Merge pull request 'Improve Join description handling for GDPR/DSGVO' (#521) from issue/mitgliederverwaltung-508 into main

Reviewed-on: #521
2026-06-04 13:02:39 +02:00 · 2026-06-04 13:02:39 +02:00 · ef21e0ada3
commit ef21e0ada3
parent 03bc895ab1 6500dead95
19 changed files with 796 additions and 25 deletions
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@ -8,11 +8,17 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]

 ### Added
+- **GDPR/DSGVO join-form description** – Custom fields can carry a "join form description" that is shown as the field's label on the public join form, with clickable external links (whole URLs and Markdown `[text](url)`). Useful for presenting a GDPR confirmation with a link to an externally hosted privacy declaration before sign-up.
+- **Join-form description tooltip in member details** – Custom fields that have a join-form description show an info tooltip (prefixed "Beitrittsformular:") on their label in the member detail view.
+- **Editable join-form description** – Admins can set a field's join-form description in the custom-field settings, with an inline hint about the supported link syntax.
 - **CSV import – groups column** – Members can be assigned to groups during CSV import via a `Groups`/`Gruppen` column; group names that do not exist yet are created automatically, and re-importing the same file does not create duplicate groups.
 - **CSV import – membership fee type column** – A `Fee Type`/`Beitragsart` column assigns each member's membership fee type; an unknown name falls back to the default fee type and is flagged in the preview with a link to create it.
 - **CSV import – mapping preview** – After uploading a file, a preview shows how every column maps (with sample rows and warnings for ignored or unknown columns) and the import only starts once you confirm.
 - **Dynamic CSV import templates** – The EN and DE import-template downloads now include the association's current custom fields instead of a fixed column set.

+### Changed
+- **Default GDPR custom field** – The seeded GDPR field was shortened from "Datenschutzerklärung akzeptiert" to "DSGVO" and now ships with a default join-form description (with a placeholder link to replace).
+
 ### Fixed
 - **CSV date round-trip** – Date custom-field values are now exported as ISO-8601 (`YYYY-MM-DD`), so an exported CSV can be re-imported without date-parsing errors.
 - **CSV import – fee-status columns ignored** – Columns such as `Bezahlstatus` / `Membership Fee Status` are always ignored on import and never stored as a custom-field value, even when a custom field of the same name exists.
--- a/lib/membership/custom_field.ex
+++ b/lib/membership/custom_field.ex
@ -12,6 +12,8 @@ defmodule Mv.Membership.CustomField do
  - `slug` - URL-friendly, immutable identifier automatically generated from name (e.g., "phone-mobile")
  - `value_type` - Data type constraint (`:string`, `:integer`, `:boolean`, `:date`, `:email`). Immutable after creation.
  - `description` - Optional human-readable description
+  - `join_description` - Optional label shown for this field on the public join form
+    (e.g., a GDPR confirmation text); supports inline external links. Falls back to `name` when nil.
  - `required` - If true, all members must have this custom field (future feature)
  - `show_in_overview` - If true, this custom field will be displayed in the member overview table and can be sorted

@ -61,7 +63,14 @@ defmodule Mv.Membership.CustomField do
  end

  actions do
-    default_accept [:name, :value_type, :description, :required, :show_in_overview]
+    default_accept [
+      :name,
+      :value_type,
+      :description,
+      :join_description,
+      :required,
+      :show_in_overview
+    ]

    read :read do
      primary? true
@ -69,13 +78,13 @@ defmodule Mv.Membership.CustomField do
    end

    create :create do
-      accept [:name, :value_type, :description, :required, :show_in_overview]
+      accept [:name, :value_type, :description, :join_description, :required, :show_in_overview]
      change Mv.Membership.Changes.GenerateSlug
      validate string_length(:slug, min: 1)
    end

    update :update do
-      accept [:name, :description, :required, :show_in_overview]
+      accept [:name, :description, :join_description, :required, :show_in_overview]
      require_atomic? false

      validate fn changeset, _context ->
@ -139,6 +148,15 @@ defmodule Mv.Membership.CustomField do
        trim?: true
      ]

