home: direnv: allow specifying default flake

home/direnv/default.nix

@@ -3,8 +3,18 @@ let
   cfg = config.my.home.direnv;
 in
 {
-  options.my.home.direnv = with lib.my; {
-    enable = mkDisableOption "direnv configuration";
+  options.my.home.direnv = with lib; {
+    enable = my.mkDisableOption "direnv configuration";
+
+    defaultFlake = mkOption {
+      type = types.str;
+      default = "pkgs";
+      example = "nixpkgs";
+      description = ''
+        Which flake from the registry should be used for
+        <command>use pkgs</command> by default.
+      '';
+    };
   };
 
   config = lib.mkIf cfg.enable {
@@ -28,5 +38,9 @@ in
             { source = libDir + "/${name}"; };
       in
       lib.my.genAttrs' files linkLibFile;
+
+    home.sessionVariables = {
+      DIRENV_DEFAULT_FLAKE = cfg.defaultFlake;
+    };
   };
 }

home/direnv/lib/nix.sh

@@ -7,7 +7,8 @@ use_pkgs() {
         return 1
     fi
 
-    local DEFAULT_FLAKE="pkgs"
+    # Use user-provided default value, or fallback to nixpkgs
+    local DEFAULT_FLAKE="${DIRENV_DEFAULT_FLAKE:-nixpkgs}"
 
     # Allow changing the default flake through a command line switch
     if [ "$1" = "-f" ] || [ "$1" = "--flake" ]; then