flake update

flake.nix

@@ -52,11 +52,15 @@
       url = "git+https://code.m3ta.dev/m3tam3re/AGENTS";
       flake = false;
     };
+    zugferd-service = {
+      url = "git+https://git.az-gruppe.com/AZ-Intec-GmbH/zugferd-service";
+    };
   };
 
   outputs = {
     self,
     agenix,
+    agents,
     deploy-rs,
     home-manager,
     nixpkgs,
@@ -84,23 +88,47 @@
         inherit system;
         config.allowUnfree = true; # Allow unfree packages in devShell
       };
+      m3taLib = m3ta-nixpkgs.lib.${system};
+      rules = m3taLib.opencode-rules.mkOpencodeRules {
+        inherit agents;
+        languages = ["nix"];
+      };
     in {
       default = pkgs.mkShell {
+        inherit (rules) instructions;
         buildInputs = with pkgs; [
-          opentofu
-          openssh
+          alejandra
+          nixd
+          opencode
           agenix.packages.${system}.default
         ];
 
         shellHook = ''
-          echo "🚀 NixOS Infrastructure Development Shell"
-          echo "Available tools:"
-          echo "  - opentofu: Infrastructure as Code"
-          echo "  - agenix: Secret management"
+          ${rules.shellHook}
+          echo "🚀 NixOS Infrastructure Development Shell with Opencode Rules"
           echo ""
-          echo "Quick start:"
-          echo "  cd terraform && tofu init init"
+          echo "Active rules:"
+          echo "  - Nix language conventions"
+          echo "  - Coding-style best practices"
+          echo "  - Naming conventions"
+          echo "  - Documentation standards"
+          echo "  - Testing guidelines"
+          echo "  - Git workflow patterns"
+          echo "  - Project structure guidelines"
           echo ""
+          echo "Generated files:"
+          echo "  - .opencode-rules/ (symlink to AGENTS repo)"
+          echo "  - opencode.json (configuration file)"
+          echo ""
+          echo "Useful commands:"
+          echo "  - cat opencode.json        View rules configuration"
+          echo "  - ls .opencode-rules/      Browse available rules"
+          echo "  - nix develop              Re-enter this shell"
+          echo ""
+          echo "Remember to add to .gitignore:"
+          echo "  .opencode-rules"
+          echo "  opencode.json"
+          echo "======================================"
         '';
       };
     });
@@ -112,6 +140,7 @@
           ./hosts/AZ-CLD-1
           agenix.nixosModules.default
           inputs.disko.nixosModules.disko
+          inputs.zugferd-service.nixosModules.default
         ];
       };
       AZ-PRM-1 = nixpkgs.lib.nixosSystem {