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/samples/getting_started/purview_agent/sample_purview_agent.py

@@ -25,7 +25,7 @@ import asyncio
 import os
 from typing import Any
 
-from agent_framework import AgentResponse, ChatAgent, ChatMessage, Role
+from agent_framework import AgentResponse, ChatAgent, ChatMessage
 from agent_framework.azure import AzureOpenAIChatClient
 from agent_framework.microsoft import (
     PurviewChatPolicyMiddleware,
@@ -159,13 +159,13 @@ async def run_with_agent_middleware() -> None:
 
     print("-- Agent Middleware Path --")
     first: AgentResponse = await agent.run(
-        ChatMessage(role=Role.USER, text="Tell me a joke about a pirate.", additional_properties={"user_id": user_id})
+        ChatMessage("user", ["Tell me a joke about a pirate."], additional_properties={"user_id": user_id})
     )
     print("First response (agent middleware):\n", first)
 
     second: AgentResponse = await agent.run(
         ChatMessage(
-            role=Role.USER, text="That was funny. Tell me another one.", additional_properties={"user_id": user_id}
+            role="user", text="That was funny. Tell me another one.", additional_properties={"user_id": user_id}
         )
     )
     print("Second response (agent middleware):\n", second)
@@ -203,7 +203,7 @@ async def run_with_chat_middleware() -> None:
     print("-- Chat Middleware Path --")
     first: AgentResponse = await agent.run(
         ChatMessage(
-            role=Role.USER,
+            role="user",
             text="Give me a short clean joke.",
             additional_properties={"user_id": user_id},
         )
@@ -212,7 +212,7 @@ async def run_with_chat_middleware() -> None:
 
     second: AgentResponse = await agent.run(
         ChatMessage(
-            role=Role.USER,
+            role="user",
             text="One more please.",
             additional_properties={"user_id": user_id},
         )
@@ -253,13 +253,13 @@ async def run_with_custom_cache_provider() -> None:
 
     first: AgentResponse = await agent.run(
         ChatMessage(
-            role=Role.USER, text="Tell me a joke about a programmer.", additional_properties={"user_id": user_id}
+            role="user", text="Tell me a joke about a programmer.", additional_properties={"user_id": user_id}
         )
     )
     print("First response (custom provider):\n", first)
 
     second: AgentResponse = await agent.run(
-        ChatMessage(role=Role.USER, text="That's hilarious! One more?", additional_properties={"user_id": user_id})
+        ChatMessage("user", ["That's hilarious! One more?"], additional_properties={"user_id": user_id})
     )
     print("Second response (custom provider):\n", second)
 
@@ -294,12 +294,12 @@ async def run_with_custom_cache_provider() -> None:
     print("Using default InMemoryCacheProvider with settings-based configuration")
 
     first: AgentResponse = await agent.run(
-        ChatMessage(role=Role.USER, text="Tell me a joke about AI.", additional_properties={"user_id": user_id})
+        ChatMessage("user", ["Tell me a joke about AI."], additional_properties={"user_id": user_id})
     )
     print("First response (default cache):\n", first)
 
     second: AgentResponse = await agent.run(
-        ChatMessage(role=Role.USER, text="Nice! Another AI joke please.", additional_properties={"user_id": user_id})
+        ChatMessage("user", ["Nice! Another AI joke please."], additional_properties={"user_id": user_id})
     )
     print("Second response (default cache):\n", second)