diff --git a/apps/api/src/services/channel_hub.py b/apps/api/src/services/channel_hub.py
index 4d61830c..facf0395 100644
--- a/apps/api/src/services/channel_hub.py
+++ b/apps/api/src/services/channel_hub.py
@@ -523,7 +523,7 @@ async def record_outbound_message(
                 :redaction_version, CAST(:source_envelope AS jsonb),
                 :provider_message_id,
                 :send_status, NOW(),
-                CASE WHEN :send_status = 'sent' THEN NOW() ELSE NULL END,
+                CASE WHEN CAST(:send_status AS text) = 'sent' THEN NOW() ELSE NULL END,
                 :triggered_by_state, :waiting_since
             )
             RETURNING message_id
diff --git a/apps/api/tests/test_channel_hub_grouped_alert_events.py b/apps/api/tests/test_channel_hub_grouped_alert_events.py
index 230b3e75..44e23b4a 100644
--- a/apps/api/tests/test_channel_hub_grouped_alert_events.py
+++ b/apps/api/tests/test_channel_hub_grouped_alert_events.py
@@ -132,5 +132,5 @@ async def test_record_outbound_message_sets_sent_at_for_sent_messages() -> None:
 
     insert_statement = session.statements[-1]
     assert "sent_at" in insert_statement
-    assert "CASE WHEN :send_status = 'sent' THEN NOW() ELSE NULL END" in insert_statement
+    assert "CASE WHEN CAST(:send_status AS text) = 'sent' THEN NOW() ELSE NULL END" in insert_statement
     assert session.param_sets[-1]["send_status"] == "sent"
diff --git a/docs/LOGBOOK.md b/docs/LOGBOOK.md
index aceee09d..0a3d5209 100644
--- a/docs/LOGBOOK.md
+++ b/docs/LOGBOOK.md
@@ -7304,4 +7304,9 @@ python -m py_compile src/services/channel_hub.py src/services/telegram_gateway.p
 OK
 ```
 
+**production smoke 途中補修**：
+
+- rollback transaction smoke 抓到 asyncpg bind parameter 型別推論問題：`CASE WHEN :send_status = 'sent'` 會被推成 text/varchar ambiguous。
+- 已改成 `CASE WHEN CAST(:send_status AS text) = 'sent' THEN NOW() ELSE NULL END`，避免 outbound mirror 在 production 寫入時失敗。
+
 **目前整體進度**：約 69%。