home: setup ssh_auth_sock

home/default.nix

@@ -1,4 +1,4 @@
-{...}: {
+{config, ...}: {
   imports = [
     ./alacritty.nix
     ./bat.nix
@@ -25,7 +25,11 @@
 
   home.username = "alarsyo";
 
-  home.sessionVariables = {
+  home.sessionVariables = let
+    gpgPackage = config.programs.gpg.package;
+  in {
     BROWSER = "firefox";
+    # FIXME: only set if gpg-agent not in use, otherwise home manager already does that
+    SSH_AUTH_SOCK = "$(${gpgPackage}/bin/gpgconf --list-dirs agent-ssh-socket)";
   };
 }