Implement continuous typing indicator in message handling

- Added a new private method `_keep_typing` to send a typing indicator continuously while processing messages, refreshing every 4 seconds to comply with Telegram/Discord limitations.
- Updated the `handle_message` method to initiate the typing indicator at the start of message processing and ensure it stops once processing is complete, improving user experience during message handling.

gateway/platforms/base.py

@@ -171,20 +171,34 @@ class BasePlatformAdapter(ABC):
         """
         pass
     
+    async def _keep_typing(self, chat_id: str, interval: float = 4.0) -> None:
+        """
+        Continuously send typing indicator until cancelled.
+        
+        Telegram/Discord typing status expires after ~5 seconds, so we refresh every 4.
+        """
+        try:
+            while True:
+                await self.send_typing(chat_id)
+                await asyncio.sleep(interval)
+        except asyncio.CancelledError:
+            pass  # Normal cancellation when handler completes
+    
     async def handle_message(self, event: MessageEvent) -> None:
         """
         Process an incoming message.
         
         Calls the registered message handler and sends the response.
+        Keeps typing indicator active throughout processing.
         """
         if not self._message_handler:
             return
         
+        # Start continuous typing indicator (refreshes every 4 seconds)
+        typing_task = asyncio.create_task(self._keep_typing(event.source.chat_id))
+        
         try:
-            # Send typing indicator
+            # Call the handler (this can take a while with tool calls)
-            await self.send_typing(event.source.chat_id)
-            
-            # Call the handler
             response = await self._message_handler(event)
             
             # Send response if any
@@ -196,6 +210,13 @@ class BasePlatformAdapter(ABC):
                 )
         except Exception as e:
             print(f"[{self.name}] Error handling message: {e}")
+        finally:
+            # Stop typing indicator
+            typing_task.cancel()
+            try:
+                await typing_task
+            except asyncio.CancelledError:
+                pass
     
     def build_source(
         self,