Add cross-platform Nix flake bootstrap

Adds a flake providing shared modules for NixOS and standalone
home-manager, a copyable NixOS host template, and the OpenSpec
tooling/change scaffolding used to plan this work.

1 files changed, 48 insertions, 0 deletions

diff --git a/flake.nix b/flake.nix
new file mode 100644
index 0000000..729ab7e
--- /dev/null
+++ b/flake.nix
@@ -0,0 +1,48 @@
+{
+  description = "Cross-platform Nix system configuration (NixOS + standalone home-manager)";
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+
+    home-manager = {
+      url = "github:nix-community/home-manager";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+  };
+
+  outputs = { self, nixpkgs, home-manager, ... }@inputs:
+    let
+      lib = import ./lib { inherit inputs; };
+
+      forAllSystems = nixpkgs.lib.genAttrs [
+        "x86_64-linux"
+        "aarch64-linux"
+        "x86_64-darwin"
+        "aarch64-darwin"
+      ];
+    in
+    {
+      # No real NixOS host exists yet. hosts/template/ is copy-source only and
+      # is deliberately not wired in here — see hosts/template/ and README.md.
+      nixosConfigurations = { };
+
+      homeConfigurations = {
+        "tom@linux" = lib.mkHome {
+          username = "tom";
+          system = "x86_64-linux";
+        };
+      };
+
+      formatter = forAllSystems (system: nixpkgs.legacyPackages.${system}.nixfmt-rfc-style);
+
+      devShells = forAllSystems (system:
+        let
+          pkgs = nixpkgs.legacyPackages.${system};
+        in
+        {
+          default = pkgs.mkShell {
+            packages = [ pkgs.statix pkgs.deadnix pkgs.nixfmt-rfc-style ];
+          };
+        });
+    };
+}