diff --git a/backend/app/models/api_key.py b/backend/app/models/api_key.py
index 1db0997d..e7d494f3 100644
--- a/backend/app/models/api_key.py
+++ b/backend/app/models/api_key.py
@@ -19,7 +19,7 @@ class BaseApiKey(UpdatableBaseModel):
 class ApiKey(BaseApiKey, table=True):
     id: Optional[int] = Field(default=None, primary_key=True)
     hashed_secret: str = Field(max_length=255, unique=True)
-    user: "User" = SQLRelationship(
+    user: "User" = SQLRelationship(  # noqa:F821
         sa_relationship_kwargs={
             "lazy": "joined",
             "primaryjoin": "ApiKey.user_id == User.id",
diff --git a/backend/app/models/chat.py b/backend/app/models/chat.py
index 2e619b47..d0bbf531 100644
--- a/backend/app/models/chat.py
+++ b/backend/app/models/chat.py
@@ -24,7 +24,7 @@ class ChatVisibility(int, enum.Enum):
 class Chat(UUIDBaseModel, UpdatableBaseModel, table=True):
     title: str = Field(max_length=256)
     engine_id: int = Field(foreign_key="chat_engines.id", nullable=True)
-    engine: "ChatEngine" = SQLRelationship(
+    engine: "ChatEngine" = SQLRelationship(  # noqa:F821
         sa_relationship_kwargs={
             "lazy": "joined",
             "primaryjoin": "Chat.engine_id == ChatEngine.id",
@@ -34,7 +34,7 @@ class Chat(UUIDBaseModel, UpdatableBaseModel, table=True):
     engine_options: Dict | str = Field(default={}, sa_column=Column(JSON))
     deleted_at: Optional[datetime] = Field(default=None, sa_column=Column(DateTime))
     user_id: UUID = Field(foreign_key="users.id", nullable=True)
-    user: "User" = SQLRelationship(
+    user: "User" = SQLRelationship(  # noqa:F821
         sa_relationship_kwargs={
             "lazy": "joined",
             "primaryjoin": "Chat.user_id == User.id",
diff --git a/backend/app/models/chat_engine.py b/backend/app/models/chat_engine.py
index ccb1ba05..3c5d7bd2 100644
--- a/backend/app/models/chat_engine.py
+++ b/backend/app/models/chat_engine.py
@@ -18,19 +18,19 @@ class ChatEngine(UpdatableBaseModel, table=True):
     name: str = Field(max_length=256)
     engine_options: Dict = Field(default={}, sa_column=Column(JSON))
     llm_id: Optional[int] = Field(foreign_key="llms.id", nullable=True)
-    llm: "LLM" = SQLRelationship(
+    llm: "LLM" = SQLRelationship(  # noqa:F821
         sa_relationship_kwargs={
             "foreign_keys": "ChatEngine.llm_id",
         },
     )
     fast_llm_id: Optional[int] = Field(foreign_key="llms.id", nullable=True)
-    fast_llm: "LLM" = SQLRelationship(
+    fast_llm: "LLM" = SQLRelationship(  # noqa:F821
         sa_relationship_kwargs={
             "foreign_keys": "ChatEngine.fast_llm_id",
         },
     )
     reranker_id: Optional[int] = Field(foreign_key="reranker_models.id", nullable=True)
-    reranker: "RerankerModel" = SQLRelationship(
+    reranker: "RerankerModel" = SQLRelationship(  # noqa:F821
         sa_relationship_kwargs={
             "foreign_keys": "ChatEngine.reranker_id",
         },
diff --git a/backend/app/models/chat_message.py b/backend/app/models/chat_message.py
index 613b758d..7e397608 100644
--- a/backend/app/models/chat_message.py
+++ b/backend/app/models/chat_message.py
@@ -32,14 +32,14 @@ class ChatMessage(UpdatableBaseModel, table=True):
     )
     finished_at: Optional[datetime] = Field(default=None, sa_column=Column(DateTime))
     chat_id: UUID = Field(foreign_key="chats.id")
-    chat: "Chat" = SQLRelationship(
+    chat: "Chat" = SQLRelationship(  # noqa:F821
         sa_relationship_kwargs={
             "lazy": "joined",
             "primaryjoin": "ChatMessage.chat_id == Chat.id",
         },
     )
     user_id: UUID = Field(foreign_key="users.id", nullable=True)
-    user: "User" = SQLRelationship(
+    user: "User" = SQLRelationship(  # noqa:F821
         sa_relationship_kwargs={
             "lazy": "joined",
             "primaryjoin": "ChatMessage.user_id == User.id",
diff --git a/backend/app/models/document.py b/backend/app/models/document.py
index a0df28db..77b3c84d 100644
--- a/backend/app/models/document.py
+++ b/backend/app/models/document.py
@@ -48,7 +48,7 @@ class Document(UpdatableBaseModel, table=True):
     # TODO: add kg_index_status, kg_index_result column, unify the index status.
 
