From 9b9e7ec99557b6c0275326c3753719e80c149859 Mon Sep 17 00:00:00 2001
From: carla <carla@local-it.org>
Date: Thu, 5 Feb 2026 15:03:25 +0100
Subject: [PATCH] fix: sorting and filter for export

---
 lib/mv/membership/member_export.ex            | 344 +++++++
 lib/mv/membership/member_export_sort.ex       |  44 +
 lib/mv/membership/members_csv.ex              | 117 +--
 lib/mv_web/components/core_components.ex      |   8 +-
 .../controllers/member_export_controller.ex   | 220 ++++-
 .../field_visibility_dropdown_component.ex    |  29 +-
 lib/mv_web/live/member_live/index.ex          | 853 ++++++------------
 lib/mv_web/live/member_live/index.html.heex   |   1 +
 .../member_live/index/field_visibility.ex     | 110 ++-
 lib/mv_web/translations/member_fields.ex      |   1 +
 10 files changed, 1013 insertions(+), 714 deletions(-)
 create mode 100644 lib/mv/membership/member_export.ex
 create mode 100644 lib/mv/membership/member_export_sort.ex

diff --git a/lib/mv/membership/member_export.ex b/lib/mv/membership/member_export.ex
new file mode 100644
index 0000000..5f771cc
--- /dev/null
+++ b/lib/mv/membership/member_export.ex
@@ -0,0 +1,344 @@
+defmodule Mv.Membership.MemberExport do
+  @moduledoc """
+  Builds member list and column specs for CSV export.
+
+  Used by `MvWeb.MemberExportController`. Does not perform translations;
+  the controller applies headers (e.g. via `MemberFields.label` / gettext)
+  and sends the download.
+  """
+
+  require Ash.Query
+  import Ash.Expr
+
+  alias Mv.Membership.CustomField
+  alias Mv.Membership.Member
+  alias Mv.Membership.MemberExportSort
+  alias MvWeb.MemberLive.Index.MembershipFeeStatus
+
+  @member_fields_allowlist (Mv.Constants.member_fields() |> Enum.map(&Atom.to_string/1)) ++
+                             ["membership_fee_status", "payment_status"]
+  @computed_export_fields ["membership_fee_status", "payment_status"]
+  @custom_field_prefix Mv.Constants.custom_field_prefix()
+  @domain_member_field_strings Mv.Constants.member_fields() |> Enum.map(&Atom.to_string/1)
+
+  @doc """
+  Fetches members and column specs for export.
+
+  - `actor` - Ash actor (e.g. current user)
+  - `parsed` - Map from controller's parse_and_validate (selected_ids, member_fields, etc.)
+
+  Returns `{:ok, members, column_specs}` or `{:error, :forbidden}`.
+  Column specs have `:kind`, `:key`, and for custom fields `:custom_field`;
+  the controller adds `:header` and optional computed columns to members before CSV export.
+  """
+  @spec fetch(struct(), map()) ::
+          {:ok, [struct()], [map()]} | {:error, :forbidden}
+  def fetch(actor, parsed) do
+    custom_field_ids_union =
+      (parsed.custom_field_ids ++ Map.keys(parsed.boolean_filters || %{})) |> Enum.uniq()
+
+    with {:ok, custom_fields_by_id} <- load_custom_fields_by_id(custom_field_ids_union, actor),
+         {:ok, members} <- load_members(actor, parsed, custom_fields_by_id) do
+      column_specs = build_column_specs(parsed, custom_fields_by_id)
+      {:ok, members, column_specs}
+    end
+  end
+
+  defp load_custom_fields_by_id([], _actor), do: {:ok, %{}}
+
+  defp load_custom_fields_by_id(custom_field_ids, actor) do
+    query =
+      CustomField
+      |> Ash.Query.filter(expr(id in ^custom_field_ids))
+      |> Ash.Query.select([:id, :name, :value_type])
+
+    case Ash.read(query, actor: actor) do
+      {:ok, custom_fields} ->
+        by_id =
+          Enum.reduce(custom_field_ids, %{}, fn id, acc ->
+            case Enum.find(custom_fields, fn cf -> to_string(cf.id) == to_string(id) end) do
+              nil -> acc
+              cf -> Map.put(acc, id, cf)
+            end
+          end)
+
+        {:ok, by_id}
+
+      {:error, %Ash.Error.Forbidden{}} ->
+        {:error, :forbidden}
+    end
+  end
+
+  defp build_column_specs(parsed, custom_fields_by_id) do
+    member_specs =
+      Enum.map(parsed.member_fields, fn f ->
+        if f in parsed.selectable_member_fields do
+          %{kind: :member_field, key: f}
+        else
+          %{kind: :computed, key: String.to_existing_atom(f)}
+        end
+      end)
+
+    custom_specs =
+      parsed.custom_field_ids
+      |> Enum.map(fn id -> Map.get(custom_fields_by_id, id) end)
+      |> Enum.reject(&is_nil/1)
+      |> Enum.map(fn cf -> %{kind: :custom_field, key: cf.id, custom_field: cf} end)
+
+    member_specs ++ custom_specs
+  end
+
+  defp load_members(actor, parsed, custom_fields_by_id) do
+    select_fields =
+      [:id] ++ Enum.map(parsed.selectable_member_fields, &String.to_existing_atom/1)
+
+    custom_field_ids_union = parsed.custom_field_ids ++ Map.keys(parsed.boolean_filters || %{})
+
+    need_cycles =
+      parsed.show_current_cycle or parsed.cycle_status_filter != nil or
+        parsed.computed_fields != []
+
+    query =
+      Member
+      |> Ash.Query.new()
+      |> Ash.Query.select(select_fields)
+      |> load_custom_field_values_query(custom_field_ids_union)
+      |> maybe_load_cycles(need_cycles, parsed.show_current_cycle)
+
+    query =
+      if parsed.selected_ids != [] do
+        Ash.Query.filter(query, expr(id in ^parsed.selected_ids))
+      else
+        query
+        |> apply_search(parsed.query)
+        |> then(fn q ->
+          {q, _sort_after_load} = maybe_sort(q, parsed.sort_field, parsed.sort_order)
+          q
+        end)
+      end
+
+    case Ash.read(query, actor: actor) do
+      {:ok, members} ->
+        members =
+          if parsed.selected_ids == [] do
+            members
+            |> apply_cycle_status_filter(parsed.cycle_status_filter, parsed.show_current_cycle)
+            |> MvWeb.MemberLive.Index.apply_boolean_custom_field_filters(
+              parsed.boolean_filters || %{},
+              Map.values(custom_fields_by_id)
+            )
+          else
+            members
+          end
+
+        members =
+          if parsed.selected_ids == [] and sort_after_load?(parsed.sort_field) do
+            sort_members_by_custom_field(
+              members,
+              parsed.sort_field,
+              parsed.sort_order,
+              Map.values(custom_fields_by_id)
+            )
+          else
+            members
+          end
+
+        {:ok, members}
+
+      {:error, %Ash.Error.Forbidden{}} ->
+        {:error, :forbidden}
+    end
+  end
+
+  defp load_custom_field_values_query(query, []), do: query
+
+  defp load_custom_field_values_query(query, custom_field_ids) do
+    cfv_query =
+      Mv.Membership.CustomFieldValue
+      |> Ash.Query.filter(expr(custom_field_id in ^custom_field_ids))
+      |> Ash.Query.load(custom_field: [:id, :name, :value_type])
+
+    Ash.Query.load(query, custom_field_values: cfv_query)
+  end
+
+  defp apply_search(query, nil), do: query
+  defp apply_search(query, ""), do: query
+
+  defp apply_search(query, q) when is_binary(q) do
+    if String.trim(q) != "" do
+      Member.fuzzy_search(query, %{query: q})
+    else
+      query
+    end
+  end
+
+  defp maybe_sort(query, nil, _order), do: {query, false}
+  defp maybe_sort(query, _field, nil), do: {query, false}
+
+  defp maybe_sort(query, field, order) when is_binary(field) do
+    if custom_field_sort?(field) do
+      {query, true}
+    else
+      field_atom = String.to_existing_atom(field)
+
+      if field_atom in (Mv.Constants.member_fields() -- [:notes]) do
+        {Ash.Query.sort(query, [{field_atom, String.to_existing_atom(order)}]), false}
+      else
+        {query, false}
+      end
+    end
+  rescue
+    ArgumentError -> {query, false}
+  end
+
+  defp sort_after_load?(field) when is_binary(field),
+    do: String.starts_with?(field, @custom_field_prefix)
+
+  defp sort_after_load?(_), do: false
+
+  defp sort_members_by_custom_field(members, _field, _order, _custom_fields) when members == [],
+    do: []
+
+  defp sort_members_by_custom_field(members, field, order, custom_fields) when is_binary(field) do
+    id_str = String.trim_leading(field, @custom_field_prefix)
+    custom_field = Enum.find(custom_fields, fn cf -> to_string(cf.id) == id_str end)
+    if is_nil(custom_field), do: members
+
+    key_fn = fn member ->
+      cfv = find_cfv(member, custom_field)
+      raw = if cfv, do: cfv.value, else: nil
+      MemberExportSort.custom_field_sort_key(custom_field.value_type, raw)
+    end
+
+    members
+    |> Enum.map(fn m -> {m, key_fn.(m)} end)
+    |> Enum.sort(fn {_, ka}, {_, kb} -> MemberExportSort.key_lt(ka, kb, order) end)
+    |> Enum.map(fn {m, _} -> m end)
+  end
+
+  defp find_cfv(member, custom_field) do
+    (member.custom_field_values || [])
+    |> Enum.find(fn cfv ->
+      to_string(cfv.custom_field_id) == to_string(custom_field.id) or
+        (Map.get(cfv, :custom_field) &&
+           to_string(cfv.custom_field.id) == to_string(custom_field.id))
+    end)
+  end
+
+  defp custom_field_sort?(field), do: String.starts_with?(field, @custom_field_prefix)
+
+  defp maybe_load_cycles(query, false, _show_current), do: query
+
+  defp maybe_load_cycles(query, true, show_current) do
+    MembershipFeeStatus.load_cycles_for_members(query, show_current)
+  end
+
+  defp apply_cycle_status_filter(members, nil, _show_current), do: members
+
+  defp apply_cycle_status_filter(members, status, show_current) when status in [:paid, :unpaid] do
+    MembershipFeeStatus.filter_members_by_cycle_status(members, status, show_current)
+  end
+
+  defp apply_cycle_status_filter(members, _status, _show_current), do: members
+
+  # Called by controller to build parsed map from raw params (kept here so controller stays thin)
+  @doc """
+  Parses and validates export params (from JSON payload).
+
+  Returns a map with :selected_ids, :member_fields, :selectable_member_fields,
+  :computed_fields, :custom_field_ids, :query, :sort_field, :sort_order,
+  :show_current_cycle, :cycle_status_filter, :boolean_filters.
+  """
+  @spec parse_params(map()) :: map()
+  def parse_params(params) do
+    member_fields = filter_allowed_member_fields(extract_list(params, "member_fields"))
+    {selectable_member_fields, computed_fields} = split_member_fields(member_fields)
+
+    %{
+      selected_ids: filter_valid_uuids(extract_list(params, "selected_ids")),
+      member_fields: member_fields,
+      selectable_member_fields: selectable_member_fields,
+      computed_fields: computed_fields,
+      custom_field_ids: filter_valid_uuids(extract_list(params, "custom_field_ids")),
+      query: extract_string(params, "query"),
+      sort_field: extract_string(params, "sort_field"),
+      sort_order: extract_sort_order(params),
+      show_current_cycle: extract_boolean(params, "show_current_cycle"),
+      cycle_status_filter: extract_cycle_status_filter(params),
+      boolean_filters: extract_boolean_filters(params)
+    }
+  end
+
+  defp split_member_fields(member_fields) do
+    selectable = Enum.filter(member_fields, fn f -> f in @domain_member_field_strings end)
+    computed = Enum.filter(member_fields, fn f -> f in @computed_export_fields end)
+    {selectable, computed}
+  end
+
+  defp extract_boolean(params, key) do
+    case Map.get(params, key) do
+      true -> true
+      "true" -> true
+      _ -> false
+    end
+  end
+
+  defp extract_cycle_status_filter(params) do
+    case Map.get(params, "cycle_status_filter") do
+      "paid" -> :paid
+      "unpaid" -> :unpaid
+      _ -> nil
+    end
+  end
+
+  defp extract_boolean_filters(params) do
+    case Map.get(params, "boolean_filters") do
+      map when is_map(map) ->
+        map
+        |> Enum.filter(fn {k, v} -> is_binary(k) and is_boolean(v) end)
+        |> Enum.filter(fn {k, _} -> match?({:ok, _}, Ecto.UUID.cast(k)) end)
+        |> Enum.into(%{})
+
+      _ ->
+        %{}
+    end
+  end
+
+  defp extract_list(params, key) do
+    case Map.get(params, key) do
+      list when is_list(list) -> list
+      _ -> []
+    end
+  end
+
+  defp extract_string(params, key) do
+    case Map.get(params, key) do
+      s when is_binary(s) -> s
+      _ -> nil
+    end
+  end
+
+  defp extract_sort_order(params) do
+    case Map.get(params, "sort_order") do
+      "asc" -> "asc"
+      "desc" -> "desc"
+      _ -> nil
+    end
+  end
+
+  defp filter_allowed_member_fields(field_list) do
+    allowlist = MapSet.new(@member_fields_allowlist)
+
+    field_list
+    |> Enum.filter(fn field -> is_binary(field) and MapSet.member?(allowlist, field) end)
+    |> Enum.uniq()
+  end
+
+  defp filter_valid_uuids(id_list) when is_list(id_list) do
+    id_list
+    |> Enum.filter(fn id ->
+      is_binary(id) and match?({:ok, _}, Ecto.UUID.cast(id))
+    end)
+    |> Enum.uniq()
+  end
+end
diff --git a/lib/mv/membership/member_export_sort.ex b/lib/mv/membership/member_export_sort.ex
new file mode 100644
index 0000000..324fb75
--- /dev/null
+++ b/lib/mv/membership/member_export_sort.ex
@@ -0,0 +1,44 @@
+defmodule Mv.Membership.MemberExportSort do
+  @moduledoc """
+  Type-stable sort keys for CSV export custom-field sorting.
+
+  Used only by `MvWeb.MemberExportController` when sorting members by a custom field
+  after load. Nil values sort last in ascending order and first in descending order.
+  String and email comparison is case-insensitive.
+  """
+  @doc """
+  Returns a comparable sort key for (value_type, value).
+
+  - Nil: rank 1 so that in asc order nil sorts last, in desc nil sorts first.
+  - date: chronological (ISO8601 string).
+  - boolean: false < true (0 < 1).
+  - integer: numerical order.
+  - string / email: case-insensitive (downcased).
+
+  Handles Ash.Union in value; value_type is the custom field's value_type atom.
+  """
+  @spec custom_field_sort_key(:string | :integer | :boolean | :date | :email, term()) ::
+          {0 | 1, term()}
+  def custom_field_sort_key(_value_type, nil), do: {1, nil}
+
+  def custom_field_sort_key(value_type, %Ash.Union{value: value, type: _type}) do
+    custom_field_sort_key(value_type, value)
+  end
+
+  def custom_field_sort_key(:date, %Date{} = d), do: {0, Date.to_iso8601(d)}
+  def custom_field_sort_key(:boolean, true), do: {0, 1}
+  def custom_field_sort_key(:boolean, false), do: {0, 0}
+  def custom_field_sort_key(:integer, v) when is_integer(v), do: {0, v}
+  def custom_field_sort_key(:string, v) when is_binary(v), do: {0, String.downcase(v)}
+  def custom_field_sort_key(:email, v) when is_binary(v), do: {0, String.downcase(v)}
+  def custom_field_sort_key(_value_type, v), do: {0, to_string(v)}
+
+  @doc """
+  Returns true if key_a should sort before key_b for the given order.
+
+  "asc" -> nil last; "desc" -> nil first. No reverse of list needed.
+  """
+  @spec key_lt({0 | 1, term()}, {0 | 1, term()}, String.t()) :: boolean()
+  def key_lt(key_a, key_b, "asc"), do: key_a < key_b
+  def key_lt(key_a, key_b, "desc"), do: key_b < key_a
+end
diff --git a/lib/mv/membership/members_csv.ex b/lib/mv/membership/members_csv.ex
index 6eab399..a0fd463 100644
--- a/lib/mv/membership/members_csv.ex
+++ b/lib/mv/membership/members_csv.ex
@@ -2,9 +2,11 @@ defmodule Mv.Membership.MembersCSV do
   @moduledoc """
   Exports members to CSV (RFC 4180) as iodata.
 