+    attribute :join_description, :string,
+      allow_nil?: true,
+      public?: true,
+      description: "Label shown for this field on the public join form; supports external links",
+      constraints: [
+        max_length: 1000,
+        trim?: true
+      ]
+
    attribute :required, :boolean,
      default: false,
      allow_nil?: false
--- a/lib/mv_web/helpers/join_description_renderer.ex
+++ b/lib/mv_web/helpers/join_description_renderer.ex
@ -0,0 +1,70 @@
+defmodule MvWeb.Helpers.JoinDescriptionRenderer do
+  @moduledoc """
+  Renders a custom field's `join_description` into Phoenix-safe HTML for the
+  public join form.
+
+  The renderer auto-links two patterns into `<a href="...">` tags:
+
+  - Markdown links of the form `[text](url)` (processed first)
+  - bare `http(s)://` URLs in the remaining text
+
+  All other content is HTML-escaped: only `<a href="...">` tags are ever
+  emitted, so arbitrary HTML in the input is rendered as inert text. This is a
+  defense-in-depth measure — `join_description` is admin-set content, never
+  end-user input — but the renderer must not become a vector for injecting
+  arbitrary markup.
+
+  Markdown links are matched before bare URLs and their matched region is
+  consumed, so a Markdown link whose URL also looks like a bare URL is linked
+  exactly once (no nested anchors).
+  """
+
+  @markdown_link ~r/\[([^\]]+)\]\((https?:\/\/[^\s)]+)\)/
+  @bare_url ~r/(https?:\/\/[^\s<]+)/
+  @bare_url_anchored ~r/\A(https?:\/\/[^\s<]+)\z/
+
+  @doc """
+  Converts `value` to a Phoenix-safe HTML iolist.
+
+  Returns `{:safe, ""}` for `nil`. For a string, returns `{:safe, iolist}` with
+  links rendered and all other text HTML-escaped.
+  """
+  @spec render(String.t() | nil) :: Phoenix.HTML.safe()
+  def render(nil), do: {:safe, ""}
+
+  def render(value) when is_binary(value) do
+    {:safe, render_segments(value)}
+  end
+
+  # Split on Markdown links first; for each non-Markdown segment, link bare URLs;
+  # everything that is not a link is HTML-escaped.
+  defp render_segments(text) do
+    Regex.split(@markdown_link, text, include_captures: true)
+    |> Enum.map(&render_markdown_or_plain/1)
+  end
+
+  defp render_markdown_or_plain(segment) do
+    case Regex.run(@markdown_link, segment) do
+      [^segment, label, url] -> anchor(url, label)
+      _ -> render_plain(segment)
+    end
+  end
+
+  # Auto-link bare URLs in a plain-text segment, escaping all surrounding text.
+  defp render_plain(segment) do
+    Regex.split(@bare_url, segment, include_captures: true)
+    |> Enum.map(fn part ->
+      if Regex.match?(@bare_url_anchored, part) do
+        anchor(part, part)
+      else
+        escape(part)
+      end
+    end)
+  end
+
+  defp anchor(url, label) do
+    ["<a href=\"", escape(url), "\" class=\"link link-primary\">", escape(label), "</a>"]
+  end
+
+  defp escape(text), do: Phoenix.HTML.html_escape(text) |> Phoenix.HTML.safe_to_string()
+end
--- a/lib/mv_web/live/custom_field_live/form_component.ex
+++ b/lib/mv_web/live/custom_field_live/form_component.ex
@ -91,6 +91,45 @@ defmodule MvWeb.CustomFieldLive.FormComponent do
          <% end %>

          <.input field={@form[:description]} type="text" label={gettext("Description")} />
+
+          <fieldset class="mb-2 fieldset">
+            <label>
+              <span class="mb-1 label flex items-center gap-2">
+                {gettext("Description for join form")}
+                <.tooltip
+                  content={
+                    gettext(
+                      "You can add links: full addresses (https://…) or as [link text](https://…)."
+                    )
+                  }
+                  position="right"
+                >
+                  <span
+                    data-testid="join-description-link-hint"
+                    aria-label={
+                      gettext(
+                        "You can add links: full addresses (https://…) or as [link text](https://…)."
+                      )
+                    }
+                  >
+                    <.icon
+                      name="hero-information-circle"
+                      class="w-4 h-4 text-base-content/60 cursor-help"
+                      aria-hidden="true"
+                    />
+                  </span>
+                </.tooltip>
+              </span>
+              <input
+                type="text"
+                name={@form[:join_description].name}
+                id={@form[:join_description].id}
+                value={Phoenix.HTML.Form.normalize_value("text", @form[:join_description].value)}
+                class="w-full input"
+              />
+            </label>
+          </fieldset>
+
          <.input field={@form[:required]} type="checkbox" label={gettext("Required")} />
          <.input
            field={@form[:show_in_overview]}
--- a/lib/mv_web/live/join_live.ex
+++ b/lib/mv_web/live/join_live.ex
@ -8,6 +8,7 @@ defmodule MvWeb.JoinLive do
  alias Ash.Resource.Info
  alias Mv.Membership
  alias Mv.Membership.CustomFieldLookup
+  alias MvWeb.Helpers.JoinDescriptionRenderer
  alias MvWeb.JoinRateLimit
  alias MvWeb.Translations.MemberFields

@ -96,14 +97,20 @@ defmodule MvWeb.JoinLive do
                          class="checkbox checkbox-sm"
                        />
                        <span class="label-text">
-                          {field.label}<span :if={field.required} aria-hidden="true"> *</span>
+                          {render_field_label(field)}<span
+                            :if={field.required}
+                            aria-hidden="true"
+                          > *</span>
                        </span>
                      </label>
                    <% else %>
                      <div>
                        <label for={"join-field-#{field.id}"} class="label">
                          <span class="label-text">
-                            {field.label}<span :if={field.required} aria-hidden="true"> *</span>
+                            {render_field_label(field)}<span
+                              :if={field.required}
+                              aria-hidden="true"
+                            > *</span>
                          </span>
                        </label>
                        <input
@ -237,6 +244,17 @@ defmodule MvWeb.JoinLive do
     |> assign(:form, to_form(params, as: "join"))}
  end

