Make category rules date-aware via effective_from

The same description can mean different things over time — bank-side
DEGIRO rows before 2026 are internal transfers (because Degiro annual
reports cover those years authoritatively), but from 2026 onwards the
user funds Degiro directly from CGD and wants those rows tagged as
Investment.

Add an effective_from date to CategoryRule and check it in matches() so
a rule only classifies movements on or after the cut-off. The seed
loader carries the field through and includes it in the natural key,
so the same (match_text, sign, scope) pair can have one rule with no
cut-off and another with one, and both round-trip through seed_finance
cleanly.

Author: xhico

finance/admin.py

@@ -44,7 +44,7 @@ class CategoryRuleAdmin(admin.ModelAdmin):
     - Ordered so the highest-priority rules show first
     """
 
-    list_display = ("match_text", "sign", "scope", "category", "priority")
+    list_display = ("match_text", "sign", "scope", "effective_from", "category", "priority")
     list_filter = ("sign", "scope", "category")
     search_fields = ("match_text",)
 

finance/management/commands/seed_finance.py

@@ -101,6 +101,7 @@ def handle(self, *args, **options):
                 match_text=entry["match_text"],
                 sign=entry.get("sign", CategoryRule.Sign.ANY),
                 scope=entry.get("scope", ""),
+                effective_from=entry.get("effective_from") or None,
                 defaults={
                     "category": category,
                     "priority": entry.get("priority", 100),

finance/migrations/0005_categoryrule_effective_from.py

@@ -0,0 +1,17 @@
+# Generated by Django 5.2.14 on 2026-05-29 08:10
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("finance", "0004_populate_account_role"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="categoryrule",
+            name="effective_from",
+            field=models.DateField(blank=True, null=True),
+        ),
+    ]

finance/models.py

@@ -129,6 +129,9 @@ class Sign(models.TextChoices):
     sign = models.CharField(max_length=6, choices=Sign.choices, default=Sign.ANY)
     # Blank scope matches any account scope
     scope = models.CharField(max_length=10, choices=Account.Scope.choices, blank=True)
+    # Only match transactions on or after this date when set; lets the same
+    # description map to different categories before and after a cut-off
+    effective_from = models.DateField(null=True, blank=True)
     category = models.ForeignKey(Category, on_delete=models.CASCADE, related_name="rules")
     priority = models.IntegerField(default=100)
 
@@ -167,6 +170,8 @@ def matches(self, txn):
             return False
         if self.scope and txn.account.scope != self.scope:
             return False
+        if self.effective_from and txn.date < self.effective_from:
+            return False
         return True
 
 

finance/tests/test_dashboard.py

@@ -184,6 +184,57 @@ def test_dashboard_requires_authentication():
     assert response.status_code in (401, 403)
 
 
+@pytest.mark.django_db
+def test_category_rule_effective_from_only_matches_later_dates():
+    """
+    A rule with effective_from set only classifies transactions on or after it.
+
+    Args:
+        None
+
+    Returns:
+        None
+    """
+
+    investment = Category.objects.create(name="Investment", kind=Category.Kind.INVESTMENT)
+    transfer = Category.objects.create(name="Internal transfer", kind=Category.Kind.TRANSFER)
+    # Cut-off rule for 2026 onwards, plus a catch-all for everything before
+    CategoryRule.objects.create(
+        match_text="BROKER",
+        sign=CategoryRule.Sign.ANY,
+        category=investment,
+        effective_from=date(2026, 1, 1),
+        priority=15,
+    )
+    CategoryRule.objects.create(
+        match_text="BROKER",
+        sign=CategoryRule.Sign.ANY,
+        category=transfer,
+        priority=20,
+    )
+
+    account = Account.objects.create(name="House", bank="Bank", iban="PT50000000000000000000020", scope="personal")
+    pre = Transaction.objects.create(
+        account=account,
+        date=date(2025, 6, 1),
+        description="BROKER deposit",
+        amount=Decimal("-500.00"),
+    )
+    post = Transaction.objects.create(
+        account=account,
+        date=date(2026, 2, 1),
+        description="BROKER deposit",
+        amount=Decimal("-500.00"),
+    )
+
+    classify_transactions()
+    pre.refresh_from_db()
+    post.refresh_from_db()
+
+    assert pre.category.name == "Internal transfer"
+    assert post.category.name == "Investment"
+
+
 @pytest.mark.django_db
 def test_seed_finance_updates_existing_rules_in_place(tmp_path):
     """