo "blank rollback complete"
    '';
  };
  fileSystems."/persist".neededForBoot = true;
  environment.persistence."/persist" = {
    directories = [
      "/etc/nixos"
      "/var/lib/nixos"
      "/var/lib/systemd"
      "/var/log/journal/"machine-id
    ];
    files = [
#      "etc/group"
#      "etc/gshadow"
      "/etc/machine-id"
#      "/etc/passwd"
#      "/etc/shadow"
#      "etc/subgid"
#      "etc/subuid"
#      "etc/zfs/zpool.cache"
    ];
  };

  networking.hostName = "nixos";
  networking.hostId = enter_an_8_byte_id_here
  networking.networkmanager.enable = true;

  time.timeZone = "America/Los_Angeles";

  users.users.jjh = {
    isNormalUser = true;
    extraGroups = [ "wheel" ];
    # Create passwd with: sudo mkpasswd -m sha-512 "passwd_here" > /mnt/persist/passwords/user during installation
    hashedPasswordFile = "/persist/passwords/jjh";
  };

  environment.systemPackages = with pkgs; [
    vim
  ];

  system.stateVersion = "25.11";
}