+  # Renders a join field's label. When a custom field has a join_description it is
+  # rendered with auto-linked URLs/Markdown; otherwise the plain field label is used.
+  # Safe: join_description is admin-set settings content, never end-user input, and
+  # JoinDescriptionRenderer escapes all non-link text (only emits <a href> tags).
+  defp render_field_label(%{join_description: join_description})
+       when is_binary(join_description) do
+    JoinDescriptionRenderer.render(join_description)
+  end
+
+  defp render_field_label(%{label: label}), do: label
+
  defp build_join_fields_with_labels(allowlist) do
    member_field_strings = Mv.Constants.member_fields() |> Enum.map(&Atom.to_string/1)
    custom_field_by_id = custom_field_map(allowlist, member_field_strings)
@ -249,20 +267,36 @@ defmodule MvWeb.JoinLive do
  defp build_join_field(id, required, member_field_strings, custom_field_by_id) do
    if id in member_field_strings do
      label = MemberFields.label(String.to_existing_atom(id))
-      %{id: id, label: label, required: required, input_type: member_field_input_type(id)}
+
+      %{
+        id: id,
+        label: label,
+        required: required,
+        input_type: member_field_input_type(id),
+        join_description: nil
+      }
    else
      custom_field = Map.get(custom_field_by_id, id)
      label = if custom_field, do: custom_field.name, else: gettext("Field")
      input_type = custom_field_input_type(custom_field && custom_field.value_type)

-      %{id: id, label: label, required: required, input_type: input_type}
+      %{
+        id: id,
+        label: label,
+        required: required,
+        input_type: input_type,
+        join_description: custom_field && custom_field.join_description
+      }
    end
  end

  defp custom_field_map(allowlist, _member_field_strings) do
    allowlist
    |> Enum.map(& &1.id)
-    |> CustomFieldLookup.fetch_map_by_ids(authorize?: false, select: [:id, :name, :value_type])
+    |> CustomFieldLookup.fetch_map_by_ids(
+      authorize?: false,
+      select: [:id, :name, :value_type, :join_description]
+    )
  end

  defp initial_form_params(join_fields) do
--- a/lib/mv_web/live/member_live/show.ex
+++ b/lib/mv_web/live/member_live/show.ex
@ -235,6 +235,19 @@ defmodule MvWeb.MemberLive.Show do
                      <%= for custom_field <- @custom_fields do %>
                        <% cfv = find_custom_field_value(@member.custom_field_values, custom_field.id) %>
                        <.data_field label={custom_field.name}>
+                          <:label_suffix :if={custom_field.join_description}>
+                            <.tooltip
+                              content={"#{gettext("Join form:")} #{custom_field.join_description}"}
+                              wrap_class="ml-1 inline-flex items-center"
+                            >
+                              <span data-testid="join-description-tooltip">
+                                <.icon
+                                  name="hero-information-circle"
+                                  class="size-3.5 text-base-content/50"
+                                />
+                              </span>
+                            </.tooltip>
+                          </:label_suffix>
                          {format_custom_field_value(cfv, custom_field.value_type)}
                        </.data_field>
                      <% end %>
@ -605,11 +618,14 @@ defmodule MvWeb.MemberLive.Show do
  attr :value, :string, default: nil
  attr :class, :string, default: ""
  slot :inner_block
+  slot :label_suffix

  defp data_field(assigns) do
    ~H"""
    <dl class={@class}>
-      <dt class="text-sm font-medium text-base-content/70">{@label}</dt>
+      <dt class="text-sm font-medium text-base-content/70 flex items-center">
+        {@label}{render_slot(@label_suffix)}
+      </dt>
      <dd class="mt-1 text-base-content">
        <%= if @inner_block != [] do %>
          {render_slot(@inner_block)}
--- a/priv/gettext/de/LC_MESSAGES/default.po
+++ b/priv/gettext/de/LC_MESSAGES/default.po
@ -3967,6 +3967,21 @@ msgstr "Zeitraum"
 msgid "To"
 msgstr "Bis"

+#: lib/mv_web/live/member_live/show.ex
+#, elixir-autogen, elixir-format
+msgid "Join form:"
+msgstr "Beitrittsformular:"
+
+#: lib/mv_web/live/custom_field_live/form_component.ex
+#, elixir-autogen, elixir-format
+msgid "Description for join form"
+msgstr "Beschreibung für das Beitrittsformular"
+
+#: lib/mv_web/live/custom_field_live/form_component.ex
+#, elixir-autogen, elixir-format
+msgid "You can add links: full addresses (https://…) or as [link text](https://…)."
+msgstr "Du kannst Links einfügen: ganze Adressen (https://…) oder als [Linktext](https://…)."
+
 #: lib/mv/membership/import/member_csv.ex
 #, elixir-autogen, elixir-format
 msgid "Fee type '%{name}' not found; using the default fee type."
--- a/priv/gettext/default.pot
+++ b/priv/gettext/default.pot
@ -3967,6 +3967,21 @@ msgstr ""
 msgid "To"
 msgstr ""

