Allow configuring oh-my-posh

lib/modules/packages/oh-my-posh.nix

@@ -0,0 +1,60 @@
+{ lib, ... }:
+  let
+    inherit (lib)
+      mkOption
+      types
+    ;
+
+    themeType = types.submodule (
+      { config, ... }: {
+        options = {
+          path = mkOption {
+            type = types.nullOr types.path;
+            description = "The path to the oh-my-posh theme to use.";
+            default = null;
+          };
+
+          name = mkOption {
+            type = types.nullOr types.str;
+            description = "The name of the theme.";
+            default = if (config.path != null)
+            then
+              lib.strings.removeSuffix ".omp" (lib.strings.removeSuffix ".json" (builtins.baseNameOf config.path))
+            else
+              null;
+          };
+        };
+      });
+
+    ompType = types.submodule (
+      { config, ... }: {
+        options = {
+          theme = mkOption {
+            type = types.either types.str themeType;
+            description = "The default theme.";
+            default = {};
+          };
+
+          additionalThemes = mkOption {
+            type = types.listOf themeType;
+            description = "A set of additional themes to install.";
+            default = [];
+          };
+        };
+      });
+  in {
+    options = {
+      valhalla.users = mkOption {
+        type = types.attrsOf (types.submodule (
+          { ... }: {
+            options = {
+              oh-my-posh = mkOption {
+                type = ompType;
+                description = "The Oh My Posh configuration to apply.";
+                default = {};
+              };
+            };
+          }));
+      };
+    };
+  }

lib/modules/valhalla.nix

@@ -7,6 +7,7 @@
   in {
     imports = [
       ./packages/git.nix
+      ./packages/oh-my-posh.nix
       ./packages/rclone.nix
       ./hardware.nix
       ./i18n.nix