Python: [BREAKING] PR2 — Wire context provider pipeline, remove old types, update all consumers (#3850)

* PR2: Wire context provider pipeline and update all internal consumers

- Replace AgentThread with AgentSession across all packages
- Replace ContextProvider with BaseContextProvider across all packages
- Replace context_provider param with context_providers (Sequence)
- Replace thread= with session= in run() signatures
- Replace get_new_thread() with create_session()
- Add get_session(service_session_id) to agent interface
- DurableAgentThread -> DurableAgentSession
- Remove _notify_thread_of_new_messages from WorkflowAgent
- Wire before_run/after_run context provider pipeline in RawAgent
- Auto-inject InMemoryHistoryProvider when no providers configured

* fix: update all tests for context provider pipeline, fix lazy-loaders, remove old test files

* refactor: update all sample files for context provider pipeline (AgentThread→AgentSession, ContextProvider→BaseContextProvider)

* fix: update remaining ag-ui references (client docstring, getting_started sample)

* fix: make get_session service_session_id keyword-only to avoid confusion with session_id

* refactor: rename _RunContext.thread_messages to session_messages

* refactor: remove _threads.py, _memory.py, and old provider files; migrate devui to use plain message lists

* rename: remove _new_ prefix from test files

* refactor: rewrite SlidingWindowChatMessageStore as SlidingWindowHistoryProvider(InMemoryHistoryProvider)

* fix: read full history from session state directly instead of reaching into provider internals

* fix: update stale .pyi stubs, sample imports, and README references for new provider types

* fix: remove stale message_store, _notify_thread_of_new_messages, and session_id.key references in samples

* refactor: merge context_providers and sessions sample folders into sessions, remove aggregate_context_provider

* refactor: UserInfoMemory stores state in session.state instead of instance attributes

* feat: add Pydantic BaseModel support to session state serialization

Pydantic models stored in session.state are now automatically serialized
via model_dump() and restored via model_validate() during to_dict()/from_dict()
round-trips. Models are auto-registered on first serialization; use
register_state_type() for cold-start deserialization.

Also export register_state_type as a public API.

* fix mem0

* Update sample README links and descriptions for session terminology

- Replace 'thread' with 'session' in sample descriptions across all READMEs
- Update file links for renamed samples (mem0_sessions, redis_sessions, etc.)
- Fix Threads section → Sessions section in main samples/README.md
- Update tools, middleware, workflows, durabletask, azure_functions READMEs
- Update architecture diagrams in concepts/tools/README.md
- Update migration guides (autogen, semantic-kernel)

* Fix broken Redis README link to renamed sample

* Fix Mem0 OSS client search: pass scoping params as direct kwargs

AsyncMemory (OSS) expects user_id/agent_id/run_id as direct kwargs,
while AsyncMemoryClient (Platform) expects them in a filters dict.
Adds tests for both client types.

Port of fix from #3844 to new Mem0ContextProvider.

* Fix rebase issues: restore missing _conversation_state.py and checkpoint decode logic

- Add back _conversation_state.py (encode/decode_chat_messages) lost in rebase
- Fix on_checkpoint_restore to decode cache/conversation with decode_chat_messages
- Fix on_checkpoint_restore to use decode_checkpoint_value for pending requests
- Add tests/workflow/__init__.py for relative import support
- Fix test_agent_executor checkpoint selection (checkpoints[1] not superstep)

* Add STORES_BY_DEFAULT ClassVar to skip redundant InMemoryHistoryProvider injection

Chat clients that store history server-side by default (OpenAI Responses API,
Azure AI Agent) now declare STORES_BY_DEFAULT = True. The agent checks this
during auto-injection and skips InMemoryHistoryProvider unless the user
explicitly sets store=False.

* Fix broken markdown links in azure_ai and redis READMEs

* Fix getting-started samples to use session API instead of removed thread/ContextProvider API

* updates to workflow as agent

* fix group chat import

* Rename Thread→Session throughout, fix service_session_id propagation, remove stale AGUIThread

- Fix: Propagate conversation_id from ChatResponse back to session.service_session_id
  in both streaming and non-streaming paths in _agents.py
- Rename AgentThreadException → AgentSessionException
- Remove stale AGUIThread from ag_ui lazy-loader
- Rename use_service_thread → use_service_session in ag-ui package
- Rename test functions from *_thread_* to *_session_*
- Rename sample files from *_thread* to *_session*
- Update docstrings and comments: thread → session
- Update _mcp.py kwargs filter: add 'session' alongside 'thread'
- Fix ContinuationToken docstring example: thread=thread → session=session
- Fix _clients.py docstring: 'Agent threads' → 'Agent sessions'