-  Uses NimbleCSV.RFC4180 for encoding. Member fields are formatted as strings;
-  custom field values use the same formatting logic as the member overview (neutral formatter).
-  Column order for custom fields follows the key order of the `custom_fields_by_id` map.
+  Uses a column-based API: `export(members, columns)` where each column has
+  `header` (display string, e.g. from Web layer), `kind` (:member_field | :custom_field | :computed),
+  and `key` (member attribute name, custom_field id, or computed key). Custom field columns
+  include a `custom_field` struct for value formatting. Domain code does not use Gettext;
+  headers and computed values come from the caller (e.g. controller).
   """
   alias Mv.Membership.CustomFieldValueFormatter
   alias NimbleCSV.RFC4180
@@ -12,57 +14,82 @@ defmodule Mv.Membership.MembersCSV do
   @doc """
   Exports a list of members to CSV iodata.
 
-  - `members` - List of member structs (with optional `custom_field_values` loaded)
-  - `member_fields` - List of member field names (strings, e.g. `["first_name", "email"]`)
-  - `custom_fields_by_id` - Map of custom_field_id => %CustomField{}. Key order defines column order.
+  - `members` - List of member structs or maps (with optional `custom_field_values` loaded)
+  - `columns` - List of column specs: `%{header: String.t(), kind: :member_field | :custom_field | :computed, key: term()}`
+    For `:custom_field`, also pass `custom_field: %CustomField{}`. Header is used as-is (localized by caller).
 
   Returns iodata suitable for `IO.iodata_to_binary/1` or sending as response body.
+  RFC 4180 escaping and formula-injection safe_cell are applied.
   """
-  @spec export(
-          [struct()],
-          [String.t()],
-          %{optional(String.t() | Ecto.UUID.t()) => struct()}
-        ) :: iodata()
-  def export(members, member_fields, custom_fields_by_id) when is_list(members) do
-    custom_entries = custom_field_entries(custom_fields_by_id)
-    header = build_header(member_fields, custom_entries)
-    rows = Enum.map(members, &build_row(&1, member_fields, custom_entries))
+  @spec export([struct() | map()], [map()]) :: iodata()
+  def export(members, columns) when is_list(members) do
+    header = build_header(columns)
+    rows = Enum.map(members, fn member -> build_row(member, columns) end)
     RFC4180.dump_to_iodata([header | rows])
   end
 
-  defp custom_field_entries(by_id) when is_map(by_id) do
-    Enum.map(by_id, fn {id, cf} -> {to_string(id), cf} end)
+  defp build_header(columns) do
+    columns
+    |> Enum.map(fn col -> col.header end)
+    |> Enum.map(&safe_cell/1)
   end
 
-  defp build_header(member_fields, custom_entries) do
-    member_headers = member_fields
-    custom_headers = Enum.map(custom_entries, fn {_id, cf} -> cf.name end)
-    member_headers ++ custom_headers
+  defp build_row(member, columns) do
+    columns
+    |> Enum.map(fn col -> cell_value(member, col) end)
+    |> Enum.map(&safe_cell/1)
   end
 
-  defp build_row(member, member_fields, custom_entries) do
-    member_cells = Enum.map(member_fields, &format_member_field(member, &1))
-
-    custom_cells =
-      Enum.map(custom_entries, fn {id, cf} -> format_custom_field(member, id, cf) end)
-
-    member_cells ++ custom_cells
-  end
-
-  defp format_member_field(member, field_name) do
-    key = member_field_key(field_name)
-    value = Map.get(member, key)
+  defp cell_value(member, %{kind: :member_field, key: key}) do
+    key_atom = key_to_atom(key)
+    value = Map.get(member, key_atom)
     format_member_value(value)
   end
 
-  defp member_field_key(field_name) when is_binary(field_name) do
+  defp cell_value(member, %{kind: :custom_field, key: id, custom_field: cf}) do
+    cfv = get_cfv_by_id(member, id)
+
+    if cfv,
+      do: CustomFieldValueFormatter.format_custom_field_value(cfv.value, cf),
+      else: ""
+  end
+
+  defp cell_value(member, %{kind: :computed, key: key}) do
+    value = Map.get(member, key_to_atom(key))
+    if is_binary(value), do: value, else: ""
+  end
+
+  defp key_to_atom(k) when is_atom(k), do: k
+
+  defp key_to_atom(k) when is_binary(k) do
     try do
-      String.to_existing_atom(field_name)
+      String.to_existing_atom(k)
     rescue
-      ArgumentError -> field_name
+      ArgumentError -> k
     end
   end
 
+  defp get_cfv_by_id(member, id) do
+    values =
+      case Map.get(member, :custom_field_values) do
+        v when is_list(v) -> v
+        _ -> []
+      end
+
+    id_str = to_string(id)
+
+    Enum.find(values, fn cfv ->
+      to_string(cfv.custom_field_id) == id_str or
+        (Map.get(cfv, :custom_field) && to_string(cfv.custom_field.id) == id_str)
+    end)
+  end
+
+  @doc false
+  @spec safe_cell(String.t()) :: String.t()
+  def safe_cell(s) when is_binary(s) do
+    if String.starts_with?(s, ["=", "+", "-", "@", "\t"]), do: "'" <> s, else: s
+  end
+
   defp format_member_value(nil), do: ""
   defp format_member_value(true), do: "true"
   defp format_member_value(false), do: "false"
@@ -70,22 +97,4 @@ defmodule Mv.Membership.MembersCSV do
   defp format_member_value(%DateTime{} = dt), do: DateTime.to_iso8601(dt)
   defp format_member_value(%NaiveDateTime{} = dt), do: NaiveDateTime.to_iso8601(dt)
   defp format_member_value(value), do: to_string(value)
-
-  defp format_custom_field(member, custom_field_id, custom_field) do
-    cfv = find_custom_field_value(member, custom_field_id)
-
-    if cfv,
-      do: CustomFieldValueFormatter.format_custom_field_value(cfv.value, custom_field),
-      else: ""
-  end
-
-  defp find_custom_field_value(member, custom_field_id) do
-    values = Map.get(member, :custom_field_values) || []
-    id_str = to_string(custom_field_id)
-
-    Enum.find(values, fn cfv ->
-      to_string(cfv.custom_field_id) == id_str or
-        (Map.get(cfv, :custom_field) && to_string(cfv.custom_field.id) == id_str)
-    end)
-  end
 end
diff --git a/lib/mv_web/components/core_components.ex b/lib/mv_web/components/core_components.ex
index 45bcae0..e74020c 100644
--- a/lib/mv_web/components/core_components.ex
+++ b/lib/mv_web/components/core_components.ex
@@ -178,7 +178,8 @@ defmodule MvWeb.CoreComponents do
         aria-haspopup="menu"
         aria-expanded={@open}
         aria-controls={@id}
-        class="btn"
+        aria-label={@button_label}
+        class="btn focus:outline-none focus-visible:ring-2 focus-visible:ring-offset-2 focus-visible:ring-base-content/20"
         phx-click="toggle_dropdown"
         phx-target={@phx_target}
         data-testid="dropdown-button"
@@ -232,11 +233,12 @@ defmodule MvWeb.CoreComponents do
             <button
               type="button"
               role={if @checkboxes, do: "menuitemcheckbox", else: "menuitem"}
+              aria-label={item.label}
               aria-checked={
                 if @checkboxes, do: to_string(Map.get(@selected, item.value, true)), else: nil
               }
               tabindex="0"
-              class="flex items-center gap-2 px-2 py-1 rounded cursor-pointer hover:bg-base-200 w-full text-left"
+              class="flex items-center gap-2 px-2 py-1 rounded cursor-pointer hover:bg-base-200 w-full text-left focus:outline-none focus-visible:ring-2 focus-visible:ring-base-content/20 focus-visible:ring-inset"
               phx-click="select_item"
               phx-keydown="select_item"
               phx-key="Enter"
@@ -247,7 +249,7 @@ defmodule MvWeb.CoreComponents do
                 <input
                   type="checkbox"
                   checked={Map.get(@selected, item.value, true)}
-                  class="checkbox checkbox-sm checkbox-primary"
+                  class="checkbox checkbox-sm checkbox-primary pointer-events-none"
                   tabindex="-1"
                   aria-hidden="true"
                 />
diff --git a/lib/mv_web/controllers/member_export_controller.ex b/lib/mv_web/controllers/member_export_controller.ex
index cad32a2..57ce630 100644
--- a/lib/mv_web/controllers/member_export_controller.ex
+++ b/lib/mv_web/controllers/member_export_controller.ex
@@ -61,6 +61,7 @@ defmodule MvWeb.MemberExportController do
     %{
       selected_ids: filter_valid_uuids(extract_list(params, "selected_ids")),
       member_fields: filter_allowed_member_fields(extract_list(params, "member_fields")),
+      computed_fields: filter_existing_atoms(extract_list(params, "computed_fields")),
       custom_field_ids: filter_valid_uuids(extract_list(params, "custom_field_ids")),
       query: extract_string(params, "query"),
       sort_field: extract_string(params, "sort_field"),
@@ -68,6 +69,20 @@ defmodule MvWeb.MemberExportController do
     }
   end
 
+  defp filter_existing_atoms(list) when is_list(list) do
+    list
+    |> Enum.filter(&is_binary/1)
+    |> Enum.filter(fn name ->
+      try do
+        _ = String.to_existing_atom(name)
+        true
+      rescue
+        ArgumentError -> false
+      end
+    end)
+    |> Enum.uniq()
+  end
+
   defp extract_list(params, key) do
     case Map.get(params, key) do
       list when is_list(list) -> list
@@ -107,9 +122,16 @@ defmodule MvWeb.MemberExportController do
   end
 
   defp run_export(conn, actor, parsed) do
+    # FIX: Wenn nach einem Custom Field sortiert wird, muss dieses Feld geladen werden,
+    # auch wenn es nicht exportiert wird (sonst kann Export nicht korrekt sortieren).
+    parsed =
+      parsed
+      |> ensure_sort_custom_field_loaded()
+
     with {:ok, custom_fields_by_id} <- load_custom_fields_by_id(parsed.custom_field_ids, actor),
          {:ok, members} <- load_members_for_export(actor, parsed, custom_fields_by_id) do
-      csv_iodata = MembersCSV.export(members, parsed.member_fields, custom_fields_by_id)
+      columns = build_columns(conn, parsed, custom_fields_by_id)
+      csv_iodata = MembersCSV.export(members, columns)
       filename = "members-#{Date.utc_today()}.csv"
 
       send_download(
@@ -124,6 +146,26 @@ defmodule MvWeb.MemberExportController do
     end
   end
 
