diff --git a/app/infrastructure/repositories.py b/app/infrastructure/repositories.py
index 8e91897..dfd6be8 100644
--- a/app/infrastructure/repositories.py
+++ b/app/infrastructure/repositories.py
@@ -3353,6 +3353,11 @@ _SHARED_ENGINES: dict[str, "object"] = {}
 
 
 def _shared_engine(url: str):
+    # 统一引擎：主库 URL 直接复用 db 模块级单例 engine（同一进程同一 URL 只有一个
+    # 连接池，避免多 engine 多池叠加导致连接数倍增 / 池不互济再满载）。
+    if url == config.DATABASE_URL:
+        from .db import engine as _main_engine
+        return _main_engine
     eng = _SHARED_ENGINES.get(url)
     if eng is None:
         from .db import make_async_engine
diff --git a/app/park/tenants.py b/app/park/tenants.py
index 22b96b7..fd812ec 100644
--- a/app/park/tenants.py
+++ b/app/park/tenants.py
@@ -41,7 +41,9 @@ _ASYNC_ENGINE = None
 def _get_session() -> AsyncSession:
     global _ASYNC_ENGINE
     if _ASYNC_ENGINE is None:
-        _ASYNC_ENGINE = make_async_engine(DATABASE_URL)
+        # 统一引擎：复用 db 模块级单例 engine（同一 URL 同一池，不另开池）
+        from ..infrastructure.db import engine as _main_engine
+        _ASYNC_ENGINE = _main_engine
     return async_sessionmaker(bind=_ASYNC_ENGINE, expire_on_commit=False)()