fix: Pass message_length param in get_task() (#384)

Fixes a2aproject/A2A#861

Author: kthota-g

src/a2a/client/transports/grpc.py

@@ -138,7 +138,10 @@ async def get_task(
     ) -> Task:
         """Retrieves the current state and history of a specific task."""
         task = await self.stub.GetTask(
-            a2a_pb2.GetTaskRequest(name=f'tasks/{request.id}')
+            a2a_pb2.GetTaskRequest(
+                name=f'tasks/{request.id}',
+                history_length=request.history_length,
+            )
         )
         return proto_utils.FromProto.task(task)
 

tests/client/test_grpc_client.py

@@ -145,11 +145,31 @@ async def test_get_task(
     response = await grpc_transport.get_task(params)
 
     mock_grpc_stub.GetTask.assert_awaited_once_with(
-        a2a_pb2.GetTaskRequest(name=f'tasks/{sample_task.id}')
+        a2a_pb2.GetTaskRequest(
+            name=f'tasks/{sample_task.id}', history_length=None
+        )
     )
     assert response.id == sample_task.id
 
 
+@pytest.mark.asyncio
+async def test_get_task_with_history(
+    grpc_transport: GrpcTransport, mock_grpc_stub: AsyncMock, sample_task: Task
+):
+    """Test retrieving a task with history."""
+    mock_grpc_stub.GetTask.return_value = proto_utils.ToProto.task(sample_task)
+    history_len = 10
+    params = TaskQueryParams(id=sample_task.id, history_length=history_len)
+
+    await grpc_transport.get_task(params)
+
+    mock_grpc_stub.GetTask.assert_awaited_once_with(
+        a2a_pb2.GetTaskRequest(
+            name=f'tasks/{sample_task.id}', history_length=history_len
+        )
+    )
+
+
 @pytest.mark.asyncio
 async def test_cancel_task(
     grpc_transport: GrpcTransport, mock_grpc_stub: AsyncMock, sample_task: Task