refactor(client)!: make ClientConfig.push_notification_config singular (#955)

Send message API only contains one and only the first was used.

Author: ishymko

src/a2a/client/base_client.py

@@ -104,10 +104,10 @@ def _apply_client_config(self, request: SendMessageRequest) -> None:
         request.configuration.return_immediately |= self._config.polling
         if (
             not request.configuration.HasField('task_push_notification_config')
-            and self._config.push_notification_configs
+            and self._config.push_notification_config
         ):
             request.configuration.task_push_notification_config.CopyFrom(
-                self._config.push_notification_configs[0]
+                self._config.push_notification_config
             )
         if (
             not request.configuration.accepted_output_modes

src/a2a/client/client.py

@@ -71,10 +71,8 @@ class ClientConfig:
     accepted_output_modes: list[str] = dataclasses.field(default_factory=list)
     """The set of accepted output modes for the client."""
 
-    push_notification_configs: list[TaskPushNotificationConfig] = (
-        dataclasses.field(default_factory=list)
-    )
-    """Push notification configurations to use for every request."""
+    push_notification_config: TaskPushNotificationConfig | None = None
+    """Push notification configuration to use for every request."""
 
 
 class ClientCallContext(BaseModel):

tests/e2e/push_notifications/test_default_push_notification_support.py

@@ -109,13 +109,11 @@ async def test_notification_triggering_with_in_message_config_e2e(
     a2a_client = ClientFactory(
         ClientConfig(
             supported_protocol_bindings=[TransportProtocol.HTTP_JSON],
-            push_notification_configs=[
-                TaskPushNotificationConfig(
-                    id='in-message-config',
-                    url=f'{notifications_server}/notifications',
-                    token=token,
-                )
-            ],
+            push_notification_config=TaskPushNotificationConfig(
+                id='in-message-config',
+                url=f'{notifications_server}/notifications',
+                token=token,
+            ),
         )
     ).create(minimal_agent_card(agent_server, [TransportProtocol.HTTP_JSON]))