fix(investments): count income categories on unit-priced accounts and transfers at their own amount

- Unit-priced accounts now honour their income categories, tags and entities:
  a matching transaction is a gain or loss, and any other unlinked one is money
  in or out at that day's market price. Before, every unlinked outflow was a
  loss and yields were booked as new money in.
- A transfer out of an account tracked by value counts its own amount. It used
  the other side converted at the day's rate, so a coin bought from a savings
  account moved the coin's price change onto the savings account.

app/apps/accounts/migrations/0021_alter_account_income_categories_help.py

@@ -0,0 +1,19 @@
+# Generated by Django 5.2.17 on 2026-11-08 20:59
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('accounts', '0020_investment_classes'),
+        ('transactions', '0052_transfer_templates'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='account',
+            name='income_categories',
+            field=models.ManyToManyField(blank=True, help_text="Transactions in this account with any of these categories are its result (interest, taxes, fees). Everything else that isn't a transfer counts as money coming in or going out.", related_name='investment_accounts', to='transactions.transactioncategory', verbose_name='Income categories'),
+        ),
+    ]

app/apps/accounts/models.py

@@ -151,8 +151,8 @@ class Account(SharedObject):
         verbose_name=_("Income categories"),
         help_text=_(
             "Transactions in this account with any of these categories are its result "
-            "(interest, taxes, fees). On accounts tracked by value, everything else "
-            "that isn't a transfer counts as money coming in or going out."
+            "(interest, taxes, fees). Everything else that isn't a transfer counts as "
+            "money coming in or going out."
         ),
     )
     income_tags = models.ManyToManyField(

app/apps/investments/services.py

@@ -1,15 +1,14 @@
 """Investment performance, derived from an account's transactions.
 
 Rules (see the account's "Investment" help text):
-- A linked transaction (a transfer) moves money in or out. Its other side says
-  what was paid or received, which is the cost or the proceeds.
-- An unlinked transaction on an account tracked by value is money coming in or
-  going out (a salary, a bill), unless it has one of the account's income
-  categories, tags or entities: then it is a gain or a loss (a reconciled balance,
-  interest, a tax withheld).
-- On a unit-priced account an unlinked outflow is a loss, and an unlinked inflow
-  (a gift, an opening balance) has no known cost, so it is costed at the market
-  price of that day and the result is flagged as estimated.
+- A linked transaction (a transfer) moves money in or out. On a unit-priced
+  account its other side says what was paid or received, which is the cost or
+  the proceeds. On an account tracked by value its own amount is.
+- An unlinked transaction is money coming in or going out (a salary, a bill, a
+  gift), unless it has one of the account's income categories, tags or entities:
+  then it is a gain or a loss (a reconciled balance, interest, a tax withheld).
+- On a unit-priced account, money that moves without a known other side is
+  valued at the market price of that day and the result is flagged as estimated.
 - Cost is tracked with the average cost method.
 """
 
@@ -42,7 +41,7 @@ class HoldingPerformance:
     contributed: Decimal = ZERO
     withdrawn: Decimal = ZERO
     estimated: bool = False
-    # Unlinked transactions counted as gains or losses, on accounts tracked by value
+    # Unlinked transactions counted as gains or losses
     result_ids: set = field(default_factory=set)
     history: list = field(default_factory=list)
     # (date, "buy" or "sell", unit price) for linked trades on unit-priced accounts
@@ -152,7 +151,6 @@ def get_holding_performance(account, as_of=None, with_history=False):
     )
 
     month_ends = _month_ends(transactions, as_of) if with_history else []
-    if not perf.priced:
     perf.result_ids = _result_ids(account)
 
     for tx in transactions:
@@ -163,34 +161,35 @@ def get_holding_performance(account, as_of=None, with_history=False):
         partner = tx.linked_transaction
         if partner and (partner.account_id == account.id or partner.deleted):
             partner = None
-        partner_value = (
-            _to(partner.amount, partner.account.currency, valuation_currency, tx.date)
-            if partner
-            else None
+        # Money in or out, as opposed to a gain or a loss
+        moved = partner or tx.id not in perf.result_ids
+        partner_value = None
+        if perf.priced and partner:
+            partner_value = _to(
+                partner.amount, partner.account.currency, valuation_currency, tx.date
             )
-        external = not (perf.priced or partner or tx.id in perf.result_ids)
+        if partner_value is not None:
+            value, estimated = partner_value, False
+        elif perf.priced:
+            # No known other side: that day's market value
+            value = _to(tx.amount, account.currency, valuation_currency, tx.date)
+            estimated = True
+        else:
+            value, estimated = tx.amount, False
+
         if perf.priced and partner_value is not None and tx.amount:
             kind = "buy" if tx.type == Transaction.Type.INCOME else "sell"
             perf.trades.append((tx.date, kind, partner_value / tx.amount))
-        elif not (perf.priced or partner or external):
+        elif not (perf.priced or moved):
             sign = 1 if tx.type == Transaction.Type.INCOME else -1
             perf.results.append((tx.date, sign * tx.amount))
 
