diff --git a/src/blackboard/db.py b/src/blackboard/db.py
index 6d48f73..1e46d40 100644
--- a/src/blackboard/db.py
+++ b/src/blackboard/db.py
@@ -179,7 +179,7 @@ MANUAL_STATUSES = frozenset({"cancelled", "paused"})
 VALID_TRANSITIONS = {
     "pending":       {"claimed", "paused", "blocked", "cancelled"},
     "claimed":       {"working", "paused", "pending", "cancelled"},
-    "working":       {"review", "done", "blocked", "failed", "paused", "escalated", "waiting_human", "cancelled"},
+    "working":       {"review", "done", "blocked", "failed", "paused", "escalated", "waiting_human", "cancelled", "pending"},  # pending: Mail spawn 失败回退
     "paused":        {"working", "claimed", "review", "escalated", "waiting_human", "cancelled"},  # 恢复到 resumed_from 记录的状态
     "review":        {"done", "pending", "failed", "paused", "escalated", "waiting_human", "cancelled"},
     "blocked":       {"pending", "escalated", "cancelled"},
diff --git a/src/daemon/dispatcher.py b/src/daemon/dispatcher.py
index d8c7023..44434f2 100644
--- a/src/daemon/dispatcher.py
+++ b/src/daemon/dispatcher.py
@@ -570,7 +570,7 @@ class Dispatcher:
                     conn.commit()
                     logger.info("Mail %s: reverted working → pending (spawn failed)", task_id)
                 else:
-                    logger.debug("Mail %s: skip revert (status=%s)", task_id, row["status"] if row else "?")
+                    logger.debug("Mail %s: skip revert (status=%s, expected working)", task_id, row["status"] if row else "not_found")
             finally:
                 conn.close()
         except Exception as e: