fix: group chat detection + article URL handling (Xiaohongshu/WeChat/zhihu)

- 群聊检测: 通过 protocol 的 group_id 字段识别群消息
- 引用消息: 处理 ref_msg 中的转发文章/引用内容
- 文章URL: 支持 mp.weixin.qq.com / xiaohongshu.com / xhslink.com / zhihu.com
- CDN图片: 占位函数，后续实现 AES 解密下载
- 图片OCR: 统一失败处理，不再发送两条消息

gateway/linux/wechat_agent.py

@@ -257,13 +257,36 @@ def fetch_article(url: str) -> dict | None:
 
 # ── Main Message Handler ──────────────────────────────────────
 
-def build_message_display_id(msg: IncomingMessage, bot: WeixinBot) -> str:
+def detect_group(msg: IncomingMessage) -> str:
     """
-    Build a display identifier for the sender.
-    Since iLink uses internal user_ids, we use the user_id as the identifier
-    and supplement with available info.
+    Detect if a message is from a group chat.
+    Returns the group_id if it's a group, or empty string if private chat.
     """
-    return msg.user_id
+    raw = msg.raw
+    # Check group_id field directly from protocol
+    gid = raw.get("group_id", "") or ""
+    if gid:
+        return gid
+    # Also check session_id for group patterns (contains 'chatroom' or multiple '@')
+    session_id = raw.get("session_id", "") or ""
+    if "@chatroom" in session_id:
+        return session_id.split("#")[0] if "#" in session_id else session_id
+    return ""
+
+
+def extract_article_url(text: str) -> str | None:
+    """Extract article URL from text. Supports WeChat public accounts, Xiaohongshu, and common share links."""
+    patterns = [
+        r"https?://mp\.weixin\.qq\.com[^\"'\s<)<>\[\]]+",
+        r"https?://(?:www\.)?xiaohongshu\.com[^\"'\s<)<>\[\]]+",
+        r"https?://xhslink\.com[^\"'\s<)<>\[\]]+",
+        r"https?://(?:www\.)?zhihu\.com[^\"'\s<)<>\[\]]+",
+    ]
+    for p in patterns:
+        m = re.search(p, text)
+        if m:
+            return m.group(0)
+    return None
 
 
 async def handle_incoming(msg: IncomingMessage, bot: WeixinBot):
@@ -274,15 +297,40 @@ async def handle_incoming(msg: IncomingMessage, bot: WeixinBot):
     content = msg.text or ""
     msg_type = msg.type
 
-    # ── text message ──
+    # ── Group chat detection ──
+    group_id = detect_group(msg)
+    if group_id:
+        log.info(f"GROUP message from {group_id}, sender={fu}")
+        # Use the group_id as the conversation identifier (like Windows version uses roomid)
+        conv_id = group_id
+        prefix = "[Group]"
+    else:
+        conv_id = fu
+        prefix = "[Private]"
+
+    # ── TEXT message ──
     if msg_type == "text":
         handler_input = content
 
-        # Detect forwarded articles
-        if "mp.weixin.qq.com" in content:
-            url_match = re.search(r"https?://mp\.weixin\.qq\.com[^\"'\s<)<>\[\]]+", content)
-            if url_match:
-                article = fetch_article(url_match.group(0))
+        # Check for ref_msg (forwarded/quoted content like articles)
+        ref_text = ""
+        for item in msg.raw.get("item_list", []):
+            ref_msg = item.get("ref_msg")
+            if ref_msg:
+                ref_title = ref_msg.get("title", "")
+                ref_item = ref_msg.get("message_item", {})
+                if isinstance(ref_item, dict) and ref_item.get("type") == 1:
+                    ref_text_data = ref_item.get("text_item", {}).get("text", "")
+                    if ref_text_data:
+                        ref_text = f"\n[引用消息] {ref_text_data[:500]}"
+                if ref_title:
+                    handler_input = f"[老莫转发了一篇文章] 标题: {ref_title}\n\n{content}{ref_text}"
+
+        # Detect article URLs (WeChat public account, Xiaohongshu, etc.)
+        article_url = extract_article_url(handler_input)
+        if article_url:
+            log.info(f"Article URL detected: {article_url[:80]}")
+            article = fetch_article(article_url)
             if article:
                 title = article.get("title", "")
                 article_text = article.get("content", "")[:2000]
@@ -292,63 +340,72 @@ async def handle_incoming(msg: IncomingMessage, bot: WeixinBot):
                     + (f"（{images}张图片已OCR）\n" if images else "")
                     + f"\n{article_text}"
                 )
+            else:
+                # Article processor failed, send original content
+                log.warning("Article processor returned no content, sending raw text")
 
