From 2dc015b360edc852fbfb0fe5a73350b81193c08c Mon Sep 17 00:00:00 2001
From: plind <59729252+plind-dm@users.noreply.github.com>
Date: Fri, 10 Apr 2026 19:55:40 +0900
Subject: [PATCH] fix(api): default parent_mode to paragraph for hierarchical
 chunking via API (#34635)

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
---
 api/services/dataset_service.py               |  4 +++
 .../services/test_dataset_service_document.py | 27 +++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/api/services/dataset_service.py b/api/services/dataset_service.py
index 3e952059ac..9c71902849 100644
--- a/api/services/dataset_service.py
+++ b/api/services/dataset_service.py
@@ -2822,6 +2822,10 @@ class DocumentService:
 
             knowledge_config.process_rule.rules.pre_processing_rules = list(unique_pre_processing_rule_dicts.values())
 
+            if knowledge_config.process_rule.mode == ProcessRuleMode.HIERARCHICAL:
+                if not knowledge_config.process_rule.rules.parent_mode:
+                    knowledge_config.process_rule.rules.parent_mode = "paragraph"
+
             if not knowledge_config.process_rule.rules.segmentation:
                 raise ValueError("Process rule segmentation is required")
 
diff --git a/api/tests/unit_tests/services/test_dataset_service_document.py b/api/tests/unit_tests/services/test_dataset_service_document.py
index e5a2541da7..9b4734b7ad 100644
--- a/api/tests/unit_tests/services/test_dataset_service_document.py
+++ b/api/tests/unit_tests/services/test_dataset_service_document.py
@@ -1069,6 +1069,33 @@ class TestDocumentServiceCreateValidation:
         assert len(knowledge_config.process_rule.rules.pre_processing_rules) == 1
         assert knowledge_config.process_rule.rules.pre_processing_rules[0].enabled is False
 
+    def test_process_rule_args_validate_hierarchical_defaults_parent_mode_to_paragraph(self):
+        knowledge_config = KnowledgeConfig(
+            indexing_technique="economy",
+            data_source=DataSource(
+                info_list=InfoList(
+                    data_source_type="upload_file",
+                    file_info_list=FileInfo(file_ids=["file-1"]),
+                )
+            ),
+            process_rule=ProcessRule(
+                mode="hierarchical",
+                rules=Rule(
+                    pre_processing_rules=[
+                        PreProcessingRule(id="remove_extra_spaces", enabled=True),
+                    ],
+                    segmentation=Segmentation(separator="\n", max_tokens=1024),
+                    subchunk_segmentation=Segmentation(separator="\n", max_tokens=512),
+                ),
+            ),
+        )
+
+        DocumentService.process_rule_args_validate(knowledge_config)
+
+        assert knowledge_config.process_rule is not None
+        assert knowledge_config.process_rule.rules is not None
+        assert knowledge_config.process_rule.rules.parent_mode == "paragraph"
+
 
 class TestDocumentServiceSaveDocumentWithDatasetId:
     """Unit tests for non-SQL validation branches in save_document_with_dataset_id."""