diff --git a/scripts/retrain_from_label_studio.sh b/scripts/retrain_from_label_studio.sh
index 6f8eec8..2e3edbb 100755
--- a/scripts/retrain_from_label_studio.sh
+++ b/scripts/retrain_from_label_studio.sh
@@ -44,7 +44,11 @@ echo "--- 3/4 训练 -> $WORK_DIR"
 echo "--- 4/4 切换权重并重启 ML backend"
 # 指向最新权重的稳定软链接：启动脚本读它，于是换模型不用改任何脚本
 ln -sfn "$WORK_DIR/weights/best.pt" "$REPO/runs/detect/current.pt"
-bash "$REPO/scripts/start_ml_backend.sh"
+# 必须显式传 YOLO_WEIGHTS 并清掉继承来的变量：本脚本是旧后端的子进程，
+# 它环境里已经 export 了 YOLO_WEIGHTS（旧权重）和可能的 RETRAIN_EXTRA_SET（冒烟参数），
+# 不清掉的话新后端会继续用旧模型、下次训练也会沿用冒烟参数
+env -u RETRAIN_EXTRA_SET YOLO_WEIGHTS="$REPO/runs/detect/current.pt" \
+    bash "$REPO/scripts/start_ml_backend.sh"
 
 echo "===== [$(date '+%F %T')] 重训完成：$WORK_DIR ====="
 echo "指标见 $WORK_DIR/metrics.json，曲线见 $WORK_DIR/results.png"