Fix ChatMessage and Role API changes in a2a and lab packages

- Fix a2a tests: Role comparisons and ChatMessage signatures
- Fix lab tau2 source: Role enum comparison in flip_messages, log_messages, sliding_window
- Fix lab tau2 tests: ChatMessage signatures and Role comparisons

Author: eavanvalkenburg

python/packages/a2a/tests/test_a2a_agent.py

@@ -128,7 +128,7 @@ async def test_run_with_message_response(a2a_agent: A2AAgent, mock_a2a_client: M
 
     assert isinstance(response, AgentResponse)
     assert len(response.messages) == 1
-    assert response.messages[0].role == "assistant"
+    assert response.messages[0].role.value == "assistant"
     assert response.messages[0].text == "Hello from agent!"
     assert response.response_id == "msg-123"
     assert mock_a2a_client.call_count == 1
@@ -143,7 +143,7 @@ async def test_run_with_task_response_single_artifact(a2a_agent: A2AAgent, mock_
 
     assert isinstance(response, AgentResponse)
     assert len(response.messages) == 1
-    assert response.messages[0].role == "assistant"
+    assert response.messages[0].role.value == "assistant"
     assert response.messages[0].text == "Generated report content"
     assert response.response_id == "task-456"
     assert mock_a2a_client.call_count == 1
@@ -169,7 +169,7 @@ async def test_run_with_task_response_multiple_artifacts(a2a_agent: A2AAgent, mo
 
     # All should be assistant messages
     for message in response.messages:
-        assert message.role == "assistant"
+        assert message.role.value == "assistant"
 
     assert response.response_id == "task-789"
 
@@ -232,7 +232,7 @@ def test_parse_messages_from_task_with_artifacts(a2a_agent: A2AAgent) -> None:
     assert len(result) == 2
     assert result[0].text == "Content 1"
     assert result[1].text == "Content 2"
-    assert all(msg.role == "assistant" for msg in result)
+    assert all(msg.role.value == "assistant" for msg in result)
 
 
 def test_parse_message_from_artifact(a2a_agent: A2AAgent) -> None:
@@ -251,7 +251,7 @@ def test_parse_message_from_artifact(a2a_agent: A2AAgent) -> None:
     result = a2a_agent._parse_message_from_artifact(artifact)
 
     assert isinstance(result, ChatMessage)
-    assert result.role == "assistant"
+    assert result.role.value == "assistant"
     assert result.text == "Artifact content"
     assert result.raw_representation == artifact
 
@@ -295,7 +295,7 @@ def test_prepare_message_for_a2a_with_error_content(a2a_agent: A2AAgent) -> None
 
     # Create ChatMessage with ErrorContent
     error_content = Content.from_error(message="Test error message")
-    message = ChatMessage("user", [error_content])
+    message = ChatMessage(role="user", contents=[error_content])
 
     # Convert to A2A message
     a2a_message = a2a_agent._prepare_message_for_a2a(message)
@@ -310,7 +310,7 @@ def test_prepare_message_for_a2a_with_uri_content(a2a_agent: A2AAgent) -> None:
 
     # Create ChatMessage with UriContent
     uri_content = Content.from_uri(uri="http://example.com/file.pdf", media_type="application/pdf")
-    message = ChatMessage("user", [uri_content])
+    message = ChatMessage(role="user", contents=[uri_content])
 
     # Convert to A2A message
     a2a_message = a2a_agent._prepare_message_for_a2a(message)
@@ -326,7 +326,7 @@ def test_prepare_message_for_a2a_with_data_content(a2a_agent: A2AAgent) -> None:
 
     # Create ChatMessage with DataContent (base64 data URI)
     data_content = Content.from_uri(uri="data:text/plain;base64,SGVsbG8gV29ybGQ=", media_type="text/plain")
-    message = ChatMessage("user", [data_content])
+    message = ChatMessage(role="user", contents=[data_content])
 
     # Convert to A2A message
     a2a_message = a2a_agent._prepare_message_for_a2a(message)
@@ -340,7 +340,7 @@ def test_prepare_message_for_a2a_with_data_content(a2a_agent: A2AAgent) -> None:
 def test_prepare_message_for_a2a_empty_contents_raises_error(a2a_agent: A2AAgent) -> None:
     """Test _prepare_message_for_a2a with empty contents raises ValueError."""
     # Create ChatMessage with no contents
-    message = ChatMessage("user", [])
+    message = ChatMessage(role="user", contents=[])
 
     # Should raise ValueError for empty contents
     with raises(ValueError, match="ChatMessage.contents is empty"):
@@ -359,7 +359,7 @@ async def test_run_streaming_with_message_response(a2a_agent: A2AAgent, mock_a2a
     # Verify streaming response
     assert len(updates) == 1
     assert isinstance(updates[0], AgentResponseUpdate)
-    assert updates[0].role == "assistant"
+    assert updates[0].role.value == "assistant"
     assert len(updates[0].contents) == 1
 
     content = updates[0].contents[0]