From 0acd12360f297456a8e8608d1913105b389f8454 Mon Sep 17 00:00:00 2001
From: Simon <s.thiessen@local-it.org>
Date: Fri, 10 Jul 2026 16:27:16 +0200
Subject: [PATCH] refactor(overview): use English identifier as_of_date for
 point-in-time filter

---
 lib/mv/constants.ex                           | 10 ++--
 .../add_filter_builder_component.ex           | 46 +++++++++----------
 lib/mv_web/live/member_live/index.ex          | 38 +++++++--------
 lib/mv_web/live/member_live/index.html.heex   |  2 +-
 .../live/member_live/index/as_of_date.ex      | 37 +++++++++++++++
 .../live/member_live/index/overview_query.ex  | 10 ++--
 lib/mv_web/live/member_live/index/stichtag.ex | 36 ---------------
 .../member_live/index_active_former_test.exs  | 16 +++----
 ...exs => index_as_of_date_property_test.exs} |  8 ++--
 .../index_filter_url_roundtrip_test.exs       |  8 ++--
 .../index_status_params_codec_test.exs        | 14 +++---
 11 files changed, 113 insertions(+), 112 deletions(-)
 create mode 100644 lib/mv_web/live/member_live/index/as_of_date.ex
 delete mode 100644 lib/mv_web/live/member_live/index/stichtag.ex
 rename test/mv_web/member_live/{index_stichtag_property_test.exs => index_as_of_date_property_test.exs} (92%)

diff --git a/lib/mv/constants.ex b/lib/mv/constants.ex
index f60f77ad..a0607078 100644
--- a/lib/mv/constants.ex
+++ b/lib/mv/constants.ex
@@ -50,7 +50,7 @@ defmodule Mv.Constants do
 
   @suspended_param "suspended"
 
-  @stichtag_param "stichtag"
+  @as_of_date_param "as_of_date"
 
   @max_boolean_filters 50
 
@@ -240,16 +240,16 @@ defmodule Mv.Constants do
   def suspended_param, do: @suspended_param
 
   @doc """
-  Returns the URL parameter name for the point-in-time membership ("Stichtag")
+  Returns the URL parameter name for the point-in-time "active on X" membership
   filter: keeps members who were active on the given ISO-8601 date X, i.e.
   `join_date <= X and (exit_date is nil or exit_date > X)`.
 
   ## Examples
 
-      iex> Mv.Constants.stichtag_param()
-      "stichtag"
+      iex> Mv.Constants.as_of_date_param()
+      "as_of_date"
   """
-  def stichtag_param, do: @stichtag_param
+  def as_of_date_param, do: @as_of_date_param
 
   @doc """
   Returns the maximum number of boolean custom field filters allowed per request.
diff --git a/lib/mv_web/live/components/add_filter_builder_component.ex b/lib/mv_web/live/components/add_filter_builder_component.ex
index fc1ee34b..4cc2c619 100644
--- a/lib/mv_web/live/components/add_filter_builder_component.ex
+++ b/lib/mv_web/live/components/add_filter_builder_component.ex
@@ -35,7 +35,7 @@ defmodule MvWeb.Components.AddFilterBuilderComponent do
     * `{:payment_filter_changed, nil | :fully_paid | {:has_unpaid, 1..3} | {:unpaid_range, pos_integer(), pos_integer() | nil}}`
     * `{:payment_period_changed, %{from: Date.t() | nil, to: Date.t() | nil}}`
     * `{:suspended_changed, boolean()}`
-    * `{:stichtag_changed, Date.t() | nil}`
+    * `{:as_of_date_changed, Date.t() | nil}`
 
   and `{:clear_all_filters}` for Clear all.
   """
@@ -91,7 +91,7 @@ defmodule MvWeb.Components.AddFilterBuilderComponent do
     |> assign(:payment_filter, assigns[:payment_filter])
     |> assign(:payment_period, assigns[:payment_period] || PaymentAging.default_period())
     |> assign(:suspended, assigns[:suspended] || false)
-    |> assign(:stichtag, assigns[:stichtag])
+    |> assign(:as_of_date, assigns[:as_of_date])
   end
 