+#: lib/mv_web/live/member_live/show.ex
+#, elixir-autogen, elixir-format
+msgid "Join form:"
+msgstr ""
+
+#: lib/mv_web/live/custom_field_live/form_component.ex
+#, elixir-autogen, elixir-format
+msgid "Description for join form"
+msgstr ""
+
+#: lib/mv_web/live/custom_field_live/form_component.ex
+#, elixir-autogen, elixir-format
+msgid "You can add links: full addresses (https://…) or as [link text](https://…)."
+msgstr ""
+
 #: lib/mv/membership/import/member_csv.ex
 #, elixir-autogen, elixir-format
 msgid "Fee type '%{name}' not found; using the default fee type."
--- a/priv/gettext/en/LC_MESSAGES/default.po
+++ b/priv/gettext/en/LC_MESSAGES/default.po
@ -3967,6 +3967,21 @@ msgstr ""
 msgid "To"
 msgstr ""

+#: lib/mv_web/live/member_live/show.ex
+#, elixir-autogen, elixir-format, fuzzy
+msgid "Join form:"
+msgstr ""
+
+#: lib/mv_web/live/custom_field_live/form_component.ex
+#, elixir-autogen, elixir-format, fuzzy
+msgid "Description for join form"
+msgstr ""
+
+#: lib/mv_web/live/custom_field_live/form_component.ex
+#, elixir-autogen, elixir-format
+msgid "You can add links: full addresses (https://…) or as [link text](https://…)."
+msgstr ""
+
 #: lib/mv/membership/import/member_csv.ex
 #, elixir-autogen, elixir-format
 msgid "Fee type '%{name}' not found; using the default fee type."
--- a/priv/repo/migrations/20260603000531_add_join_description_to_custom_fields.exs
+++ b/priv/repo/migrations/20260603000531_add_join_description_to_custom_fields.exs
@ -0,0 +1,21 @@
+defmodule Mv.Repo.Migrations.AddJoinDescriptionToCustomFields do
+  @moduledoc """
+  Updates resources based on their most recent snapshots.
+
+  This file was autogenerated with `mix ash_postgres.generate_migrations`
+  """
+
+  use Ecto.Migration
+
+  def up do
+    alter table(:custom_fields) do
+      add :join_description, :text
+    end
+  end
+
+  def down do
+    alter table(:custom_fields) do
+      remove :join_description
+    end
+  end
+end
--- a/priv/repo/seeds_bootstrap.exs
+++ b/priv/repo/seeds_bootstrap.exs
@ -81,9 +81,11 @@ custom_field_configs = [
    show_in_overview: true
  },
  %{
-    name: "Datenschutzerklärung akzeptiert",
+    name: "DSGVO",
    value_type: :boolean,
-    description: "Angabe, ob Datenschutzerklärung akzeptiert wurde",
+    description: "Angabe, ob die Datenschutzerklärung akzeptiert wurde",
+    join_description:
+      "Ich habe die [Datenschutzerklärung](https://example.org/datenschutz) gelesen und akzeptiere sie.",
    required: false,
    show_in_overview: false
  },
@ -302,11 +304,15 @@ case Membership.get_settings() do
            ArgumentError -> Map.has_key?(vis, k)
          end
        end
+
        merged =
          Enum.reduce(default_hidden_in_overview, visibility_config, fn {key, val}, vis ->
            if has_key.(vis, key), do: vis, else: Map.put(vis, key, val)
          end)
-        if merged != visibility_config, do: Map.put(acc, :member_field_visibility, merged), else: acc
+
+        if merged != visibility_config,
+          do: Map.put(acc, :member_field_visibility, merged),
+          else: acc
      end)

    if map_size(updates) > 0 do
@ -332,9 +338,7 @@ IO.puts(
  "   - Fee types: 5 (Standard, Ermäßigt, Unterstützer, Fördermitglied, Probemitgliedschaft)"
 )

-IO.puts(
-  "   - Custom fields: 6 (Geburtsdatum shown in overview; others hidden by default)"
-)
+IO.puts("   - Custom fields: 6 (Geburtsdatum shown in overview; others hidden by default)")

 IO.puts("   - Roles: 5 (Mitglied, Vorstand, Kassenwart, Buchhaltung, Admin)")
 IO.puts("   - Default fee type: Standard (120€ yearly)")
--- a/priv/repo/seeds_dev.exs
+++ b/priv/repo/seeds_dev.exs
@ -431,15 +431,16 @@ end)
 all_custom_fields = Ash.read!(Membership.CustomField, actor: admin_user_with_role)
 find_field = fn name -> Enum.find(all_custom_fields, &(&1.name == name)) end