+  defp ensure_sort_custom_field_loaded(%{custom_field_ids: ids, sort_field: sort_field} = parsed) do
+    case extract_sort_custom_field_id(sort_field) do
+      nil ->
+        parsed
+
+      id ->
+        %{parsed | custom_field_ids: Enum.uniq([id | ids])}
+    end
+  end
+
+  defp extract_sort_custom_field_id(field) when is_binary(field) do
+    if String.starts_with?(field, @custom_field_prefix) do
+      String.trim_leading(field, @custom_field_prefix)
+    else
+      nil
+    end
+  end
+
+  defp extract_sort_custom_field_id(_), do: nil
+
   defp load_custom_fields_by_id([], _actor), do: {:ok, %{}}
 
   defp load_custom_fields_by_id(custom_field_ids, actor) do
@@ -148,17 +190,13 @@ defmodule MvWeb.MemberExportController do
 
   defp build_custom_fields_by_id(custom_field_ids, custom_fields) do
     Enum.reduce(custom_field_ids, %{}, fn id, acc ->
-      find_and_add_custom_field(acc, id, custom_fields)
+      case Enum.find(custom_fields, fn cf -> to_string(cf.id) == to_string(id) end) do
+        nil -> acc
+        cf -> Map.put(acc, id, cf)
+      end
     end)
   end
 
-  defp find_and_add_custom_field(acc, id, custom_fields) do
-    case Enum.find(custom_fields, fn cf -> to_string(cf.id) == to_string(id) end) do
-      nil -> acc
-      cf -> Map.put(acc, id, cf)
-    end
-  end
-
   defp load_members_for_export(actor, parsed, custom_fields_by_id) do
     select_fields = [:id] ++ Enum.map(parsed.member_fields, &String.to_existing_atom/1)
 
@@ -170,20 +208,20 @@ defmodule MvWeb.MemberExportController do
 
     query =
       if parsed.selected_ids != [] do
+        # selected export: filtert die Menge, aber die Sortierung muss trotzdem wie in der Tabelle angewandt werden
         Ash.Query.filter(query, expr(id in ^parsed.selected_ids))
       else
         query
         |> apply_search_export(parsed.query)
-        |> then(fn q ->
-          {q, _sort_after_load} = maybe_sort_export(q, parsed.sort_field, parsed.sort_order)
-          q
-        end)
       end
 
+    # FIX: Sortierung IMMER anwenden (auch bei selected_ids)
+    {query, sort_after_load} = maybe_sort_export(query, parsed.sort_field, parsed.sort_order)
+
     case Ash.read(query, actor: actor) do
       {:ok, members} ->
         members =
-          if parsed.selected_ids == [] and sort_after_load?(parsed.sort_field) do
+          if sort_after_load do
             sort_members_by_custom_field_export(
               members,
               parsed.sort_field,
@@ -191,7 +229,6 @@ defmodule MvWeb.MemberExportController do
               Map.values(custom_fields_by_id)
             )
           else
-            # selected_ids != []: no sort. selected_ids == [] and DB sort: already in query.
             members
           end
 
@@ -228,25 +265,29 @@ defmodule MvWeb.MemberExportController do
   defp maybe_sort_export(query, _field, nil), do: {query, false}
 
   defp maybe_sort_export(query, field, order) when is_binary(field) do
-    if custom_field_sort?(field) do
-      {query, true}
-    else
-      field_atom = String.to_existing_atom(field)
+    cond do
+      custom_field_sort?(field) ->
+        # Custom field sort → in-memory nach dem Read (wie Tabelle)
+        {query, true}
 
-      if field_atom in (Mv.Constants.member_fields() -- [:notes]) do
-        {Ash.Query.sort(query, [{field_atom, String.to_existing_atom(order)}]), false}
-      else
-        {query, false}
-      end
+      true ->
+        field_atom = String.to_existing_atom(field)
+
+        if field_atom in (Mv.Constants.member_fields() -- [:notes]) do
+          {Ash.Query.sort(query, [{field_atom, String.to_existing_atom(order)}]), false}
+        else
+          {query, false}
+        end
     end
   rescue
     ArgumentError -> {query, false}
   end
 
-  defp sort_after_load?(field) when is_binary(field),
-    do: String.starts_with?(field, @custom_field_prefix)
+  defp custom_field_sort?(field), do: String.starts_with?(field, @custom_field_prefix)
 
-  defp sort_after_load?(_), do: false
+  # ------------------------------------------------------------------
+  # Custom field sorting (match member table behavior)
+  # ------------------------------------------------------------------
 
   defp sort_members_by_custom_field_export(members, _field, _order, _custom_fields)
        when members == [],
@@ -254,26 +295,60 @@ defmodule MvWeb.MemberExportController do
 
   defp sort_members_by_custom_field_export(members, field, order, custom_fields)
        when is_binary(field) do
+    order = order || "asc"
     id_str = String.trim_leading(field, @custom_field_prefix)
-    custom_field = Enum.find(custom_fields, fn cf -> to_string(cf.id) == id_str end)
-    if is_nil(custom_field), do: members
 
-    extract_sort_val = fn member ->
-      cfv = find_cfv(member, custom_field)
-      if cfv, do: extract_sort_value(cfv.value, custom_field.value_type), else: nil
-    end
+    custom_field =
+      Enum.find(custom_fields, fn cf -> to_string(cf.id) == id_str end)
 
-    sorted =
+    if is_nil(custom_field) do
       members
-      |> Enum.sort_by(extract_sort_val, fn
-        nil, _ -> false
-        _, nil -> true
-        a, b -> if order == "desc", do: a >= b, else: a <= b
-      end)
+    else
+      # Match table:
+      # 1) values first, empty last
+      # 2) sort only values
+      # 3) for desc, reverse only the values-part
+      {with_values, without_values} =
+        Enum.split_with(members, fn member ->
+          has_non_empty_custom_field_value?(member, custom_field)
+        end)
 
-    if order == "desc", do: Enum.reverse(sorted), else: sorted
+      sorted_with_values =
+        Enum.sort_by(with_values, fn member ->
+          member
+          |> find_cfv(custom_field)
+          |> case do
+            nil -> nil
+            cfv -> extract_sort_value(cfv.value, custom_field.value_type)
+          end
+        end)
+
+      sorted_with_values =
+        if order == "desc", do: Enum.reverse(sorted_with_values), else: sorted_with_values
+
+      sorted_with_values ++ without_values
+    end
   end
 
+  defp has_non_empty_custom_field_value?(member, custom_field) do
+    case find_cfv(member, custom_field) do
+      nil ->
+        false
+
+      cfv ->
+        extracted = extract_sort_value(cfv.value, custom_field.value_type)
+        not empty_value?(extracted, custom_field.value_type)
+    end
+  end
+
+  defp empty_value?(nil, _type), do: true
+
+  defp empty_value?(value, type) when type in [:string, :email] and is_binary(value) do
+    String.trim(value) == ""
+  end
+
+  defp empty_value?(_value, _type), do: false
+
   defp find_cfv(member, custom_field) do
     (member.custom_field_values || [])
     |> Enum.find(fn cfv ->
@@ -283,15 +358,76 @@ defmodule MvWeb.MemberExportController do
     end)
   end
 
+  defp build_columns(conn, parsed, custom_fields_by_id) do
+    member_cols =
+      Enum.map(parsed.member_fields, fn field ->
+        %{
+          header: member_field_header(conn, field),
+          kind: :member_field,
+          key: field
+        }
+      end)
+
+    computed_cols =
+      Enum.map(parsed.computed_fields, fn key ->
+        %{
+          header: computed_field_header(conn, key),
+          kind: :computed,
+          key: key
+        }
+      end)
+
+    custom_cols =
+      parsed.custom_field_ids
+      |> Enum.map(fn id ->
+        cf = Map.get(custom_fields_by_id, id) || Map.get(custom_fields_by_id, to_string(id))
+
+        if cf do
+          %{
+            header: custom_field_header(conn, cf),
+            kind: :custom_field,
+            key: to_string(id),
+            custom_field: cf
+          }
+        else
+          nil
+        end
+      end)
+      |> Enum.reject(&is_nil/1)
+
+    member_cols ++ computed_cols ++ custom_cols
+  end
+
+  # --- headers: hier solltest du idealerweise eure bestehenden "display name" Helfer verwenden ---
+  defp member_field_header(_conn, field) when is_binary(field) do
+    # TODO: hier euren bestehenden display-name helper verwenden (wie Tabelle)
+    humanize_field(field)
+  end
+
+  defp computed_field_header(_conn, key) when is_binary(key) do
+    # TODO: display-name helper für computed fields verwenden
+    humanize_field(key)
+  end
+
+  defp custom_field_header(_conn, cf) do
+    # Custom fields: meist ist cf.name bereits der Display Name
+    cf.name
+  end
+
+  defp humanize_field(str) do
+    str
+    |> String.replace("_", " ")
+    |> String.capitalize()
+  end
+
   defp extract_sort_value(%Ash.Union{value: value, type: type}, _),
     do: extract_sort_value(value, type)
 
+  defp extract_sort_value(nil, _), do: nil
   defp extract_sort_value(value, :string) when is_binary(value), do: value
   defp extract_sort_value(value, :integer) when is_integer(value), do: value
   defp extract_sort_value(value, :boolean) when is_boolean(value), do: value
   defp extract_sort_value(%Date{} = d, :date), do: d
   defp extract_sort_value(value, :email) when is_binary(value), do: value
   defp extract_sort_value(value, _), do: to_string(value)
-
-  defp custom_field_sort?(field), do: String.starts_with?(field, @custom_field_prefix)
 end
diff --git a/lib/mv_web/live/components/field_visibility_dropdown_component.ex b/lib/mv_web/live/components/field_visibility_dropdown_component.ex
index 426daed..0c9492b 100644
--- a/lib/mv_web/live/components/field_visibility_dropdown_component.ex
+++ b/lib/mv_web/live/components/field_visibility_dropdown_component.ex
@@ -41,24 +41,29 @@ defmodule MvWeb.Components.FieldVisibilityDropdownComponent do
   # RENDER
   # ---------------------------------------------------------------------------
 
+  # Export-only alias; must not appear in dropdown (canonical UI key is membership_fee_status).
+  @payment_status_value "payment_status"
+
   @impl true
   def render(assigns) do
     all_fields = assigns.all_fields || []
     custom_fields = assigns.custom_fields || []
 
     all_items =
-      Enum.map(extract_member_field_keys(all_fields), fn field ->
-        %{
-          value: field_to_string(field),
-          label: format_field_label(field)
-        }
-      end) ++
-        Enum.map(extract_custom_field_keys(all_fields), fn field ->
-          %{
-            value: field,
-            label: format_custom_field_label(field, custom_fields)
-          }
-        end)
+      (Enum.map(extract_member_field_keys(all_fields), fn field ->
+         %{
+           value: field_to_string(field),
+           label: format_field_label(field)
+         }
+       end) ++
+         Enum.map(extract_custom_field_keys(all_fields), fn field ->
+           %{
+             value: field,
+             label: format_custom_field_label(field, custom_fields)
+           }
+         end))
+      |> Enum.reject(fn item -> item.value == @payment_status_value end)
+      |> Enum.uniq_by(fn item -> item.value end)
 
     assigns = assign(assigns, :all_items, all_items)
 
diff --git a/lib/mv_web/live/member_live/index.ex b/lib/mv_web/live/member_live/index.ex
index acafcf3..a18ef41 100644
--- a/lib/mv_web/live/member_live/index.ex
+++ b/lib/mv_web/live/member_live/index.ex
@@ -39,10 +39,7 @@ defmodule MvWeb.MemberLive.Index do
   alias MvWeb.MemberLive.Index.Formatter
   alias MvWeb.MemberLive.Index.MembershipFeeStatus
 
-  # Prefix used in sort field names for custom fields (e.g., "custom_field_<id>")
   @custom_field_prefix Mv.Constants.custom_field_prefix()
-
-  # Prefix used for boolean custom field filter URL parameters (e.g., "bf_<id>")
   @boolean_filter_prefix Mv.Constants.boolean_filter_prefix()
 
   # Maximum number of boolean custom field filters allowed per request (DoS protection)
@@ -99,10 +96,12 @@ defmodule MvWeb.MemberLive.Index do
     # Load user field selection from session
     session_selection = FieldSelection.get_from_session(session)
 
-    # Get all available fields (for dropdown - includes ALL custom fields)
-    all_available_fields = FieldVisibility.get_all_available_fields(all_custom_fields)
+    # FIX: ensure dropdown doesn’t show duplicate fields (e.g. membership fee status twice)
+    all_available_fields =
+      all_custom_fields
+      |> FieldVisibility.get_all_available_fields()
+      |> dedupe_available_fields()
 
