Eval before deployment

flake.nix

@@ -41,13 +41,29 @@
         let
           pkgs = nixpkgs.legacyPackages.${system};
 
+          evalServerScript = pkgs.writeShellApplication {
+            name = "eval-server";
+            runtimeInputs = [ pkgs.nix ];
+            text = ''
+              set -euo pipefail
+
+              echo "▶ Evaluating NixOS configuration for '.#server'..."
+              nix eval .#nixosConfigurations.server.config.system.build.toplevel > /dev/null
+              echo "✅ Evaluation succeeded — configuration is valid."
+            '';
+          };
+
           deployServerScript = pkgs.writeShellApplication {
             name = "deploy-server";
-            runtimeInputs = [
-              pkgs.nix
-              pkgs.openssh
+            runtimeInputs = with pkgs; [
+              nix
+              openssh
             ];
             text = ''
+              set -euo pipefail
+
+              "${evalServerScript}/bin/eval-server"
+
               nix run nixpkgs#nixos-rebuild-ng -- \
                 --flake .#server \
                 --target-host thohlt@91.98.171.83 \
@@ -58,6 +74,11 @@
           };
         in
         {
+          eval-server = {
+            type = "app";
+            program = "${evalServerScript}/bin/eval-server";
+          };
+
           deploy-server = {
             type = "app";
             program = "${deployServerScript}/bin/deploy-server";