feat: Add timestamp to TaskStatus updates on TaskUpdater (#140)

Author: irshadnilam

src/a2a/server/tasks/task_updater.py

@@ -1,5 +1,6 @@
 import uuid
 
+from datetime import datetime, timezone
 from typing import Any
 
 from a2a.server.events import EventQueue
@@ -34,15 +35,23 @@ def __init__(self, event_queue: EventQueue, task_id: str, context_id: str):
         self.context_id = context_id
 
     def update_status(
-        self, state: TaskState, message: Message | None = None, final=False
+        self,
+        state: TaskState,
+        message: Message | None = None,
+        final=False,
+        timestamp: str | None = None,
     ):
         """Updates the status of the task and publishes a `TaskStatusUpdateEvent`.
 
         Args:
             state: The new state of the task.
             message: An optional message associated with the status update.
             final: If True, indicates this is the final status update for the task.
+            timestamp: Optional ISO 8601 datetime string. Defaults to current time.
         """
+        current_timestamp = (
+            timestamp if timestamp else datetime.now(timezone.utc).isoformat()
+        )
         self.event_queue.enqueue_event(
             TaskStatusUpdateEvent(
                 taskId=self.task_id,
@@ -51,6 +60,7 @@ def update_status(
                 status=TaskStatus(
                     state=state,
                     message=message,
+                    timestamp=current_timestamp,
                 ),
             )
         )