-    # Merge session selection with global settings for initial state (use all_custom_fields)
     initial_selection =
       FieldVisibility.merge_with_global_settings(
         session_selection,
@@ -129,11 +128,18 @@ defmodule MvWeb.MemberLive.Index do
         :member_fields_visible,
         FieldVisibility.get_visible_member_fields(initial_selection)
       )
+      |> assign(
+        :member_fields_visible_db,
+        FieldVisibility.get_visible_member_fields_db(initial_selection)
+      )
+      |> assign(
+        :member_fields_visible_computed,
+        FieldVisibility.get_visible_member_fields_computed(initial_selection)
+      )
       |> assign(:show_current_cycle, false)
       |> assign(:membership_fee_status_filter, nil)
       |> assign_export_payload()
 
-    # We call handle params to use the query from the URL
     {:ok, socket}
   end
 
@@ -230,7 +236,6 @@ defmodule MvWeb.MemberLive.Index do
       |> load_members()
       |> update_selection_assigns()
 
-    # Update URL to reflect cycle view change
     query_params =
       build_query_params(
         socket.assigns.query,
@@ -300,9 +305,7 @@ defmodule MvWeb.MemberLive.Index do
     Enum.join(error_messages, ", ")
   end
 
-  defp format_error(error) do
-    inspect(error)
-  end
+  defp format_error(error), do: inspect(error)
 
   # -----------------------------------------------------------------
   # Handle Infos from Child Components
@@ -328,14 +331,29 @@ defmodule MvWeb.MemberLive.Index do
       end
 
     {new_field, new_order} = determine_new_sort(field, socket)
-
     old_field = socket.assigns.sort_field
 
-    socket
-    |> assign(:sort_field, new_field)
-    |> assign(:sort_order, new_order)
-    |> update_sort_components(old_field, new_field, new_order)
-    |> push_sort_url(new_field, new_order)
+    socket =
+      socket
+      |> assign(:sort_field, new_field)
+      |> assign(:sort_order, new_order)
+      |> update_sort_components(old_field, new_field, new_order)
+      |> load_members()
+      |> update_selection_assigns()
+
+    # URL sync
+    query_params =
+      build_query_params(
+        socket.assigns.query,
+        export_sort_field(socket.assigns.sort_field),
+        export_sort_order(socket.assigns.sort_order),
+        socket.assigns.cycle_status_filter,
+        socket.assigns.show_current_cycle,
+        socket.assigns.boolean_custom_field_filters
+      )
+      |> maybe_add_field_selection(socket.assigns[:user_field_selection])
+
+    {:noreply, push_patch(socket, to: ~p"/members?#{query_params}", replace: true)}
   end
 
   @impl true
@@ -346,29 +364,19 @@ defmodule MvWeb.MemberLive.Index do
       |> load_members()
       |> update_selection_assigns()
 
-    existing_field_query = socket.assigns.sort_field
-    existing_sort_query = socket.assigns.sort_order
-
-    # Build the URL with queries
     query_params =
       build_query_params(
         q,
-        existing_field_query,
-        existing_sort_query,
+        socket.assigns.sort_field,
+        socket.assigns.sort_order,
         socket.assigns.cycle_status_filter,
         socket.assigns.show_current_cycle,
         socket.assigns.boolean_custom_field_filters
       )
 
-    # Set the new path with params
     new_path = ~p"/members?#{query_params}"
 
-    # Push the new URL
-    {:noreply,
-     push_patch(socket,
-       to: new_path,
-       replace: true
-     )}
+    {:noreply, push_patch(socket, to: new_path, replace: true)}
   end
 
   @impl true
@@ -379,7 +387,6 @@ defmodule MvWeb.MemberLive.Index do
       |> load_members()
       |> update_selection_assigns()
 
-    # Build the URL with all params including new filter
     query_params =
       build_query_params(
         socket.assigns.query,
@@ -391,23 +398,15 @@ defmodule MvWeb.MemberLive.Index do
       )
 
     new_path = ~p"/members?#{query_params}"
-
-    {:noreply,
-     push_patch(socket,
-       to: new_path,
-       replace: true
-     )}
+    {:noreply, push_patch(socket, to: new_path, replace: true)}
   end
 
   @impl true
   def handle_info({:boolean_filter_changed, custom_field_id_str, filter_value}, socket) do
-    # Update boolean filters map
     updated_filters =
       if filter_value == nil do
-        # Remove filter if nil (All option selected)
         Map.delete(socket.assigns.boolean_custom_field_filters, custom_field_id_str)
       else
-        # Add or update filter
         Map.put(socket.assigns.boolean_custom_field_filters, custom_field_id_str, filter_value)
       end
 
@@ -417,7 +416,6 @@ defmodule MvWeb.MemberLive.Index do
       |> load_members()
       |> update_selection_assigns()
 
-    # Build the URL with all params including new filter
     query_params =
       build_query_params(
         socket.assigns.query,
@@ -429,18 +427,11 @@ defmodule MvWeb.MemberLive.Index do
       )
 
     new_path = ~p"/members?#{query_params}"
-
-    {:noreply,
-     push_patch(socket,
-       to: new_path,
-       replace: true
-     )}
+    {:noreply, push_patch(socket, to: new_path, replace: true)}
   end
 
   @impl true
   def handle_info({:reset_all_filters, cycle_status_filter, boolean_filters}, socket) do
-    # Reset all filters at once (performance optimization)
-    # This avoids N×2 load_members() calls when resetting multiple filters
     socket =
       socket
       |> assign(:cycle_status_filter, cycle_status_filter)
@@ -448,7 +439,6 @@ defmodule MvWeb.MemberLive.Index do
       |> load_members()
       |> update_selection_assigns()
 
-    # Build the URL with all params including reset filters
     query_params =
       build_query_params(
         socket.assigns.query,
@@ -460,23 +450,14 @@ defmodule MvWeb.MemberLive.Index do
       )
 
     new_path = ~p"/members?#{query_params}"
-
-    {:noreply,
-     push_patch(socket,
-       to: new_path,
-       replace: true
-     )}
+    {:noreply, push_patch(socket, to: new_path, replace: true)}
   end
 
   @impl true
   def handle_info({:field_toggled, field_string, visible}, socket) do
-    # Update user field selection
     new_selection = Map.put(socket.assigns.user_field_selection, field_string, visible)
-
-    # Save to session (cookie will be saved on next page load via handle_params)
     socket = update_session_field_selection(socket, new_selection)
 
-    # Merge with global settings (use all_custom_fields to allow enabling globally hidden fields)
     final_selection =
       FieldVisibility.merge_with_global_settings(
         new_selection,
@@ -484,14 +465,24 @@ defmodule MvWeb.MemberLive.Index do
         socket.assigns.all_custom_fields
       )
 
-    # Get visible fields
-    visible_member_fields = FieldVisibility.get_visible_member_fields(final_selection)
+    visible_member_fields =
+      final_selection
+      |> FieldVisibility.get_visible_member_fields()
+      |> Enum.uniq()
+
+    visible_member_fields_db = FieldVisibility.get_visible_member_fields_db(final_selection)
+
+    visible_member_fields_computed =
+      FieldVisibility.get_visible_member_fields_computed(final_selection)
+
     visible_custom_fields = FieldVisibility.get_visible_custom_fields(final_selection)
 
     socket =
       socket
       |> assign(:user_field_selection, final_selection)
       |> assign(:member_fields_visible, visible_member_fields)
+      |> assign(:member_fields_visible_db, visible_member_fields_db)
+      |> assign(:member_fields_visible_computed, visible_member_fields_computed)
       |> assign(:visible_custom_field_ids, extract_custom_field_ids(visible_custom_fields))
       |> load_members()
       |> prepare_dynamic_cols()
@@ -503,10 +494,8 @@ defmodule MvWeb.MemberLive.Index do
 
   @impl true
   def handle_info({:fields_selected, selection}, socket) do
-    # Save to session
     socket = update_session_field_selection(socket, selection)
 
-    # Merge with global settings (use all_custom_fields for merging)
     final_selection =
       FieldVisibility.merge_with_global_settings(
         selection,
@@ -514,14 +503,24 @@ defmodule MvWeb.MemberLive.Index do
         socket.assigns.all_custom_fields
       )
 
-    # Get visible fields
-    visible_member_fields = FieldVisibility.get_visible_member_fields(final_selection)
+    visible_member_fields =
+      final_selection
+      |> FieldVisibility.get_visible_member_fields()
+      |> Enum.uniq()
+
+    visible_member_fields_db = FieldVisibility.get_visible_member_fields_db(final_selection)
+
+    visible_member_fields_computed =
+      FieldVisibility.get_visible_member_fields_computed(final_selection)
+
     visible_custom_fields = FieldVisibility.get_visible_custom_fields(final_selection)
 
     socket =
       socket
       |> assign(:user_field_selection, final_selection)
       |> assign(:member_fields_visible, visible_member_fields)
+      |> assign(:member_fields_visible_db, visible_member_fields_db)
+      |> assign(:member_fields_visible_computed, visible_member_fields_computed)
       |> assign(:visible_custom_field_ids, extract_custom_field_ids(visible_custom_fields))
       |> load_members()
       |> prepare_dynamic_cols()
@@ -534,22 +533,12 @@ defmodule MvWeb.MemberLive.Index do
   # -----------------------------------------------------------------
   # Handle Params from the URL
   # -----------------------------------------------------------------
-  @doc """
-  Handles URL parameter changes.
 
-  Parses query parameters for search query, sort field, sort order, and payment filter,  and field selection,
-  then loads members accordingly. This enables bookmarkable URLs and
-  browser back/forward navigation.
-  """
   @impl true
   def handle_params(params, _url, socket) do
-    # Build signature BEFORE updates to detect if anything actually changed
     prev_sig = build_signature(socket)
-
-    # Parse field selection from URL
     url_selection = FieldSelection.parse_from_url(params)
 
-    # Merge with session selection (URL has priority)
     merged_selection =
       FieldSelection.merge_sources(
         url_selection,
@@ -557,7 +546,6 @@ defmodule MvWeb.MemberLive.Index do
         %{}
       )
 
-    # Merge with global settings (use all_custom_fields for merging)
     final_selection =
       FieldVisibility.merge_with_global_settings(
         merged_selection,
@@ -565,11 +553,18 @@ defmodule MvWeb.MemberLive.Index do
         socket.assigns.all_custom_fields
       )
 
-    # Get visible fields
-    visible_member_fields = FieldVisibility.get_visible_member_fields(final_selection)
+    visible_member_fields =
+      final_selection
+      |> FieldVisibility.get_visible_member_fields()
+      |> Enum.uniq()
+
+    visible_member_fields_db = FieldVisibility.get_visible_member_fields_db(final_selection)
+
+    visible_member_fields_computed =
+      FieldVisibility.get_visible_member_fields_computed(final_selection)
+
     visible_custom_fields = FieldVisibility.get_visible_custom_fields(final_selection)
 
-    # Apply all updates
     socket =
       socket
       |> maybe_update_search(params)
@@ -580,21 +575,18 @@ defmodule MvWeb.MemberLive.Index do
       |> assign(:query, params["query"])
       |> assign(:user_field_selection, final_selection)
       |> assign(:member_fields_visible, visible_member_fields)
+      |> assign(:member_fields_visible_db, visible_member_fields_db)
+      |> assign(:member_fields_visible_computed, visible_member_fields_computed)
       |> assign(:visible_custom_field_ids, extract_custom_field_ids(visible_custom_fields))
 
-    # Build signature AFTER updates
     next_sig = build_signature(socket)
 
-    # Only load members if signature changed (optimization: avoid duplicate loads)
-    # OR if members haven't been loaded yet (first handle_params call after mount)
     socket =
       if prev_sig == next_sig && Map.has_key?(socket.assigns, :members) do
-        # Nothing changed AND members already loaded, skip expensive load_members() call
         socket
         |> prepare_dynamic_cols()
         |> update_selection_assigns()
       else
-        # Signature changed OR members not loaded yet, reload members
         socket
         |> load_members()
         |> prepare_dynamic_cols()
@@ -604,20 +596,6 @@ defmodule MvWeb.MemberLive.Index do
     {:noreply, socket}
   end
 
-  # Builds a signature tuple representing all filter/sort parameters that affect member loading.
-  #
-  # This signature is used to detect if member data needs to be reloaded when handle_params
-  # is called. If the signature hasn't changed, we can skip the expensive load_members() call.
-  #
-  # Returns a tuple containing all relevant parameters:
-  # - query: Search query string
-  # - sort_field: Field to sort by
-  # - sort_order: Sort direction (:asc or :desc)
-  # - cycle_status_filter: Payment filter (:paid, :unpaid, or nil)
-  # - show_current_cycle: Whether to show current cycle
-  # - boolean_custom_field_filters: Map of active boolean filters
-  # - user_field_selection: Map of user's field visibility selections
-  # - visible_custom_field_ids: List of visible custom field IDs (affects which custom fields are loaded)
   defp build_signature(socket) do
     {
       socket.assigns.query,
@@ -631,32 +609,22 @@ defmodule MvWeb.MemberLive.Index do
     }
   end
 
-  # Prepares dynamic column definitions for custom fields that should be shown in the overview.
-  #
-  # Creates a list of column definitions, each containing:
-  # - `:custom_field` - The CustomField resource
-  # - `:render` - A function that formats the custom field value for a given member
-  #
-  # Only includes custom fields that are visible according to user field selection.
-  #
-  # Returns the socket with `:dynamic_cols` assigned.
   defp prepare_dynamic_cols(socket) do
     visible_custom_field_ids = socket.assigns[:visible_custom_field_ids] || []
+    visible_set = MapSet.new(visible_custom_field_ids)
 