   # --------------------------------------------------------------------------
@@ -461,23 +461,23 @@ defmodule MvWeb.Components.AddFilterBuilderComponent do
         </fieldset>
 
         <%!-- Separate paragraph (not part of the Active/Former button-join): the
-        point-in-time "active on X" Stichtag filter (§1.24). --%>
-        <div class="flex flex-col gap-1" data-testid="stichtag-paragraph">
+        point-in-time "active on X" as-of-date filter (§1.24). --%>
+        <div class="flex flex-col gap-1" data-testid="as-of-date-paragraph">
           <.input
             type="date"
-            name="stichtag"
+            name="as_of_date"
             label={gettext("Active on reference date")}
             class="input input-sm input-bordered"
-            value={date_iso(@stichtag)}
-            data-testid="stichtag-input"
+            value={date_iso(@as_of_date)}
+            data-testid="as-of-date-input"
           />
         </div>
       </form>
 
-      <%!-- Third paragraph "Eigener Zeitraum": the same native From/To range the
+      <%!-- Third paragraph, a custom range: the same native From/To range the
         join-date builder uses, wired to the exit_date custom mode — members whose
         exit date falls within [from, to] (§1.24). A sibling form (not the
-        quick/Stichtag one) so committing a bound only touches the exit_date
+        quick/as-of-date one) so committing a bound only touches the exit_date
         slice and never re-reads the quick radios. --%>
       <form
         phx-change="commit"
@@ -614,7 +614,7 @@ defmodule MvWeb.Components.AddFilterBuilderComponent do
         {local_range(@from_val, @to_val)}
       </p>
 
-      <%!-- Separate "Eigener Zeitraum" paragraph: two native <input type="date">
+      <%!-- Separate custom-range paragraph: two native <input type="date">
       controls side by side (§3.12 native-first — no cally). Committing a bound
       through the shared date dispatch applies the custom range; the browser's
       own date popup gives year-jump, manual entry and WCAG a11y for free. --%>
@@ -722,7 +722,7 @@ defmodule MvWeb.Components.AddFilterBuilderComponent do
   def handle_event("commit", params, socket) do
     dispatch_payment(socket, params)
     dispatch_quick(socket, params)
-    dispatch_stichtag(socket, params)
+    dispatch_as_of_date(socket, params)
     dispatch_exit_range(socket, params)
 
     dispatch_prefix(
@@ -824,14 +824,14 @@ defmodule MvWeb.Components.AddFilterBuilderComponent do
     end
   end
 
-  defp dispatch_stichtag(socket, params) do
-    if Map.has_key?(params, "stichtag") do
-      date = parse_date(Map.get(params, "stichtag"))
-      maybe_send(date != socket.assigns.stichtag, {:stichtag_changed, date})
+  defp dispatch_as_of_date(socket, params) do
+    if Map.has_key?(params, "as_of_date") do
+      date = parse_date(Map.get(params, "as_of_date"))
+      maybe_send(date != socket.assigns.as_of_date, {:as_of_date_changed, date})
     end
   end
 
-  # The exit-date "Eigener Zeitraum" range writes only the exit_date slice
+  # The exit-date custom range writes only the exit_date slice
   # (mode :custom + bounds), preserving join_date and custom-date entries — so
   # editing the exit range never wipes another active date filter. Committing an
   # empty range simply parks exit_date in :custom with nil bounds (no chip, no
@@ -917,7 +917,7 @@ defmodule MvWeb.Components.AddFilterBuilderComponent do
   end
 
   defp remove_chip("suspended", _id, _socket), do: send(self(), {:suspended_changed, false})
-  defp remove_chip("stichtag", _id, _socket), do: send(self(), {:stichtag_changed, nil})
+  defp remove_chip("as_of_date", _id, _socket), do: send(self(), {:as_of_date_changed, nil})
 
   defp remove_chip("group", id, _socket), do: send(self(), {:group_filter_changed, id, nil})
   defp remove_chip("fee_type", id, _socket), do: send(self(), {:fee_type_filter_changed, id, nil})
@@ -947,7 +947,7 @@ defmodule MvWeb.Components.AddFilterBuilderComponent do
       fee_type_chips(assigns) ++
       boolean_chips(assigns) ++
       date_chips(assigns) ++
-      stichtag_chip(assigns) ++
+      as_of_date_chip(assigns) ++
       payment_chips(assigns) ++
       suspended_chip(assigns)
   end
@@ -1117,18 +1117,18 @@ defmodule MvWeb.Components.AddFilterBuilderComponent do
 
   defp suspended_chip(_), do: []
 