     data_source_id: int = Field(foreign_key="data_sources.id", nullable=True)
-    data_source: "DataSource" = SQLRelationship(
+    data_source: "DataSource" = SQLRelationship(  # noqa:F821
         sa_relationship_kwargs={
             "lazy": "joined",
             "primaryjoin": "Document.data_source_id == DataSource.id",
@@ -56,7 +56,7 @@ class Document(UpdatableBaseModel, table=True):
     )
 
     knowledge_base_id: int = Field(foreign_key="knowledge_bases.id", nullable=True)
-    knowledge_base: "KnowledgeBase" = SQLRelationship(
+    knowledge_base: "KnowledgeBase" = SQLRelationship(  # noqa:F821
         sa_relationship_kwargs={
             "lazy": "joined",
             "primaryjoin": "Document.knowledge_base_id == KnowledgeBase.id",
diff --git a/backend/app/models/evaluation_dataset.py b/backend/app/models/evaluation_dataset.py
index c453242c..8f7b216b 100644
--- a/backend/app/models/evaluation_dataset.py
+++ b/backend/app/models/evaluation_dataset.py
@@ -17,7 +17,7 @@ class EvaluationDataset(UpdatableBaseModel, table=True):
     name: str = Field(max_length=255)
 
     user_id: UUID = Field(foreign_key="users.id", nullable=True)
-    user: "User" = SQLRelationship(
+    user: "User" = SQLRelationship(  # noqa:F821
         sa_relationship_kwargs={
             "lazy": "joined",
             "primaryjoin": "EvaluationDataset.user_id == User.id",
diff --git a/backend/app/models/evaluation_task.py b/backend/app/models/evaluation_task.py
index cf0b592b..f84cc318 100644
--- a/backend/app/models/evaluation_task.py
+++ b/backend/app/models/evaluation_task.py
@@ -27,7 +27,7 @@ class EvaluationTask(UpdatableBaseModel, table=True):
     name: str = Field(max_length=255)
 
