Preserve compiler metadata context and diagnose exact identity differences (#931)

source-qualification.nix

@@ -5,6 +5,8 @@
 }:
 let
   comparisonIdentity = import ../tools/local-first/derivation-identity.nix;
+  # Inspect the actual .drv as data, without its derivation-deep output context.
+  productionDerivation = builtins.unsafeDiscardOutputDependency library.drvPath;
   source = pkgs.lib.fileset.toSource {
     root = ./.;
     fileset = pkgs.lib.fileset.unions [
@@ -28,14 +30,23 @@ let
   };
   inputs = pkgs.writeText "protocol-source-inputs.json" (
     builtins.toJSON {
-      inherit source nixpkgsNarHash;
+      inherit source nixpkgsNarHash productionDerivation;
+      narHashContext = builtins.getContext nixpkgsNarHash;
+      evaluatorVersion = builtins.nixVersion;
+      pinnedNixVersion = pkgs.nix.version;
       nixpkgs = pkgs.path;
       system = pkgs.stdenv.hostPlatform.system;
       expected = comparisonIdentity library;
+      expectedSource = builtins.unsafeDiscardStringContext (toString library.src);
       yarn = comparisonIdentity library.yarn-freestanding;
     }
   );
-  closure = pkgs.closureInfo { rootPaths = [ pkgs.path ]; };
+  closure = pkgs.closureInfo {
+    rootPaths = [
+      pkgs.path
+      productionDerivation
+    ];
+  };
 in
 pkgs.runCommand "quixos-protocol-source-check"
   {