-  defp stichtag_chip(%{stichtag: %Date{} = date}) do
+  defp as_of_date_chip(%{as_of_date: %Date{} = date}) do
     [
       %{
-        kind: "stichtag",
-        id: "stichtag",
+        kind: "as_of_date",
+        id: "as_of_date",
         edit_key: "active_former",
         label: gettext("Active on %{date}", date: DateFormatter.format_date(date))
       }
     ]
   end
 
-  defp stichtag_chip(_), do: []
+  defp as_of_date_chip(_), do: []
 
   defp unpaid_range_label(min, nil) when min <= 1, do: gettext("Open contributions")
   defp unpaid_range_label(min, nil), do: gettext("≥ %{n} unpaid", n: min)
@@ -1235,7 +1235,7 @@ defmodule MvWeb.Components.AddFilterBuilderComponent do
   defp date_iso(_), do: nil
 
   # ISO string for a bound of the exit_date custom range, pre-filling the
-  # "Eigener Zeitraum" inputs only when the exit filter is actually in :custom
+  # custom-range inputs only when the exit filter is actually in :custom
   # mode (the quick active/former/all states carry no user range).
   defp exit_bound_iso(filters, bound) do
     case Map.get(filters, :exit_date, %{}) do
diff --git a/lib/mv_web/live/member_live/index.ex b/lib/mv_web/live/member_live/index.ex
index 2173025f..af0214e7 100644
--- a/lib/mv_web/live/member_live/index.ex
+++ b/lib/mv_web/live/member_live/index.ex
@@ -49,6 +49,7 @@ defmodule MvWeb.MemberLive.Index do
   alias Mv.MembershipFees
   alias Mv.MembershipFees.MembershipFeeType
   alias MvWeb.Helpers.DateFormatter
+  alias MvWeb.MemberLive.Index.AsOfDate
   alias MvWeb.MemberLive.Index.CustomFieldValueLookup
   alias MvWeb.MemberLive.Index.DateFilter
   alias MvWeb.MemberLive.Index.ExportPayload
@@ -59,7 +60,6 @@ defmodule MvWeb.MemberLive.Index do
   alias MvWeb.MemberLive.Index.MembershipFeeStatus
   alias MvWeb.MemberLive.Index.OverviewQuery
   alias MvWeb.MemberLive.Index.PaymentAging
-  alias MvWeb.MemberLive.Index.Stichtag
   alias MvWeb.MemberLive.Index.ViewSettings
 
   require Ash.Query
@@ -179,7 +179,7 @@ defmodule MvWeb.MemberLive.Index do
       |> assign(:payment_filter, nil)
       |> assign(:payment_period, PaymentAging.default_period())
       |> assign(:suspended, false)
-      |> assign(:stichtag, nil)
+      |> assign(:as_of_date, nil)
       |> assign(:group_filters, %{})
       |> assign(:groups, groups)
       |> assign(:fee_type_filters, %{})
@@ -473,7 +473,7 @@ defmodule MvWeb.MemberLive.Index do
          payment_filter: nil,
          payment_period: PaymentAging.default_period(),
          suspended: false,
-         stichtag: nil,
+         as_of_date: nil,
          group_filters: %{},
          fee_type_filters: %{},
          boolean_filters: %{},
@@ -504,16 +504,16 @@ defmodule MvWeb.MemberLive.Index do
   end
 
