feat: 完善 AI-Core 文档解析器

- 添加多种文档解析器 (PDF, Word, Excel, Markdown 等)
- 添加基础解析器和链式解析器
- 添加存储和注册机制
- 添加 gRPC 服务实现

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ai-core/parser/markitdown_parser.py

@@ -0,0 +1,107 @@
+import io
+import logging
+import re
+import base64
+
+from markitdown import MarkItDown
+
+from docreader.models.document import Document
+from docreader.parser.base_parser import BaseParser
+from docreader.parser.chain_parser import PipelineParser
+from docreader.parser.markdown_parser import MarkdownParser
+
+# 尝试导入 VLMClient
+try:
+    from parser.vlm_client import VLMClient
+except ImportError:
+    VLMClient = None
+
+logger = logging.getLogger(__name__)
+
+
+class StdMarkitdownParser(BaseParser):
+    """
+    Standard MarkItDown Parser Wrapper
+
+    This parser uses the markitdown library to convert various document formats
+    (docx, pptx, pdf, etc.) into text/markdown.
+    Optionally uses VLM to process images.
+    """
+
+    def __init__(self, *args, vlm_config=None, **kwargs):
+        # 这里的 super() 会调用 BaseParser 的初始化，确保 self.file_type 被正确赋值
+        super().__init__(*args, **kwargs)
+        self.markitdown = MarkItDown()
+        self.vlm_config = vlm_config
+        self.vlm_client = None
+
+        # 如果有 VLM 配置，初始化 VLM 客户端
+        if vlm_config and vlm_config.get("enabled") and VLMClient:
+            try:
+                self.vlm_client = VLMClient(vlm_config)
+                logger.info(f"VLM client initialized: provider={vlm_config.get('provider')}, model={vlm_config.get('model')}")
+            except Exception as e:
+                logger.warning(f"Failed to initialize VLM client: {e}")
+
+    def parse_into_text(self, content: bytes) -> Document:
+        """
+        Parses content using MarkItDown.
+        Uses self.file_type (inherited from BaseParser) to hint the stream format.
+        """
+        ext = self.file_type
+        if ext and not ext.startswith('.'):
+            ext = '.' + ext
+
+        # 直接调用 convert，移除 try-catch，让异常由上层 PipelineParser 统一捕获
+        result = self.markitdown.convert(
+            io.BytesIO(content),
+            file_extension=ext,
+            keep_data_uris=True
+        )
+
+        markdown_content = result.text_content
+
+        # 如果有 VLM 客户端，尝试处理图片
+        if self.vlm_client and markdown_content:
+            markdown_content = self._process_images_with_vlm(markdown_content)
+
+        return Document(content=markdown_content)
+
+    def _process_images_with_vlm(self, content: str) -> str:
+        """
+        处理 Markdown 内容中的图片，使用 VLM 分析并替换
+        """
+        # 匹配 data:image 开头的 Base64 图片
+        pattern = r'!\[([^\]]*)\]\((data:image/([^;]+);base64,([A-Za-z0-9+/=]+))\)'
+
+        def replace_image(match):
+            alt_text = match.group(1)
+            data_url = match.group(2)
+            mime_type = match.group(3) or "image/png"
+            base64_data = match.group(4)
+
+            try:
+                # 解码 Base64 图片
+                image_bytes = base64.b64decode(base64_data)
+
+                # 调用 VLM 分析图片
+                logger.info(f"Processing image with VLM: {alt_text or 'unnamed'}")
+                vlm_result = self.vlm_client.analyze_image(image_bytes, mime_type)
+
+                if vlm_result.get("success"):
+                    vlm_content = vlm_result.get("content", "")
+                    logger.info(f"VLM processed image successfully, content length: {len(vlm_content)}")
+                    # 替换为 VLM 解析的内容
+                    return f"<!-- Image: {alt_text} -->\n{vlm_content}\n<!-- End Image -->"
+                else:
+                    logger.warning(f"VLM failed for image: {vlm_result.get('error')}")
+                    return match.group(0)  # 保留原图片引用
+            except Exception as e:
+                logger.error(f"Error processing image with VLM: {e}")
+                return match.group(0)  # 保留原图片引用
+
+        return re.sub(pattern, replace_image, content)
+
+
+class MarkitdownParser(PipelineParser):
+    _parser_cls = (StdMarkitdownParser, MarkdownParser)