fix: add message deduplication to WhatsApp channel

Prevent infinite loops by tracking processed message IDs in WhatsApp
channel. The bridge may send duplicate messages which caused the bot
to respond repeatedly with the same generic message.

Changes:
- Add _processed_message_ids deque (max 2000) to track seen messages
- Skip processing if message_id was already processed
- Align WhatsApp dedup with other channels (Feishu, Email, Mochat, QQ)

This fixes the issue where WhatsApp gets stuck in a loop sending
identical responses repeatedly.

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

nanobot/channels/whatsapp.py

@@ -2,6 +2,7 @@
 
 import asyncio
 import json
+from collections import deque
 from typing import Any
 
 from loguru import logger
@@ -15,18 +16,20 @@ from nanobot.config.schema import WhatsAppConfig
 class WhatsAppChannel(BaseChannel):
     """
     WhatsApp channel that connects to a Node.js bridge.
-    
+
     The bridge uses @whiskeysockets/baileys to handle the WhatsApp Web protocol.
     Communication between Python and Node.js is via WebSocket.
     """
-    
+
     name = "whatsapp"
-    
+    MAX_PROCESSED_MESSAGE_IDS = 2000
+
     def __init__(self, config: WhatsAppConfig, bus: MessageBus):
         super().__init__(config, bus)
         self.config: WhatsAppConfig = config
         self._ws = None
         self._connected = False
+        self._processed_message_ids: deque[str] = deque(maxlen=self.MAX_PROCESSED_MESSAGE_IDS)
     
     async def start(self) -> None:
         """Start the WhatsApp channel by connecting to the bridge."""
@@ -105,26 +108,35 @@ class WhatsAppChannel(BaseChannel):
             # Incoming message from WhatsApp
             # Deprecated by whatsapp: old phone number style typically: <phone>@s.whatspp.net
             pn = data.get("pn", "")
-            # New LID sytle typically: 
+            # New LID sytle typically:
             sender = data.get("sender", "")
             content = data.get("content", "")
-            
+            message_id = data.get("id", "")
+
+            # Dedup by message ID to prevent loops
+            if message_id and message_id in self._processed_message_ids:
+                logger.debug("Duplicate message {}, skipping", message_id)
+                return
+
+            if message_id:
+                self._processed_message_ids.append(message_id)
+
             # Extract just the phone number or lid as chat_id
             user_id = pn if pn else sender
             sender_id = user_id.split("@")[0] if "@" in user_id else user_id
             logger.info("Sender {}", sender)
-            
+
             # Handle voice transcription if it's a voice message
             if content == "[Voice Message]":
                 logger.info("Voice message received from {}, but direct download from bridge is not yet supported.", sender_id)
                 content = "[Voice Message: Transcription not available for WhatsApp yet]"
-            
+
             await self._handle_message(
                 sender_id=sender_id,
                 chat_id=sender,  # Use full LID for replies
                 content=content,
                 metadata={
-                    "message_id": data.get("id"),
+                    "message_id": message_id,
                     "timestamp": data.get("timestamp"),
                     "is_group": data.get("isGroup", False)
                 }