   @impl true
-  def handle_info({:stichtag_changed, stichtag}, socket) do
+  def handle_info({:as_of_date_changed, as_of_date}, socket) do
     socket =
       socket
-      |> assign(:stichtag, stichtag)
+      |> assign(:as_of_date, as_of_date)
       |> load_members()
       |> scroll_list_to_top()
       |> update_selection_assigns()
 
     query_params =
-      build_query_params(opts_for_query_params(socket, %{stichtag: stichtag}))
+      build_query_params(opts_for_query_params(socket, %{as_of_date: as_of_date}))
       |> maybe_add_field_selection(
         socket.assigns[:user_field_selection],
         socket.assigns[:fields_in_url?] || false
@@ -638,7 +638,7 @@ defmodule MvWeb.MemberLive.Index do
       |> assign(:boolean_custom_field_filters, Map.get(opts, :boolean_filters, %{}))
       |> assign(:date_filters, Map.get(opts, :date_filters, DateFilter.default()))
       |> assign(:suspended, Map.get(opts, :suspended, false))
-      |> assign(:stichtag, Map.get(opts, :stichtag))
+      |> assign(:as_of_date, Map.get(opts, :as_of_date))
       |> load_members()
       |> scroll_list_to_top()
       |> update_selection_assigns()
@@ -727,7 +727,7 @@ defmodule MvWeb.MemberLive.Index do
       |> maybe_update_payment_filter(params)
       |> maybe_update_payment_period(params)
       |> maybe_update_suspended(params)
-      |> maybe_update_stichtag(params)
+      |> maybe_update_as_of_date(params)
       |> maybe_update_group_filters(params)
       |> maybe_update_fee_type_filters(params)
       |> maybe_update_boolean_filters(params)
@@ -778,7 +778,7 @@ defmodule MvWeb.MemberLive.Index do
       socket.assigns.payment_filter,
       socket.assigns.payment_period,
       socket.assigns[:suspended],
-      socket.assigns[:stichtag],
+      socket.assigns[:as_of_date],
       socket.assigns[:group_filters],
       socket.assigns[:fee_type_filters],
       socket.assigns.boolean_custom_field_filters,
@@ -934,17 +934,17 @@ defmodule MvWeb.MemberLive.Index do
     base_params = add_group_filters(base_params, opts.group_filters || %{})
     base_params = add_fee_type_filters(base_params, opts.fee_type_filters || %{})
     base_params = add_payment_params(base_params, opts.payment_filter, opts.payment_period)
-    base_params = add_status_params(base_params, opts[:suspended], opts[:stichtag])
+    base_params = add_status_params(base_params, opts[:suspended], opts[:as_of_date])
     base_params = add_boolean_filters(base_params, opts.boolean_filters || %{})
     add_date_filters(base_params, opts.date_filters)
   end
 
-  # Suspended-status flag and Stichtag date serialize additively into the flat
-  # URL contract (suspended=1 / stichtag=<iso>), omitted when inactive (§2.1).
-  defp add_status_params(params, suspended, stichtag) do
+  # Suspended-status flag and as-of date serialize additively into the flat
+  # URL contract (suspended=1 / as_of_date=<iso>), omitted when inactive (§2.1).
+  defp add_status_params(params, suspended, as_of_date) do
     params
     |> Map.merge(PaymentAging.suspended_to_params(suspended))
-    |> Map.merge(Stichtag.to_params(stichtag))
+    |> Map.merge(AsOfDate.to_params(as_of_date))
   end
 
   # Period-scoped payment model (§3.3): the payment-count filter and the active
@@ -967,7 +967,7 @@ defmodule MvWeb.MemberLive.Index do
       payment_filter: socket.assigns.payment_filter,
       payment_period: socket.assigns.payment_period,
       suspended: socket.assigns[:suspended] || false,
-      stichtag: socket.assigns[:stichtag],
+      as_of_date: socket.assigns[:as_of_date],
       group_filters: socket.assigns[:group_filters] || %{},
       boolean_filters: socket.assigns.boolean_custom_field_filters || %{},
       fee_type_filters: socket.assigns[:fee_type_filters] || %{},
@@ -1429,7 +1429,7 @@ defmodule MvWeb.MemberLive.Index do
       payment_filter: socket.assigns.payment_filter,
       payment_period: socket.assigns.payment_period,
       suspended: socket.assigns[:suspended] || false,
-      stichtag: socket.assigns[:stichtag],
+      as_of_date: socket.assigns[:as_of_date],
       sort_field: socket.assigns.sort_field,
       sort_order: socket.assigns.sort_order,
       custom_fields: socket.assigns.all_custom_fields
@@ -1644,14 +1644,14 @@ defmodule MvWeb.MemberLive.Index do
   defp maybe_update_payment_period(socket, params),
     do: assign(socket, :payment_period, PaymentAging.parse_period(params))
 
