feat(feishu): add global group mention policy

- Add group_policy config: 'open' (default) or 'mention'
- 'open': Respond to all group messages (backward compatible)
- 'mention': Only respond when @mentioned in any group
- Auto-detect bot mentions by pattern matching:
  * If open_id configured: match against mentions
  * Otherwise: detect bot by empty user_id + ou_ open_id pattern
- Support @_all mentions
- Private chats unaffected (always respond)
- Clean implementation with minimal logging

docs: update Feishu README with group policy documentation

README.md

@@ -482,7 +482,8 @@ Uses **WebSocket** long connection — no public IP required.
       "appSecret": "xxx",
       "encryptKey": "",
       "verificationToken": "",
-      "allowFrom": ["ou_YOUR_OPEN_ID"]
+      "allowFrom": ["ou_YOUR_OPEN_ID"],
+      "groupPolicy": "open"
     }
   }
 }
@@ -491,6 +492,18 @@ Uses **WebSocket** long connection — no public IP required.
 > `encryptKey` and `verificationToken` are optional for Long Connection mode.
 > `allowFrom`: Add your open_id (find it in nanobot logs when you message the bot). Use `["*"]` to allow all users.
 
+**Group Chat Policy** (optional):
+
+| Option | Values | Default | Description |
+|--------|--------|---------|-------------|
+| `groupPolicy` | `"open"` | `"open"` | Respond to all group messages (backward compatible) |
+| | `"mention"` | | Only respond when @mentioned |
+
+> [!NOTE]
+> - `"open"`: Respond to all messages in all groups
+> - `"mention"`: Only respond when @mentioned in any group
+> - Private chats are unaffected (always respond)
+
 **3. Run**
 
 ```bash

nanobot/channels/feishu.py

@@ -352,6 +352,74 @@ class FeishuChannel(BaseChannel):
         self._running = False
         logger.info("Feishu bot stopped")
 
+    def _get_bot_open_id_sync(self) -> str | None:
+        """Get bot's own open_id for mention detection.
+        
+        飞书 SDK 没有直接的 bot info API，从配置或缓存获取。
+        """
+        # 尝试从配置获取 open_id（用户可以在配置中指定）
+        if hasattr(self.config, 'open_id') and self.config.open_id:
+            return self.config.open_id
+        
+        return None
+
+    def _is_bot_mentioned(self, message: Any, bot_open_id: str | None) -> bool:
+        """Check if bot is mentioned in the message.
+        
+        飞书 mentions 数组包含被@的对象。匹配策略：
+        1. 如果配置了 bot_open_id，则匹配 open_id
+        2. 否则，检查 mentions 中是否有空的 user_id（bot 的特征）
+        
+        Handles:
+        - Direct mentions in message.mentions
+        - @all mentions
+        """
+        # Check @all
+        raw_content = message.content or ""
+        if "@_all" in raw_content:
+            logger.debug("Feishu: @_all mention detected")
+            return True
+        
+        # Check mentions array
+        mentions = message.mentions if hasattr(message, 'mentions') and message.mentions else []
+        if mentions:
+            if bot_open_id:
+                # 策略 1: 匹配配置的 open_id
+                for mention in mentions:
+                    if mention.id:
+                        open_id = getattr(mention.id, 'open_id', None)
+                        if open_id == bot_open_id:
+                            logger.debug("Feishu: bot mention matched")
+                            return True
+            else:
+                # 策略 2: 检查 bot 特征 - user_id 为空且 open_id 存在
+                for mention in mentions:
+                    if mention.id:
+                        user_id = getattr(mention.id, 'user_id', None)
+                        open_id = getattr(mention.id, 'open_id', None)
+                        # Bot 的特征：user_id 为空字符串，open_id 存在
+                        if user_id == '' and open_id and open_id.startswith('ou_'):
+                            logger.debug("Feishu: bot mention matched")
+                            return True
+        
+        return False
+
+    def _should_respond_in_group(
+        self, 
+        chat_id: str, 
+        mentioned: bool
+    ) -> tuple[bool, str]:
+        """Determine if bot should respond in a group chat.
+        
+        Returns:
+            (should_respond, reason)
+        """
+        # Check mention requirement
+        if self.config.group_policy == "mention" and not mentioned:
+            return False, "not mentioned in group"
+        
+        return True, ""
+
     def _add_reaction_sync(self, message_id: str, emoji_type: str) -> None:
         """Sync helper for adding reaction (runs in thread pool)."""
         from lark_oapi.api.im.v1 import CreateMessageReactionRequest, CreateMessageReactionRequestBody, Emoji
@@ -892,6 +960,16 @@ class FeishuChannel(BaseChannel):
             chat_type = message.chat_type
             msg_type = message.message_type
 
+            # Check group policy and mention requirement
+            if chat_type == "group":
+                bot_open_id = self._get_bot_open_id_sync()
+                mentioned = self._is_bot_mentioned(message, bot_open_id)
+                should_respond, reason = self._should_respond_in_group(chat_id, mentioned)
+                
+                if not should_respond:
+                    logger.debug("Feishu: ignoring group message - {}", reason)
+                    return
+            
             # Add reaction
             await self._add_reaction(message_id, self.config.react_emoji)
 

nanobot/config/schema.py

@@ -47,6 +47,8 @@ class FeishuConfig(Base):
     react_emoji: str = (
         "THUMBSUP"  # Emoji type for message reactions (e.g. THUMBSUP, OK, DONE, SMILE)
     )
+    # Group chat settings
+    group_policy: Literal["open", "mention"] = "open"  # Group response policy (default: open for backward compatibility)
 
 
 class DingTalkConfig(Base):