{ config, pkgs, ... }: {
  # tarsnap periodic backup configuration
  # {{{
  launchd.agents.tarsnap =
    let
      logPath = "${config.xdg.stateHome}/tarsnap";
      tarsnapBackup = pkgs.writeShellScriptBin "tarsnap-backup-helper" ''
        /opt/homebrew/bin/tarsnap -c \
          --configfile ${config.home.homeDirectory}/.tarsnaprc \
          --keyfile ${config.xdg.configHome}/tarsnap/write-only.key \
          -f $(uname -n)-$(date -u +%Y-%m-%dT%H:%M:%SZ) \
          ${config.home.homeDirectory}/{dotfiles.nix,Desktop,Development,Documents,Downloads}
      '';
    in
    {
      enable = true;
      config = {
        Label = "com.tarsnap.tarsnap";
        StandardErrorPath = "${logPath}/error.log";
        StandardOutPath = "${logPath}/out.log";
        StartCalendarInterval = [
          {
            # every sunday
            Weekday = 0;
            # at midnight
            Hour = 0;
            Minute = 0;
          }
          {
            # every wednesday
            Weekday = 3;
            # at noon
            Hour = 12;
            Minute = 0;
          }
        ];
        Program = "${tarsnapBackup}/bin/tarsnap-backup-helper";
      };
    };
  # }}}
}