WIP: ADD NOTE FOR FUTURE SELF

Otherwise it keeps nagging me with a hint to set it.

I'm not a big fan of this UI, I wish I add something closer to Git's
patch interface.

modules/home/discord/default.nix

@@ -1,8 +1,6 @@
 { config, lib, pkgs, ... }:
 let
   cfg = config.my.home.discord;
-
-  jsonFormat = pkgs.formats.json { };
 in
 {
   options.my.home.discord = with lib; {
@@ -12,14 +10,15 @@ in
   };
 
   config = lib.mkIf cfg.enable {
-    home.packages = with pkgs; [
-      cfg.package
-    ];
+    programs.discord = {
+      enable = true;
 
-    xdg.configFile."discord/settings.json".source =
-      jsonFormat.generate "discord.json" {
+      inherit (cfg) package;
+
+      settings = {
         # Do not keep me from using the app just to force an update
         SKIP_HOST_UPDATE = true;
       };
+    };
   };
 }

pkgs/diff-flake/diff-flake

@@ -24,11 +24,15 @@ current_system() {
     nix eval --raw --impure --expr 'builtins.currentSystem'
 }
 
+add_darwin() {
+    FLAKE_OUTPUTS+=("darwinConfigurations.\"$1\".config.system.build.toplevel")
+}
+
 add_home() {
     FLAKE_OUTPUTS+=("homeConfigurations.\"$1\".activationPackage")
 }
 
-add_host() {
+add_nixos() {
     FLAKE_OUTPUTS+=("nixosConfigurations.\"$1\".config.system.build.toplevel")
 }
 
@@ -37,6 +41,10 @@ add_shell() {
     FLAKE_OUTPUTS+=("devShells.\"$(current_system)\".\"$1\".inputDerivation")
 }
 
+add_system() {
+    FLAKE_OUTPUTS+=("systemConfigs.\"$1\".config.system.build.toplevel")
+}
+
 usage() {
     print_err "Usage: $0 [option]... [-- [nix build option]...]"
     print_err ""
@@ -54,11 +62,15 @@ usage() {
     print_err "  -p, --previous-rev"
     print_err "    which git revision should be considered the 'previous' state,"
     print_err "    defaults to HEAD~"
+    print_err "  --darwin [name]"
+    print_err "    specify the name of a nix-darwin output configuration whose"
+    print_err "    closure should be diffed, can be used multiple times"
+    print_err "    if no host name is given, defaults to current hostname"
     print_err "  --home [name]"
     print_err "    specify the name of a home-manager output configuration whose"
     print_err "    closure should be diffed, can be used multiple times"
     print_err "    if no configuration name is given, defaults to current username"
-    print_err "  --host [name]"
+    print_err "  --nixos [name]"
     print_err "    specify the name of a NixOS output configuration whose"
     print_err "    closure should be diffed, can be used multiple times"
     print_err "    if no host name is given, defaults to current hostname"
@@ -66,6 +78,10 @@ usage() {
     print_err "    specify a specific devShell configuration name whose closure"
     print_err "    should be diffed, can be used multiple times"
     print_err "    if no name is given, defaults to 'default'"
+    print_err "  --system [name]"
+    print_err "    specify the name of a system-manager output configuration whose"
+    print_err "    closure should be diffed, can be used multiple times"
+    print_err "    if no host name is given, defaults to current hostname"
     print_err ""
     print_err "when no flake outputs are specified, automatically queries for"
     print_err "all NixOS configurations, and devShells for current system"
@@ -101,6 +117,14 @@ parse_args() {
                 PREVIOUS_REV="$(git rev-parse "$1")"
                 shift
                 ;;
+            --darwin)
+                if [ $# -gt 0 ] && ! is_option "$1"; then
+                    add_darwin "$1"
+                    shift
+                else
+                    add_darwin "$(hostname)"
+                fi
+                ;;
             --home)
                 if [ $# -gt 0 ] && ! is_option "$1"; then
                     add_home "$1"
@@ -109,12 +133,12 @@ parse_args() {
                     add_home "$USER"
                 fi
                 ;;
-            --host)
+            --nixos)
                 if [ $# -gt 0 ] && ! is_option "$1"; then
-                    add_host "$1"
+                    add_nixos "$1"
                     shift
                 else
-                    add_host "$(hostname)"
+                    add_nixos "$(hostname)"
                 fi
                 ;;
             --shell)
@@ -125,6 +149,14 @@ parse_args() {
                     add_shell "default"
                 fi
                 ;;
+            --system)
+                if [ $# -gt 0 ] && ! is_option "$1"; then
+                    add_system "$1"
+                    shift
+                else
+                    add_system "$(hostname)"
+                fi
+                ;;
             --)
                 NIX_BUILD_ARGS=("$@")
                 break
@@ -138,6 +170,12 @@ parse_args() {
     done
 }
 
+list_darwin_configurations() {
+    nix eval '.#darwinConfigurations' \
+        --apply 'attrs: with builtins; concatStringsSep "\n" (attrNames attrs)' \
+        --raw
+}
+
 list_home_configurations() {
     nix eval '.#homeConfigurations' \
         --apply 'attrs: with builtins; concatStringsSep "\n" (attrNames attrs)' \
@@ -156,6 +194,12 @@ list_dev_shells() {
         --raw
 }
 
+list_system_configurations() {
+    nix eval '.#systemConfigs' \
+        --apply 'attrs: with builtins; concatStringsSep "\n" (attrNames attrs)' \
+        --raw
+}
+
 diff_output() {
     local PREV NEW
     PREV="$(mktemp --dry-run)"
@@ -175,15 +219,21 @@ diff_output() {
 parse_args "$@"
 
 if [ "${#FLAKE_OUTPUTS[@]}" -eq 0 ]; then
+    for darwin in $(list_darwin_configurations); do
+        add_darwin "$darwin"
+    done
     for home in $(list_home_configurations); do
         add_home "$home"
     done
-    for host in $(list_nixos_configurations); do
-        add_host "$host"
+    for nixos in $(list_nixos_configurations); do
+        add_nixos "$nixos"
     done
     for shell in $(list_dev_shells); do
         add_shell "$shell"
     done
+    for system in $(list_system_configurations); do
+        add_system "$system"
+    done
 fi
 
 for out in "${FLAKE_OUTPUTS[@]}"; do