upd

flake.nix

@@ -3,19 +3,66 @@
 
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    # home-manager is declared so consumers can do
+    #   inputs.home-manager.follows = "steam-rom-manager/home-manager"
+    # and so nix flake check can instantiate the module correctly.
     home-manager = {
       url = "github:nix-community/home-manager";
       inputs.nixpkgs.follows = "nixpkgs";
     };
   };
 
-  outputs = { self, nixpkgs, home-manager, ... }:
+  outputs =
+    {
+      self,
+      nixpkgs,
+      home-manager,
+    }:
     let
-      supportedSystems = [ "x86_64-linux" "aarch64-linux" ];
-      forAllSystems = nixpkgs.lib.genAttrs supportedSystems;
+      # Linux systems where Steam (and AppImages) are supported.
+      # Darwin is intentionally excluded: the SRM AppImage is Linux-only.
+      linuxSystems = [
+        "x86_64-linux"
+        "aarch64-linux"
+      ];
+      forLinux = nixpkgs.lib.genAttrs linuxSystems;
     in
     {
+      # Home Manager module — available under both the conventional .default
+      # key and an explicit name for clarity in consumer flakes.
       homeManagerModules.default = import ./modules/steam-rom-manager;
       homeManagerModules.steam-rom-manager = import ./modules/steam-rom-manager;
+
+      # `nix flake check` target: instantiate the module with a minimal config
+      # to catch evaluation errors before they reach users.
+      checks = forLinux (
+        system:
+        let
+          pkgs = nixpkgs.legacyPackages.${system};
+          hmLib = home-manager.lib;
+        in
+        {
+          module-eval =
+            (hmLib.homeManagerConfiguration {
+              inherit pkgs;
+              modules = [
+                self.homeManagerModules.default
+                {
+                  home = {
+                    username = "test";
+                    homeDirectory = "/home/test";
+                    stateVersion = "24.11";
+                  };
+                  programs.steam-rom-manager = {
+                    enable = true;
+                    steamUsername = "testuser";
+                    # retroarch is cross-platform; use it as the check target
+                    emulators.retroarch.enable = true;
+                  };
+                }
+              ];
+            }).activationPackage;
+        }
+      );
     };
-}
+}