flake: add coding-agent validation workflow

flake/registry.nix

@@ -25,23 +25,63 @@ let
     else
       { };
   configurations = dotfilesLib.hosts.mkConfigurations hostSpecs;
+
+  validationMetadata = {
+    schemaVersion = 1;
+
+    hosts = lib.mapAttrs (
+      name: spec:
+      let
+        isDarwin = lib.hasSuffix "-darwin" spec.system;
+      in
+      {
+        inherit (spec) system user;
+        kind = if isDarwin then "darwin" else "nixos";
+        homeManager = spec.homeManager or true;
+        selectedUnits = dotfilesLib.hosts.selectedUnits spec;
+        buildAttr =
+          if isDarwin then
+            "darwinConfigurations.${name}.system"
+          else
+            "nixosConfigurations.${name}.config.system.build.toplevel";
+      }
+    ) hostSpecs;
+
+    units = lib.mapAttrs (
+      _id: unit: {
+        inherit (unit) id relativePath;
+        directory = "modules/${lib.concatStringsSep "/" unit.relativePath}";
+        includes = unit.meta.includes;
+        fragments = builtins.attrNames (lib.filterAttrs (_: value: value != null) unit.fragments);
+      }
+    ) dotfilesLib.registry.units;
+  };
 in
 {
   flake = {
     inherit (configurations) darwinConfigurations nixosConfigurations;
-    lib = dotfilesLib;
+    lib = dotfilesLib // { inherit validationMetadata; };
   };
 
   perSystem =
     { pkgs, system, ... }:
     let
-      nixosChecks =
-        lib.mapAttrs' (name: nixos: lib.nameValuePair "nixos-${name}" nixos.config.system.build.toplevel)
-          (
-            lib.filterAttrs (
-              _: nixos: nixos.pkgs.stdenv.hostPlatform.system == system
-            ) configurations.nixosConfigurations
-          );
+      nixosChecks = lib.mapAttrs' (
+        name: nixos:
+        lib.nameValuePair "nixos-${name}" nixos.config.system.build.toplevel
+      ) (
+        lib.filterAttrs (
+          name: _: hostSpecs.${name}.system == system
+        ) configurations.nixosConfigurations
+      );
+      darwinChecks = lib.mapAttrs' (
+        name: darwin:
+        lib.nameValuePair "darwin-${name}" darwin.system
+      ) (
+        lib.filterAttrs (
+          name: _: hostSpecs.${name}.system == system
+        ) configurations.darwinConfigurations
+      );
     in
     {
       checks = {
@@ -49,6 +89,7 @@ in
           inherit inputs lib pkgs;
         };
       }
-      // nixosChecks;
+      // nixosChecks
+      // darwinChecks;
     };
 }