-  # Suspended-status filter (§1.23) and point-in-time Stichtag (§1.24/§2.6):
+  # Suspended-status filter (§1.23) and point-in-time as-of date (§1.24/§2.6):
   # both decoded straight from the URL so `handle_params` remains the single
   # source of truth. Absent params fall back to no filter.
   defp maybe_update_suspended(socket, params),
     do: assign(socket, :suspended, PaymentAging.parse_suspended(params))
 
-  defp maybe_update_stichtag(socket, params),
-    do: assign(socket, :stichtag, Stichtag.parse(params))
+  defp maybe_update_as_of_date(socket, params),
+    do: assign(socket, :as_of_date, AsOfDate.parse(params))
 
   defp maybe_update_group_filters(socket, params) when is_map(params) do
     prefix = @group_filter_prefix
diff --git a/lib/mv_web/live/member_live/index.html.heex b/lib/mv_web/live/member_live/index.html.heex
index 2a060282..e1de0fff 100644
--- a/lib/mv_web/live/member_live/index.html.heex
+++ b/lib/mv_web/live/member_live/index.html.heex
@@ -64,7 +64,7 @@
       payment_filter={@payment_filter}
       payment_period={@payment_period}
       suspended={@suspended}
-      stichtag={@stichtag}
+      as_of_date={@as_of_date}
     />
   </div>
 
diff --git a/lib/mv_web/live/member_live/index/as_of_date.ex b/lib/mv_web/live/member_live/index/as_of_date.ex
new file mode 100644
index 00000000..6ec9d9a1
--- /dev/null
+++ b/lib/mv_web/live/member_live/index/as_of_date.ex
@@ -0,0 +1,37 @@
+defmodule MvWeb.MemberLive.Index.AsOfDate do
+  @moduledoc """
+  URL codec for the point-in-time "active on X" membership filter (§1.24/§2.6).
+
+  The as-of date is a single ISO-8601 date X carried in the flat URL contract
+  under the `as_of_date` key. When set, the overview keeps members who were
+  active on X (`join_date <= X and (exit_date is nil or exit_date > X)`); the
+  predicate itself lives in `OverviewQuery`. Absent or malformed values decode
+  to nil (no filter), and nil encodes to the empty map so a fresh URL stays
+  canonical.
+  """
+
+  @as_of_date_param Mv.Constants.as_of_date_param()
+
+  @doc """
+  Decodes the as-of date from a params map. Missing or malformed ISO-8601
+  values yield nil.
+  """
+  @spec parse(map()) :: Date.t() | nil
+  def parse(params) when is_map(params), do: parse_date(Map.get(params, @as_of_date_param))
+
+  @doc """
+  Encodes an as-of date into URL params. nil yields the empty map.
+  """
+  @spec to_params(Date.t() | nil) :: %{optional(String.t()) => String.t()}
+  def to_params(%Date{} = date), do: %{@as_of_date_param => Date.to_iso8601(date)}
+  def to_params(_), do: %{}
+
+  defp parse_date(value) when is_binary(value) do
+    case Date.from_iso8601(String.trim(value)) do
+      {:ok, date} -> date
+      _ -> nil
+    end
+  end
+
+  defp parse_date(_), do: nil
+end
diff --git a/lib/mv_web/live/member_live/index/overview_query.ex b/lib/mv_web/live/member_live/index/overview_query.ex
index dc125d65..fa5559ca 100644
--- a/lib/mv_web/live/member_live/index/overview_query.ex
+++ b/lib/mv_web/live/member_live/index/overview_query.ex
@@ -46,7 +46,7 @@ defmodule MvWeb.MemberLive.Index.OverviewQuery do
       opts[:boolean_custom_fields]
     )
     |> apply_date_filters(opts[:date_filters])
-    |> apply_stichtag_filter(opts[:stichtag])
+    |> apply_as_of_date_filter(opts[:as_of_date])
     |> apply_custom_date_filters(opts[:date_filters], opts[:date_custom_fields])
     |> apply_payment_filter(opts[:payment_filter], payment_period(opts))
     |> apply_suspended_filter(opts[:suspended], payment_period(opts))
@@ -285,20 +285,20 @@ defmodule MvWeb.MemberLive.Index.OverviewQuery do
   defp apply_custom_date_filters(query, _filters, _custom_fields), do: query
 
