diff --git a/tests/applications/abri/test_abri_trigger_request.py b/tests/applications/abri/test_abri_trigger_request.py
index 928c6973a..134264458 100644
--- a/tests/applications/abri/test_abri_trigger_request.py
+++ b/tests/applications/abri/test_abri_trigger_request.py
@@ -115,6 +115,41 @@ def test_a_blank_surveyor_identifier_is_treated_as_missing(blank: str) -> None:
         AbriTriggerRequest.model_validate(message)
 
 
+def test_a_message_carries_the_client_booking_reference() -> None:
+    # The Job Number OpenHousing returns on a successful log; the consumer
+    # reads it to tell "job exists" (amend/abandon) from "never logged" (log).
+    message = _full_message()
+    message["client_booking_reference"] = "AD0226519"
+
+    # Act
+    request = AbriTriggerRequest.model_validate(message)
+
+    # Assert
+    assert request.client_booking_reference == "AD0226519"
+
+
+@pytest.mark.parametrize("blank", ["", "   "])
+def test_a_blank_client_booking_reference_is_treated_as_missing(blank: str) -> None:
+    # A blank reference means no Job Number: the consumer must treat it as
+    # "never logged / reference lost", not "job exists".
+    message = _full_message()
+    message["client_booking_reference"] = blank
+
+    # Act
+    request = AbriTriggerRequest.model_validate(message)
+
+    # Assert
+    assert request.client_booking_reference is None
+
+
+def test_a_message_without_a_client_booking_reference_defaults_to_none() -> None:
+    # Act
+    request = AbriTriggerRequest.model_validate(_full_message())
+
+    # Assert
+    assert request.client_booking_reference is None
+
+
 def test_a_message_carries_the_outcome_for_the_abandonment_reason_mapping() -> None:
     # Arrange
     message = _full_message()