diff --git a/bioflow_service/app/main.py b/bioflow_service/app/main.py
index aa04d66..9bced0c 100644
--- a/bioflow_service/app/main.py
+++ b/bioflow_service/app/main.py
@@ -10,6 +10,13 @@
 from __future__ import annotations
 
 import logging
+from pathlib import Path
+
+from dotenv import load_dotenv
+
+# 把 bioflow_service/.env 注入 os.environ（llm.py 等模块直读 DOCGEN_LLM_*，
+# 不走 pydantic-settings 的 env_file，避免「.env 配了但 os.environ 读不到」的配置断层）。
+load_dotenv(Path(__file__).resolve().parent.parent / ".env")
 from contextlib import asynccontextmanager
 
 from fastapi import FastAPI