Python: [BREAKING] Types API Review improvements (#3647)

* Replace Role and FinishReason classes with NewType + Literal

- Remove EnumLike metaclass from _types.py
- Replace Role class with NewType('Role', str) + RoleLiteral
- Replace FinishReason class with NewType('FinishReason', str) + FinishReasonLiteral
- Update all usages across codebase to use string literals
- Remove .value access patterns (direct string comparison now works)
- Add backward compatibility for legacy dict serialization format
- Update tests to reflect new string-based types

Addresses #3591, #3615

* Simplify ChatResponse and AgentResponse type hints (#3592)

- Remove overloads from ChatResponse.__init__
- Remove text parameter from ChatResponse.__init__
- Remove | dict[str, Any] from finish_reason and usage_details params
- Remove **kwargs from AgentResponse.__init__
- Both now accept ChatMessage | Sequence[ChatMessage] | None for messages
- Update docstrings and examples to reflect changes
- Fix tests that were using removed kwargs
- Fix Role type hint usage in ag-ui utils

* Remove text parameter from ChatResponseUpdate and AgentResponseUpdate (#3597)

- Remove text parameter from ChatResponseUpdate.__init__
- Remove text parameter from AgentResponseUpdate.__init__
- Remove **kwargs from both update classes
- Simplify contents parameter type to Sequence[Content] | None
- Update all usages to use contents=[Content.from_text(...)] pattern
- Fix imports in test files
- Update docstrings and examples

* Rename from_chat_response_updates to from_updates (#3593)

- ChatResponse.from_chat_response_updates → ChatResponse.from_updates
- ChatResponse.from_chat_response_generator → ChatResponse.from_update_generator
- AgentResponse.from_agent_run_response_updates → AgentResponse.from_updates

* Remove try_parse_value method from ChatResponse and AgentResponse (#3595)

- Remove try_parse_value method from ChatResponse
- Remove try_parse_value method from AgentResponse
- Remove try_parse_value calls from from_updates and from_update_generator methods
- Update samples to use try/except with response.value instead
- Update tests to use response.value pattern
- Users should now use response.value with try/except for safe parsing

* Add agent_id to AgentResponse and clarify author_name documentation (#3596)

- Add agent_id parameter to AgentResponse class
- Document that author_name is on ChatMessage objects, not responses
- Update ChatResponse docstring with author_name note
- Update AgentResponse docstring with author_name note

* Simplify ChatMessage.__init__ signature (#3618)

- Make contents a positional argument accepting Sequence[Content | str]
- Auto-convert strings in contents to TextContent
- Remove overloads, keep text kwarg for backward compatibility with serialization
- Update _parse_content_list to handle string items
- Update all usages across codebase to use new format: ChatMessage("role", ["text"])

* Allow Content as input on run and get_response

- Update prepare_messages and normalize_messages to accept Content
- Update type signatures in _agents.py and _clients.py
- Add tests for Content input handling

* Fix ChatMessage usage across packages and samples

Update all remaining ChatMessage(role=..., text=...) to use new
ChatMessage('role', ['text']) signature.

* Fix Role string usage and response format parsing

- Fix redis provider: remove .value access on string literals
- Fix durabletask ensure_response_format: set _response_format before accessing .value

* Fix ollama .value and ai_model_id issues, handle None in content list

- Fix ollama _chat_client: remove .value on string literals
- Fix ollama _chat_client: rename ai_model_id to model_id
- Fix _parse_content_list: skip None values gracefully

* Fix A2AAgent type signature to include Content

* Fix Role/FinishReason NewType dict annotations and improve test coverage to 95%

* Fix mypy errors for Role/FinishReason NewType usage

* Fix Role.TOOL and Role.ASSISTANT usage in _orchestrator_helpers.py

* Fix Role NewType usage in durabletask _models.py

python/packages/github_copilot/agent_framework_github_copilot/_agent.py

@@ -16,7 +16,6 @@ from agent_framework import (
     ChatMessage,
     Content,
     ContextProvider,
-    Role,
     normalize_messages,
 )
 from agent_framework._tools import FunctionTool, ToolProtocol
@@ -330,7 +329,7 @@ class GitHubCopilotAgent(BaseAgent, Generic[TOptions]):
             if response_event.data.content:
                 response_messages.append(
                     ChatMessage(
-                        role=Role.ASSISTANT,
+                        role="assistant",
                         contents=[Content.from_text(response_event.data.content)],
                         message_id=message_id,
                         raw_representation=response_event,
@@ -385,7 +384,7 @@ class GitHubCopilotAgent(BaseAgent, Generic[TOptions]):
             if event.type == SessionEventType.ASSISTANT_MESSAGE_DELTA:
                 if event.data.delta_content:
                     update = AgentResponseUpdate(
-                        role=Role.ASSISTANT,
+                        role="assistant",
                         contents=[Content.from_text(event.data.delta_content)],
                         response_id=event.data.message_id,
                         message_id=event.data.message_id,

python/packages/github_copilot/tests/test_github_copilot_agent.py

@@ -13,7 +13,6 @@ from agent_framework import (
     AgentThread,
     ChatMessage,
     Content,
-    Role,
 )
 from agent_framework.exceptions import ServiceException
 from copilot.generated.session_events import Data, SessionEvent, SessionEventType
@@ -282,7 +281,7 @@ class TestGitHubCopilotAgentRun:
 
         assert isinstance(response, AgentResponse)
         assert len(response.messages) == 1
-        assert response.messages[0].role == Role.ASSISTANT
+        assert response.messages[0].role == "assistant"
         assert response.messages[0].contents[0].text == "Test response"
 
     async def test_run_chat_message(
@@ -295,7 +294,7 @@ class TestGitHubCopilotAgentRun:
         mock_session.send_and_wait.return_value = assistant_message_event
 
         agent = GitHubCopilotAgent(client=mock_client)
-        chat_message = ChatMessage(role=Role.USER, contents=[Content.from_text("Hello")])
+        chat_message = ChatMessage("user", [Content.from_text("Hello")])
         response = await agent.run(chat_message)
 
         assert isinstance(response, AgentResponse)
@@ -390,7 +389,7 @@ class TestGitHubCopilotAgentRunStream:
 
         assert len(responses) == 1
         assert isinstance(responses[0], AgentResponseUpdate)
-        assert responses[0].role == Role.ASSISTANT
+        assert responses[0].role == "assistant"
         assert responses[0].contents[0].text == "Hello"
 
     async def test_run_stream_with_thread(