feat(investments): show exchanged amounts in movements and honor the display switch

Movements without an other-currency transfer side now show the exchanged
amount, and the converted value card follows show_exchanged_amounts.

app/apps/investments/tests/test_services.py

@@ -447,6 +447,34 @@ class InvestmentViewTests(TestCase):
         response = self.client.get(reverse("investments_charts"), **self.HTMX)
         self.assertContains(response, "investment-charts-0")
 
+    def test_detail_follows_show_exchanged_amounts(self):
+        brl = self.account.currency
+        usd = Currency.objects.create(
+            code="USD", name="Dollar", decimal_places=2, prefix="US$ ",
+            exchange_currency=brl,
+        )
+        ExchangeRate.objects.create(
+            from_currency=usd, to_currency=brl, rate=D("5"),
+            date=timezone.make_aware(datetime.datetime(2026, 1, 1)),
+        )
+        # Tracked by value in USD: movements and the "In Real" card come from USD's chain
+        account = Account.all_objects.create(
+            name="Broker", currency=usd, is_investment=True, owner=self.owner
+        )
+        tx(account, IN, "10", datetime.date(2026, 1, 2))
+        self.client.force_login(self.owner)
+        url = reverse("investment_detail", args=[account.id])
+
+        response = self.client.get(url, **self.HTMX)
+        self.assertContains(response, 'data-amount="50"', count=3)  # 10 USD at 5: ≈ line, card, movement
+        self.assertContains(response, "In Real")
+
+        usd.show_exchanged_amounts = False
+        usd.save()
+        response = self.client.get(url, **self.HTMX)
+        self.assertNotContains(response, 'data-amount="50"')
+        self.assertNotContains(response, "In Real")
+
     def test_stranger_cannot_see_detail(self):
         self.client.force_login(self.stranger)
         response = self.client.get(

app/apps/investments/views.py

@@ -209,7 +209,12 @@ def investment_detail(request, account_id):
     perf = get_holding_performance(account, with_history=True)
     transactions = (
         Transaction.objects.filter(account=account)
-        .select_related("linked_transaction__account__currency", "category")
+        .select_related(
+            "linked_transaction__account__currency",
+            "category",
+            "account__currency__exchange_currency",
+            "account__exchange_currency",
+        )
         .order_by("-date", "-id")[:50]
     )
     income = []
@@ -246,7 +251,8 @@ def investment_detail(request, account_id):
         {
             "account": account,
             "perf": perf,
-            "home": in_home_currency(perf),
+            # The valuation currency provides the next hop, so its switch decides
+            "home": in_home_currency(perf) if perf.currency.show_exchanged_amounts else None,
             "transactions": transactions,
             "income": income,
             "income_entities": list(account.income_entities.all()),

app/templates/investments/fragments/detail.html

@@ -286,11 +286,16 @@
                 </td>
                 <td class="text-end tabular-nums whitespace-nowrap">
                   <c-amount.display :amount="tx.amount" :prefix="a.prefix" :suffix="a.suffix" :decimal_places="a.decimal_places" color="{% if tx.type == 'IN' %}green{% else %}red{% endif %}" divless></c-amount.display>
+                  {# What the other side paid beats a rate conversion, so it's shown first #}
                   {% if p and p.account.currency != a %}
                     <div class="text-xs text-base-content/50">
                       <c-amount.display :amount="p.amount" :prefix="p.account.currency.prefix" :suffix="p.account.currency.suffix" :decimal_places="p.account.currency.decimal_places" divless></c-amount.display>
                     </div>
-                  {% endif %}
+                  {% else %}{% with exchanged=tx.displayed_exchanged_amount %}{% if exchanged %}
+                    <div class="text-xs text-base-content/50">
+                      <c-amount.display :amount="exchanged.amount" :prefix="exchanged.prefix" :suffix="exchanged.suffix" :decimal_places="exchanged.decimal_places" divless></c-amount.display>
+                    </div>
+                  {% endif %}{% endwith %}{% endif %}
                 </td>
                 <td class="w-8 px-1">
                   <button class="btn btn-ghost btn-xs btn-square text-base-content/40 hover:text-base-content"