fix: auth 测试改用 monkeypatch.setattr，MarkdownSplitter 跳过代码块内标题识别

src/core/splitters/markdown.py

@@ -31,8 +31,20 @@ class MarkdownSplitter(BaseTextSplitter):
         return chunks
 
     def _split_by_headings(self, text: str) -> list[dict]:
+        # 识别代码块范围，跳过其中的假标题
+        code_block_ranges = []
+        fence_re = re.compile(r"^```", re.MULTILINE)
+        fences = [m.start() for m in fence_re.finditer(text)]
+        for i in range(0, len(fences), 2):
+            if i + 1 < len(fences):
+                code_block_ranges.append((fences[i], fences[i + 1]))
+
+        def in_code_block(pos: int) -> bool:
+            return any(start <= pos <= end for start, end in code_block_ranges)
+
         heading_pattern = re.compile(r"^(#{1,6})\s+(.+)$", re.MULTILINE)
-        matches = list(heading_pattern.finditer(text))
+        all_matches = list(heading_pattern.finditer(text))
+        matches = [m for m in all_matches if not in_code_block(m.start())]
 
         if not matches:
             return [{