diff --git a/api/core/rag/index_processor/processor/paragraph_index_processor.py b/api/core/rag/index_processor/processor/paragraph_index_processor.py
index 4a731bf277..a487c49053 100644
--- a/api/core/rag/index_processor/processor/paragraph_index_processor.py
+++ b/api/core/rag/index_processor/processor/paragraph_index_processor.py
@@ -3,8 +3,7 @@
 import logging
 import re
 import uuid
-from collections.abc import Mapping
-from typing import Any, cast
+from typing import Any, TypedDict, cast
 
 logger = logging.getLogger(__name__)
 
@@ -55,6 +54,12 @@ from services.summary_index_service import SummaryIndexService
 _file_access_controller = DatabaseFileAccessController()
 
 
+class ParagraphFormatPreviewDict(TypedDict):
+    chunk_structure: str
+    preview: list[dict[str, Any]]
+    total_segments: int
+
+
 class ParagraphIndexProcessor(BaseIndexProcessor):
     def extract(self, extract_setting: ExtractSetting, **kwargs) -> list[Document]:
         text_docs = ExtractProcessor.extract(
@@ -266,16 +271,17 @@ class ParagraphIndexProcessor(BaseIndexProcessor):
                 keyword = Keyword(dataset)
                 keyword.add_texts(documents)
 
-    def format_preview(self, chunks: Any) -> Mapping[str, Any]:
+    def format_preview(self, chunks: Any) -> ParagraphFormatPreviewDict:
         if isinstance(chunks, list):
             preview = []
             for content in chunks:
                 preview.append({"content": content})
-            return {
+            result: ParagraphFormatPreviewDict = {
                 "chunk_structure": IndexStructureType.PARAGRAPH_INDEX,
                 "preview": preview,
                 "total_segments": len(chunks),
             }
+            return result
         else:
             raise ValueError("Chunks is not a list")
 
diff --git a/api/core/rag/index_processor/processor/parent_child_index_processor.py b/api/core/rag/index_processor/processor/parent_child_index_processor.py
index 53596b5de8..2db233874a 100644
--- a/api/core/rag/index_processor/processor/parent_child_index_processor.py
+++ b/api/core/rag/index_processor/processor/parent_child_index_processor.py
@@ -3,8 +3,7 @@
 import json
 import logging
 import uuid
-from collections.abc import Mapping
-from typing import Any
+from typing import Any, TypedDict
 
 from sqlalchemy import delete, select
 
@@ -36,6 +35,13 @@ from services.summary_index_service import SummaryIndexService
 logger = logging.getLogger(__name__)
 
 
+class ParentChildFormatPreviewDict(TypedDict):
+    chunk_structure: str
+    parent_mode: str
+    preview: list[dict[str, Any]]
+    total_segments: int
+
+
 class ParentChildIndexProcessor(BaseIndexProcessor):
     def extract(self, extract_setting: ExtractSetting, **kwargs) -> list[Document]:
         text_docs = ExtractProcessor.extract(
@@ -351,17 +357,18 @@ class ParentChildIndexProcessor(BaseIndexProcessor):
                 if all_multimodal_documents and dataset.is_multimodal:
                     vector.create_multimodal(all_multimodal_documents)
 
-    def format_preview(self, chunks: Any) -> Mapping[str, Any]:
+    def format_preview(self, chunks: Any) -> ParentChildFormatPreviewDict:
         parent_childs = ParentChildStructureChunk.model_validate(chunks)
         preview = []
         for parent_child in parent_childs.parent_child_chunks:
             preview.append({"content": parent_child.parent_content, "child_chunks": parent_child.child_contents})
-        return {
+        result: ParentChildFormatPreviewDict = {
             "chunk_structure": IndexStructureType.PARENT_CHILD_INDEX,
             "parent_mode": parent_childs.parent_mode,
             "preview": preview,
             "total_segments": len(parent_childs.parent_child_chunks),
         }
+        return result
 
     def generate_summary_preview(
         self,
diff --git a/api/core/rag/index_processor/processor/qa_index_processor.py b/api/core/rag/index_processor/processor/qa_index_processor.py
index 273ea0f852..b0f7928092 100644
--- a/api/core/rag/index_processor/processor/qa_index_processor.py
+++ b/api/core/rag/index_processor/processor/qa_index_processor.py
@@ -4,8 +4,7 @@ import logging
 import re
 import threading
 import uuid
-from collections.abc import Mapping
-from typing import Any
+from typing import Any, TypedDict
 
 import pandas as pd
 from flask import Flask, current_app
@@ -36,6 +35,12 @@ from services.summary_index_service import SummaryIndexService
 logger = logging.getLogger(__name__)
 
 
+class QAFormatPreviewDict(TypedDict):
+    chunk_structure: str
+    qa_preview: list[dict[str, Any]]
+    total_segments: int
+
+
 class QAIndexProcessor(BaseIndexProcessor):
     def extract(self, extract_setting: ExtractSetting, **kwargs) -> list[Document]:
         text_docs = ExtractProcessor.extract(
@@ -230,16 +235,17 @@ class QAIndexProcessor(BaseIndexProcessor):
             else:
                 raise ValueError("Indexing technique must be high quality.")
 
-    def format_preview(self, chunks: Any) -> Mapping[str, Any]:
+    def format_preview(self, chunks: Any) -> QAFormatPreviewDict:
         qa_chunks = QAStructureChunk.model_validate(chunks)
         preview = []
         for qa_chunk in qa_chunks.qa_chunks:
             preview.append({"question": qa_chunk.question, "answer": qa_chunk.answer})
-        return {
+        result: QAFormatPreviewDict = {
             "chunk_structure": IndexStructureType.QA_INDEX,
             "qa_preview": preview,
             "total_segments": len(qa_chunks.qa_chunks),
         }
+        return result
 
     def generate_summary_preview(
         self,