diff --git a/tests/orchestration/test_abri_log_job_orchestrator.py b/tests/orchestration/test_abri_log_job_orchestrator.py
index 689dc99d9..4673726d9 100644
--- a/tests/orchestration/test_abri_log_job_orchestrator.py
+++ b/tests/orchestration/test_abri_log_job_orchestrator.py
@@ -1,3 +1,5 @@
+import json
+import traceback
 import xml.etree.ElementTree as ET
 from datetime import date
 from pathlib import Path
@@ -6,6 +8,7 @@ from unittest.mock import MagicMock, patch
 
 import pytest
 import requests
+from hubspot.crm.deals import ApiException as DealsApiException  # type: ignore[reportMissingTypeStubs]
 from hubspot.crm.deals import SimplePublicObjectInput  # type: ignore[reportMissingTypeStubs]
 
 from domain.abri.models import AbriRequestRejected, PlaceRef
@@ -17,6 +20,7 @@ from orchestration.abri_log_job_orchestrator import (
     AbriLogJobOrchestrator,
     ConfirmedSurveyBooking,
     LogJobSummary,
+    LogJobWriteBackError,
 )
 
 FIXTURE_DIR = Path(__file__).parents[1] / "abri"
@@ -221,3 +225,70 @@ def test_run_raises_a_transport_error_when_the_relay_is_unreachable(
         orchestrator.run(BOOKING)
     assert sdk_client.mock_calls == []
     assert deal_database.recorded_job_nos == []
+
+
+# --- partial failure: job logged in OpenHousing, HubSpot write failed ---
+
+
+def _body_echoing_api_error() -> DealsApiException:
+    """A HubSpot validation error whose body echoes the submitted values."""
+    api_error = DealsApiException(status=400, reason="Bad Request")
+    api_error.body = json.dumps(
+        {
+            "status": "error",
+            "message": 'Invalid value "AD0226519" for client_booking_reference',
+            "correlationId": "corr-abc-123",
+            "category": "VALIDATION_ERROR",
+        }
+    )
+    api_error.headers = {}
+    return api_error
+
+
+def test_run_raises_an_error_carrying_the_orphaned_job_no_when_the_hubspot_write_fails(
+    orchestrator: AbriLogJobOrchestrator,
+    mock_session: MagicMock,
+    sdk_client: MagicMock,
+    deal_database: FakeDealDatabase,
+) -> None:
+    # Arrange
+    mock_session.post.return_value.content = _load_fixture(
+        "abri_relay_logjob_success_response.xml"
+    )
+    sdk_client.crm.deals.basic_api.update.side_effect = _body_echoing_api_error()
+
+    # Act
+    with pytest.raises(LogJobWriteBackError) as exc_info:
+        orchestrator.run(BOOKING)
+
+    # Assert: the orphaned job_no is reported for manual paste-in, the
+    # database write is skipped, and log_job is never retried.
+    error = exc_info.value
+    assert error.deal_id == DEAL_ID
+    assert error.job_no == "AD0226519"
+    assert "AD0226519" in str(error)
+    assert deal_database.recorded_job_nos == []
+    assert mock_session.post.call_count == 1
+
+
+def test_run_raises_a_write_back_error_scrubbed_of_the_hubspot_response_body(
+    orchestrator: AbriLogJobOrchestrator,
+    mock_session: MagicMock,
+    sdk_client: MagicMock,
+) -> None:
+    # Arrange
+    mock_session.post.return_value.content = _load_fixture(
+        "abri_relay_logjob_success_response.xml"
+    )
+    sdk_client.crm.deals.basic_api.update.side_effect = _body_echoing_api_error()
+
+    # Act
+    with pytest.raises(LogJobWriteBackError) as exc_info:
+        orchestrator.run(BOOKING)
+
+    # Assert: non-PII diagnostics survive; the echoed body does not
+    rendered_traceback = "".join(traceback.format_exception(exc_info.value))
+    assert "400" in str(exc_info.value)
+    assert "VALIDATION_ERROR" in str(exc_info.value)
+    assert "corr-abc-123" in str(exc_info.value)
+    assert "Invalid value" not in rendered_traceback