Modulize home.nix into a couple of modules.

modules/home-manager/zsh.nix

@@ -0,0 +1,45 @@
+{
+  config,
+  lib,
+  ...
+}: {
+  options = {
+    crony.zsh.enable = lib.mkEnableOption "Enable zsh and customize it.";
+  };
+
+  config = lib.mkIf config.crony.zsh.enable {
+    # Setup zsh
+    programs.zsh = {
+      enable = true;
+      enableCompletion = true;
+      autosuggestion.enable = true;
+      historySubstringSearch.enable = true;
+
+      dotDir = ".config/zsh";
+
+      initExtra = ''
+        # VI Mode escape timeout fix
+        export KEYTIMEOUT=1
+
+        # Substring search settings
+        export HISTORY_SUBSTRING_SEARCH_HIGHLIGHT_FOUND="bg=blue,fg=black,bold"
+        export HISTORY_SUBSTRING_SEARCH_HIGHLIGHT_NOT_FOUND='bg=red,fg=black,bold'
+        bindkey -M vicmd 'k' history-substring-search-up
+        bindkey -M vicmd 'j' history-substring-search-down
+      '';
+
+      zplug = {
+        enable = true;
+        plugins = [
+          {name = "zap-zsh/supercharge";}
+          {name = "zap-zsh/completions";}
+          {name = "zap-zsh/vim";}
+          {name = "chivalryq/git-alias";}
+          {name = "zdharma-continuum/fast-syntax-highlighting";}
+          {name = "zsh-users/zsh-history-substring-search";}
+          {name = "MichaelAquilina/zsh-you-should-use";}
+        ];
+      };
+    };
+  };
+}