-    # Use all_custom_fields to allow users to enable globally hidden custom fields
     dynamic_cols =
       socket.assigns.all_custom_fields
-      |> Enum.filter(fn custom_field -> custom_field.id in visible_custom_field_ids end)
+      |> Enum.filter(fn custom_field ->
+        MapSet.member?(visible_set, to_string(custom_field.id))
+      end)
       |> Enum.map(fn custom_field ->
         %{
           custom_field: custom_field,
           render: fn member ->
             case get_custom_field_value(member, custom_field) do
-              nil ->
-                ""
-
-              cfv ->
-                Formatter.format_custom_field_value(cfv.value, custom_field)
+              nil -> ""
+              cfv -> Formatter.format_custom_field_value(cfv.value, custom_field)
             end
           end
         }
@@ -666,10 +634,9 @@ defmodule MvWeb.MemberLive.Index do
   end
 
   # -------------------------------------------------------------
-  # FUNCTIONS
+  # Sorting
   # -------------------------------------------------------------
 
-  # Determines new sort field and order based on current state
   defp determine_new_sort(field, socket) do
     if socket.assigns.sort_field == field do
       {field, toggle_order(socket.assigns.sort_order)}
@@ -678,19 +645,16 @@ defmodule MvWeb.MemberLive.Index do
     end
   end
 
-  # Updates both the active and old SortHeader components
   defp update_sort_components(socket, old_field, new_field, new_order) do
     active_id = to_sort_id(new_field)
     old_id = to_sort_id(old_field)
 
-    # Update the new SortHeader
     send_update(MvWeb.Components.SortHeaderComponent,
       id: active_id,
       sort_field: new_field,
       sort_order: new_order
     )
 
-    # Reset the current SortHeader
     send_update(MvWeb.Components.SortHeaderComponent,
       id: old_id,
       sort_field: new_field,
@@ -700,8 +664,6 @@ defmodule MvWeb.MemberLive.Index do
     socket
   end
 
-  # Converts a field (atom or string) to a sort component ID atom
-  # Handles both existing atoms and strings that need to be converted
   defp to_sort_id(field) when is_binary(field) do
     try do
       String.to_existing_atom("sort_#{field}")
@@ -710,11 +672,8 @@ defmodule MvWeb.MemberLive.Index do
     end
   end
 
-  defp to_sort_id(field) when is_atom(field) do
-    :"sort_#{field}"
-  end
+  defp to_sort_id(field) when is_atom(field), do: :"sort_#{field}"
 
-  # Builds sort URL and pushes navigation patch
   defp push_sort_url(socket, field, order) do
     field_str =
       if is_atom(field) do
@@ -735,14 +694,9 @@ defmodule MvWeb.MemberLive.Index do
 
     new_path = ~p"/members?#{query_params}"
 
-    {:noreply,
-     push_patch(socket,
-       to: new_path,
-       replace: true
-     )}
+    {:noreply, push_patch(socket, to: new_path, replace: true)}
   end
 
-  # Adds field selection to query params if present
   defp maybe_add_field_selection(params, nil), do: params
 
   defp maybe_add_field_selection(params, selection) when is_map(selection) do
@@ -752,7 +706,6 @@ defmodule MvWeb.MemberLive.Index do
 
   defp maybe_add_field_selection(params, _), do: params
 
-  # Pushes URL with updated field selection
   defp push_field_selection_url(socket) do
     query_params =
       build_query_params(
@@ -766,20 +719,13 @@ defmodule MvWeb.MemberLive.Index do
       |> maybe_add_field_selection(socket.assigns[:user_field_selection])
 
     new_path = ~p"/members?#{query_params}"
-
     push_patch(socket, to: new_path, replace: true)
   end
 
-  # Updates session field selection (stored in socket for now, actual session update via controller)
   defp update_session_field_selection(socket, selection) do
-    # Store in socket for now - actual session persistence would require a controller
-    # This is a placeholder for future session persistence
     assign(socket, :user_field_selection, selection)
   end
 
-  # Builds URL query parameters map including all filter/sort state.
-  # Converts cycle_status_filter atom to string for URL.
-  # Adds boolean custom field filters as bf_<id>=true|false.
   defp build_query_params(
          query,
          sort_field,
@@ -808,7 +754,6 @@ defmodule MvWeb.MemberLive.Index do
       "sort_order" => order_str
     }
 
-    # Only add cycle_status_filter to URL if it's set
     base_params =
       case cycle_status_filter do
         nil -> base_params
@@ -816,7 +761,6 @@ defmodule MvWeb.MemberLive.Index do
         :unpaid -> Map.put(base_params, "cycle_status_filter", "unpaid")
       end
 
-    # Add show_current_cycle if true
     base_params =
       if show_current_cycle do
         Map.put(base_params, "show_current_cycle", "true")
@@ -824,7 +768,6 @@ defmodule MvWeb.MemberLive.Index do
         base_params
       end
 
-    # Add boolean custom field filters
     Enum.reduce(boolean_filters, base_params, fn {custom_field_id, filter_value}, acc ->
       param_key = "#{@boolean_filter_prefix}#{custom_field_id}"
       param_value = if filter_value == true, do: "true", else: "false"
@@ -832,25 +775,10 @@ defmodule MvWeb.MemberLive.Index do
     end)
   end
 
-  # Loads members from the database with custom field values and applies search/sort/payment filters.
-  #
-  # Process:
-  # 1. Builds base query with selected fields
-  # 2. Loads custom field values for visible custom fields (filtered at database level)
-  # 3. Applies search filter if provided
-  # 4. Applies payment status filter if set
-  # 5. Applies sorting (database-level for regular fields, in-memory for custom fields)
-  #
-  # Performance Considerations:
-  # - Database-level filtering: Custom field values are filtered directly in the database
-  #   using Ash relationship filters, reducing memory usage and improving performance.
-  # - In-memory sorting: Custom field sorting is done in memory after loading.
-  #   This is suitable for small to medium datasets (<1000 members).
-  #   For larger datasets, consider implementing database-level sorting or pagination.
-  # - No pagination: All matching members are loaded at once. For large result sets,
-  #   consider implementing pagination (see Issue #165).
-  #
-  # Returns the socket with `:members` assigned.
+  # -------------------------------------------------------------
+  # Loading members
+  # -------------------------------------------------------------
+
   defp load_members(socket) do
     search_query = socket.assigns.query
 
@@ -859,12 +787,8 @@ defmodule MvWeb.MemberLive.Index do
       |> Ash.Query.new()
       |> Ash.Query.select(@overview_fields)
 
-    # Load custom field values for visible custom fields AND active boolean filters
-    # This ensures boolean filters work even when the custom field is not visible in overview
     visible_custom_field_ids = socket.assigns[:visible_custom_field_ids] || []
 
-    # Get IDs of active boolean filters (whitelisted against boolean_custom_fields)
-    # Convert boolean_custom_fields list to map for efficient lookup (consistent with maybe_update_boolean_filters)
     boolean_custom_fields_map =
       socket.assigns.boolean_custom_fields
       |> Map.new(fn cf -> {to_string(cf.id), cf} end)
@@ -873,40 +797,36 @@ defmodule MvWeb.MemberLive.Index do
       socket.assigns.boolean_custom_field_filters
       |> Map.keys()
       |> Enum.filter(fn id_str ->
-        # Validate UUID format and check against whitelist
         String.length(id_str) <= @max_uuid_length &&
           match?({:ok, _}, Ecto.UUID.cast(id_str)) &&
           Map.has_key?(boolean_custom_fields_map, id_str)
       end)
 
-    # Union of visible IDs and active filter IDs
     ids_to_load =
       (visible_custom_field_ids ++ active_boolean_filter_ids)
       |> Enum.uniq()
 
     query = load_custom_field_values(query, ids_to_load)
 
-    # Load membership fee cycles for status display
     query = MembershipFeeStatus.load_cycles_for_members(query, socket.assigns.show_current_cycle)
 
-    # Apply the search filter first
     query = apply_search_filter(query, search_query)
 
-    # Apply sorting based on current socket state
-    # For custom fields, we sort after loading
+    # Use ALL custom fields for sorting (not just show_in_overview subset)
+    custom_fields_for_sort = socket.assigns.all_custom_fields
+
     {query, sort_after_load} =
       maybe_sort(
         query,
         socket.assigns.sort_field,
         socket.assigns.sort_order,
-        socket.assigns.custom_fields_visible
+        custom_fields_for_sort
       )
 
     # Errors in handle_params are handled by Phoenix LiveView
     actor = current_actor(socket)
     {time_microseconds, members} = :timer.tc(fn -> Ash.read!(query, actor: actor) end)
-    time_milliseconds = time_microseconds / 1000
-    Logger.info("Ash.read! in load_members/1 took #{time_milliseconds} ms")
+    Logger.info("Ash.read! in load_members/1 took #{time_microseconds / 1000} ms")
 
     # Custom field values are already filtered at the database level in load_custom_field_values/2
     # No need for in-memory filtering anymore
@@ -927,14 +847,15 @@ defmodule MvWeb.MemberLive.Index do
         socket.assigns.all_custom_fields
       )
 
-    # Sort in memory if needed (for custom fields)
+    # Sort in memory if needed (custom fields only; computed fields are blocked)
     members =
-      if sort_after_load do
+      if sort_after_load and
+           socket.assigns.sort_field not in FieldVisibility.computed_member_fields() do
         sort_members_in_memory(
           members,
           socket.assigns.sort_field,
           socket.assigns.sort_order,
-          socket.assigns.custom_fields_visible
+          custom_fields_for_sort
         )
       else
         members
@@ -943,22 +864,9 @@ defmodule MvWeb.MemberLive.Index do
     assign(socket, :members, members)
   end
 
-  # Load custom field values for the given custom field IDs
-  #
-  # Filters custom field values directly in the database using Ash relationship filters.
-  # This is more efficient than loading all values and filtering in memory.
-  #
-  # Performance: Database-level filtering reduces:
-  # - Memory usage (only visible custom field values are loaded)
-  # - Network transfer (less data from database to application)
-  # - Processing time (no need to iterate through all members and filter)
-  defp load_custom_field_values(query, []) do
-    query
-  end
+  defp load_custom_field_values(query, []), do: query
 
   defp load_custom_field_values(query, custom_field_ids) do
-    # Filter custom field values at the database level using Ash relationship query
-    # This ensures only visible custom field values are loaded
     custom_field_values_query =
       Mv.Membership.CustomFieldValue
       |> Ash.Query.filter(expr(custom_field_id in ^custom_field_ids))
@@ -972,24 +880,15 @@ defmodule MvWeb.MemberLive.Index do
   # Helper Functions
   # -------------------------------------------------------------
 
-  # Function to apply search query
   defp apply_search_filter(query, search_query) do
     if search_query && String.trim(search_query) != "" do
       query
-      |> Mv.Membership.Member.fuzzy_search(%{
-        query: search_query
-      })
+      |> Mv.Membership.Member.fuzzy_search(%{query: search_query})
     else
       query
     end
   end
 
-  # Applies cycle status filter to members list.
-  #
-  # Filter values:
-  # - nil: No filter, return all members
-  # - :paid: Only members with paid status in the selected cycle (last or current)
-  # - :unpaid: Only members with unpaid status in the selected cycle (last or current)
   defp apply_cycle_status_filter(members, nil, _show_current), do: members
 
   defp apply_cycle_status_filter(members, status, show_current)
@@ -997,50 +896,78 @@ defmodule MvWeb.MemberLive.Index do
     MembershipFeeStatus.filter_members_by_cycle_status(members, status, show_current)
   end
 
-  # Functions to toggle sorting order
   defp toggle_order(:asc), do: :desc
   defp toggle_order(:desc), do: :asc
   defp toggle_order(nil), do: :asc
 
-  # Function to sort the column if needed
-  # Returns {query, sort_after_load} where sort_after_load is true if we need to sort in memory
-  defp maybe_sort(query, nil, _, _), do: {query, false}
+  # Function to sort the column if needed.
+  # Only DB member fields and custom fields; computed fields (e.g. membership_fee_status) are never passed to Ash.
+  # Returns {query, sort_after_load} where sort_after_load is true if we need to sort in memory.
+  defp maybe_sort(query, nil, _order, _custom_fields), do: {query, false}
+  defp maybe_sort(query, _field, nil, _custom_fields), do: {query, false}
 
-  defp maybe_sort(query, field, order, _custom_fields) when not is_nil(field) do
-    if custom_field_sort?(field) do
-      # Custom fields need to be sorted in memory after loading
-      {query, true}
-    else
-      # Only sort by atom fields (regular member fields) in database
-      if is_atom(field) do
-        {Ash.Query.sort(query, [{field, order}]), false}
-      else
+  defp maybe_sort(query, field, order, _custom_fields) do
+    computed_atoms = FieldVisibility.computed_member_fields()
+    computed_strings = Enum.map(computed_atoms, &Atom.to_string/1)
+
+    cond do
+      # Block computed fields (atom and string variants)
+      (is_atom(field) and field in computed_atoms) or
+          (is_binary(field) and field in computed_strings) ->
+        {query, false}
+
+      # Custom field sort -> after load
+      custom_field_sort?(field) ->
+        {query, true}
+
+      # DB field sort (atom)
+      is_atom(field) ->
+        {Ash.Query.sort(query, [{field, order}]), false}
+
+      # DB field sort (string) -> convert only if allowed
+      is_binary(field) ->
+        case safe_member_field_atom_only(field) do
+          nil -> {query, false}
+          atom -> {Ash.Query.sort(query, [{atom, order}]), false}
+        end
+
+      true ->
         {query, false}
-      end
     end
   end
 
