diff --git a/tests/unit/test_text_splitter.py b/tests/unit/test_text_splitter.py
index 831253df2..faff5b971 100755
--- a/tests/unit/test_text_splitter.py
+++ b/tests/unit/test_text_splitter.py
@@ -1,100 +1,295 @@
-"""text_splitter 单元测试."""
+"""TTS 文本分段工具单元测试."""
+
+import pytest
 
 from packages.application.tts_job.text_splitter import split_text
 
 
-class TestSplitText:
-    def test_empty_text_returns_empty(self):
+class TestSplitTextEmpty:
+    """空文本测试"""
+
+    def test_empty_string(self):
+        """空字符串返回空列表."""
         assert split_text("") == []
 
-    def test_whitespace_only(self):
-        assert split_text("   \n\t  ") == []
+    def test_only_whitespace(self):
+        """纯空白文本返回空列表."""
+        assert split_text("   \n  \t  ") == []
 
-    def test_short_text_single_segment(self):
-        text = "你好世界。"
+    def test_none_not_allowed(self):
+        """None 会抛出异常（不是我们的职责）."""
+        with pytest.raises(AttributeError):
+            split_text(None)  # type: ignore
+
+
+class TestSplitTextShort:
+    """短文本测试"""
+
+    def test_short_text_one_segment(self):
+        """短文本返回一个段落."""
+        text = "你好，世界。"
         result = split_text(text, max_chars=500)
         assert len(result) == 1
         assert result[0] == text
 
-    def test_exact_max_chars(self):
+    def test_exactly_max_chars(self):
+        """刚好等于 max_chars 的文本返回一个段落."""
         text = "a" * 500
         result = split_text(text, max_chars=500)
         assert len(result) == 1
         assert len(result[0]) == 500
 
-    def test_splits_on_sentence_boundary(self):
-        # 两个长句子，各300字左右，超过50字阈值
-        sent1 = "你" * 300 + "。"
-        sent2 = "我" * 300 + "。"
-        text = sent1 + sent2
+    def test_one_under_max(self):
+        """max_chars-1 的文本返回一个段落."""
+        text = "a" * 499
         result = split_text(text, max_chars=500)
-        assert len(result) == 2
-        assert result[0] == sent1
-        assert result[1] == sent2
+        assert len(result) == 1
+        assert len(result[0]) == 499
 
-    def test_long_sentence_hard_cut(self):
-        # 一个超长句子，没有句末标点，会被硬切
-        text = "长" * 800
-        result = split_text(text, max_chars=500)
+
+class TestSplitTextSentenceBoundary:
+    """句子边界分段测试"""
+
+    def test_split_at_period(self):
+        """在句号处拆分."""
+        text = "第一句。第二句。第三句。"
+        # 每句5字符，max_chars=10，每次两句就接近10
+        result = split_text(text, max_chars=10)
         assert len(result) >= 2
-        assert all(len(seg) <= 500 for seg in result)
-        # 合起来应该等于原文本
-        assert "".join(result) == text
+        # 所有段落都不超过 max_chars
+        for seg in result:
+            assert len(seg) <= 10
+
+    def test_split_at_exclamation(self):
+        """在感叹号处拆分."""
+        text = "好棒！真的好棒！太厉害了！"
+        result = split_text(text, max_chars=10)
+        assert len(result) >= 2
+        for seg in result:
+            assert len(seg) <= 10
+
+    def test_split_at_question(self):
+        """在问号处拆分."""
+        text = "你好吗？你是谁？你在哪？"
+        result = split_text(text, max_chars=10)
+        assert len(result) >= 2
+        for seg in result:
+            assert len(seg) <= 10
+
+    def test_split_at_newline(self):
+        """在换行处拆分."""
+        text = "第一段\n第二段\n第三段"
+        result = split_text(text, max_chars=10)
+        assert len(result) >= 2
+        for seg in result:
+            assert len(seg) <= 10
+
+    def test_split_at_semicolon(self):
+        """在分号处拆分."""
+        text = "第一项；第二项；第三项；"
+        result = split_text(text, max_chars=10)
+        assert len(result) >= 2
+
+    def test_english_punctuation(self):
+        """英文标点也能拆分."""
+        text = "Hello world. How are you? I am fine!"
+        result = split_text(text, max_chars=20)
+        assert len(result) >= 2
+        for seg in result:
+            assert len(seg) <= 20
+
+    def test_mixed_punctuation(self):
+        """中英文标点混合."""
+        text = "你好！Hello. 你好吗？How are you?"
+        result = split_text(text, max_chars=15)
+        assert len(result) >= 2
+
+
+class TestSplitTextForceSplit:
+    """强制分段测试"""
+
+    def test_very_long_sentence_forced_split(self):
+        """超长单句强制分段."""
+        text = "a" * 1000  # 没有标点的长文本
+        result = split_text(text, max_chars=100)
+        assert len(result) == 10
+        for seg in result:
+            assert len(seg) == 100
+
+    def test_mixed_long_and_short_sentences(self):
+        """长短句混合."""
+        long = "我" * 200
+        text = f"短句。{long}。短句。"
+        result = split_text(text, max_chars=100)
+        # 所有段都不超过100
+        for seg in result:
+            assert len(seg) <= 100
+        # 至少有3段（长句被强制拆分）
+        assert len(result) >= 3
+
+
+class TestSplitTextMerging:
+    """短段落合并测试"""
 
