fix(claude_agent_sdk): log ResultMessage.is_error and AssistantMessage.error

[Mahhheshh (Mahhheshh)]

• If the ResultMessage has the is_error field. it would be logged to root_span.
• If AssistantMessage has error field, it would be logged to associate span.

ref 4, 6 #149.

[Abhijeet Prasad (AbhiPrasad)]

I think we can also update the test to assert on this right?

[Mahhheshh (Mahhheshh)]

I was not sure about the way this will be tested

--- a/py/src/braintrust/integrations/claude_agent_sdk/test_claude_agent_sdk.py
+++ b/py/src/braintrust/integrations/claude_agent_sdk/test_claude_agent_sdk.py
@@ -2083,6 +2083,8 @@ async def test_setup_claude_agent_sdk_repro_import_before_setup(memory_logger, m
     loop_errors = []
     received_types = []
 
+    result_message = None
+    assistant_message = None
     with _patched_claude_sdk():
         assert setup_claude_agent_sdk(project=PROJECT_NAME, api_key=logger.TEST_API_KEY)
         assert getattr(consumer_module, "ClaudeSDKClient") is not original_client
@@ -2107,7 +2109,12 @@ async def test_setup_claude_agent_sdk_repro_import_before_setup(memory_logger, m
             async with getattr(consumer_module, "ClaudeSDKClient")(options=options, transport=transport) as client:
                 await client.query("Say hi")
                 async for message in client.receive_response():
-                    received_types.append(type(message).__name__)
+                    message_type = type(message).__name__
+                    if message_type == "ResultMessage":
+                        result_message = message
+                    if message_type == AssistantMessage:
+                        assistant_message = message
+                    received_types.append(message_type)
 
         await main()
 
@@ -2117,10 +2124,17 @@ async def test_setup_claude_agent_sdk_repro_import_before_setup(memory_logger, m
 
     spans = memory_logger.pop()
     task_spans = [s for s in spans if s["span_attributes"]["type"] == SpanTypeAttribute.TASK]
+    llm_spans = [s for s in spans if s["span_attributes"]["type"] == SpanTypeAttribute.LLM]
     assert len(task_spans) == 1
     assert task_spans[0]["span_attributes"]["name"] == "Claude Agent"
     assert task_spans[0]["input"] == "Say hi"
 
+    if result_message is not None and getattr(result_message, "is_error", False):
+        assert task_spans[0]["error"] == result_message.is_error
+
+    if assistant_message is not None and getattr(assistant_message, "error", False):
+        assert llm_spans[0]["error"] == assistant_message.error
+```

[Mahhheshh (Mahhheshh)]

This should be just
(error=error_field). will fix it once I have idea about tests