refactor

lib/mv/membership/import/header_mapper.ex

@@ -97,31 +97,16 @@ defmodule Mv.Membership.Import.HeaderMapper do
   }
 
   # Build reverse map: normalized_variant -> canonical_field
-  # Cached on first access for performance
+  # Computed on each access - the map is small enough that recomputing is fast
+  # This avoids Module.get_attribute issues while maintaining simplicity
   defp normalized_to_canonical do
-    cached = Process.get({__MODULE__, :normalized_to_canonical})
-
-    if cached do
-      cached
-    else
-      map = build_normalized_to_canonical_map()
-      Process.put({__MODULE__, :normalized_to_canonical}, map)
-      map
-    end
-  end
-
-  # Builds the normalized variant -> canonical field map
-  defp build_normalized_to_canonical_map do
     @member_field_variants_raw
-    |> Enum.flat_map(&map_variants_to_normalized/1)
-    |> Map.new()
-  end
-
-  # Maps a canonical field and its variants to normalized tuples
-  defp map_variants_to_normalized({canonical, variants}) do
-    Enum.map(variants, fn variant ->
-      {normalize_header(variant), canonical}
+    |> Enum.flat_map(fn {canonical, variants} ->
+      Enum.map(variants, fn variant ->
+        {normalize_header(variant), canonical}
+      end)
     end)
+    |> Map.new()
   end
 
   @doc """
@@ -139,28 +124,21 @@ defmodule Mv.Membership.Import.HeaderMapper do
       iex> HeaderMapper.known_member_fields()
       #MapSet<["email", "firstname", "lastname", "street", "postalcode", "city"]>
   """
+  # Known member fields computed at compile-time for performance and determinism
+  @known_member_fields @member_field_variants_raw
+                       |> Map.keys()
+                       |> Enum.map(fn canonical ->
+                         # Normalize the canonical field name (e.g., :first_name -> "firstname")
+                         canonical
+                         |> Atom.to_string()
+                         |> String.replace("_", "")
+                         |> String.downcase()
+                       end)
+                       |> MapSet.new()
+
   @spec known_member_fields() :: MapSet.t(String.t())
   def known_member_fields do
-    cached = Process.get({__MODULE__, :known_member_fields})
-
-    if cached do
-      cached
-    else
-      fields =
-        @member_field_variants_raw
-        |> Map.keys()
-        |> Enum.map(fn canonical ->
-          # Normalize the canonical field name (e.g., :first_name -> "firstname")
-          canonical
-          |> Atom.to_string()
-          |> String.replace("_", "")
-          |> String.downcase()
-        end)
-        |> MapSet.new()
-
-      Process.put({__MODULE__, :known_member_fields}, fields)
-      fields
-    end
+    @known_member_fields
   end
 
   @doc """