-  defp maybe_sort(query, _, _, _), do: {query, false}
-
-  # Validate that a field is sortable
-  # Uses member fields from constants, but excludes fields that don't make sense to sort
-  # (e.g., :notes is too long, :paid is boolean and not very useful for sorting)
   defp valid_sort_field?(field) when is_atom(field) do
-    # All member fields are sortable, but we exclude some that don't make sense
-    # :id is not in member_fields, but we don't want to sort by it anyway
-    non_sortable_fields = [:notes]
-    valid_fields = Mv.Constants.member_fields() -- non_sortable_fields
-
-    field in valid_fields or custom_field_sort?(field)
+    if field in FieldVisibility.computed_member_fields(),
+      do: false,
+      else: valid_sort_field_db_or_custom?(field)
   end
 
   defp valid_sort_field?(field) when is_binary(field) do
-    custom_field_sort?(field)
+    if field in Enum.map(FieldVisibility.computed_member_fields(), &Atom.to_string/1) do
+      false
+    else
+      valid_sort_field_db_or_custom?(field)
+    end
   end
 
   defp valid_sort_field?(_), do: false
 
-  # Check if field is a custom field sort field (format: custom_field_<id>)
+  defp valid_sort_field_db_or_custom?(field) when is_atom(field) do
+    non_sortable_fields = [:notes]
+    valid_fields = Mv.Constants.member_fields() -- non_sortable_fields
+    field in valid_fields or custom_field_sort?(field)
+  end
+
+  defp valid_sort_field_db_or_custom?(field) when is_binary(field) do
+    custom_field_sort?(field) or
+      ((atom = safe_member_field_atom_only(field)) != nil and valid_sort_field_db_or_custom?(atom))
+  end
+
+  defp safe_member_field_atom_only(str) do
+    allowed = MapSet.new(Mv.Constants.member_fields() |> Enum.map(&Atom.to_string/1))
+    if MapSet.member?(allowed, str), do: String.to_existing_atom(str), else: nil
+  end
+
   defp custom_field_sort?(field) when is_atom(field) do
     field_str = Atom.to_string(field)
     String.starts_with?(field_str, @custom_field_prefix)
@@ -1052,18 +979,8 @@ defmodule MvWeb.MemberLive.Index do
 
   defp custom_field_sort?(_), do: false
 
-  # Extracts the custom field ID from a sort field name.
-  #
-  # Sort fields for custom fields use the format: "custom_field_<id>"
-  # This function extracts the ID part.
-  #
-  # Examples:
-  #   extract_custom_field_id("custom_field_123") -> "123"
-  #   extract_custom_field_id(:custom_field_123) -> "123"
-  #   extract_custom_field_id("first_name") -> nil
   defp extract_custom_field_id(field) when is_atom(field) do
-    field_str = Atom.to_string(field)
-    extract_custom_field_id(field_str)
+    field |> Atom.to_string() |> extract_custom_field_id()
   end
 
   defp extract_custom_field_id(field) when is_binary(field) do
@@ -1075,8 +992,6 @@ defmodule MvWeb.MemberLive.Index do
 
   defp extract_custom_field_id(_), do: nil
 
-  # Extracts custom field IDs from visible custom field strings
-  # Format: "custom_field_<id>" -> <id>
   defp extract_custom_field_ids(visible_custom_fields) do
     Enum.map(visible_custom_fields, fn field_string ->
       case String.split(field_string, @custom_field_prefix) do
@@ -1087,79 +1002,40 @@ defmodule MvWeb.MemberLive.Index do
     |> Enum.filter(&(&1 != nil))
   end
 
-  # Sorts members in memory by a custom field value.
-  #
-  # Process:
-  # 1. Extracts custom field ID from sort field name
-  # 2. Finds the corresponding CustomField resource
-  # 3. Splits members into those with values and those without
-  # 4. Sorts members with values by the extracted value
-  # 5. Combines: sorted values first, then NULL/empty values at the end
-  #
-  # Performance Note:
-  # This function sorts in memory, which is suitable for small to medium datasets (<1000 members).
-  # For larger datasets, consider implementing database-level sorting or pagination.
-  #
-  # Parameters:
-  # - `members` - List of Member resources to sort
-  # - `field` - Sort field name (format: "custom_field_<id>" or atom)
-  # - `order` - Sort order (`:asc` or `:desc`)
-  # - `custom_fields` - List of visible CustomField resources
-  #
-  # Returns the sorted list of members.
   defp sort_members_in_memory(members, field, order, custom_fields) do
     custom_field_id_str = extract_custom_field_id(field)
 
     case custom_field_id_str do
-      nil ->
-        members
-
-      id_str ->
-        sort_members_by_custom_field(members, id_str, order, custom_fields)
+      nil -> members
+      id_str -> sort_members_by_custom_field(members, id_str, order, custom_fields)
     end
   end
 
-  # Sorts members by a specific custom field ID
   defp sort_members_by_custom_field(members, id_str, order, custom_fields) do
     custom_field = find_custom_field_by_id(custom_fields, id_str)
 
     case custom_field do
-      nil ->
-        members
-
-      cf ->
-        sort_members_with_custom_field(members, cf, order)
+      nil -> members
+      cf -> sort_members_with_custom_field(members, cf, order)
     end
   end
 
-  # Finds a custom field by matching its ID string
   defp find_custom_field_by_id(custom_fields, id_str) do
-    Enum.find(custom_fields, fn cf ->
-      to_string(cf.id) == id_str
-    end)
+    Enum.find(custom_fields, fn cf -> to_string(cf.id) == id_str end)
   end
 
-  # Sorts members that have a specific custom field
   defp sort_members_with_custom_field(members, custom_field, order) do
-    # Split members into those with values and those without (NULL/empty)
     {members_with_values, members_without_values} =
       split_members_by_value_presence(members, custom_field)
 
-    # Sort members with values
     sorted_with_values = sort_members_with_values(members_with_values, custom_field, order)
-
-    # Combine: sorted values first, then NULL/empty values at the end
     sorted_with_values ++ members_without_values
   end
 
-  # Splits members into those with values and those without
   defp split_members_by_value_presence(members, custom_field) do
-    Enum.split_with(members, fn member ->
-      has_non_empty_value?(member, custom_field)
-    end)
+    Enum.split_with(members, fn member -> has_non_empty_value?(member, custom_field) end)
   end
 
-  # Checks if a member has a non-empty value for the custom field
   defp has_non_empty_value?(member, custom_field) do
     case get_custom_field_value(member, custom_field) do
       nil ->
@@ -1171,7 +1047,6 @@ defmodule MvWeb.MemberLive.Index do
     end
   end
 
-  # Sorts members that have values for the custom field
   defp sort_members_with_values(members_with_values, custom_field, order) do
     sorted =
       Enum.sort_by(members_with_values, fn member ->
@@ -1180,24 +1055,11 @@ defmodule MvWeb.MemberLive.Index do
         normalize_sort_value(extracted, order)
       end)
 
-    # For DESC, reverse only the members with values
-    if order == :desc do
-      Enum.reverse(sorted)
-    else
-      sorted
-    end
+    if order == :desc, do: Enum.reverse(sorted), else: sorted
   end
 
-  # Extracts a sortable value from a custom field value based on its type.
-  #
-  # Handles different value formats:
-  # - `%Ash.Union{}` - Extracts value and type from union
-  # - Direct values - Returns as-is for primitive types
-  #
-  # Returns the extracted value suitable for sorting.
-  defp extract_sort_value(%Ash.Union{value: value, type: type}, _expected_type) do
-    extract_sort_value(value, type)
-  end
+  defp extract_sort_value(%Ash.Union{value: value, type: type}, _expected_type),
+    do: extract_sort_value(value, type)
 
   defp extract_sort_value(value, :string) when is_binary(value), do: value
   defp extract_sort_value(value, :integer) when is_integer(value), do: value
@@ -1206,25 +1068,12 @@ defmodule MvWeb.MemberLive.Index do
   defp extract_sort_value(value, :email) when is_binary(value), do: value
   defp extract_sort_value(value, _type), do: to_string(value)
 
-  # Check if a value is considered empty (NULL or empty string)
-  defp empty_value?(value, :string) when is_binary(value) do
-    String.trim(value) == ""
-  end
-
-  defp empty_value?(value, :email) when is_binary(value) do
-    String.trim(value) == ""
-  end
-
+  defp empty_value?(value, :string) when is_binary(value), do: String.trim(value) == ""
+  defp empty_value?(value, :email) when is_binary(value), do: String.trim(value) == ""
   defp empty_value?(_value, _type), do: false
 
-  # Normalize sort value for DESC order
-  # For DESC, we sort ascending first, then reverse the list
-  # This function is kept for consistency but doesn't need to invert values
   defp normalize_sort_value(value, _order), do: value
 
-  # Updates sort field and order from URL parameters if present.
-  #
-  # Validates the sort field and order, falling back to defaults if invalid.
   defp maybe_update_sort(socket, %{"sort_field" => sf, "sort_order" => so}) do
     field = determine_field(socket.assigns.sort_field, sf)
     order = determine_order(socket.assigns.sort_order, so)
@@ -1236,50 +1085,38 @@ defmodule MvWeb.MemberLive.Index do
 
   defp maybe_update_sort(socket, _), do: socket
 
-  # Determine sort field from URL parameter, validating against allowed fields
   defp determine_field(default, ""), do: default
   defp determine_field(default, nil), do: default
 
-  # Determines the valid sort field from a URL parameter.
-  #
-  # Validates the field against allowed sort fields (regular member fields or custom fields).
-  # Falls back to default if the field is invalid.
-  #
-  # Parameters:
-  # - `default` - Default field to use if validation fails
-  # - `sf` - Sort field from URL (can be atom, string, nil, or empty string)
-  #
-  # Returns a valid sort field (atom or string for custom fields).
   defp determine_field(default, sf) when is_binary(sf) do
-    # Check if it's a custom field sort (starts with "custom_field_")
-    if custom_field_sort?(sf) do
-      if valid_sort_field?(sf), do: sf, else: default
-    else
-      # Try to convert to atom for regular fields
-      try do
-        atom = String.to_existing_atom(sf)
-        if valid_sort_field?(atom), do: atom, else: default
-      rescue
-        ArgumentError -> default
-      end
-    end
+    computed_strings = Enum.map(FieldVisibility.computed_member_fields(), &Atom.to_string/1)
+
+    if sf in computed_strings,
+      do: default,
+      else: determine_field_after_computed_check(default, sf)
   end
 
   defp determine_field(default, sf) when is_atom(sf) do
-    if valid_sort_field?(sf), do: sf, else: default
+    if sf in FieldVisibility.computed_member_fields(),
+      do: default,
+      else: determine_field_after_computed_check(default, sf)
   end
 
   defp determine_field(default, _), do: default
 
-  # Determines the valid sort order from a URL parameter.
-  #
-  # Validates that the order is either "asc" or "desc", falling back to default if invalid.
-  #
-  # Parameters:
-  # - `default` - Default order to use if validation fails
-  # - `so` - Sort order from URL (string, atom, nil, or empty string)
-  #
-  # Returns `:asc` or `:desc`.
+  defp determine_field_after_computed_check(default, sf) when is_binary(sf) do
+    if custom_field_sort?(sf) do
+      if valid_sort_field?(sf), do: sf, else: default
+    else
+      atom = safe_member_field_atom_only(sf)
+      if atom != nil and valid_sort_field?(atom), do: atom, else: default
+    end
+  end
+
+  defp determine_field_after_computed_check(default, sf) when is_atom(sf) do
+    if valid_sort_field?(sf), do: sf, else: default
+  end
+
   defp determine_order(default, so) do
     case so do
       "" -> default
@@ -1289,59 +1126,29 @@ defmodule MvWeb.MemberLive.Index do
     end
   end
 
-  # Function to update search parameters
-  defp maybe_update_search(socket, %{"query" => query}) when query != "" do
-    assign(socket, :query, query)
-  end
+  defp maybe_update_search(socket, %{"query" => query}) when query != "",
+    do: assign(socket, :query, query)
 
-  defp maybe_update_search(socket, _params) do
-    # Keep the previous search query if no new one is provided
-    socket
-  end
+  defp maybe_update_search(socket, _params), do: socket
 
-  # Updates cycle status filter from URL parameters if present.
-  #
-  # Validates the filter value, falling back to nil (no filter) if invalid.
   defp maybe_update_cycle_status_filter(socket, %{"cycle_status_filter" => filter_str}) do
     filter = determine_cycle_status_filter(filter_str)
     assign(socket, :cycle_status_filter, filter)
   end
 
-  defp maybe_update_cycle_status_filter(socket, _params) do
-    # Reset filter if not in URL params
-    assign(socket, :cycle_status_filter, nil)
-  end
+  defp maybe_update_cycle_status_filter(socket, _params),
+    do: assign(socket, :cycle_status_filter, nil)
 
-  # Determines valid cycle status filter from URL parameter.
-  #
-  # SECURITY: This function whitelists allowed filter values. Only "paid" and "unpaid"
-  # are accepted - all other input (including malicious strings) falls back to nil.
-  # This ensures no raw user input is ever passed to filter functions.
   defp determine_cycle_status_filter("paid"), do: :paid
   defp determine_cycle_status_filter("unpaid"), do: :unpaid
   defp determine_cycle_status_filter(_), do: nil
 
