{ config, lib, ... }:
let
  cfg = config.sane.programs.alsa-ucm-conf;
in
{
  sane.programs.alsa-ucm-conf = {
    sandbox.enable = false;  #< only provides #out/share/alsa

    # alsa-lib package only looks in its $out/share/alsa to find runtime config data, by default.
    # but ALSA_CONFIG_UCM2 is an env var that can override that.
    # this is particularly needed by wireplumber;
    #   also *maybe* pipewire and pipewire-pulse.
    # taken from <repo:nixos/mobile-nixos:modules/quirks/audio.nix>
    env.ALSA_CONFIG_UCM2 = "/run/current-system/sw/share/alsa/ucm2";

    enableFor.system = lib.mkIf (builtins.any (en: en) (builtins.attrValues cfg.enableFor.user)) true;
  };

  environment.pathsToLink = lib.mkIf cfg.enabled [
    "/share/alsa/ucm2"
  ];
}