-# 16 members with 4–6 custom field values each (Geburtsdatum, Datenschutz, SEPA, Rechnungs-E-Mail, IBAN, Stunden)
+# 16 members with 4–6 custom field values each (Geburtsdatum, DSGVO, SEPA, Rechnungs-E-Mail, IBAN, Stunden)
 custom_value_assignments =
  Enum.map(1..16, fn n ->
    email = "mitglied#{n}@example.de"
    # Vary birth dates and values per index
    base_date = Date.add(~D[1970-01-01], 365 * (n + 10) + rem(n * 31, 365))
+
    values = [
      {"Geburtsdatum", %{"_union_type" => "date", "_union_value" => base_date}},
-      {"Datenschutzerklärung akzeptiert",
+      {"DSGVO",
       %{"_union_type" => "boolean", "_union_value" => n in [1, 2, 3, 5, 7, 9, 11, 13, 15]}},
      {"SEPA-Mandat", %{"_union_type" => "boolean", "_union_value" => rem(n, 3) != 0}},
      {"Rechnungs-E-Mail",
@ -448,10 +449,12 @@ custom_value_assignments =
       %{
         "_union_type" => "string",
         "_union_value" =>
-           "DE8937040044#{String.pad_leading(to_string(rem(532013000 + n, 1_000_000_000)), 10, "0")}"
+           "DE8937040044#{String.pad_leading(to_string(rem(532_013_000 + n, 1_000_000_000)), 10, "0")}"
       }},
-      {"Stunden ehrenamtlich", %{"_union_type" => "integer", "_union_value" => 5 + rem(n * 3, 25)}}
+      {"Stunden ehrenamtlich",
+       %{"_union_type" => "integer", "_union_value" => 5 + rem(n * 3, 25)}}
    ]
+
    # Drop 0–2 fields per member so not all have 6 (still ~80% overall filled)
    drop_count = rem(n, 3)
    {email, Enum.take(values, 6 - drop_count)}
@ -502,19 +505,36 @@ case Membership.get_settings() do
      Membership.update_settings(settings, %{
        join_form_enabled: true,
        join_form_field_ids: settings.join_form_field_ids || default_join_form_field_ids,
-        join_form_field_required: settings.join_form_field_required || default_join_form_field_required
+        join_form_field_required:
+          settings.join_form_field_required || default_join_form_field_required
      })
    end
+
  _ ->
    :ok
 end

 # Membership applications (join requests) for UI testing: 4 submitted, 1 with extra form_data
 join_request_configs = [
-  %{email: "antrag1@example.de", first_name: "Sandra", last_name: "Meier", form_data: %{"city" => "Berlin"}},
+  %{
+    email: "antrag1@example.de",
+    first_name: "Sandra",
+    last_name: "Meier",
+    form_data: %{"city" => "Berlin"}
+  },
  %{email: "antrag2@example.de", first_name: "Thomas", last_name: "Bauer", form_data: %{}},
-  %{email: "antrag3@example.de", first_name: "Julia", last_name: "Krause", form_data: %{"city" => "Hamburg", "notes" => "Interesse an Jugendgruppe"}},
-  %{email: "antrag4@example.de", first_name: "Michael", last_name: "Schmitt", form_data: %{"city" => "München"}}
+  %{
+    email: "antrag3@example.de",
+    first_name: "Julia",
+    last_name: "Krause",
+    form_data: %{"city" => "Hamburg", "notes" => "Interesse an Jugendgruppe"}
+  },
+  %{
+    email: "antrag4@example.de",
+    first_name: "Michael",
+    last_name: "Schmitt",
+    form_data: %{"city" => "München"}
+  }
 ]

 for config <- join_request_configs do
@ -532,8 +552,15 @@ for config <- join_request_configs do
 end

 IO.puts("✅ Dev seeds completed.")
-IO.puts("   - Members: 20 with country (mostly Deutschland, 1 Österreich, 1 Schweiz), fee types distributed, 5 with exit date")
-IO.puts("   - Test users: 4 linked to mitglied1–4 with roles Mitglied, Vorstand, Kassenwart, Buchhaltung")
+
+IO.puts(
+  "   - Members: 20 with country (mostly Deutschland, 1 Österreich, 1 Schweiz), fee types distributed, 5 with exit date"
+)
+
+IO.puts(
+  "   - Test users: 4 linked to mitglied1–4 with roles Mitglied, Vorstand, Kassenwart, Buchhaltung"
+)
+
 IO.puts("   - Groups: Vorstand, Jugend, Newsletter (with assignments)")
 IO.puts("   - Custom field values: ~80% filled (16 members, 4–6 fields each)")
 IO.puts("   - Join form enabled; 4 membership applications (join requests) for UI testing")
--- a/priv/resource_snapshots/repo/custom_fields/20260603000204.json
+++ b/priv/resource_snapshots/repo/custom_fields/20260603000204.json
@ -0,0 +1,145 @@
+{
+  "attributes": [
+    {
+      "allow_nil?": false,
+      "default": "fragment(\"gen_random_uuid()\")",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": true,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "id",
+      "type": "uuid"
+    },
+    {
+      "allow_nil?": false,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "name",
+      "type": "text"
+    },
+    {
+      "allow_nil?": false,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "slug",
+      "type": "text"
+    },
+    {
+      "allow_nil?": false,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "value_type",
+      "type": "text"
+    },
+    {
+      "allow_nil?": true,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "description",
+      "type": "text"
+    },
+    {
+      "allow_nil?": true,
+      "default": "nil",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "join_description",
+      "type": "text"
+    },
+    {
+      "allow_nil?": false,
+      "default": "false",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "required",
+      "type": "boolean"
+    },
+    {
+      "allow_nil?": false,
+      "default": "true",
+      "generated?": false,
+      "precision": null,
+      "primary_key?": false,
+      "references": null,
+      "scale": null,
+      "size": null,
+      "source": "show_in_overview",
+      "type": "boolean"
+    }
+  ],
+  "base_filter": null,
+  "check_constraints": [],
+  "create_table_options": null,
+  "custom_indexes": [],
+  "custom_statements": [],
+  "has_create_action": true,
+  "hash": "2600667D140A2A846F9A848ACEFCADA1F1206950B38EF407B0BB13816E508A2A",
+  "identities": [
+    {
+      "all_tenants?": false,
+      "base_filter": null,
+      "index_name": "custom_fields_unique_name_index",
+      "keys": [
+        {
+          "type": "atom",
+          "value": "name"
+        }
+      ],
+      "name": "unique_name",
+      "nils_distinct?": true,
+      "where": null
+    },
+    {
+      "all_tenants?": false,
+      "base_filter": null,
+      "index_name": "custom_fields_unique_slug_index",
+      "keys": [
+        {
+          "type": "atom",
+          "value": "slug"
+        }
+      ],
+      "name": "unique_slug",
+      "nils_distinct?": true,
+      "where": null
+    }
+  ],
+  "multitenancy": {
+    "attribute": null,
+    "global": null,
+    "strategy": null
+  },
+  "repo": "Elixir.Mv.Repo",
+  "schema": null,
+  "table": "custom_fields"
+}
--- a/test/membership/custom_field_validation_test.exs
+++ b/test/membership/custom_field_validation_test.exs
@ -159,6 +159,61 @@ defmodule Mv.Membership.CustomFieldValidationTest do
    end
  end