-  # Updates boolean custom field filters from URL parameters if present.
-  #
-  # Parses all URL parameters with prefix @boolean_filter_prefix and validates them:
-  # - Extracts custom field ID from parameter name (explicitly removes prefix)
-  # - Validates filter value using determine_boolean_filter/1
-  # - Whitelisting: Only custom field IDs that exist and have value_type: :boolean
-  # - Security: Limits to maximum @max_boolean_filters filters to prevent DoS attacks
-  # - Security: Validates UUID length (max @max_uuid_length characters)
-  #
-  # Returns socket with updated :boolean_custom_field_filters assign.
   defp maybe_update_boolean_filters(socket, params) do
-    # Get all boolean custom fields for whitelisting (keyed by ID as string for consistency)
     boolean_custom_fields =
       socket.assigns.all_custom_fields
       |> Enum.filter(&(&1.value_type == :boolean))
       |> Map.new(fn cf -> {to_string(cf.id), cf} end)
 
-    # Parse all boolean filter parameters
-    # Security: Use reduce_while to abort early after @max_boolean_filters to prevent DoS attacks
-    # This protects CPU/Parsing costs, not just memory/state
-    # We count processed parameters (not just valid filters) to protect against parsing DoS
     prefix_length = String.length(@boolean_filter_prefix)
 
     {filters, total_processed} =
@@ -1360,13 +1167,10 @@ defmodule MvWeb.MemberLive.Index do
               acc
             )
 
-          # Increment counter for each processed parameter (DoS protection)
-          # Note: We count processed params, not just valid filters, to protect parsing costs
           {:cont, {new_acc, count + 1}}
         end
       end)
 
-    # Log warning if we hit the limit
     if total_processed >= @max_boolean_filters do
       Logger.warning(
         "Boolean filter limit reached: processed #{total_processed} parameters, accepted #{map_size(filters)} valid filters (max: #{@max_boolean_filters})"
@@ -1376,63 +1180,27 @@ defmodule MvWeb.MemberLive.Index do
     assign(socket, :boolean_custom_field_filters, filters)
   end
 
-  # Processes a single boolean filter parameter from URL params.
-  #
-  # Validates the parameter and adds it to the accumulator if valid.
-  # Returns the accumulator unchanged if validation fails.
-  defp process_boolean_filter_param(
-         key,
-         value_str,
-         prefix_length,
-         boolean_custom_fields,
-         acc
-       ) do
-    # Extract custom field ID from parameter name (explicitly remove prefix)
-    # This is more secure than String.replace_prefix which only removes first occurrence
+  defp process_boolean_filter_param(key, value_str, prefix_length, boolean_custom_fields, acc) do
     custom_field_id_str = String.slice(key, prefix_length, String.length(key) - prefix_length)
 
-    # Validate custom field ID length (UUIDs are max @max_uuid_length characters)
-    # This provides an additional security layer beyond UUID format validation
     if String.length(custom_field_id_str) > @max_uuid_length do
       acc
     else
-      validate_and_add_boolean_filter(
-        custom_field_id_str,
-        value_str,
-        boolean_custom_fields,
-        acc
-      )
+      validate_and_add_boolean_filter(custom_field_id_str, value_str, boolean_custom_fields, acc)
     end
   end
 
-  # Validates UUID format and custom field existence, then adds filter if valid.
-  defp validate_and_add_boolean_filter(
-         custom_field_id_str,
-         value_str,
-         boolean_custom_fields,
-         acc
-       ) do
+  defp validate_and_add_boolean_filter(custom_field_id_str, value_str, boolean_custom_fields, acc) do
     case Ecto.UUID.cast(custom_field_id_str) do
       {:ok, _custom_field_id} ->
-        add_boolean_filter_if_valid(
-          custom_field_id_str,
-          value_str,
-          boolean_custom_fields,
-          acc
-        )
+        add_boolean_filter_if_valid(custom_field_id_str, value_str, boolean_custom_fields, acc)
 
       :error ->
         acc
     end
   end
 
-  # Adds boolean filter to accumulator if custom field exists and value is valid.
-  defp add_boolean_filter_if_valid(
-         custom_field_id_str,
-         value_str,
-         boolean_custom_fields,
-         acc
-       ) do
+  defp add_boolean_filter_if_valid(custom_field_id_str, value_str, boolean_custom_fields, acc) do
     if Map.has_key?(boolean_custom_fields, custom_field_id_str) do
       case determine_boolean_filter(value_str) do
         nil -> acc
@@ -1443,45 +1211,19 @@ defmodule MvWeb.MemberLive.Index do
     end
   end
 
-  # Determines valid boolean filter value from URL parameter.
-  #
-  # SECURITY: This function whitelists allowed filter values. Only "true" and "false"
-  # are accepted - all other input (including malicious strings) falls back to nil.
-  # This ensures no raw user input is ever passed to filter functions.
-  #
-  # Returns:
-  # - `true` for "true" string
-  # - `false` for "false" string
-  # - `nil` for any other value
   defp determine_boolean_filter("true"), do: true
   defp determine_boolean_filter("false"), do: false
   defp determine_boolean_filter(_), do: nil
 
-  # Updates show_current_cycle from URL parameters if present.
-  defp maybe_update_show_current_cycle(socket, %{"show_current_cycle" => "true"}) do
-    assign(socket, :show_current_cycle, true)
-  end
+  defp maybe_update_show_current_cycle(socket, %{"show_current_cycle" => "true"}),
+    do: assign(socket, :show_current_cycle, true)
 
-  defp maybe_update_show_current_cycle(socket, _params) do
-    socket
-  end
+  defp maybe_update_show_current_cycle(socket, _params), do: socket
 
   # -------------------------------------------------------------
-  # Helper Functions for Custom Field Values
+  # Custom Field Value Helpers
   # -------------------------------------------------------------
 
-  # Retrieves the custom field value for a specific member and custom field.
-  #
-  # Searches through the member's `custom_field_values` relationship to find
-  # the value matching the given custom field.
-  #
-  # Returns:
-  # - `%CustomFieldValue{}` if found
-  # - `nil` if not found or if member has no custom field values
-  #
-  # Examples:
-  #   get_custom_field_value(member, custom_field) -> %CustomFieldValue{...}
-  #   get_custom_field_value(member, non_existent_field) -> nil
   def get_custom_field_value(member, custom_field) do
     case member.custom_field_values do
       nil ->
@@ -1498,46 +1240,17 @@ defmodule MvWeb.MemberLive.Index do
     end
   end
 
-  # Extracts the boolean value from a member's custom field value.
-  #
-  # Handles different value formats:
-  # - `%Ash.Union{value: value, type: :boolean}` - Extracts value from union
-  # - Map format with `"type"` and `"value"` keys - Extracts from map
-  # - Map format with `"_union_type"` and `"_union_value"` keys - Extracts from map
-  #
-  # Returns:
-  # - `true` if the custom field value is boolean true
-  # - `false` if the custom field value is boolean false
-  # - `nil` if no custom field value exists, value is nil, or value is not boolean
-  #
-  # Examples:
-  #   get_boolean_custom_field_value(member, boolean_field) -> true
-  #   get_boolean_custom_field_value(member, non_existent_field) -> nil
   def get_boolean_custom_field_value(member, custom_field) do
     case get_custom_field_value(member, custom_field) do
-      nil ->
-        nil
-
-      cfv ->
-        extract_boolean_value(cfv.value)
+      nil -> nil
+      cfv -> extract_boolean_value(cfv.value)
     end
   end
 
-  # Extracts boolean value from custom field value, handling different formats.
-  #
-  # Handles:
-  # - `%Ash.Union{value: value, type: :boolean}` - Union struct format
-  # - Map with `"type"` and `"value"` keys - JSONB map format
-  # - Map with `"_union_type"` and `"_union_value"` keys - Alternative map format
-  # - Direct boolean value - Primitive boolean
-  #
-  # Returns `true`, `false`, or `nil`.
-  defp extract_boolean_value(%Ash.Union{value: value, type: :boolean}) do
-    extract_boolean_value(value)
-  end
+  defp extract_boolean_value(%Ash.Union{value: value, type: :boolean}),
+    do: extract_boolean_value(value)
 
   defp extract_boolean_value(value) when is_map(value) do
-    # Handle map format from JSONB
     type = Map.get(value, "type") || Map.get(value, "_union_type")
     val = Map.get(value, "value") || Map.get(value, "_union_value")
 
@@ -1552,94 +1265,43 @@ defmodule MvWeb.MemberLive.Index do
   defp extract_boolean_value(nil), do: nil
   defp extract_boolean_value(_), do: nil
 
-  # Applies boolean custom field filters to a list of members.
-  #
-  # Filters members based on boolean custom field values. Only members that match
-  # ALL active filters (AND logic) are returned.
-  #
-  # Parameters:
-  # - `members` - List of Member resources with loaded custom_field_values
-  # - `filters` - Map of `%{custom_field_id_string => true | false}`
-  # - `all_custom_fields` - List of all CustomField resources (for validation)
-  #
-  # Returns:
-  # - Filtered list of members that match all active filters
-  # - All members if filters map is empty
-  # - Filters with non-existent custom field IDs are ignored
-  #
-  # Examples:
-  #   apply_boolean_custom_field_filters(members, %{"uuid-123" => true}, all_custom_fields) -> [member1, ...]
-  #   apply_boolean_custom_field_filters(members, %{}, all_custom_fields) -> members
   def apply_boolean_custom_field_filters(members, filters, _all_custom_fields)
       when map_size(filters) == 0 do
     members
   end
 
   def apply_boolean_custom_field_filters(members, filters, all_custom_fields) do
-    # Build a map of valid boolean custom field IDs (as strings) for quick lookup
     valid_custom_field_ids =
       all_custom_fields
       |> Enum.filter(&(&1.value_type == :boolean))
       |> MapSet.new(fn cf -> to_string(cf.id) end)
 
-    # Filter out invalid custom field IDs from filters
     valid_filters =
       Enum.filter(filters, fn {custom_field_id_str, _value} ->
         MapSet.member?(valid_custom_field_ids, custom_field_id_str)
       end)
       |> Enum.into(%{})
 
-    # If no valid filters remain, return all members
     if map_size(valid_filters) == 0 do
       members
     else
-      Enum.filter(members, fn member ->
-        matches_all_filters?(member, valid_filters)
-      end)
+      Enum.filter(members, fn member -> matches_all_filters?(member, valid_filters) end)
     end
   end
 
-  # Checks if a member matches all active boolean filters.
-  #
-  # A member matches a filter if:
-  # - The filter value is `true` and the member's custom field value is `true`
-  # - The filter value is `false` and the member's custom field value is `false`
-  #
-  # Members without a custom field value or with `nil` value do not match any filter.
-  #
-  # Returns `true` if all filters match, `false` otherwise.
   defp matches_all_filters?(member, filters) do
     Enum.all?(filters, fn {custom_field_id_str, filter_value} ->
       matches_filter?(member, custom_field_id_str, filter_value)
     end)
   end
 
-  # Checks if a member matches a specific boolean filter.
-  #
-  # Finds the custom field value by ID and checks if the member's boolean value
-  # matches the filter value.
-  #
-  # Returns:
-  # - `true` if the member's boolean value matches the filter value
-  # - `false` if no custom field value exists (member is filtered out)
-  # - `false` if value is nil or values don't match
   defp matches_filter?(member, custom_field_id_str, filter_value) do
     case find_custom_field_value_by_id(member, custom_field_id_str) do
-      nil ->
-        false
-
-      cfv ->
-        boolean_value = extract_boolean_value(cfv.value)
-        boolean_value == filter_value
+      nil -> false
+      cfv -> extract_boolean_value(cfv.value) == filter_value
     end
   end
 
-  # Finds a custom field value by custom field ID string.
-  #
-  # Searches through the member's custom_field_values to find one matching
-  # the given custom field ID.
-  #
-  # Returns the CustomFieldValue or nil.
   defp find_custom_field_value_by_id(member, custom_field_id_str) do
     case member.custom_field_values do
       nil ->
@@ -1657,9 +1319,6 @@ defmodule MvWeb.MemberLive.Index do
     end
   end
 
-  # Filters selected members with email addresses and formats them.
-  # Returns a list of formatted email strings in the format "First Last <email>".
-  # Used by both copy_emails and mailto links.
   def format_selected_member_emails(members, selected_members) do
     members
     |> Enum.filter(fn member ->
@@ -1668,18 +1327,8 @@ defmodule MvWeb.MemberLive.Index do
     |> Enum.map(&format_member_email/1)
   end
 
-  @doc """
-  Returns a JS command to toggle member selection when clicking the checkbox column.
+  def checkbox_column_click(member), do: JS.push("select_member", value: %{id: member.id})
 
-  Used as `col_click` handler to ensure clicking anywhere in the checkbox column
-  toggles the checkbox instead of navigating to the member details.
-  """
-  def checkbox_column_click(member) do
-    JS.push("select_member", value: %{id: member.id})
-  end
-
-  # Formats a member's email in the format "First Last <email>"
-  # Used for copy_emails feature and mailto links to create email-client-friendly format.
   def format_member_email(member) do
     first_name = member.first_name || ""
     last_name = member.last_name || ""
@@ -1689,33 +1338,17 @@ defmodule MvWeb.MemberLive.Index do
       |> Enum.filter(&(&1 != ""))
       |> Enum.join(" ")
 
-    if name == "" do
-      member.email
-    else
-      "#{name} <#{member.email}>"
-    end
+    if name == "", do: member.email, else: "#{name} <#{member.email}>"
   end
 
