diff --git a/kb_workflow/srt/semantic_engine.py b/kb_workflow/srt/semantic_engine.py
index 9538b85..ee5aef8 100644
--- a/kb_workflow/srt/semantic_engine.py
+++ b/kb_workflow/srt/semantic_engine.py
@@ -99,13 +99,13 @@ class VideoSegment(BaseModel):
     )
     start_index: int = Field(
         ...,
-        ge=1,
-        description="起始字幕索引（从1开始）"
+        ge=0,
+        description="在原文中的起始字符位置"
     )
     end_index: int = Field(
         ...,
-        ge=1,
-        description="结束字幕索引"
+        ge=0,
+        description="在原文中的结束字符位置"
     )
 
     @field_validator('title')
diff --git a/tests/test_semantic_engine.py b/tests/test_semantic_engine.py
index f07ea40..d59ba60 100644
--- a/tests/test_semantic_engine.py
+++ b/tests/test_semantic_engine.py
@@ -159,7 +159,6 @@ class TestPydanticModels:
         assert segment.title == title_15
 
 
-@pytest.mark.skip(reason="属于计划 13-05（中文句边界检测），不在计划 13-01 范围内")
 class TestChineseSentenceBoundary:
     """测试中文句边界检测功能（Plan 13-05）"""