   # ---------------------------------------------------------------------------
-  # Point-in-time membership ("Stichtag"): a member counts as a member on the
+  # Point-in-time membership (as-of date): a member counts as a member on the
   # reference date X iff it had joined by X and had not yet left as of X
   # (§1.24/§2.6). "Left as of X" means a non-nil exit_date at or before X, so an
   # exit_date strictly after X (or nil) still counts as a member on X.
   # ---------------------------------------------------------------------------
 
-  defp apply_stichtag_filter(query, %Date{} = x) do
+  defp apply_as_of_date_filter(query, %Date{} = x) do
     Ash.Query.filter(
       query,
       expr(join_date <= ^x and (is_nil(exit_date) or exit_date > ^x))
     )
   end
 
-  defp apply_stichtag_filter(query, _), do: query
+  defp apply_as_of_date_filter(query, _), do: query
 
   # ---------------------------------------------------------------------------
   # Sort (always append the unique id tie-breaker for keyset stability)
@@ -327,7 +327,7 @@ defmodule MvWeb.MemberLive.Index.OverviewQuery do
     ])
   end
 
-  # "Beiträge" (payment) column: sort DB-side by the period-scoped unpaid-cycle
+  # Fees (payment) column: sort DB-side by the period-scoped unpaid-cycle
   # count (§1.27). The count calculation takes the active period as arguments so
   # the sort key matches the displayed value; the id tie-breaker keeps keyset
   # pages stable across equal counts.
diff --git a/lib/mv_web/live/member_live/index/stichtag.ex b/lib/mv_web/live/member_live/index/stichtag.ex
deleted file mode 100644
index 647d609d..00000000
--- a/lib/mv_web/live/member_live/index/stichtag.ex
+++ /dev/null
@@ -1,36 +0,0 @@
-defmodule MvWeb.MemberLive.Index.Stichtag do
-  @moduledoc """
-  URL codec for the point-in-time membership ("Stichtag") filter (§1.24/§2.6).
-
-  The Stichtag is a single ISO-8601 date X carried in the flat URL contract
-  under the `stichtag` key. When set, the overview keeps members who were active
-  on X (`join_date <= X and (exit_date is nil or exit_date > X)`); the predicate
-  itself lives in `OverviewQuery`. Absent or malformed values decode to nil (no
-  filter), and nil encodes to the empty map so a fresh URL stays canonical.
-  """
-
-  @stichtag_param Mv.Constants.stichtag_param()
-
-  @doc """
-  Decodes the Stichtag date from a params map. Missing or malformed ISO-8601
-  values yield nil.
-  """
-  @spec parse(map()) :: Date.t() | nil
-  def parse(params) when is_map(params), do: parse_date(Map.get(params, @stichtag_param))
-
-  @doc """
-  Encodes a Stichtag date into URL params. nil yields the empty map.
-  """
-  @spec to_params(Date.t() | nil) :: %{optional(String.t()) => String.t()}
-  def to_params(%Date{} = date), do: %{@stichtag_param => Date.to_iso8601(date)}
-  def to_params(_), do: %{}
-
-  defp parse_date(value) when is_binary(value) do
-    case Date.from_iso8601(String.trim(value)) do
-      {:ok, date} -> date
-      _ -> nil
-    end
-  end
-
-  defp parse_date(_), do: nil
-end
diff --git a/test/mv_web/member_live/index_active_former_test.exs b/test/mv_web/member_live/index_active_former_test.exs
index 4bb2c731..e959643d 100644
--- a/test/mv_web/member_live/index_active_former_test.exs
+++ b/test/mv_web/member_live/index_active_former_test.exs
@@ -62,16 +62,16 @@ defmodule MvWeb.MemberLive.IndexActiveFormerTest do
     assert has_element?(view, "#row-#{ctx.former.id}")
   end
 
