Fix (Billing): API usage notification evaluates against actual plan limit instead of cache

api/organisations/task_helpers.py

@@ -125,7 +125,7 @@ def handle_api_usage_notification_for_organisation(organisation: Organisation) -
         month_delta = _get_total_months(relativedelta(now, billing_starts_at))
         period_starts_at = relativedelta(months=month_delta) + billing_starts_at
 
-        allowed_api_calls = subscription_cache.allowed_30d_api_calls
+        allowed_api_calls = organisation.subscription.max_api_calls
 
     openfeature_client = get_openfeature_client()
     # TODO: Default to get_total_events_count — https://github.com/Flagsmith/flagsmith/issues/6985

api/organisations/tasks.py

@@ -131,7 +131,7 @@ def handle_api_usage_notifications() -> None:
         # threshold in the last 30d, it must be below it for the current billing period
         # (which by definition is <30d).
         subscription_information_cache__api_calls_30d__gte=F(
-            "subscription_information_cache__allowed_30d_api_calls"
+            "subscription__max_api_calls"
         )
         * threshold_percentage,
     ).select_related("subscription", "subscription_information_cache"):

api/tests/unit/organisations/test_unit_organisations_tasks.py

@@ -431,6 +431,7 @@ def test_handle_api_usage_notifications__usage_below_100_percent__sends_90_perce
     now = timezone.now()
     organisation.subscription.plan = SCALE_UP
     organisation.subscription.subscription_id = "fancy_id"
+    organisation.subscription.max_api_calls = 100
     organisation.subscription.save()
     OrganisationSubscriptionInformationCache.objects.create(
         organisation=organisation,
@@ -530,6 +531,61 @@ def test_handle_api_usage_notifications__usage_below_100_percent__sends_90_perce
     )
 
 
+@pytest.mark.freeze_time("2023-01-19T09:09:47.325132+00:00")
+def test_handle_api_usage_notifications__stale_cache_lower_than_subscription_limit__sends_no_email(
+    mocker: MockerFixture,
+    organisation: Organisation,
+    mailoutbox: list[EmailMultiAlternatives],
+    enable_features: EnableFeaturesFixture,
+) -> None:
+    # Given
+    now = timezone.now()
+    usage = 95
+    stale_cache_allowance = 100
+    true_subscription_allowance = 50_000
+
+    # 1. Set the TRUE subscription limit to 50,000
+    organisation.subscription.plan = SCALE_UP
+    organisation.subscription.subscription_id = "fancy_id"
+    organisation.subscription.max_api_calls = true_subscription_allowance
+    organisation.subscription.save()
+
+    # 2. Set the STALE cache limit to 100
+    OrganisationSubscriptionInformationCache.objects.create(
+        organisation=organisation,
+        allowed_30d_api_calls=stale_cache_allowance,
+        current_billing_term_starts_at=now - timedelta(days=45),
+        current_billing_term_ends_at=now + timedelta(days=320),
+        api_calls_30d=usage,
+    )
+
+    mock_api_usage = mocker.patch(
+        "organisations.task_helpers.get_current_api_usage",
+    )
+    mock_api_usage.return_value = usage
+    enable_features("api_usage_alerting")
+
+    assert not OrganisationAPIUsageNotification.objects.filter(
+        organisation=organisation,
+    ).exists()
+
+    # When
+    handle_api_usage_notifications()
+
+    # Then
+    # Because usage (95) is evaluated against the true allowance (50,000),
+    # it is < 1%, so no notification should be sent.
+    mock_api_usage.assert_not_called()
+    assert len(mailoutbox) == 0
+
+    assert (
+        OrganisationAPIUsageNotification.objects.filter(
+            organisation=organisation,
+        ).count()
+        == 0
+    )
+
+
 @pytest.mark.freeze_time("2023-01-19T09:09:47.325132+00:00")
 def test_handle_api_usage_notifications__usage_below_alert_thresholds__sends_no_email(
     mocker: MockerFixture,
@@ -592,6 +648,7 @@ def test_handle_api_usage_notifications__usage_above_100_percent__sends_limit_no
     now = timezone.now()
     organisation.subscription.plan = SCALE_UP
     organisation.subscription.subscription_id = "fancy_id"
+    organisation.subscription.max_api_calls = allowance
     organisation.subscription.save()
     OrganisationSubscriptionInformationCache.objects.create(
         organisation=organisation,
@@ -680,6 +737,7 @@ def test_handle_api_usage_notifications__processing_error__logs_error_message(
     now = timezone.now()
     organisation.subscription.plan = SCALE_UP
     organisation.subscription.subscription_id = "fancy_id"
+    organisation.subscription.max_api_calls = 100
     organisation.subscription.save()
     OrganisationSubscriptionInformationCache.objects.create(
         organisation=organisation,
@@ -735,6 +793,8 @@ def test_handle_api_usage_notifications__free_account_over_limit__sends_limit_no
     assert organisation.is_paid is False
     assert organisation.subscription.is_free_plan is True
     assert organisation.subscription.max_api_calls == MAX_API_CALLS_IN_FREE_PLAN
+    organisation.subscription.max_api_calls = MAX_API_CALLS_IN_FREE_PLAN
+    organisation.subscription.save()
 
     OrganisationSubscriptionInformationCache.objects.create(
         organisation=organisation,