Python: [BREAKING] Simplify API: ChatAgent -> Agent, ChatMessage -> Message (#3747)

* [BREAKING] Rename ChatAgent -> Agent, ChatMessage -> Message, ChatClientProtocol -> SupportsChatGetResponse

Simplify the public API by removing redundant 'Chat' prefix from core types:
- ChatAgent -> Agent
- RawChatAgent -> RawAgent
- ChatMessage -> Message
- ChatClientProtocol -> SupportsChatGetResponse

Also renamed internal WorkflowMessage (was Message in _runner_context) to avoid collision.

No backward compatibility aliases - this is a clean breaking change.

* [BREAKING] Rename Agent chat_client parameter to client

* Fix rebase issues: WorkflowMessage references and broken markdown links

* Fix formatting and lint issues from code quality checks

* Fix import ordering in workflow sample files

* fixed rebase

* Fix test failures: use WorkflowMessage and A2AMessage after ChatMessage→Message rename

- Replace Message(data=..., source_id=...) with WorkflowMessage(...) in workflow tests
- Fix isinstance check in A2A agent to use A2AMessage instead of Message
- Fix import in test_workflow_observability.py (Message→WorkflowMessage)

* Fix lint, fmt, and sample errors after ChatMessage→Message rename

- Auto-fix 70+ ruff lint issues across samples (ChatMessage→Message refs)
- Fix HostedVectorStoreContent→Content.from_hosted_vector_store in file search sample
- Fix _normalize_messages→normalize_messages in custom agent sample
- Fix context.terminate→raise MiddlewareTermination in middleware samples
- Fix with_update_hook→with_transform_hook in override middleware sample
- Add TOptions_co import back to custom_chat_client sample
- Add noqa for FastAPI File() default in chatkit sample
- Fix B023 loop variable capture in weather agent sample

* fix: update Agent constructor calls from chat_client to client in declaration-only tool tests

* fix: add register_cleanup to devui lazy-loading proxy and type stub

* fixed tests and updated new pieces

* fix agui typevar

* fix merge errors

* fix merge conflicts

* fiux merge

* Remove unused links

---------

Co-authored-by: Evan Mattson <evan.mattson@microsoft.com>

python/packages/purview/agent_framework_purview/_middleware.py

@@ -26,13 +26,11 @@ class PurviewPolicyMiddleware(AgentMiddleware):
 
     .. code-block:: python
         from agent_framework.microsoft import PurviewPolicyMiddleware, PurviewSettings
-        from agent_framework import ChatAgent
+        from agent_framework import Agent
 
         credential = ...  # TokenCredential or AsyncTokenCredential
         settings = PurviewSettings(app_name="My App")
-        agent = ChatAgent(
-            chat_client=client, instructions="...", middleware=[PurviewPolicyMiddleware(credential, settings)]
-        )
+        agent = Agent(client=client, instructions="...", middleware=[PurviewPolicyMiddleware(credential, settings)])
     """
 
     def __init__(
@@ -77,10 +75,10 @@ class PurviewPolicyMiddleware(AgentMiddleware):
                 context.messages, Activity.UPLOAD_TEXT, session_id=session_id
             )
             if should_block_prompt:
-                from agent_framework import AgentResponse, ChatMessage
+                from agent_framework import AgentResponse, Message
 
                 context.result = AgentResponse(
-                    messages=[ChatMessage(role="system", text=self._settings.blocked_prompt_message)]
+                    messages=[Message(role="system", text=self._settings.blocked_prompt_message)]
                 )
                 raise MiddlewareTermination
         except MiddlewareTermination:
@@ -110,10 +108,10 @@ class PurviewPolicyMiddleware(AgentMiddleware):
                     user_id=resolved_user_id,
                 )
                 if should_block_response:
-                    from agent_framework import AgentResponse, ChatMessage
+                    from agent_framework import AgentResponse, Message
 
                     context.result = AgentResponse(
-                        messages=[ChatMessage(role="system", text=self._settings.blocked_response_message)]
+                        messages=[Message(role="system", text=self._settings.blocked_response_message)]
                     )
             else:
                 # Streaming responses are not supported for post-checks
@@ -173,9 +171,9 @@ class PurviewChatPolicyMiddleware(ChatMiddleware):
                 context.messages, Activity.UPLOAD_TEXT, session_id=session_id
             )
             if should_block_prompt:
-                from agent_framework import ChatMessage, ChatResponse
+                from agent_framework import ChatResponse, Message
 
-                blocked_message = ChatMessage(role="system", text=self._settings.blocked_prompt_message)
+                blocked_message = Message(role="system", text=self._settings.blocked_prompt_message)
                 context.result = ChatResponse(messages=[blocked_message])
                 raise MiddlewareTermination
         except MiddlewareTermination:
@@ -205,9 +203,9 @@ class PurviewChatPolicyMiddleware(ChatMiddleware):
                         messages, Activity.UPLOAD_TEXT, session_id=session_id_response, user_id=resolved_user_id
                     )
                     if should_block_response:
-                        from agent_framework import ChatMessage, ChatResponse
+                        from agent_framework import ChatResponse, Message
 
-                        blocked_message = ChatMessage(role="system", text=self._settings.blocked_response_message)
+                        blocked_message = Message(role="system", text=self._settings.blocked_response_message)
                         context.result = ChatResponse(messages=[blocked_message])
             else:
                 logger.debug("Streaming responses are not supported for Purview policy post-checks")

python/packages/purview/agent_framework_purview/_processor.py

@@ -6,7 +6,7 @@ import uuid
 from collections.abc import Iterable, MutableMapping
 from typing import Any
 
-from agent_framework import ChatMessage
+from agent_framework import Message
 from agent_framework._logging import get_logger
 
 from ._cache import CacheProvider, InMemoryCacheProvider, create_protection_scopes_cache_key
@@ -64,7 +64,7 @@ class ScopedContentProcessor:
 
     async def process_messages(
         self,
-        messages: Iterable[ChatMessage],
+        messages: Iterable[Message],
         activity: Activity,
         session_id: str | None = None,
         user_id: str | None = None,
@@ -97,7 +97,7 @@ class ScopedContentProcessor:
 
     async def _map_messages(
         self,
-        messages: Iterable[ChatMessage],
+        messages: Iterable[Message],
         activity: Activity,
         session_id: str | None = None,
         provided_user_id: str | None = None,