Fix vesktop build on darwin via overlay

Upstream electron-builder no longer respects CSC_IDENTITY_AUTO_DISCOVERY;
pass -c.mac.identity=null directly instead. Mirrors NixOS/nixpkgs#489725.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: tomrfitz

flake.nix

@@ -62,7 +62,10 @@
       darwinConfigurations.trfmbp = nix-darwin.lib.darwinSystem {
         specialArgs = { inherit agenix user; };
         modules = [
-          { nixpkgs.hostPlatform = "aarch64-darwin"; }
+          {
+            nixpkgs.hostPlatform = "aarch64-darwin";
+            nixpkgs.overlays = [ (import ./overlays/vesktop-darwin.nix) ];
+          }
           ./hosts/trfmbp
           home-manager.darwinModules.home-manager
           (mkHM [

overlays/vesktop-darwin.nix

@@ -0,0 +1,12 @@
+# Fix vesktop build on macOS — codesign not available in Nix sandbox.
+# Upstream: https://github.com/NixOS/nixpkgs/pull/489725
+# Remove once that PR lands in nixpkgs-unstable.
+final: prev:
+prev.lib.optionalAttrs prev.stdenv.hostPlatform.isDarwin {
+  vesktop = prev.vesktop.overrideAttrs (old: {
+    postConfigure = "";
+    buildPhase =
+      builtins.replaceStrings [ "-c.electronVersion=" ] [ "-c.mac.identity=null -c.electronVersion=" ]
+        old.buildPhase;
+  });
+}