diff --git a/tests/infrastructure/abri/test_abri_client.py b/tests/infrastructure/abri/test_abri_client.py
index ab8f3d87c..55aa5deb5 100644
--- a/tests/infrastructure/abri/test_abri_client.py
+++ b/tests/infrastructure/abri/test_abri_client.py
@@ -293,3 +293,30 @@ def test_amend_job_returns_rejection_with_openhousing_error_code_and_message_ver
         code="RelayError",
         message="Job_no 1019905 is invalid. Job not found.",
     )
+
+
+# --- amend_job: ambiguous responses are retriable, never success or rejection ---
+
+
+@pytest.mark.parametrize(
+    "body",
+    [
+        b'<Root><AmendOptiAppt appointment_date="24/06/2026"'
+        b' appointment_time="PM" job_no="AC0439951" success="N" /></Root>',
+        b'<Root><AmendOptiAppt appointment_date="24/06/2026"'
+        b' appointment_time="PM" job_no="AC0439951" /></Root>',
+        b'<Root><AmendOptiAppt appointment_date="24/06/2026"'
+        b' appointment_time="PM" success="Y" /></Root>',
+        b"<Root></Root>",
+        b"<unexpected />",
+    ],
+)
+def test_amend_job_raises_retriable_parse_error_when_the_amendment_is_unconfirmed(
+    client: AbriClient, mock_session: MagicMock, body: bytes
+) -> None:
+    # Arrange
+    mock_session.post.return_value.content = body
+
+    # Act / Assert
+    with pytest.raises(AbriResponseParseError):
+        client.amend_job(_spec_example_amend_request())