     user_id: UUID = Field(foreign_key="users.id", nullable=True)
-    user: "User" = SQLRelationship(
+    user: "User" = SQLRelationship(  # noqa:F821
         sa_relationship_kwargs={
             "lazy": "joined",
             "primaryjoin": "EvaluationTask.user_id == User.id",
diff --git a/backend/app/models/feedback.py b/backend/app/models/feedback.py
index a6e76af7..aa4e7a52 100644
--- a/backend/app/models/feedback.py
+++ b/backend/app/models/feedback.py
@@ -32,21 +32,21 @@ class BaseFeedback(UpdatableBaseModel):
 class Feedback(BaseFeedback, table=True):
     id: Optional[int] = Field(default=None, primary_key=True)
     chat_id: UUID = Field(foreign_key="chats.id")
-    chat: "Chat" = SQLRelationship(
+    chat: "Chat" = SQLRelationship(  # noqa:F821
         sa_relationship_kwargs={
             "lazy": "joined",
             "primaryjoin": "Feedback.chat_id == Chat.id",
         },
     )
     chat_message_id: int = Field(foreign_key="chat_messages.id")
-    chat_message: "ChatMessage" = SQLRelationship(
+    chat_message: "ChatMessage" = SQLRelationship(  # noqa:F821
         sa_relationship_kwargs={
             "lazy": "joined",
             "primaryjoin": "Feedback.chat_message_id == ChatMessage.id",
         },
     )
     user_id: UUID = Field(foreign_key="users.id", nullable=True)
-    user: "User" = SQLRelationship(
+    user: "User" = SQLRelationship(  # noqa:F821
         sa_relationship_kwargs={
             "lazy": "joined",
             "primaryjoin": "Feedback.user_id == User.id",
diff --git a/backend/app/models/recommend_question.py b/backend/app/models/recommend_question.py
index fc449625..37e4e64d 100644
--- a/backend/app/models/recommend_question.py
+++ b/backend/app/models/recommend_question.py
@@ -14,7 +14,7 @@ class RecommendQuestion(UpdatableBaseModel, table=True):
     id: Optional[int] = Field(default=None, primary_key=True)
     questions: List = Field(default=[], sa_column=Column(JSON))
     chat_message_id: int = Field(foreign_key="chat_messages.id", index=True)
-    chat_message: "ChatMessage" = SQLRelationship(
+    chat_message: "ChatMessage" = SQLRelationship(  # noqa:F821
         sa_relationship_kwargs={
             "lazy": "joined",
             "primaryjoin": "RecommendQuestion.chat_message_id == ChatMessage.id",
diff --git a/backend/app/models/upload.py b/backend/app/models/upload.py
index 8f3d2ea8..3c84c776 100644
--- a/backend/app/models/upload.py
+++ b/backend/app/models/upload.py
@@ -19,7 +19,7 @@ class Upload(UpdatableBaseModel, table=True):
     path: str = Field(max_length=255)
     mime_type: MimeTypes = Field(sa_column=Column(String(128), nullable=False))
     user_id: UUID = Field(foreign_key="users.id", nullable=True)
-    user: "User" = SQLRelationship(
+    user: "User" = SQLRelationship(  # noqa:F821
         sa_relationship_kwargs={
             "lazy": "joined",
             "primaryjoin": "Upload.user_id == User.id",
diff --git a/backend/app/rag/chat_config.py b/backend/app/rag/chat_config.py
index f7ff3c6b..b2ed15d5 100644
--- a/backend/app/rag/chat_config.py
+++ b/backend/app/rag/chat_config.py
@@ -20,7 +20,7 @@
     RerankerModel as DBRerankerModel,
     KnowledgeBase,
 )
-from app.repositories import chat_engine_repo
+from app.repositories import chat_engine_repo, knowledge_base_repo
 from app.rag.default_prompt import (
     DEFAULT_INTENT_GRAPH_KNOWLEDGE,
     DEFAULT_NORMAL_GRAPH_KNOWLEDGE,
diff --git a/backend/pyproject.toml b/backend/pyproject.toml
index 560b776d..68654781 100644
--- a/backend/pyproject.toml
+++ b/backend/pyproject.toml
@@ -78,4 +78,4 @@ dev-dependencies = [
 ]
 
 [tool.ruff.lint]
-ignore = ["E711", "E712", "F811", "F821", "F841"]
+ignore = ["E711", "E712", "F811",  "F841"]
diff --git a/frontend/app/src/pages/docs/llm.mdx b/frontend/app/src/pages/docs/llm.mdx
index feeec75b..697b7d82 100644
--- a/frontend/app/src/pages/docs/llm.mdx
+++ b/frontend/app/src/pages/docs/llm.mdx
@@ -80,7 +80,8 @@ Default config:
 
 To learn more about OpenRouter, please visit [OpenRouter](https://openrouter.ai/).
 
-<!-- #### ZhipuAI BigModel
+{/*
+#### ZhipuAI BigModel
 
 Default config:
 
@@ -91,7 +92,8 @@ Default config:
 }
 ```
 
-To learn more about BigModel, please visit [BigModel](https://open.bigmodel.cn/). -->
+To learn more about BigModel, please visit [BigModel](https://open.bigmodel.cn/). 
+*/}
 
 #### Ollama