feat(reports): load user summaries on demand

apps/reports/tests/test_views.py

@@ -10,7 +10,7 @@ from apps.projects.models import Project
 from apps.tags.models import Tag
 from apps.time_entries.models import TimeEntry
 from apps.users.models import User
-from apps.workspaces.models import Workspace, WorkspaceMembership
+from apps.workspaces.models import Workspace, WorkspaceMembership, WorkspaceUserRate
 
 
 class ReportViewTests(APITestCase):
@@ -320,6 +320,75 @@ class ReportViewTests(APITestCase):
             {"amount": "35.00", "currency": "USD"},
         )
 
+    def test_user_summary_endpoint_keeps_workspace_rate_history_and_marks_current_row_open(self):
+        self.client.force_authenticate(user=self.owner)
+
+        TimeEntry.objects.create(
+            workspace=self.workspace,
+            user=self.owner,
+            project=None,
+            description="Legacy workspace rate",
+            start_time="2026-04-08T08:00:00+03:30",
+            end_time="2026-04-08T09:00:00+03:30",
+            duration=timedelta(hours=1),
+            is_billable=True,
+            hourly_rate=Decimal("12.00"),
+            currency="USD",
+        )
+        TimeEntry.objects.create(
+            workspace=self.workspace,
+            user=self.owner,
+            project=self.project,
+            description="Current project rate",
+            start_time="2026-04-12T08:00:00+03:30",
+            end_time="2026-04-12T10:00:00+03:30",
+            duration=timedelta(hours=2),
+            is_billable=True,
+            hourly_rate=Decimal("25.00"),
+            currency="USD",
+        )
+        WorkspaceUserRate.objects.create(
+            workspace=self.workspace,
+            user=self.owner,
+            hourly_rate=Decimal("12.00"),
+            currency="USD",
+            effective_from="2026-04-01T00:00:00+03:30",
+            is_active=True,
+        )
+
+        with patch(
+            "apps.reports.services.aggregation.timezone.localdate",
+            return_value=date(2026, 4, 20),
+        ):
+            response = self.client.get(
+                "/api/reports/user-summary/",
+                {
+                    "workspace": str(self.workspace.id),
+                    "period": "this_month",
+                    "user": str(self.owner.id),
+                },
+            )
+
+        self.assertEqual(response.status_code, 200)
+        rate_periods = response.data["user_summary"]["rate_periods"]
+        self.assertEqual(
+            rate_periods,
+            [
+                {
+                    "amount": "12.00",
+                    "currency": "USD",
+                    "from_date": "2026-04-08",
+                    "to_date": None,
+                },
+                {
+                    "amount": "25.00",
+                    "currency": "USD",
+                    "from_date": "2026-04-10",
+                    "to_date": "2026-04-12",
+                },
+            ],
+        )
+
     def test_custom_period_longer_than_31_days_is_rejected(self):
         self.client.force_authenticate(user=self.owner)