         if tx.type == Transaction.Type.INCOME:
-            if external:
-                cost = tx.amount
-                perf.contributed += cost
-            elif partner_value is not None:
-                cost = partner_value
-                perf.contributed += cost
-            elif perf.priced or partner:
-                # No known cost: price it at that day's market value
-                cost = _to(tx.amount, account.currency, valuation_currency, tx.date)
-                perf.estimated = True
-                if partner:
+            cost = ZERO  # a gain
+            if moved:
+                cost = value
                 perf.contributed += cost or ZERO
-            else:
-                cost = ZERO  # value-tracked: a gain
+                perf.estimated |= estimated
             if cost:
                 perf.flows.append((tx.date, -cost, "in"))
             perf.quantity += tx.amount
@@ -200,11 +199,9 @@ def get_holding_performance(account, as_of=None, with_history=False):
                 removed = perf.cost_basis * min(tx.amount, perf.quantity) / perf.quantity
             else:
                 removed = ZERO
-            if partner or external:
-                proceeds = tx.amount if external else partner_value
-                if proceeds is None:
-                    proceeds = _to(tx.amount, account.currency, valuation_currency, tx.date) or ZERO
-                    perf.estimated = True
+            if moved:
+                proceeds = value or ZERO
+                perf.estimated |= estimated
                 perf.realized += proceeds - removed
                 perf.withdrawn += proceeds
                 perf.flows.append((tx.date, proceeds, "out"))

app/apps/investments/tests/test_services.py

@@ -101,7 +101,41 @@ class HoldingPerformanceTests(TestCase):
 
         self.assertEqual(perf.cost_basis, D("180"))
         self.assertTrue(perf.estimated)
-        self.assertEqual(perf.contributed, D("0"))
+        self.assertEqual(perf.contributed, D("180"))
+
+    def test_priced_account_separates_money_from_yield(self):
+        # A foreign-currency account: pay in, interest, then money out unlinked
+        self.rate("100", self.d1)
+        result = TransactionCategory.objects.create(name="Interest")
+        self.etf.income_categories.set([result])
+        tx(self.etf, IN, "10", self.d1)  # paid in from outside
+        tx(self.etf, IN, "1", self.d2, category=result)
+        tx(self.etf, EX, "5", self.d3)  # taken out, not a loss
+
+        perf = get_holding_performance(self.etf)
+
+        self.assertEqual(perf.contributed, D("1000"))
+        self.assertEqual(perf.withdrawn, D("500"))
+        self.assertEqual(perf.quantity, D("6"))
+        self.assertEqual(perf.market_value, D("600"))
+        # The interest is the whole return: 600 held + 500 out - 1000 in
+        self.assertEqual(perf.total_return, D("100"))
+        self.assertEqual(perf.results, [])
+
+    def test_value_tracked_transfer_counts_its_own_amount(self):
+        # Paying 1000 for units now worth 900 is the units' loss, not the cash's
+        cash = Account.objects.create(
+            name="Savings", currency=self.eur, is_investment=True
+        )
+        tx(cash, IN, "5000", self.d1)
+        transfer(cash, "1000", self.etf, "10", self.d2)
+        self.rate("90", timezone.localdate())
+
+        perf = get_holding_performance(cash)
+
+        self.assertEqual(perf.withdrawn, D("1000"))
+        self.assertEqual(perf.total_return, D("0"))
+        self.assertEqual(get_holding_performance(self.etf).total_return, D("-100"))
 
     def test_value_tracked_cdb_with_tax_on_redemption(self):
         cdb = Account.objects.create(

app/templates/investments/fragments/detail.html

@@ -45,7 +45,7 @@
       <div class="text-sm text-base-content/60 mt-1">
         {% if account.group %}{{ account.group.name }} · {% endif %}
         {% if perf.priced %}{{ a.name }} → {{ c.name }}{% else %}{% translate 'Tracked by value' %}{% endif %}
-        {% if perf.estimated %}<i class="fa-solid fa-circle-exclamation text-warning ml-1" data-tippy-content="{% translate 'Some incoming units have no linked payment, so their cost was estimated from the market price of that day' %}"></i>{% endif %}
+        {% if perf.estimated %}<i class="fa-solid fa-circle-exclamation text-warning ml-1" data-tippy-content="{% translate 'Some units moved in or out without a linked payment, so they were valued at the market price of that day' %}"></i>{% endif %}
       </div>
     </div>
   </div>
@@ -284,7 +284,7 @@
                       {% if tx.type == 'IN' %}{% translate 'Bought / contributed' %}{% else %}{% translate 'Sold / withdrew' %}{% endif %}
                       · {{ p.account.name }}
                     {% else %}
-                      {% if not perf.priced and tx.id not in perf.result_ids %}
+                      {% if tx.id not in perf.result_ids %}
                         {% if tx.type == 'IN' %}{% translate 'Money in' %}{% else %}{% translate 'Money out' %}{% endif %}
                       {% else %}
                         {% if tx.type == 'IN' %}{% if perf.priced %}{% translate 'Gain' %}{% else %}{% translate 'Earnings' %}{% endif %}{% else %}{% translate 'Loss, tax or fee' %}{% endif %}