diff --git a/pipeline_service/init.py b/pipeline_service/init.py
index 79667b4..62f25a7 100644
--- a/pipeline_service/init.py
+++ b/pipeline_service/init.py
@@ -379,7 +379,9 @@ _WORKDIR_FALLBACK = '/tmp/pipeline_workspaces'
 
 def _resolve_workdir():
     """选择可写的工作目录根。"""
-    if os.path.isdir(_SHELL_BASE_DIR) or os.access(os.path.dirname(_SHELL_BASE_DIR), os.W_OK):
+    parent = os.path.dirname(_SHELL_BASE_DIR)
+    if os.path.isdir(parent) and os.access(parent, os.W_OK):
+        os.makedirs(_SHELL_BASE_DIR, exist_ok=True)
         return _SHELL_BASE_DIR
     os.makedirs(_WORKDIR_FALLBACK, exist_ok=True)
     return _WORKDIR_FALLBACK