configs/nixos/modules/host/default.nix

@@ -53,6 +53,7 @@ in
         home.username = config.user.name;
         home.homeDirectory = "/home/${config.user.name}";
         home.stateVersion = config.system.stateVersion;
+        home.sessionVariables = lib.attrByPath [ config.networking.hostName ] { } config.registry.env;
         home.packages = with pkgs; [
           eza
           unzip

configs/nixos/modules/shell/python.nix

@@ -13,9 +13,8 @@ in
     lib.mkEnableOption "Python tools for the primary user's shell environment";
 
   config = lib.mkIf config.modules.shell.python.enable {
-    home-manager.users.${user}.home = {
-      sessionVariables.PYTHON_TOOLCHAIN_ROOT = "${pkgs.python3}";
-      packages = [ pkgs.python3 ];
-    };
+    registry.env.${config.networking.hostName}.PYTHON_TOOLCHAIN_ROOT = "${pkgs.python3}";
+
+    home-manager.users.${user}.home.packages = [ pkgs.python3 ];
   };
 }

configs/nixos/modules/shell/rust.nix

@@ -23,9 +23,9 @@ in
     lib.mkEnableOption "Rust tools for the primary user's shell environment";
 
   config = lib.mkIf config.modules.shell.rust.enable {
-    home-manager.users.${user} = {
-      home.sessionVariables.RUST_TOOLCHAIN_ROOT = "${toolchain}";
+    registry.env.${config.networking.hostName}.RUST_TOOLCHAIN_ROOT = "${toolchain}";
 
+    home-manager.users.${user} = {
       home.packages = [
         toolchain
         pkgs.rust-analyzer

configs/nixos/registry/env.nix

@@ -0,0 +1,4 @@
+{ lib, ... }:
+{
+  type = lib.types.str;
+}