change default terminal emulator to ghostty

home-manager/progs/alacritty.nix

@@ -1,5 +1,9 @@
 { pkgs, ... }:
 {
+  home.sessionVariables = {
+    TERMINAL = "alacritty";
+  };
+
   programs.alacritty = {
     enable = true;
     package = pkgs.alacritty;

home-manager/progs/ghostty.nix

@@ -0,0 +1,16 @@
+{ pkgs, ... }:
+{
+  # https://mynixos.com/home-manager/option/programs.ghostty
+  programs.ghostty = {
+    enable = true;
+    enableFishIntegration = true;
+    settings = {
+      theme = "Adventure";
+      background-opacity = 0.7;
+    };
+  };
+
+  home.sessionVariables = {
+    TERMINAL = "ghostty";
+  };
+}

home-manager/progs/niri.nix

@@ -133,7 +133,7 @@
         "Mod+O".action = toggle-overview;
 
         # open a terminal
-        "Mod+T".action = spawn "${pkgs.alacritty}/bin/alacritty";
+        "Mod+T".action = spawn config.home.sessionVariables.TERMINAL;
 
         # lock the screen
         "Mod+X".action = spawn "${pkgs.swaylock}/bin/swaylock";