-  describe "Stichtag paragraph (§1.24)" do
+  describe "as-of-date paragraph (§1.24)" do
     test "the active/former control carries a separate 'active on reference date' input", ctx do
       {:ok, view, _html} = live(ctx.conn, ~p"/members")
 
       pick_field(view, "active_former")
 
-      # The Stichtag input sits in its own paragraph, not inside the
+      # The as-of-date input sits in its own paragraph, not inside the
       # Active/Former button-join.
-      assert has_element?(view, "[data-testid='stichtag-paragraph'] input[name='stichtag']")
-      refute has_element?(view, ".join input[name='stichtag']")
+      assert has_element?(view, "[data-testid='as-of-date-paragraph'] input[name='as_of_date']")
+      refute has_element?(view, ".join input[name='as_of_date']")
     end
 
     test "setting a reference date activates the point-in-time membership filter", ctx do
@@ -81,22 +81,22 @@ defmodule MvWeb.MemberLive.IndexActiveFormerTest do
 
       view
       |> element("[data-testid='value-control-active-former']")
-      |> render_change(%{"quick" => "active", "stichtag" => "2024-06-15"})
+      |> render_change(%{"quick" => "active", "as_of_date" => "2024-06-15"})
 
       _ = render(view)
       path = assert_patch(view)
-      assert path =~ "stichtag=2024-06-15"
+      assert path =~ "as_of_date=2024-06-15"
     end
   end
 
-  describe "Eigener Zeitraum exit-date range (§1.24)" do
+  describe "custom exit-date range (§1.24)" do
     test "the exit-date control carries a separate native From/To range paragraph", ctx do
       {:ok, view, _html} = live(ctx.conn, ~p"/members")
 
       pick_field(view, "active_former")
 
       # Third paragraph, same native two-input range control the join-date
-      # builder uses — separate from the Active/Former join and the Stichtag box.
+      # builder uses — separate from the Active/Former join and the as-of-date box.
       assert has_element?(view, "[data-testid='value-control-exit-range']")
 
       assert has_element?(
diff --git a/test/mv_web/member_live/index_stichtag_property_test.exs b/test/mv_web/member_live/index_as_of_date_property_test.exs
similarity index 92%
rename from test/mv_web/member_live/index_stichtag_property_test.exs
rename to test/mv_web/member_live/index_as_of_date_property_test.exs
index 017d08fb..a30fef52 100644
--- a/test/mv_web/member_live/index_stichtag_property_test.exs
+++ b/test/mv_web/member_live/index_as_of_date_property_test.exs
@@ -1,8 +1,8 @@
-defmodule MvWeb.MemberLive.IndexStichtagPropertyTest do
+defmodule MvWeb.MemberLive.IndexAsOfDatePropertyTest do
   @moduledoc """
   §2.6 — Point-in-time membership ("member on the reference date X").
 
-  For arbitrary (join_date, exit_date) pairs and reference dates X, the Stichtag
+  For arbitrary (join_date, exit_date) pairs and reference dates X, the as-of-date
   filter keeps a member iff `join_date <= X and (exit_date is nil or exit_date > X)`.
   Verified at the `OverviewQuery` layer against an in-memory oracle.
   """
@@ -42,7 +42,7 @@ defmodule MvWeb.MemberLive.IndexStichtagPropertyTest do
     end)
   end
 