-  # Public helper function to format dates for use in templates
   def format_date(date), do: DateFormatter.format_date(date)
 
-  # Updates selection-related assigns (selected_count, any_selected?, mailto_bcc)
-  # to avoid recalculating Enum.any? and Enum.count multiple times in templates.
-  #
-  # Note: Mailto URLs have length limits that vary by email client.
-  # For large selections, consider using export functionality instead.
-  #
-  # Handles case where members haven't been loaded yet (e.g., when signature didn't change in handle_params).
   defp update_selection_assigns(socket) do
-    # Handle case where members haven't been loaded yet (e.g., when signature didn't change)
     members = socket.assigns[:members] || []
     selected_members = socket.assigns.selected_members
 
-    selected_count =
-      Enum.count(members, &MapSet.member?(selected_members, &1.id))
-
-    any_selected? =
-      Enum.any?(members, &MapSet.member?(selected_members, &1.id))
+    selected_count = Enum.count(members, &MapSet.member?(selected_members, &1.id))
+    any_selected? = Enum.any?(members, &MapSet.member?(selected_members, &1.id))
 
     mailto_bcc =
       if any_selected? do
@@ -1733,27 +1366,52 @@ defmodule MvWeb.MemberLive.Index do
     |> assign_export_payload()
   end
 
-  # Builds the export payload map and assigns :export_payload_json for the CSV export form.
-  # Called when selection, visible fields, query, or sort change so the form always has current data.
   defp assign_export_payload(socket) do
     payload = build_export_payload(socket)
     assign(socket, :export_payload_json, Jason.encode!(payload))
   end
 
   defp build_export_payload(socket) do
-    member_fields_visible = socket.assigns[:member_fields_visible] || []
     visible_custom_field_ids = socket.assigns[:visible_custom_field_ids] || []
 
+    member_fields_db = socket.assigns[:member_fields_visible_db] || []
+    member_fields_computed = socket.assigns[:member_fields_visible_computed] || []
+
+    # Order DB member fields exactly like the table/constants
+    ordered_member_fields_db =
+      Mv.Constants.member_fields()
+      |> Enum.filter(&(&1 in member_fields_db))
+
+    # Order computed fields in canonical order
+    ordered_computed_fields =
+      FieldVisibility.computed_member_fields()
+      |> Enum.filter(&(&1 in member_fields_computed))
+
+    # Order custom fields like the table (same as dynamic_cols / all_custom_fields order)
+    ordered_custom_field_ids =
+      socket.assigns.all_custom_fields
+      |> Enum.map(&to_string(&1.id))
+      |> Enum.filter(&(&1 in visible_custom_field_ids))
+
     %{
       selected_ids: socket.assigns.selected_members |> MapSet.to_list(),
-      member_fields: Enum.map(member_fields_visible, &Atom.to_string/1),
-      custom_field_ids: visible_custom_field_ids,
+      member_fields: Enum.map(ordered_member_fields_db, &Atom.to_string/1),
+      computed_fields: Enum.map(ordered_computed_fields, &Atom.to_string/1),
+      custom_field_ids: ordered_custom_field_ids,
       query: socket.assigns[:query] || nil,
       sort_field: export_sort_field(socket.assigns[:sort_field]),
-      sort_order: export_sort_order(socket.assigns[:sort_order])
+      sort_order: export_sort_order(socket.assigns[:sort_order]),
+      show_current_cycle: socket.assigns[:show_current_cycle] || false,
+      cycle_status_filter: export_cycle_status_filter(socket.assigns[:cycle_status_filter]),
+      boolean_filters: socket.assigns[:boolean_custom_field_filters] || %{}
     }
   end
 
+  defp export_cycle_status_filter(nil), do: nil
+  defp export_cycle_status_filter(:paid), do: "paid"
+  defp export_cycle_status_filter(:unpaid), do: "unpaid"
+  defp export_cycle_status_filter(_), do: nil
+
   defp export_sort_field(nil), do: nil
   defp export_sort_field(f) when is_atom(f), do: Atom.to_string(f)
   defp export_sort_field(f) when is_binary(f), do: f
@@ -1762,4 +1420,25 @@ defmodule MvWeb.MemberLive.Index do
   defp export_sort_order(:asc), do: "asc"
   defp export_sort_order(:desc), do: "desc"
   defp export_sort_order(o) when is_binary(o), do: o
+
+  # -------------------------------------------------------------
+  # Internal utility: dedupe dropdown fields defensively
+  # -------------------------------------------------------------
+
+  defp dedupe_available_fields(fields) when is_list(fields) do
+    Enum.uniq_by(fields, fn item ->
+      cond do
+        is_map(item) ->
+          Map.get(item, :key) || Map.get(item, :id) || Map.get(item, :field) || item
+
+        is_tuple(item) and tuple_size(item) >= 1 ->
+          elem(item, 0)
+
+        true ->
+          item
+      end
+    end)
+  end
+
+  defp dedupe_available_fields(other), do: other
 end
diff --git a/lib/mv_web/live/member_live/index.html.heex b/lib/mv_web/live/member_live/index.html.heex
index 79017a9..543d16b 100644
--- a/lib/mv_web/live/member_live/index.html.heex
+++ b/lib/mv_web/live/member_live/index.html.heex
@@ -293,6 +293,7 @@
     </:col>
     <:col
       :let={member}
+      :if={:membership_fee_status in @member_fields_visible}
       label={gettext("Membership Fee Status")}
     >
       <%= if badge = MvWeb.MemberLive.Index.MembershipFeeStatus.format_cycle_status_badge(
diff --git a/lib/mv_web/live/member_live/index/field_visibility.ex b/lib/mv_web/live/member_live/index/field_visibility.ex
index 9ba9267..0b0cb67 100644
--- a/lib/mv_web/live/member_live/index/field_visibility.ex
+++ b/lib/mv_web/live/member_live/index/field_visibility.ex
@@ -18,10 +18,25 @@ defmodule MvWeb.MemberLive.Index.FieldVisibility do
   1. User-specific selection (from URL/Session/Cookie)
   2. Global settings (from database)
   3. Default (all fields visible)
+
+  ## Pseudo Member Fields
+
+  Overview-only fields that are not in `Mv.Constants.member_fields()` (e.g. computed/UI-only).
+  They appear in the field dropdown and in `member_fields_visible` but are not domain attributes.
   """
 
   alias Mv.Membership.Helpers.VisibilityConfig
 
+  # Single UI key for "Membership Fee Status"; only this appears in the dropdown.
+  @pseudo_member_fields [:membership_fee_status]
+
+  # Export/API may accept this as alias; must not appear in the UI options list.
+  @export_only_alias :payment_status
+
+  defp overview_member_fields do
+    Mv.Constants.member_fields() ++ @pseudo_member_fields
+  end
+
   @doc """
   Gets all available fields for selection.
 
@@ -39,7 +54,10 @@ defmodule MvWeb.MemberLive.Index.FieldVisibility do
   """
   @spec get_all_available_fields([struct()]) :: [atom() | String.t()]
   def get_all_available_fields(custom_fields) do
-    member_fields = Mv.Constants.member_fields()
+    member_fields =
+      overview_member_fields()
+      |> Enum.reject(fn field -> field == @export_only_alias end)
+
     custom_field_names = Enum.map(custom_fields, &"custom_field_#{&1.id}")
 
     member_fields ++ custom_field_names
@@ -115,6 +133,7 @@ defmodule MvWeb.MemberLive.Index.FieldVisibility do
     field_selection
     |> Enum.filter(fn {_field, visible} -> visible end)
     |> Enum.map(fn {field_string, _visible} -> to_field_identifier(field_string) end)
+    |> Enum.uniq()
   end
 
   def get_visible_fields(_), do: []
@@ -132,7 +151,7 @@ defmodule MvWeb.MemberLive.Index.FieldVisibility do
   """
   @spec get_visible_member_fields(%{String.t() => boolean()}) :: [atom()]
   def get_visible_member_fields(field_selection) when is_map(field_selection) do
-    member_fields = Mv.Constants.member_fields()
+    member_fields = overview_member_fields()
 
     field_selection
     |> Enum.filter(fn {field_string, visible} ->
@@ -140,10 +159,61 @@ defmodule MvWeb.MemberLive.Index.FieldVisibility do
       visible && field_atom in member_fields
     end)
     |> Enum.map(fn {field_string, _visible} -> to_field_identifier(field_string) end)
+    |> Enum.uniq()
   end
 
   def get_visible_member_fields(_), do: []
 
+  @doc """
+  Returns the list of computed (UI-only) member field atoms.
+
+  These fields are not in the database; they must not be used for Ash query
+  select/sort. Use this to filter sort options and validate sort_field.
+  """
+  @spec computed_member_fields() :: [atom()]
+  def computed_member_fields, do: @pseudo_member_fields
+
+  @doc """
+  Visible member fields that are real DB attributes (from `Mv.Constants.member_fields()`).
+
+  Use for query select/sort. Not for rendering column visibility (use
+  `get_visible_member_fields/1` for that).
+  """
+  @spec get_visible_member_fields_db(%{String.t() => boolean()}) :: [atom()]
+  def get_visible_member_fields_db(field_selection) when is_map(field_selection) do
+    db_fields = MapSet.new(Mv.Constants.member_fields())
+
+    field_selection
+    |> Enum.filter(fn {field_string, visible} ->
+      field_atom = to_field_identifier(field_string)
+      visible && field_atom in db_fields
+    end)
+    |> Enum.map(fn {field_string, _visible} -> to_field_identifier(field_string) end)
+    |> Enum.uniq()
+  end
+
+  def get_visible_member_fields_db(_), do: []
+
+  @doc """
+  Visible member fields that are computed/UI-only (e.g. membership_fee_status).
+
+  Use for rendering; do not use for query select or sort.
+  """
+  @spec get_visible_member_fields_computed(%{String.t() => boolean()}) :: [atom()]
+  def get_visible_member_fields_computed(field_selection) when is_map(field_selection) do
+    computed_set = MapSet.new(@pseudo_member_fields)
+
+    field_selection
+    |> Enum.filter(fn {field_string, visible} ->
+      field_atom = to_field_identifier(field_string)
+      visible && field_atom in computed_set
+    end)
+    |> Enum.map(fn {field_string, _visible} -> to_field_identifier(field_string) end)
+    |> Enum.uniq()
+  end
+
+  def get_visible_member_fields_computed(_), do: []
+
   @doc """
   Gets visible custom fields from field selection.
 
@@ -176,19 +246,23 @@ defmodule MvWeb.MemberLive.Index.FieldVisibility do
     Map.merge(member_visibility, custom_field_visibility)
   end
 
-  # Gets member field visibility from settings
+  # Gets member field visibility from settings (domain fields from settings, pseudo fields default true)
   defp get_member_field_visibility_from_settings(settings) do
     visibility_config =
       VisibilityConfig.normalize(Map.get(settings, :member_field_visibility, %{}))
 
-    member_fields = Mv.Constants.member_fields()
+    domain_fields = Mv.Constants.member_fields()
 
-    Enum.reduce(member_fields, %{}, fn field, acc ->
-      field_string = Atom.to_string(field)
-      # exit_date defaults to false (hidden), all other fields default to true
-      default_visibility = if field == :exit_date, do: false, else: true
-      show_in_overview = Map.get(visibility_config, field, default_visibility)
-      Map.put(acc, field_string, show_in_overview)
+    domain_map =
+      Enum.reduce(domain_fields, %{}, fn field, acc ->
+        field_string = Atom.to_string(field)
+        default_visibility = if field == :exit_date, do: false, else: true
+        show_in_overview = Map.get(visibility_config, field, default_visibility)
+        Map.put(acc, field_string, show_in_overview)
+      end)
+
+    Enum.reduce(@pseudo_member_fields, domain_map, fn field, acc ->
+      Map.put(acc, Atom.to_string(field), true)
     end)
   end
 
@@ -203,16 +277,20 @@ defmodule MvWeb.MemberLive.Index.FieldVisibility do
     end)
   end
 
-  # Converts field string to atom (for member fields) or keeps as string (for custom fields)
+  # Converts field string to atom (for member fields) or keeps as string (for custom fields).
+  # Maps export-only alias to canonical UI key so only one option controls the column.
   defp to_field_identifier(field_string) when is_binary(field_string) do
     if String.starts_with?(field_string, Mv.Constants.custom_field_prefix()) do
       field_string
     else
-      try do
-        String.to_existing_atom(field_string)
-      rescue
-        ArgumentError -> field_string
-      end
+      atom =
+        try do
+          String.to_existing_atom(field_string)
+        rescue
+          ArgumentError -> field_string
+        end
+
+      if atom == @export_only_alias, do: :membership_fee_status, else: atom
     end
   end
 
diff --git a/lib/mv_web/translations/member_fields.ex b/lib/mv_web/translations/member_fields.ex
index 26f55ac..83ab139 100644
--- a/lib/mv_web/translations/member_fields.ex
+++ b/lib/mv_web/translations/member_fields.ex
@@ -28,6 +28,7 @@ defmodule MvWeb.Translations.MemberFields do
   def label(:house_number), do: gettext("House Number")
   def label(:postal_code), do: gettext("Postal Code")
   def label(:membership_fee_start_date), do: gettext("Membership Fee Start Date")
+  def label(:membership_fee_status), do: gettext("Membership Fee Status")
 
   # Fallback for unknown fields
   def label(field) do