Add initial installer

home-manager/default.nix

@@ -0,0 +1,51 @@
+{ lib, hmFlakes, inputs, pkgs', modules }:
+let
+  inherit (builtins) removeAttrs mapAttrs;
+  inherit (lib) flatten optional recursiveUpdate;
+  inherit (lib.my) homeStateVersion;
+
+  mkHome = name: {
+    system,
+    nixpkgs ? "unstable",
+    home-manager ? nixpkgs,
+    config,
+    ...
+  }@args:
+  let
+    rest = removeAttrs args [ "nixpkgs" "home-manager" "config" ];
+  in
+  # homeManagerConfiguration doesn't allow us to set lib directly (inherits from passed pkgs)
+  hmFlakes.${home-manager}.lib.homeManagerConfiguration (recursiveUpdate rest {
+    configuration = config;
+    # Passing pkgs here doesn't set the global pkgs, just where it'll be imported from (and where the global lib is
+    # derived from). We want home-manager to import pkgs itself so it'll apply config and overlays modularly. Any config
+    # and overlays previously applied will be passed on by `homeManagerConfiguration` though.
+    pkgs = pkgs'.${nixpkgs}.${system};
+    extraModules = modules ++ [
+      {
+        warnings = flatten [
+          (optional (nixpkgs != home-manager)
+          ''
+            Using nixpkgs ${nixpkgs} with home-manager ${home-manager} may cause issues.
+          '')
+        ];
+
+        _module.args = {
+          inherit inputs;
+          pkgs' = mapAttrs (_: p: p.${system}) pkgs';
+        };
+      }
+      (homeStateVersion home-manager)
+    ];
+  });
+in
+mapAttrs mkHome {
+  "dev@castle" = {
+    system = "x86_64-linux";
+    nixpkgs = "unstable";
+    config = configs/castle.nix;
+
+    homeDirectory = "/home/dev";
+    username = "dev";
+  };
+}