feat: mute 'astyanax' speakers when disconnecting AC

hosts/astyanax/default.nix

@@ -26,12 +26,13 @@ in
       device = "/dev/nvme0n1";
     })
     ../../modules/desktops/niri
+    ../../modules/audio
+    ../../modules/audio-automation
     ../../modules/backups
     ../../modules/bluetooth
     ../../modules/keyboard
     (import ../../modules/networking { inherit hostName; })
     ../../modules/users
-    ../../modules/audio
     ../../modules/localization
     ../../modules/fonts
     ../../modules/ssh/hardened-openssh.nix

modules/audio-automation/default.nix

@@ -0,0 +1,17 @@
+{ pkgs, ... }:
+
+{
+  environment.systemPackages = [ pkgs.libnotify ];
+
+  services.udev.extraRules = ''
+    SUBSYSTEM=="power_supply", ATTR{online}=="0", ACTION=="change", TAG+="systemd", ENV{SYSTEMD_USER_WANTS}+="mute-audio.service"
+  '';
+
+  systemd.user.services.mute-audio = {
+    description = "mute audio when switching to battery power";
+    serviceConfig = {
+      Type = "oneshot";
+      ExecStart = "${pkgs.bash}/bin/bash -c '${pkgs.pulseaudio}/bin/pactl set-sink-mute $(${pkgs.pulseaudio}/bin/pactl get-default-sink) true && ${pkgs.libnotify}/bin/notify-send \"audio Muted\" \"switched to battery power\"'";
+    };
+  };
+}