diff --git a/pageindex/config.yaml b/pageindex/config.yaml
index e7c13e5..591fe93 100644
--- a/pageindex/config.yaml
+++ b/pageindex/config.yaml
@@ -7,5 +7,4 @@ max_token_num_each_node: 20000
 if_add_node_id: "yes"
 if_add_node_summary: "yes"
 if_add_doc_description: "no"
-if_add_node_text: "no"
-pdf_parser: "PyPDF2"  # text extractor: "PyPDF2" (default, no extra install), "pypdfium2" (pip install pypdfium2), or "PyMuPDF"
\ No newline at end of file
+if_add_node_text: "no"
\ No newline at end of file
diff --git a/pageindex/utils.py b/pageindex/utils.py
index 5c73a62..a5adc54 100644
--- a/pageindex/utils.py
+++ b/pageindex/utils.py
@@ -685,10 +685,14 @@ def format_structure(structure, order=None):
 
 
 class ConfigLoader:
+    # Code-side defaults for non-tuning settings (kept out of config.yaml).
+    # yaml entries override these if present.
+    _CODE_DEFAULTS = {"pdf_parser": "PyPDF2"}
+
     def __init__(self, default_path: str = None):
         if default_path is None:
             default_path = Path(__file__).parent / "config.yaml"
-        self._default_dict = self._load_yaml(default_path)
+        self._default_dict = {**self._CODE_DEFAULTS, **self._load_yaml(default_path)}
 
     @staticmethod
     def _load_yaml(path):