feat(cache): add targeted server-side response caching

apps/workspaces/tests/test_rates.py

@@ -1,5 +1,6 @@
 from decimal import Decimal
 
+from django.core.cache import cache
 from django.test import TestCase
 from rest_framework.test import APITestCase
 
@@ -53,6 +54,9 @@ class WorkspaceRateTests(APITestCase):
             symbol="EUR",
         )
 
+    def setUp(self):
+        cache.clear()
+
     def test_resolve_rate_uses_workspace_user_rate(self):
         WorkspaceUserRate.objects.create(
             workspace=self.workspace,
@@ -122,6 +126,72 @@ class WorkspaceRateTests(APITestCase):
 
         self.assertEqual(response.status_code, 403)
 
+    def test_workspace_user_rates_cache_invalidates_after_rate_save(self):
+        rate = WorkspaceUserRate.objects.create(
+            workspace=self.workspace,
+            user=self.member,
+            hourly_rate=Decimal("30.00"),
+            currency="USD",
+            effective_from=self.workspace.created_at,
+            is_active=True,
+        )
+        self.client.force_authenticate(user=self.admin)
+
+        first_response = self.client.get(
+            "/api/workspace-user-rates/",
+            {"workspace": str(self.workspace.id)},
+        )
+        self.assertEqual(first_response.status_code, 200)
+        self.assertEqual(first_response.data["items"][0]["hourly_rate"], "30.00")
+
+        WorkspaceUserRate.objects.filter(id=rate.id).update(hourly_rate=Decimal("45.00"))
+
+        cached_response = self.client.get(
+            "/api/workspace-user-rates/",
+            {"workspace": str(self.workspace.id)},
+        )
+        self.assertEqual(cached_response.status_code, 200)
+        self.assertEqual(cached_response.data["items"][0]["hourly_rate"], "30.00")
+
+        rate.refresh_from_db()
+        rate.currency = "EUR"
+        rate.save(update_fields=["currency"])
+
+        fresh_response = self.client.get(
+            "/api/workspace-user-rates/",
+            {"workspace": str(self.workspace.id)},
+        )
+        self.assertEqual(fresh_response.status_code, 200)
+        self.assertEqual(fresh_response.data["items"][0]["hourly_rate"], "45.00")
+        self.assertEqual(fresh_response.data["items"][0]["currency"], "EUR")
+
+    def test_price_unit_cache_invalidates_after_price_unit_create(self):
+        self.client.force_authenticate(user=self.owner)
+
+        first_response = self.client.get("/api/price-units/")
+        self.assertEqual(first_response.status_code, 200)
+        self.assertEqual(first_response.data[0]["name"], "Euro")
+        self.assertEqual(len(first_response.data), 2)
+
+        PriceUnit.objects.filter(code="EUR").update(name="Updated Euro")
+
+        cached_response = self.client.get("/api/price-units/")
+        self.assertEqual(cached_response.status_code, 200)
+        self.assertEqual(cached_response.data[0]["name"], "Euro")
+
+        PriceUnit.objects.create(
+            code="GBP",
+            name="British Pound",
+            local_name="Pound",
+            symbol="£",
+        )
+
+        fresh_response = self.client.get("/api/price-units/")
+        self.assertEqual(fresh_response.status_code, 200)
+        self.assertEqual(len(fresh_response.data), 3)
+        euro_row = next(item for item in fresh_response.data if item["code"] == "EUR")
+        self.assertEqual(euro_row["name"], "Updated Euro")
+
 
 class WorkspaceRateServiceTests(TestCase):
     @classmethod