+  describe "join_description" do
+    test "persists join_description when set", %{actor: actor} do
+      assert {:ok, custom_field} =
+               CustomField
+               |> Ash.Changeset.for_create(:create, %{
+                 name: "dsgvo_field",
+                 value_type: :boolean,
+                 join_description: "hereby I confirm the GDPR"
+               })
+               |> Ash.create(actor: actor)
+
+      assert custom_field.join_description == "hereby I confirm the GDPR"
+    end
+
+    test "defaults to nil when not given", %{actor: actor} do
+      assert {:ok, custom_field} =
+               CustomField
+               |> Ash.Changeset.for_create(:create, %{
+                 name: "no_join_desc",
+                 value_type: :boolean
+               })
+               |> Ash.create(actor: actor)
+
+      assert custom_field.join_description == nil
+    end
+
+    test "rejects join_description longer than 1000 characters", %{actor: actor} do
+      assert {:error, changeset} =
+               CustomField
+               |> Ash.Changeset.for_create(:create, %{
+                 name: "too_long_join_desc",
+                 value_type: :boolean,
+                 join_description: String.duplicate("a", 1001)
+               })
+               |> Ash.create(actor: actor)
+
+      assert [%{field: :join_description, message: message}] = changeset.errors
+      assert message =~ "max" or message =~ "length" or message =~ "1000"
+    end
+
+    test "is writable via the update action", %{actor: actor} do
+      {:ok, custom_field} =
+        CustomField
+        |> Ash.Changeset.for_create(:create, %{name: "updatable", value_type: :boolean})
+        |> Ash.create(actor: actor)
+
+      assert {:ok, updated} =
+               custom_field
+               |> Ash.Changeset.for_update(:update, %{join_description: "Accept the GDPR"})
+               |> Ash.update(actor: actor)
+
+      assert updated.join_description == "Accept the GDPR"
+    end
+  end
+
  describe "name uniqueness" do
    test "rejects duplicate names", %{actor: actor} do
      assert {:ok, _} =
--- a/test/mv_web/helpers/join_description_renderer_test.exs
+++ b/test/mv_web/helpers/join_description_renderer_test.exs
@ -0,0 +1,85 @@
+defmodule MvWeb.Helpers.JoinDescriptionRendererTest do
+  @moduledoc """
+  Tests for the join-description renderer that auto-links raw URLs and Markdown
+  links while escaping all other content.
+  """
+  use ExUnit.Case, async: true
+  use ExUnitProperties
+
+  alias MvWeb.Helpers.JoinDescriptionRenderer
+
+  defp html(value) do
+    value
+    |> JoinDescriptionRenderer.render()
+    |> Phoenix.HTML.safe_to_string()
+  end
+
+  describe "render/1" do
+    test "converts a raw URL to an anchor tag with the standard link class" do
+      result = html("Akzeptiere https://example.com/dsgvo")
+
+      assert result =~ ~s(<a href="https://example.com/dsgvo" class="link link-primary")
+      assert result =~ "https://example.com/dsgvo</a>"
+      assert result =~ "Akzeptiere "
+    end
+
+    test "converts Markdown [text](url) to an anchor tag with the standard link class" do
+      result = html("[Datenschutzerklärung](https://example.com/dsgvo)")
+
+      assert result =~ ~s(<a href="https://example.com/dsgvo" class="link link-primary")
+      assert result =~ ">Datenschutzerklärung</a>"
+    end
+
+    test "returns an empty safe string for nil input" do
+      assert JoinDescriptionRenderer.render(nil) == {:safe, ""}
+    end
+
+    test "escapes arbitrary HTML in non-link text" do
+      result = html("<script>alert(1)</script>")
+
+      refute result =~ "<script>"
+      assert result =~ "&lt;script&gt;"
+    end
+
+    test "does not double-link a Markdown link whose URL also looks like a raw URL" do
+      result = html("[Datenschutz](https://example.com/x)")
+
+      # exactly one anchor, no nested anchor for the inner raw URL
+      assert result |> :binary.matches("<a ") |> length() == 1
+    end
+  end
+
+  describe "property: link-free text" do
+    property "preserves non-link text content as HTML-escaped output" do
+      check all(text <- link_free_string()) do
+        result = html(text)
+
+        # No links emitted, and text content equals the HTML-escaped input.
+        refute result =~ "<a "
+        assert result == Phoenix.HTML.html_escape(text) |> Phoenix.HTML.safe_to_string()
+      end
+    end
+  end
+
+  describe "property: well-formed Markdown links" do
+    property "renders every [text](https://...) as a single anchor with verbatim text and url" do
+      check all(
+              label <- string(:alphanumeric, min_length: 1),
+              path <- string(:alphanumeric)
+            ) do
+        url = "https://example.com/#{path}"
+        result = html("[#{label}](#{url})")
+
+        assert result =~ ~s(<a href="#{url}" class="link link-primary">#{label}</a>)
+        assert result |> :binary.matches("<a ") |> length() == 1
+      end
+    end
+  end
+
+  # Printable strings that contain no bare URLs and no Markdown-link opening bracket.