-  property "Stichtag filter keeps exactly the members active on X" do
+  property "as-of-date filter keeps exactly the members active on X" do
     actor = Mv.Helpers.SystemActor.get_system_actor()
 
     check all(
@@ -67,7 +67,7 @@ defmodule MvWeb.MemberLive.IndexStichtagPropertyTest do
             do: id
 
       actual =
-        %{stichtag: x}
+        %{as_of_date: x}
         |> OverviewQuery.build()
         |> Ash.read!(actor: actor)
         |> MapSet.new(& &1.id)
diff --git a/test/mv_web/member_live/index_filter_url_roundtrip_test.exs b/test/mv_web/member_live/index_filter_url_roundtrip_test.exs
index 8fe3405a..b01a9705 100644
--- a/test/mv_web/member_live/index_filter_url_roundtrip_test.exs
+++ b/test/mv_web/member_live/index_filter_url_roundtrip_test.exs
@@ -1,7 +1,7 @@
 defmodule MvWeb.MemberLive.IndexFilterUrlRoundtripTest do
   @moduledoc """
   §2.1 (extended) — the v2 filter keys survive the LiveView decode→encode round
-  trip. Loading `/members` with a Stichtag date, the suspended flag, and a
+  trip. Loading `/members` with an as-of date, the suspended flag, and a
   two-sided payment count range, then triggering an unrelated re-patch (a sort
   click), preserves every one of those keys in the pushed URL.
   """
@@ -21,15 +21,15 @@ defmodule MvWeb.MemberLive.IndexFilterUrlRoundtripTest do
     %{conn: conn_with_oidc_user(conn)}
   end
 
-  test "stichtag, suspended and payment count range persist through a re-patch", %{conn: conn} do
-    url = "/members?stichtag=2026-03-15&suspended=1&pay_filter=has_unpaid&pay_min=2&pay_max=4"
+  test "as-of date, suspended and payment count range persist through a re-patch", %{conn: conn} do
+    url = "/members?as_of_date=2026-03-15&suspended=1&pay_filter=has_unpaid&pay_min=2&pay_max=4"
     {:ok, view, _html} = live(conn, url)
 
     # Trigger an unrelated URL re-patch by sorting a stable column.
     view |> element("[data-testid='payment']") |> render_click()
     path = assert_patch(view)
 
-    assert path =~ "stichtag=2026-03-15"
+    assert path =~ "as_of_date=2026-03-15"
     assert path =~ "suspended=1"
     assert path =~ "pay_filter=has_unpaid"
     assert path =~ "pay_min=2"
diff --git a/test/mv_web/member_live/index_status_params_codec_test.exs b/test/mv_web/member_live/index_status_params_codec_test.exs
index b1438969..bf32962e 100644
--- a/test/mv_web/member_live/index_status_params_codec_test.exs
+++ b/test/mv_web/member_live/index_status_params_codec_test.exs
@@ -1,28 +1,28 @@
 defmodule MvWeb.MemberLive.IndexStatusParamsCodecTest do
   @moduledoc """
   §2.1 (extended) — URL codec round-trip for the new v2 filter keys: the
-  point-in-time Stichtag date and the suspended-status flag. Encoding a state to
+  point-in-time as-of date and the suspended-status flag. Encoding a state to
   params then decoding yields the canonical state, and the default (no filter)
   encodes to the empty map so a fresh URL is canonical.
   """
   use ExUnit.Case, async: true
 
+  alias MvWeb.MemberLive.Index.AsOfDate
   alias MvWeb.MemberLive.Index.PaymentAging
-  alias MvWeb.MemberLive.Index.Stichtag
 
-  describe "Stichtag date" do
+  describe "as-of date" do
     test "a set date round-trips" do
       date = ~D[2026-03-15]
-      assert date |> Stichtag.to_params() |> Stichtag.parse() == date
+      assert date |> AsOfDate.to_params() |> AsOfDate.parse() == date
     end
 
     test "nil encodes to the empty map and decodes to nil" do
-      assert Stichtag.to_params(nil) == %{}
-      assert Stichtag.parse(%{}) == nil
+      assert AsOfDate.to_params(nil) == %{}
+      assert AsOfDate.parse(%{}) == nil
     end
 
     test "a malformed date param decodes to nil" do
-      assert Stichtag.parse(%{"stichtag" => "not-a-date"}) == nil
+      assert AsOfDate.parse(%{"as_of_date" => "not-a-date"}) == nil
     end
   end