oops

common/services.nix

···
   services.tailscale.useRoutingFeatures = "both";
   services.tailscale.authKeyFile = lib.mkIf (config ? age && config.age ? secrets) 
     config.age.secrets."headscale-authkey".path;
+  services.tailscale.extraUpFlags = [
+    "--login-server=https://headscale.nekomimi.pet"
+  ];
 }

flake.nix

···
             ./hosts/buer
 
             agenix.nixosModules.default
+
+            { imports = builtins.attrValues nixosModules; }
           ];
         };
       };