+  defp link_free_string do
+    :printable
+    |> string()
+    |> filter(fn s -> not String.contains?(s, "http") and not String.contains?(s, "[") end)
+  end
+end
--- a/test/mv_web/live/custom_field_live/form_test.exs
+++ b/test/mv_web/live/custom_field_live/form_test.exs
@ -0,0 +1,102 @@
+defmodule MvWeb.CustomFieldLive.FormTest do
+  @moduledoc """
+  Tests for the CustomFieldLive.FormComponent join_description input.
+
+  Covers that an admin can set and persist a custom field's join_description via
+  the settings edit form.
+  """
+  use MvWeb.ConnCase, async: true
+
+  import Phoenix.LiveViewTest
+  require Ash.Query
+
+  alias Mv.Membership.CustomField
+
+  setup do
+    system_actor = Mv.Helpers.SystemActor.get_system_actor()
+    admin_role = Mv.Fixtures.role_fixture("admin")
+
+    {:ok, user} =
+      Mv.Accounts.User
+      |> Ash.Changeset.for_create(:register_with_password, %{
+        email: "admin#{System.unique_integer([:positive])}@mv.local",
+        password: "testpassword123"
+      })
+      |> Ash.create(actor: system_actor)
+
+    {:ok, user} =
+      user
+      |> Ash.Changeset.for_update(:update, %{})
+      |> Ash.Changeset.manage_relationship(:role, admin_role, type: :append_and_remove)
+      |> Ash.update(actor: system_actor)
+
+    user_with_role = Ash.load!(user, :role, domain: Mv.Accounts, actor: system_actor)
+    conn = log_in_user(build_conn(), user_with_role)
+    session = conn.private[:plug_session] || %{}
+    conn = Plug.Test.init_test_session(conn, Map.put(session, "locale", "en"))
+    %{conn: conn, actor: system_actor}
+  end
+
+  defp log_in_user(conn, user) do
+    conn
+    |> Phoenix.ConnTest.init_test_session(%{})
+    |> AshAuthentication.Plug.Helpers.store_in_session(user)
+  end
+
+  defp open_edit_form(view, custom_field) do
+    view
+    |> element("tr#custom_fields-#{custom_field.id} td", custom_field.name)
+    |> render_click()
+  end
+
+  describe "join_description input" do
+    test "form shows a join_description input", %{conn: conn, actor: actor} do
+      {:ok, custom_field} =
+        CustomField
+        |> Ash.Changeset.for_create(:create, %{name: "dsgvo_field", value_type: :boolean})
+        |> Ash.create(actor: actor)
+
+      {:ok, view, _html} = live(conn, ~p"/admin/datafields")
+      open_edit_form(view, custom_field)
+
+      assert has_element?(view, "input[name='custom_field[join_description]']")
+    end
+
+    test "form shows an info tooltip explaining allowed link syntax", %{conn: conn, actor: actor} do
+      {:ok, custom_field} =
+        CustomField
+        |> Ash.Changeset.for_create(:create, %{name: "dsgvo_field", value_type: :boolean})
+        |> Ash.create(actor: actor)
+
+      {:ok, view, _html} = live(conn, ~p"/admin/datafields")
+      open_edit_form(view, custom_field)
+
+      assert has_element?(
+               view,
+               "[data-testid='join-description-link-hint'] .hero-information-circle"
+             )
+    end
+
+    test "form accepts and persists join_description", %{conn: conn, actor: actor} do
+      {:ok, custom_field} =
+        CustomField
+        |> Ash.Changeset.for_create(:create, %{name: "dsgvo_field", value_type: :boolean})
+        |> Ash.create(actor: actor)
+
+      {:ok, view, _html} = live(conn, ~p"/admin/datafields")
+      open_edit_form(view, custom_field)
+
+      view
+      |> form("#custom-field-form-#{custom_field.id}-form", %{
+        "custom_field" => %{
+          "name" => custom_field.name,
+          "join_description" => "Accept the GDPR at https://example.com/dsgvo"
+        }
+      })
+      |> render_submit()
+
+      updated = Ash.get!(CustomField, custom_field.id, actor: actor)
+      assert updated.join_description == "Accept the GDPR at https://example.com/dsgvo"
+    end
+  end
+end
--- a/test/mv_web/live/join_live_test.exs
+++ b/test/mv_web/live/join_live_test.exs
@ -165,6 +165,36 @@ defmodule MvWeb.JoinLiveTest do
               custom_field.name
             )
    end
+
+    @tag role: :unauthenticated
+    test "renders join_description with rendered link as label when set", %{conn: conn} do
+      {:ok, settings} = Membership.get_settings()
+      system_actor = Mv.Helpers.SystemActor.get_system_actor()
+
+      {:ok, custom_field} =
+        Membership.create_custom_field(
+          %{
+            name: "DSGVO",
+            value_type: :boolean,
+            join_description: "Akzeptiere die [Datenschutzerklärung](https://example.com/dsgvo)"
+          },
+          actor: system_actor
+        )
+
+      {:ok, _} =
+        Membership.update_settings(settings, %{
+          join_form_enabled: true,
+          join_form_field_ids: ["email", custom_field.id],
+          join_form_field_required: %{"email" => true, custom_field.id => false}
+        })
+
+      {:ok, _view, html} = live(conn, "/join")
+
+      assert html =~
+               ~s(<a href="https://example.com/dsgvo" class="link link-primary">Datenschutzerklärung</a>)
+
+      assert html =~ "Akzeptiere die"
+    end
  end

