diff --git a/src/blackboard/operations.py b/src/blackboard/operations.py
index 59c058c..91e76a0 100644
--- a/src/blackboard/operations.py
+++ b/src/blackboard/operations.py
@@ -133,6 +133,11 @@ class Blackboard:
                     conn.execute("SELECT retry_count FROM tasks WHERE id=?",
                                  (task_id,)).fetchone()["retry_count"] + 1
                 )
+                # BUG-1: failed→pending 必须清空 assignee/claimed_at/current_agent
+                # 否则 dispatcher 会走确定性路由而非广播
+                updates["assignee"] = None
+                updates["claimed_at"] = None
+                updates["current_agent"] = None
 
             set_clause = ", ".join(f"{k}=?" for k in updates)
             conn.execute(