     def test_short_segments_merged(self):
-        # 多个短句应该被合并
-        sentences = [f"第{i}句。" for i in range(10)]
-        text = "".join(sentences)
-        result = split_text(text, max_chars=200)
-        # 每句5字左右，10句才50字，应该合并成1段
-        assert len(result) < 10
-        assert len(result[0]) <= 200
-
-    def test_preserves_content(self):
-        text = "今天天气真好。我们去公园玩吧！你觉得怎么样？好的，走吧。"
-        result = split_text(text, max_chars=20)
-        # 合并后内容应一致
-        assert "".join(result) == text
-
-    def test_multiple_punctuation_types(self):
-        # 构造足够长的文本触发分段
-        text = "第一" * 30 + "。" + "第二" * 30 + "！" + "第三" * 30 + "？" + "第四" * 30 + "；"
+        """多个短段合并为一个."""
+        # 生成5个短句，每句5字符，max_chars=100，应该合并成一段
+        text = "一。二。三。四。五。"
         result = split_text(text, max_chars=100)
-        assert len(result) >= 2
-        assert "".join(result) == text
+        assert len(result) == 1
+        assert len(result[0]) <= 100
 
-    def test_custom_max_chars(self):
-        text = "a" * 100 + "。" + "b" * 100 + "。"
-        result = split_text(text, max_chars=150)
-        assert len(result) == 2
-        assert "a" in result[0]
-        assert "b" in result[1]
+    def test_merge_within_limit(self):
+        """合并后不超过 max_chars."""
+        # 10个短句，每句4字符 = 40字符
+        text = "句子。" * 10
+        result = split_text(text, max_chars=100)
+        assert len(result) == 1
+        assert len(result[0]) <= 100
 
-    def test_newline_as_sentence_end(self):
-        text = "第一段\n第二段\n第三段"
+    def test_merge_across_multiple(self):
+        """多个短段依次合并."""
+        text = "短。" * 30  # 30个短句，每句2字符=60字符
+        result = split_text(text, max_chars=100)
+        assert len(result) == 1
+        assert len(result[0]) == 60  # 全部合并
+
+
+class TestSplitTextChinese:
+    """中文文本测试"""
+
+    def test_chinese_paragraph(self):
+        """典型中文段落."""
+        text = (
+            "在一个阳光明媚的早晨，小明来到了公园。"
+            "他看到了很多人在锻炼身体。"
+            "有的人在跑步，有的人在打太极，还有的人在跳舞。"
+            "小明也加入了他们，开始了愉快的一天。"
+        )
         result = split_text(text, max_chars=50)
-        assert len(result) >= 1
-        assert "".join(result) == text.strip()
+        assert len(result) >= 2
+        for seg in result:
+            assert len(seg) <= 50
+        # 重新拼回应该等于原文本（除了可能的空格处理）
+        combined = "".join(result)
+        assert combined == text.replace(" ", "")  # strip 不影响中文字符
 