-        reply = call_hermes(fu, handler_input)
+        reply = call_hermes(conv_id, handler_input)
         if reply and reply.strip():
-            await process_reply(reply, fu, bot)
+            await process_reply(reply, conv_id, bot)
 
-    # ── image message ──
+    # ── IMAGE message ──
     elif msg_type == "image":
-        log.info(f"Image from {fu}, attempting OCR...")
+        log.info(f"Image from {conv_id}, attempting OCR...")
 
         # Get image URL from the raw message
         img_url = None
         for item in msg.raw.get("item_list", []):
             if item.get("type") in (2,):  # IMAGE
                 img_item = item.get("image_item", {})
-                # Try direct URL first, then CDN
                 img_url = img_item.get("url", "")
                 if not img_url:
-                    # CDN media - need decryption
+                    # CDN media - download via CDN API
                     media = img_item.get("media", {})
-                    aes_key = media.get("aes_key", "")
-                    encrypt_query = media.get("encrypt_query_param", "")
-                    # For now, log the CDN info and continue
-                    log.info(f"Image has CDN media: aes_key={aes_key[:15]}...")
-                    img_url = None
+                    if media:
+                        log.info("Image has CDN media, attempting CDN download...")
+                        img_url = download_cdn_image(media)
                 break
 
         ocr_text = None
         if img_url:
             ocr_text = ocr_image_from_url(img_url)
+            if not ocr_text:
+                log.warning("OCR returned no text from image URL")
         else:
-            log.info("No direct image URL, sending raw iLink image to Hermes for description")
-            handler_input = "[老莫发送了一张图片]"
-            reply = call_hermes(fu, handler_input)
-            if reply and reply.strip():
-                await bot.reply(msg, reply.strip())
-            return
+            log.info("No image URL available, cannot OCR")
 
         if ocr_text:
             handler_input = f"[老莫发送了一张图片，OCR识别结果如下]\n{ocr_text}"
         else:
-            handler_input = "[老莫发送了一张图片，但OCR识别失败，无法读取内容]"
+            handler_input = "[老莫发送了一张图片，但无法识别图片内容]"
 
-        reply = call_hermes(fu, handler_input)
+        reply = call_hermes(conv_id, handler_input)
         if reply and reply.strip():
             await bot.reply(msg, reply.strip())
 
-    # ── voice message ──
+    # ── VOICE message ──
     elif msg_type == "voice":
-        reply = call_hermes(fu, "[voice message]")
+        reply = call_hermes(conv_id, "[voice message]")
         if reply and reply.strip():
             await bot.reply(msg, reply.strip())
 
-    # ── unknown type ──
+    # ── Unknown type ──
     else:
         log.info(f"Unhandled message type: {msg_type}")
 
 
+def download_cdn_image(media: dict) -> str | None:
+    """
+    Download an image from WeChat CDN using the iLink media protocol.
+    The media dict contains aes_key and encrypt_query_param for AES-128-ECB decryption.
+    For now, this is a placeholder - CDN download requires AES decryption.
+    """
+    logger = log
+    logger.info(f"CDN media available but direct download not yet implemented")
+    logger.debug(f"CDN media keys: {list(media.keys())}")
+    return None
+
+
 async def process_reply(reply: str, fu: str, bot: WeixinBot):
     """
     Process Hermes reply text, handling tags like [FILE], [IMG], [EMOJI].