* Fix broken markdown links after thread→session file renames

* fix azure ai test

python/packages/ag-ui/agent_framework_ag_ui/_agent.py

@@ -18,7 +18,7 @@ class AgentConfig:
         self,
         state_schema: Any | None = None,
         predict_state_config: dict[str, dict[str, str]] | None = None,
-        use_service_thread: bool = False,
+        use_service_session: bool = False,
         require_confirmation: bool = True,
     ):
         """Initialize agent configuration.
@@ -26,12 +26,12 @@ class AgentConfig:
         Args:
             state_schema: Optional state schema for state management; accepts dict or Pydantic model/class
             predict_state_config: Configuration for predictive state updates
-            use_service_thread: Whether the agent thread is service-managed
+            use_service_session: Whether the agent session is service-managed
             require_confirmation: Whether predictive updates require user confirmation before applying
         """
         self.state_schema = self._normalize_state_schema(state_schema)
         self.predict_state_config = predict_state_config or {}
-        self.use_service_thread = use_service_thread
+        self.use_service_session = use_service_session
         self.require_confirmation = require_confirmation
 
     @staticmethod
@@ -77,7 +77,7 @@ class AgentFrameworkAgent:
         state_schema: Any | None = None,
         predict_state_config: dict[str, dict[str, str]] | None = None,
         require_confirmation: bool = True,
-        use_service_thread: bool = False,
+        use_service_session: bool = False,
     ):
         """Initialize the AG-UI compatible agent wrapper.
 
@@ -88,7 +88,7 @@ class AgentFrameworkAgent:
             state_schema: Optional state schema for state management; accepts dict or Pydantic model/class
             predict_state_config: Configuration for predictive state updates
             require_confirmation: Whether predictive updates require user confirmation before applying
-            use_service_thread: Whether the agent thread is service-managed
+            use_service_session: Whether the agent session is service-managed
         """
         self.agent = agent
         self.name = name or getattr(agent, "name", "agent")
@@ -97,7 +97,7 @@ class AgentFrameworkAgent:
         self.config = AgentConfig(
             state_schema=state_schema,
             predict_state_config=predict_state_config,
-            use_service_thread=use_service_thread,
+            use_service_session=use_service_session,
             require_confirmation=require_confirmation,
         )
 

python/packages/ag-ui/agent_framework_ag_ui/_client.py

@@ -171,11 +171,11 @@ class AGUIChatClient(
 
             client = AGUIChatClient(endpoint="http://localhost:8888/")
             agent = Agent(name="assistant", client=client)
-            thread = await agent.get_new_thread()
+            session = agent.create_session()
 
             # Agent automatically maintains history and sends full context
-            response = await agent.run("Hello!", thread=thread)
-            response2 = await agent.run("How are you?", thread=thread)
+            response = await agent.run("Hello!", session=session)
+            response2 = await agent.run("How are you?", session=session)
 
         Streaming usage:
 

python/packages/ag-ui/agent_framework_ag_ui/_run.py

@@ -27,7 +27,7 @@ from ag_ui.core import (
     ToolCallStartEvent,
 )
 from agent_framework import (
-    AgentThread,
+    AgentSession,
     Content,
     Message,
     SupportsAgentRun,
@@ -809,12 +809,12 @@ async def run_agent_stream(
     register_additional_client_tools(agent, client_tools)
     tools = merge_tools(server_tools, client_tools)
 
-    # Create thread (with service thread support)
-    if config.use_service_thread:
+    # Create session (with service session support)
+    if config.use_service_session:
         supplied_thread_id = input_data.get("thread_id") or input_data.get("threadId")
-        thread = AgentThread(service_thread_id=supplied_thread_id)
+        session = AgentSession(service_session_id=supplied_thread_id)
     else:
-        thread = AgentThread()
+        session = AgentSession()
 
     # Inject metadata for AG-UI orchestration (Feature #2: Azure-safe truncation)
     base_metadata: dict[str, Any] = {
@@ -823,16 +823,16 @@ async def run_agent_stream(
     }
     if flow.current_state:
         base_metadata["current_state"] = flow.current_state
-    thread.metadata = _build_safe_metadata(base_metadata)  # type: ignore[attr-defined]
+    session.metadata = _build_safe_metadata(base_metadata)  # type: ignore[attr-defined]
 
     # Build run kwargs (Feature #6: Azure store flag when metadata present)
-    run_kwargs: dict[str, Any] = {"thread": thread}
+    run_kwargs: dict[str, Any] = {"session": session}
     if tools:
         run_kwargs["tools"] = tools
     # Filter out AG-UI internal metadata keys before passing to chat client
     # These are used internally for orchestration and should not be sent to the LLM provider
     client_metadata = {
-        k: v for k, v in (getattr(thread, "metadata", None) or {}).items() if k not in AG_UI_INTERNAL_METADATA_KEYS
+        k: v for k, v in (getattr(session, "metadata", None) or {}).items() if k not in AG_UI_INTERNAL_METADATA_KEYS
     }
     safe_metadata = _build_safe_metadata(client_metadata) if client_metadata else {}
     if safe_metadata: