fix: Add type definitions for task update callbacks

demo/ui/utils/agent_card.py

@@ -1,14 +1,15 @@
-import requests
+import httpx
 
 from a2a.types import AgentCard
 from a2a.utils.constants import AGENT_CARD_WELL_KNOWN_PATH
 
 
-def get_agent_card(remote_agent_address: str) -> AgentCard:
+async def get_agent_card(remote_agent_address: str) -> AgentCard:
     """Get the agent card."""
     if not remote_agent_address.startswith(('http://', 'https://')):
         remote_agent_address = 'http://' + remote_agent_address
-    agent_card = requests.get(
-        f'{remote_agent_address}{AGENT_CARD_WELL_KNOWN_PATH}'
-    )
-    return AgentCard(**agent_card.json())
+    async with httpx.AsyncClient() as client:
+        agent_card = await client.get(
+            f'{remote_agent_address}{AGENT_CARD_WELL_KNOWN_PATH}'
+        )
+        return AgentCard(**agent_card.json())

samples/python/hosts/multiagent/remote_agent_connection.py

@@ -1,4 +1,5 @@
 import traceback
+from collections.abc import Callable
 
 from a2a.client import (
     Client,
@@ -8,10 +9,18 @@
     AgentCard,
     Message,
     Task,
+    TaskArtifactUpdateEvent,
     TaskState,
+    TaskStatusUpdateEvent,
 )
 
 
+TaskCallbackArg = Task | TaskStatusUpdateEvent | TaskArtifactUpdateEvent
+# A callable that processes a task update and returns an updated task.
+# It's important that implementations of this callback return a `Task` object.
+TaskUpdateCallback = Callable[[TaskCallbackArg, AgentCard], Task]
+
+
 class RemoteAgentConnections:
     """A class to hold the connections to the remote agents."""