diff --git a/libs/ktem/ktem/index/file/graph/light_graph_index.py b/libs/ktem/ktem/index/file/graph/light_graph_index.py
index 297844889..aae864ed4 100644
--- a/libs/ktem/ktem/index/file/graph/light_graph_index.py
+++ b/libs/ktem/ktem/index/file/graph/light_graph_index.py
@@ -1,8 +1,9 @@
-from typing import Any
+from typing import Any, Optional
 from uuid import uuid4
 
 from ktem.db.engine import engine
 from sqlalchemy.orm import Session
+
 from ..base import BaseFileIndexIndexing, BaseFileIndexRetriever
 from .graph_index import GraphRAGIndex
 from .lightrag_pipelines import LightRAGIndexingPipeline, LightRAGRetrieverPipeline
@@ -11,7 +12,7 @@
 class LightRAGIndex(GraphRAGIndex):
     def __init__(self, app, id: int, name: str, config: dict):
         super().__init__(app, id, name, config)
-        self._collection_graph_id = None
+        self._collection_graph_id: Optional[str] = None
 
     def _setup_indexing_cls(self):
         self._indexing_pipeline_cls = LightRAGIndexingPipeline
@@ -20,21 +21,24 @@ def _setup_retriever_cls(self):
         self._retriever_pipeline_cls = [LightRAGRetrieverPipeline]
 
     def _get_or_create_collection_graph_id(self):
-        if not self._collection_graph_id:
-            # Try to find existing graph ID for this collection
-            with Session(engine) as session:
-                result = (
-                    session.query(self._resources["Index"].target_id)
-                    .filter(self._resources["Index"].relation_type == "graph")
-                    .first()
+        if self._collection_graph_id:
+            return self._collection_graph_id
+
+        # Try to find existing graph ID for this collection
+        with Session(engine) as session:
+            result = (
+                session.query(self._resources["Index"].target_id)  # type: ignore
+                .filter(
+                    self._resources["Index"].relation_type == "graph"  # type: ignore
                 )
-                if result:
-                    self._collection_graph_id = result[0]
-                else:
-                    self._collection_graph_id = str(uuid4())
+                .first()
+            )
+            if result:
+                self._collection_graph_id = result[0]
+            else:
+                self._collection_graph_id = str(uuid4())
         return self._collection_graph_id
 
-
     def get_indexing_pipeline(self, settings, user_id) -> BaseFileIndexIndexing:
         pipeline = super().get_indexing_pipeline(settings, user_id)
         # indexing settings
diff --git a/libs/ktem/ktem/index/file/graph/lightrag_pipelines.py b/libs/ktem/ktem/index/file/graph/lightrag_pipelines.py
index b4deaf299..a1631c0d7 100644
--- a/libs/ktem/ktem/index/file/graph/lightrag_pipelines.py
+++ b/libs/ktem/ktem/index/file/graph/lightrag_pipelines.py
@@ -247,7 +247,7 @@ class LightRAGIndexingPipeline(GraphRAGIndexingPipeline):
     def store_file_id_with_graph_id(self, file_ids: list[str | None]):
         # Use the collection-wide graph ID for LightRAG
         graph_id = self.collection_graph_id
-        
+
         # Record all files under this graph_id
         with Session(engine) as session:
             for file_id in file_ids:
@@ -349,7 +349,10 @@ def call_graphrag_index(self, graph_id: str, docs: list[Document]):
         process_doc_count = 0
         yield Document(
             channel="debug",
-            text=f"[GraphRAG] {'Updating' if is_incremental else 'Creating'} index: {process_doc_count} / {total_docs} documents.",
+            text=(
+                f"[GraphRAG] {'Updating' if is_incremental else 'Creating'} index: "
+                f"{process_doc_count} / {total_docs} documents."
+            ),
         )
 
         for doc_id in range(0, len(all_docs), INDEX_BATCHSIZE):