-    def test_minimum_segment_length(self):
-        # 句子太短（<50字）不会立即分段
-        text = "短句一。短句二。短句三。"
+    def test_chinese_long_paragraph(self):
+        """长中文段落."""
+        text = "这是一个测试句子。" * 100  # 100个句子
         result = split_text(text, max_chars=200)
+        assert len(result) > 1
+        for seg in result:
+            assert len(seg) <= 200
+        # 总字符数不变
+        assert sum(len(s) for s in result) == len(text)
+
+
+class TestSplitTextCustomMaxChars:
+    """自定义 max_chars 测试"""
+
+    def test_small_max_chars(self):
+        """很小的 max_chars."""
+        text = "一二三四五六七八九十。"
+        result = split_text(text, max_chars=5)
+        for seg in result:
+            assert len(seg) <= 5
+
+    def test_large_max_chars(self):
+        """很大的 max_chars（不拆分）."""
+        text = "这是一段测试文本。" * 10
+        result = split_text(text, max_chars=10000)
         assert len(result) == 1
 
-    def test_trailing_content_added(self):
-        # 最后一段不完整的句子也要加上
-        text = "完整的句子。剩余内容"
-        result = split_text(text, max_chars=50)
-        assert "".join(result) == text
+    def test_max_chars_zero(self):
+        """max_chars=0 时的行为."""
+        text = "测试文本。"
+        # 0 会导致每加一个字符就触发强制分段
+        result = split_text(text, max_chars=0)
+        # 每个字符一段？或者至少有结果
+        assert isinstance(result, list)
+        assert len(result) > 0
+
+    def test_max_chars_one(self):
+        """max_chars=1."""
+        text = "abc"
+        result = split_text(text, max_chars=1)
+        assert len(result) == 3
+        assert result == ["a", "b", "c"]
+
+
+class TestSplitTextPreservesContent:
+    """内容完整性测试"""
+
+    def test_preserves_all_chars(self):
+        """分段后拼接等于原文（忽略空白调整）."""
+        text = "第一句。第二句！第三句？第四句。第五句。"
+        result = split_text(text, max_chars=10)
+        combined = "".join(result)
+        assert combined == text
 
     def test_no_empty_segments(self):
-        text = "。。。。。"  # 全是标点
-        result = split_text(text, max_chars=2)
-        assert all(len(seg) > 0 for seg in result)
+        """没有空字符串段落."""
+        text = "句子。。。双标点。"
+        result = split_text(text, max_chars=10)
+        assert all(seg for seg in result)  # 所有段非空
 
-    def test_chinese_and_english_mixed(self):
-        text = "Hello世界。这是测试Test文本。Mixed混合。"
-        result = split_text(text, max_chars=20)
+    def test_stripped_segments(self):
+        """段落首尾没有多余空白."""
+        text = "  第一句。  第二句。  "
+        result = split_text(text, max_chars=10)
+        for seg in result:
+            assert seg == seg.strip()
+
+
+class TestSplitTextEdgeCases:
+    """边界情况测试"""
+
+    def test_single_char(self):
+        """单字符."""
+        result = split_text("我", max_chars=10)
+        assert len(result) == 1
+        assert result[0] == "我"
+
+    def test_only_punctuation(self):
+        """纯标点."""
+        text = "。。。！！？？"
+        result = split_text(text, max_chars=5)
+        assert len(result) >= 1
+        assert sum(len(s) for s in result) == len(text)
+
+    def test_numbers_and_symbols(self):
+        """数字和符号."""
+        text = "第1章。第2节。第3段。"
+        result = split_text(text, max_chars=10)
+        assert len(result) >= 1
+        assert all(len(s) <= 10 for s in result)
+
+    def test_mixed_chinese_english(self):
+        """中英文混合."""
+        text = "Hello你好World世界。Test测试。"
+        result = split_text(text, max_chars=10)
         assert len(result) >= 2
-        assert "".join(result) == text
+        assert all(len(s) <= 10 for s in result)
+
+    def test_consecutive_punctuation(self):
+        """连续标点."""
+        text = "真的吗！？不对。。。好吧。"
+        result = split_text(text, max_chars=20)
+        assert len(result) >= 1
+        combined = "".join(result)
+        assert combined == text
+
+
+class TestSplitTextDefaultParams:
+    """默认参数测试"""
+
+    def test_default_max_chars_is_500(self):
+        """默认 max_chars=500."""
+        text = "a" * 500
+        result = split_text(text)
+        assert len(result) == 1
+
+        text2 = "a" * 501
+        result2 = split_text(text2)
+        assert len(result2) >= 2