diff --git a/src/shared/database/init_db.py b/src/shared/database/init_db.py
index c0c9a4c..b81210c 100644
--- a/src/shared/database/init_db.py
+++ b/src/shared/database/init_db.py
@@ -35,11 +35,15 @@ async def _run_alembic_migrations() -> None:
     - 既有但无 alembic_version（历史 DB）：先 stamp head 基线，再 upgrade（no-op）
     """
     async with db_manager.engine.begin() as conn:
-        has_alembic = await conn.execute(text("SELECT to_regclass('public.alembic_version')")).scalar()
+        # 注意括号：await 优先级低于属性访问，await conn.execute(...).scalar()
+        # 实际是 await (conn.execute(...).scalar())——会在协程对象上调 .scalar()
+        # 直接 AttributeError。必须 (await conn.execute(...)).scalar()。
+        # 曾因漏括号让启动迁移自诞生起一次都没跑通过（2026-09-26 事故根因）。
+        has_alembic = (await conn.execute(text("SELECT to_regclass('public.alembic_version')"))).scalar()
         if not has_alembic:
-            table_count = await conn.execute(
+            table_count = (await conn.execute(
                 text("SELECT count(*) FROM information_schema.tables WHERE table_schema='public' AND table_name <> 'alembic_version'")
-            ).scalar()
+            )).scalar()
             if table_count and table_count > 0:
                 logger.info("检测到既有 DB 未纳入 alembic 管理，自动 stamp head 作为基线")
                 await asyncio.to_thread(_alembic_stamp_head)