From 01106110fe027fd6bf93dad3f7e4652ef86321fb Mon Sep 17 00:00:00 2001
From: Jonas Rabenstein <nonapode@fbs42.ddnss.de>
Date: Wed, 26 Nov 2025 02:40:42 +0100
Subject: [PATCH 1/3] automatically import ${namespace}.${class(es)} as modules

Allow to specify a list of classes in the host/<hostname>.nix (by
default the class <hostname> is used) that will automatically load
specified outputs of inputs.
---
 export/nixosConfigurations.nix | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/export/nixosConfigurations.nix b/export/nixosConfigurations.nix
index f8dba98..eb8c570 100644
--- a/export/nixosConfigurations.nix
+++ b/export/nixosConfigurations.nix
@@ -15,6 +15,7 @@ let
     {
       namespace ? "fbs42",
       nixpkgs ? "nixpkgs",
+      classes ? [ hostname ],
     }:
     inputs.${nixpkgs}.lib.nixosSystem {
       specialArgs = { inherit inputs flake namespace; };
@@ -24,6 +25,9 @@ let
             base: builtins.attrValues (flake.lib.scan { base = "${base}/host/${hostname}"; })
           ) flake.lib.schema.base
         )
+        ++ map (class: {
+          imports = map (input: input.${namespace}.${class} or { }) (builtins.attrValues inputs);
+        }) classes
         ++ [ { config.networking.hostName = hostname; } ]
         ++ [ nixosModules.default ]
         ++ inputs.${nixpkgs}.lib.optional (inputs ? home-manager) {

From 1df1a59788b96b19e520c41d8eced0480e85bd32 Mon Sep 17 00:00:00 2001
From: Jonas Rabenstein <nonapode@fbs42.ddnss.de>
Date: Wed, 26 Nov 2025 15:58:37 +0100
Subject: [PATCH 2/3] nixosConfiguration: preSwitchCkeck: nvd

---
 export/nixosConfigurations.nix | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/export/nixosConfigurations.nix b/export/nixosConfigurations.nix
index f8dba98..9c52a84 100644
--- a/export/nixosConfigurations.nix
+++ b/export/nixosConfigurations.nix
@@ -10,6 +10,21 @@
 { ... }@inputs:
 { host, ... }@imports:
 let
+  pre-switch-check =
+    { pkgs, lib, config, ... }:
+    {
+      config.system.preSwitchChecks.nvd = ''
+        ${lib.getExe pkgs.nvd} --nix-bin-dir ${config.nix.package}/bin diff /run/current-system "''${1}"
+        if [[ -t 0 ]]; then
+          printf 'really %s to %s? [y]es/[N]o ' "''${2}" "''${1}"
+          read -r nvd_check
+        else
+          nvd_check=y
+        fi
+        [[ "''${nvd_check}" == y ]]
+      '';
+    };
+
   system =
     hostname:
     {
@@ -24,6 +39,7 @@ let
             base: builtins.attrValues (flake.lib.scan { base = "${base}/host/${hostname}"; })
           ) flake.lib.schema.base
         )
+        ++ [ pre-switch-check ]
         ++ [ { config.networking.hostName = hostname; } ]
         ++ [ nixosModules.default ]
         ++ inputs.${nixpkgs}.lib.optional (inputs ? home-manager) {

From d1e661df5d4ed4d754ecf3b93af65964f3617b47 Mon Sep 17 00:00:00 2001
From: Jonas Rabenstein <nonapode@fbs42.ddnss.de>
Date: Wed, 26 Nov 2025 15:58:37 +0100
Subject: [PATCH 3/3] nixosConfiguration: preSwitchCkeck: nvd

---
 export/nixosConfigurations.nix | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/export/nixosConfigurations.nix b/export/nixosConfigurations.nix
index eb8c570..21e8a45 100644
--- a/export/nixosConfigurations.nix
+++ b/export/nixosConfigurations.nix
@@ -10,6 +10,23 @@
 { ... }@inputs:
 { host, ... }@imports:
 let
+  pre-switch-check =
+    { pkgs, lib, config, ... }:
+    {
+      config.system.preSwitchChecks.nvd = ''
+        nvd_check=y
+        if [[ -d /run/current-system ]]
+        then
+          ${lib.getExe pkgs.nvd} --nix-bin-dir ${config.nix.package}/bin diff /run/current-system "''${1}"
+          if [[ -t 0 ]]; then
+            printf 'really %s to %s? [y]es/[N]o ' "''${2}" "''${1}"
+            read -r nvd_check
+          fi
+        fi
+        [[ "''${nvd_check}" == y ]]
+      '';
+    };
+
   system =
     hostname:
     {
@@ -28,6 +45,7 @@ let
         ++ map (class: {
           imports = map (input: input.${namespace}.${class} or { }) (builtins.attrValues inputs);
         }) classes
+        ++ [ pre-switch-check ]
         ++ [ { config.networking.hostName = hostname; } ]
         ++ [ nixosModules.default ]
         ++ inputs.${nixpkgs}.lib.optional (inputs ? home-manager) {