comment on how to test the overlay is needed.

modules/darwin/default.nix

@@ -1,7 +1,7 @@
 { config, pkgs, ... }:
 
 let
-  emacsOverlaySha256 = "0ph4w9c8si2flsgin17k0xnpkv48q82m7fvrqd8jqw5vlq100rii";
+  emacsOverlaySha256 = "1smprpp3zqh04jdv0b7ibc69n025j1bnpp76lnwyvidilf055g2h";
 in
 {
   home-manager.backupFileExtension = "nix-backup";

modules/darwin/packages.nix

@@ -110,6 +110,7 @@ with pkgs;
       flask-socketio
       h11
       idna
+      intelhex
       importlib-metadata
       itsdangerous
       jinja2

overlays/10-feather-font.nix

@@ -1,30 +0,0 @@
-self: super: with super; {
-
-  feather-font = let
-    version = "1.0";
-    pname = "feather-font";
-  in stdenv.mkDerivation {
-    name = "${pname}-${version}";
-
-    src = fetchzip {
-      url = "https://github.com/dustinlyons/feather-font/archive/refs/tags/${version}.zip";
-      sha256 = "sha256-Zsz8/qn7XAG6BVp4XdqooEqioFRV7bLH0bQkHZvFbsg=";
-    };
-
-    buildInputs = [ unzip ];
-    phases = [ "unpackPhase" "installPhase" ];
-
-    installPhase = ''
-      mkdir -p $out/share/fonts/truetype
-      cp $src/feather.ttf $out/share/fonts/truetype/
-    '';
-
-    meta = with lib; {
-      homepage = "https://www.feathericons.com/";
-      description = "Set of font icons from the open source collection Feather Icons";
-      license = licenses.mit;
-      maintainers = [ maintainers.dlyons ];
-      platforms = [ platforms.x86_64-darwin ];
-    };
-  };
-}

overlays/20-zotero-pin.nix

@@ -0,0 +1,27 @@
+# To test if a new Zotero package works without the overlay try
+# nix --extra-experimental-features 'nix-command flakes' eval --raw --impure --expr '
+# let
+#  flake = builtins.getFlake (toString ./.);
+#  pkgs = import flake.inputs.nixpkgsAarch64 {
+#    system = "aarch64-darwin";
+#    config.allowUnfree = true;
+#  };
+# in
+# pkgs.zotero.version
+# '
+
+final: prev:
+
+let
+  pinnedPkgs = import (builtins.fetchTarball {
+    # Last nixpkgs Zotero package revision before 10.0.2.
+    url = "https://github.com/NixOS/nixpkgs/archive/4118d63e017feb54b48e7341e4b6f0ac5348f074.tar.gz";
+    sha256 = "1w33226pjk7hs9hbzy0ghcvgps0yicm0r2zxnnrzsr26pzvjjm6z";
+  }) {
+    system = prev.stdenv.hostPlatform.system;
+    config = prev.config;
+  };
+in
+{
+  zotero = pinnedPkgs.zotero;
+}