diff --git a/plugins/platforms/feishu/adapter.py b/plugins/platforms/feishu/adapter.py
index 14ab109162..041ff06c41 100644
--- a/plugins/platforms/feishu/adapter.py
+++ b/plugins/platforms/feishu/adapter.py
@@ -4768,10 +4768,18 @@ class FeishuAdapter(BasePlatformAdapter):
         # same way #83906 did for the other gateway persist paths. The lock
         # keeps flushes in mutation order (the snapshot inside the worker is
         # taken under _dedup_lock, but the write itself is not).
-        async with self._dedup_persist_lock:
+        async with self._dedup_persist_lock_or_create():
             await asyncio.to_thread(self._persist_seen_message_ids)
         return False
 
+    def _dedup_persist_lock_or_create(self) -> asyncio.Lock:
+        # Tests build bare adapters via object.__new__ and install dedup state
+        # by hand; create the lock lazily so those fixtures keep working.
+        lock = getattr(self, "_dedup_persist_lock", None)
+        if lock is None:
+            lock = self._dedup_persist_lock = asyncio.Lock()
+        return lock
+
     # =========================================================================
     # Outbound payload construction and send pipeline
     # =========================================================================
diff --git a/tests/gateway/feishu_helpers.py b/tests/gateway/feishu_helpers.py
index 97771daaa3..f9b7822a21 100644
--- a/tests/gateway/feishu_helpers.py
+++ b/tests/gateway/feishu_helpers.py
@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import asyncio
 import threading
 from types import SimpleNamespace
 from typing import Any, Optional
@@ -59,6 +60,7 @@ def install_dedup_state(adapter: Any, seen: Optional[dict] = None) -> None:
     adapter._seen_message_order = list((seen or {}).keys())
     adapter._dedup_cache_size = 100
     adapter._dedup_lock = threading.Lock()
+    adapter._dedup_persist_lock = asyncio.Lock()
     adapter._dedup_state_path = None
     adapter._persist_seen_message_ids = lambda: None