diff --git a/B04_PreProcess/B04_PreProcess_Router_Basins.py b/B04_PreProcess/B04_PreProcess_Router_Basins.py
index 6130b2962..e382f6929 100644
--- a/B04_PreProcess/B04_PreProcess_Router_Basins.py
+++ b/B04_PreProcess/B04_PreProcess_Router_Basins.py
@@ -494,7 +494,7 @@ async def _resolve(
     saved = requested is None and stored is not None
 
     if analysis_route_signature(context.stored_path) != signature:
-        if points is None:
+        if points is None or auto is not None:  # 자동 자리 = 지금 노선 분석이 있어야(369)
             return JSONResponse(
                 status_code=409, content={"status": "stale", "message": STALE_MESSAGE}
             )
diff --git a/resources/tester/test_369_drainage_auto.py b/resources/tester/test_369_drainage_auto.py
index 7c9109869..2022901a8 100644
--- a/resources/tester/test_369_drainage_auto.py
+++ b/resources/tester/test_369_drainage_auto.py
@@ -115,3 +115,19 @@ def test_틀린_auto_는_400_열쇠에_auto(tmp_path, monkeypatch):
     points = [PipePoint(chainage_m=20.0)]
     keys = {basins._detail_key(CONTEXT, points, auto) for auto in basins.AUTO_MODES}
     assert len(keys) == 3
+
+
+def test_낡은_분석에_auto_는_409(monkeypatch):
+    async def load(project_id):
+        return CONTEXT, ""
+
+    monkeypatch.setattr(basins, "load_drainage_context", load)
+    monkeypatch.setattr(basins, "analysis_route_signature", lambda stored: "옛 노선")
+    points = [{"chainage_m": 20.0}]
+    for auto in ("all", "add"):
+        result = asyncio.run(
+            basins._resolve(uuid4(), {"points": points, "auto": auto}, use_stored=False)
+        )
+        assert result.status_code == 409  # 말없이 그대로 돌려주지 않음 — 낡음 까닭
+    kept = asyncio.run(basins._resolve(uuid4(), {"points": points}, use_stored=False))
+    assert kept[-1] is True  # auto 없음 = 관 자리만 낡음으로(그대로)