  describe "join field input types" do
--- a/test/mv_web/member_live/show_test.exs
+++ b/test/mv_web/member_live/show_test.exs
@ -220,4 +220,59 @@ defmodule MvWeb.MemberLive.ShowTest do
      assert html =~ "private@example.com"
    end
  end
+
+  describe "custom field join_description tooltip" do
+    test "shows a tooltip on the custom field label when join_description is set", %{
+      conn: conn,
+      member: member,
+      actor: actor
+    } do
+      {:ok, custom_field} =
+        CustomField
+        |> Ash.Changeset.for_create(:create, %{
+          name: "DSGVO",
+          value_type: :boolean,
+          join_description: "Accept the privacy policy"
+        })
+        |> Ash.create(actor: actor)
+
+      conn = conn_with_oidc_user(conn)
+      {:ok, view, html} = live(conn, ~p"/members/#{member}")
+
+      assert has_element?(view, "[data-tip*='Accept the privacy policy']")
+      # Tooltip content conveys both the join-form context and the description text.
+      assert has_element?(view, "[data-tip*='Join form:']")
+      assert html =~ "Accept the privacy policy"
+      assert html =~ custom_field.name
+
+      # The info-icon wrapper must center the icon vertically with the label,
+      # matching the flex-items-center idiom used elsewhere (e.g. custom field edit),
+      # so the icon is flush with the label text and not offset downward.
+      assert has_element?(
+               view,
+               "[data-tip*='Accept the privacy policy'].inline-flex.items-center"
+             )
+    end
+
+    test "shows no tooltip on the custom field label when join_description is nil", %{
+      conn: conn,
+      member: member,
+      actor: actor
+    } do
+      {:ok, _custom_field} =
+        CustomField
+        |> Ash.Changeset.for_create(:create, %{
+          name: "Plain field",
+          value_type: :string
+        })
+        |> Ash.create(actor: actor)
+
+      conn = conn_with_oidc_user(conn)
+      {:ok, view, _html} = live(conn, ~p"/members/#{member}")
+
+      assert has_element?(view, "dt", "Plain field")
+      # The info-icon tooltip beside the label is only rendered when join_description is set.
+      refute has_element?(view, "[data-testid='join-description-tooltip']")
+    end
+  end
 end
--- a/test/seeds_test.exs
+++ b/test/seeds_test.exs
@ -123,5 +123,24 @@ defmodule Mv.SeedsTest do
      assert mitglied.permission_set_name == "own_data",
             "Mitglied role must have own_data permission set"
    end
+
+    test "bootstrap seeds create the DSGVO custom field and not the old long name", %{
+      actor: actor
+    } do
+      {:ok, custom_fields} = Ash.read(Mv.Membership.CustomField, actor: actor)
+      names = Enum.map(custom_fields, & &1.name)
+
+      assert "DSGVO" in names, "Bootstrap seeds must create a custom field named DSGVO"
+
+      refute "Datenschutzerklärung akzeptiert" in names,
+             "Old long field name must no longer be seeded"
+
+      dsgvo = Enum.find(custom_fields, &(&1.name == "DSGVO"))
+      assert dsgvo.value_type == :boolean
+
+      assert dsgvo.join_description ==
+               "Ich habe die [Datenschutzerklärung](https://example.org/datenschutz) gelesen und akzeptiere sie.",
+             "DSGVO field must be seeded with a default join_description"
+    end
  end
 end