fix: improve maintenance and synchronize live conversations

backend/tests/services/test_ticket_service.py

@@ -15,6 +15,7 @@ limitations under the License.
 """
 
 from unittest.mock import patch
+from datetime import datetime, timezone
 from uuid import uuid4
 
 import pytest
@@ -28,7 +29,7 @@ from app.models.ticket import (
     TicketSource,
     TicketStatus,
 )
-from app.models.ticket_activity import TicketActivity, TicketActivityType, TicketActorType
+from app.models.ticket_activity import TicketActivityType, TicketActorType
 from app.services.ticket import NATIVE_INTEGRATION_TYPE, TicketService, render_customer_template
 
 
@@ -315,6 +316,34 @@ class TestCustomerEmailPath:
         row = db.query(ChatHistory).filter_by(session_id=test_session.session_id).one()
         assert deliver.await_args.kwargs["message_id"] == row.id
         assert row.attributes["delivery_status"] == "window_expired"
+        assert ticket.first_response_at is None
+        assert TicketActivityType.CUSTOMER_NOTIFIED.value not in [
+            activity.activity_type
+            for activity in service.activity_repo.list_for_ticket(ticket.id)
+        ]
+
+    @pytest.mark.asyncio
+    async def test_refused_channel_reply_preserves_an_existing_first_response(
+        self, service, db, test_organization, test_session
+    ):
+        test_session.channel = "whatsapp"
+        db.commit()
+        ticket = make_ticket(service, db, test_organization, session_id=test_session.session_id)
+        prior_response = datetime(2026, 10, 1, tzinfo=timezone.utc)
+        ticket.first_response_at = prior_response
+        db.commit()
+        db.refresh(ticket)
+        prior_response = ticket.first_response_at
+        refused = DeliveryResult(ok=False, reason="window_expired", can_template=True)
+
+        with patch("app.services.ticket.deliver_to_customer", return_value=refused):
+            await service.send_customer_message(ticket, "Your refund is on its way")
+
+        assert ticket.first_response_at == prior_response
+        assert TicketActivityType.CUSTOMER_NOTIFIED.value not in [
+            activity.activity_type
+            for activity in service.activity_repo.list_for_ticket(ticket.id)
+        ]
 
     @pytest.mark.asyncio
     async def test_a_send_that_raises_is_marked_undelivered(