diff --git a/backend/app/services/jira_service.py b/backend/app/services/jira_service.py
index e68fe75..96796b1 100644
--- a/backend/app/services/jira_service.py
+++ b/backend/app/services/jira_service.py
@@ -1246,14 +1246,6 @@ def _jira_datetime(dt: datetime) -> str:
     return dt.strftime("%Y-%m-%dT%H:%M:%S.000+0000")
 
 
-def _compute_hours(start: Optional[datetime], end: Optional[datetime]) -> Optional[float]:
-    """Return the elapsed time between two timestamps in hours, or None if unavailable."""
-    if not start or not end:
-        return None
-    delta_hours = (end - start).total_seconds() / 3600
-    return round(delta_hours, 2) if delta_hours >= 0 else None
-
-
 def _update_test_fields(db: Session, test: Test, fields: dict) -> None:
     """Best-effort update of custom fields on the Jira issue linked to *test*.
 
@@ -1343,7 +1335,15 @@ def push_bt_started(db: Session, test: Test) -> None:
 
 
 def push_bt_submitted(db: Session, test: Test) -> None:
-    """Set BT End Date, Attack Detected/Contained, and time-to-detect/contain — Blue submits for review."""
+    """Set BT End Date, Attack Detected/Contained, and Time to Detect/Contain — Blue submits for review.
+
+    Time to Detect / Time to Contain are Jira **datetime** fields (confirmed
+    via issue_editmeta), not numeric duration fields — despite the name.
+    This used to push a computed hour count, which Jira rejected outright;
+    since Jira validates the whole fields payload atomically, that one bad
+    field silently sank BT End Date and Attack Detected too. Now pushes the
+    actual detection_time/containment_time timestamps.
+    """
     fields: dict = {JIRA_FIELD_BT_END_DATE: _jira_datetime(datetime.utcnow())}
 
     detection_result = _enum_value(test.detection_result)
@@ -1354,13 +1354,11 @@ def push_bt_submitted(db: Session, test: Test) -> None:
     if containment_result in _CONTAINMENT_TO_JIRA:
         fields[JIRA_FIELD_ATTACK_CONTAINED] = _select_field(_CONTAINMENT_TO_JIRA[containment_result])
 
-    time_to_detect = _compute_hours(test.execution_end_time, test.detection_time)
-    if time_to_detect is not None:
-        fields[JIRA_FIELD_TIME_TO_DETECT] = time_to_detect
+    if test.detection_time:
+        fields[JIRA_FIELD_TIME_TO_DETECT] = _jira_datetime(test.detection_time)
 
-    time_to_contain = _compute_hours(test.detection_time, test.containment_time)
-    if time_to_contain is not None:
-        fields[JIRA_FIELD_TIME_TO_CONTAIN] = time_to_contain
+    if test.containment_time:
+        fields[JIRA_FIELD_TIME_TO_CONTAIN] = _jira_datetime(test.containment_time)
 
     _update_test_fields(db, test, fields)
 
diff --git a/backend/tests/test_jira_service.py b/backend/tests/test_jira_service.py
index b44aba1..7143cf5 100644
--- a/backend/tests/test_jira_service.py
+++ b/backend/tests/test_jira_service.py
@@ -570,15 +570,18 @@ def test_push_rt_submitted_rt_start_date_survives_reopen(mock_get_client, mock_c
 
 @patch("app.services.jira_service.has_admin_jira_configured", return_value=True)
 @patch("app.services.jira_service.get_admin_jira_client")
-def test_push_bt_submitted_includes_detection_and_hours(mock_get_client, mock_configured, db):
+def test_push_bt_submitted_includes_detection_and_timestamps(mock_get_client, mock_configured, db):
+    """Regression: Time to Detect / Time to Contain are Jira *datetime*
+    fields, not numeric hour counts — pushing a computed duration made Jira
+    reject the whole fields payload (atomic validation), silently sinking
+    BT End Date and Attack Detected too even though only these two were
+    actually wrong."""
     mock_jira = MagicMock()
     mock_get_client.return_value = mock_jira
-    exec_end = datetime(2026, 1, 1, 10, 0, 0)
     detect = datetime(2026, 1, 1, 12, 0, 0)
     contain = datetime(2026, 1, 1, 13, 30, 0)
     test = _make_test(
         detection_result=MagicMock(value="detected"),
-        execution_end_time=exec_end,
         detection_time=detect,
         containment_time=contain,
     )
@@ -590,8 +593,8 @@ def test_push_bt_submitted_includes_detection_and_hours(mock_get_client, mock_co
 
     fields = mock_jira.update_issue_field.call_args[1]["fields"]
     assert fields[jira_service.JIRA_FIELD_ATTACK_DETECTED] == {"value": "Yes"}
-    assert fields[jira_service.JIRA_FIELD_TIME_TO_DETECT] == 2.0
-    assert fields[jira_service.JIRA_FIELD_TIME_TO_CONTAIN] == 1.5
+    assert fields[jira_service.JIRA_FIELD_TIME_TO_DETECT] == "2026-01-01T12:00:00.000+0000"
+    assert fields[jira_service.JIRA_FIELD_TIME_TO_CONTAIN] == "2026-01-01T13:30:00.000+0000"
 
 
 @patch("app.services.jira_service.has_admin_jira_configured", return_value=True)