{
  pkgs,
  inputs,
  self,
}: let
  localPackages = import ../pkgs {inherit pkgs inputs;};
  mkPkgs = overlays:
    import inputs.nixpkgs {
      system = pkgs.stdenv.hostPlatform.system;
      config.allowUnfree = true;
      inherit overlays;
    };

  upstreamPkgs = mkPkgs [];
  modifiedPkgs = mkPkgs [self.overlays.modifications];
  defaultPkgs = mkPkgs [self.overlays.default];

  expectedVersion = "2.28.6";
  expectedSrcHash = "sha256-xll2dZon+WyJUXaCoel0htwgOGUqzpZvef/tDLTomZQ=";
  expectedPnpmHash = "sha256-SjmKXjxIuRY1uFbFLTMlXd0WW+3cVfu4TU+NoZtEYSo=";
  expectedChangelog = "https://github.com/n8n-io/n8n/releases/tag/n8n@${expectedVersion}";
  expectedXlsxIntegrity = "sha512-+nKZ39+nvK7Qq6i0PvWWRA4j/EkfWOtkP/YhMtupm+lJIiHxUrgTr1CcKv1nBk1rHtkRRQ3O2+Ih/q/sA+FXZA==";

  checkN8nOverride = overlayName: package:
    if package.version != expectedVersion
    then throw "${overlayName} n8n version is ${package.version}, expected ${expectedVersion}"
    else if package.src.outputHash != expectedSrcHash
    then throw "${overlayName} n8n src hash is ${package.src.outputHash}, expected ${expectedSrcHash}"
    else if package.pnpmDeps.outputHash != expectedPnpmHash
    then throw "${overlayName} n8n pnpmDeps hash is ${package.pnpmDeps.outputHash}, expected ${expectedPnpmHash}"
    else if package.meta.changelog != expectedChangelog
    then throw "${overlayName} n8n changelog is ${package.meta.changelog}, expected ${expectedChangelog}"
    else "ok";

  checkPhasesInherited = overlayName: package:
    if (package.preBuild or null) != (upstreamPkgs.n8n.preBuild or null)
    then throw "${overlayName} n8n preBuild should be inherited from upstream nixpkgs"
    else if package.buildPhase != upstreamPkgs.n8n.buildPhase
    then throw "${overlayName} n8n buildPhase should be inherited from upstream nixpkgs"
    else "ok";

  checkXlsxIntegrity = overlayName: package:
    pkgs.runCommand "${overlayName}-n8n-xlsx-integrity-test" {
      inherit expectedXlsxIntegrity;
    } ''
      grep -F "xlsx@https://cdn.sheetjs.com/xlsx-0.20.2/xlsx-0.20.2.tgz:" ${package.src}/pnpm-lock.yaml
      grep -F "resolution: {integrity: $expectedXlsxIntegrity, tarball: https://cdn.sheetjs.com/xlsx-0.20.2/xlsx-0.20.2.tgz}" ${package.src}/pnpm-lock.yaml
      touch $out
    '';
in
  pkgs.runCommand "n8n-overlay-test" {
    n8nOverlayFile =
      if builtins.pathExists ../overlays/mods/n8n.nix
      then "ok"
      else throw "n8n overlay override must live in overlays/mods/n8n.nix";
    localN8nAbsent =
      if localPackages ? n8n
      then throw "pkgs/default.nix must not export a local n8n package"
      else "ok";
    modificationsOverlayN8n = checkN8nOverride "overlays.modifications" modifiedPkgs.n8n;
    defaultOverlayN8n = checkN8nOverride "overlays.default" defaultPkgs.n8n;
    modificationsOverlayPhases = checkPhasesInherited "overlays.modifications" modifiedPkgs.n8n;
    defaultOverlayPhases = checkPhasesInherited "overlays.default" defaultPkgs.n8n;
    modificationsOverlayXlsxIntegrity = checkXlsxIntegrity "overlays.modifications" modifiedPkgs.n8n;
    defaultOverlayXlsxIntegrity = checkXlsxIntegrity "overlays.default" defaultPkgs.n8n;
  } ''
    touch $out
  ''