feat: Make decline-all endpoint support decline reason

enterprise_access/apps/api/serializers/subsidy_requests.py

@@ -404,6 +404,12 @@ class LearnerCreditRequestDeclineAllSerializer(serializers.Serializer):  # pylin
         required=True,
         help_text="The UUID of the SubsidyAccessPolicy to filter requests by."
     )
+    decline_reason = serializers.CharField(
+        required=False,
+        allow_blank=True,
+        allow_null=True,
+        help_text="Reason for declining all matching requests.",
+    )
 
 
 # pylint: disable=abstract-method

enterprise_access/apps/api/v1/tests/test_browse_and_request_views.py

@@ -4625,6 +4625,32 @@ def test_decline_all_success(self, _mock_decline_notification_task):
         self.assertEqual(len(results['declined']), 5)
         self.assertEqual(len(results['non_declinable']), 0)
 
+    @mock.patch('enterprise_access.apps.subsidy_request.api.send_learner_credit_bnr_decline_notification_task')
+    def test_decline_all_forwards_decline_reason(self, _mock_decline_notification_task):
+        """Test decline_all persists decline_reason on each declined request."""
+        self.set_jwt_cookie([{
+            'system_wide_role': SYSTEM_ENTERPRISE_ADMIN_ROLE,
+            'context': str(self.enterprise_customer_uuid_1)
+        }])
+
+        response = self.client.post(
+            reverse('api:v1:learner-credit-requests-decline-all'),
+            data={
+                'policy_uuid': str(self.policy.uuid),
+                'enterprise_customer_uuid': str(self.enterprise_customer_uuid_1),
+                'decline_reason': 'Budget constraints for Q2',
+            },
+            content_type='application/json',
+        )
+
+        self.assertEqual(response.status_code, status.HTTP_202_ACCEPTED)
+        self.user_request_1.refresh_from_db()
+        self.user_request_2.refresh_from_db()
+        self.enterprise_request.refresh_from_db()
+        self.assertEqual(self.user_request_1.decline_reason, 'Budget constraints for Q2')
+        self.assertEqual(self.user_request_2.decline_reason, 'Budget constraints for Q2')
+        self.assertEqual(self.enterprise_request.decline_reason, 'Budget constraints for Q2')
+
     def test_decline_all_no_declinable_requests(self):
         """Test decline_all returns 404 when no declinable requests exist."""
         self.set_jwt_cookie([{

enterprise_access/apps/api/v1/views/browse_and_request.py

@@ -1442,6 +1442,7 @@ def decline_all(self, request, *args, **kwargs):
             result = subsidy_request_api.decline_learner_credit_requests(
                 learner_credit_requests,
                 reviewer=request.user,
+                reason=serializer.validated_data.get('decline_reason'),
             )
             response_data = {
                 'declined': [str(r.uuid) for r in result.get('declined', [])],