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/azurefunctions/agent_framework_azurefunctions/_app.py

@@ -135,8 +135,8 @@ class AgentFunctionApp(DFAppBase):
         @app.orchestration_trigger(context_name="context")
         def my_orchestration(context):
             writer = app.get_agent(context, "WeatherAgent")
-            thread = writer.get_new_thread()
-            forecast_task = writer.run("What's the forecast?", thread=thread)
+            session = writer.create_session()
+            forecast_task = writer.run("What's the forecast?", session=session)
             forecast = yield forecast_task
             return forecast
 

python/packages/azurefunctions/agent_framework_azurefunctions/_orchestration.py

@@ -9,7 +9,7 @@ from collections.abc import Callable
 from typing import TYPE_CHECKING, Any, TypeAlias
 
 import azure.durable_functions as df
-from agent_framework import AgentThread, get_logger
+from agent_framework import AgentSession, get_logger
 from agent_framework_durabletask import (
     DurableAgentExecutor,
     RunRequest,
@@ -178,11 +178,11 @@ class AzureFunctionsAgentExecutor(DurableAgentExecutor[AgentTask]):
         self,
         agent_name: str,
         run_request: RunRequest,
-        thread: AgentThread | None = None,
+        session: AgentSession | None = None,
     ) -> AgentTask:
 
         # Resolve session
-        session_id = self._create_session_id(agent_name, thread)
+        session_id = self._create_session_id(agent_name, session)
 
         entity_id = df.EntityId(
             name=session_id.entity_name,

python/packages/azurefunctions/tests/test_orchestration.py

@@ -214,10 +214,10 @@ class TestAzureFunctionsFireAndForget:
         context.call_entity = Mock(return_value=_create_entity_task())
 
         agent = DurableAIAgent(executor, "TestAgent")
-        thread = agent.get_new_thread()
+        session = agent.create_session()
 
         # Run with wait_for_response=False
-        result = agent.run("Test message", thread=thread, options={"wait_for_response": False})
+        result = agent.run("Test message", session=session, options={"wait_for_response": False})
 
         # Verify signal_entity was called and call_entity was not
         assert context.signal_entity.call_count == 1
@@ -232,9 +232,9 @@ class TestAzureFunctionsFireAndForget:
         context.signal_entity = Mock()
 
         agent = DurableAIAgent(executor, "TestAgent")
-        thread = agent.get_new_thread()
+        session = agent.create_session()
 
-        result = agent.run("Test message", thread=thread, options={"wait_for_response": False})
+        result = agent.run("Test message", session=session, options={"wait_for_response": False})
 
         # Task should be immediately complete
         assert isinstance(result, AgentTask)
@@ -246,9 +246,9 @@ class TestAzureFunctionsFireAndForget:
         context.signal_entity = Mock()
 
         agent = DurableAIAgent(executor, "TestAgent")
-        thread = agent.get_new_thread()
+        session = agent.create_session()
 
-        result = agent.run("Test message", thread=thread, options={"wait_for_response": False})
+        result = agent.run("Test message", session=session, options={"wait_for_response": False})
 
         # Get the result
         response = result.result
@@ -267,9 +267,9 @@ class TestAzureFunctionsFireAndForget:
         context.call_entity = Mock(return_value=_create_entity_task())
 
         agent = DurableAIAgent(executor, "TestAgent")
-        thread = agent.get_new_thread()
+        session = agent.create_session()
 
-        result = agent.run("Test message", thread=thread, options={"wait_for_response": True})
+        result = agent.run("Test message", session=session, options={"wait_for_response": True})
 
         # Verify call_entity was called and signal_entity was not
         assert context.call_entity.call_count == 1
@@ -298,15 +298,15 @@ class TestOrchestrationIntegration:
         # Create agent directly with executor (not via app.get_agent)
         agent = DurableAIAgent(executor, "WriterAgent")
 
-        # Create thread
-        thread = agent.get_new_thread()
+        # Create session
+        session = agent.create_session()
 
         # First call - returns AgentTask
-        task1 = agent.run("Write something", thread=thread)
+        task1 = agent.run("Write something", session=session)
         assert isinstance(task1, AgentTask)
 
         # Second call - returns AgentTask
-        task2 = agent.run("Improve: something", thread=thread)
+        task2 = agent.run("Improve: something", session=session)
         assert isinstance(task2, AgentTask)
 
         # Verify both calls used the same entity (same session key)
@@ -315,7 +315,7 @@ class TestOrchestrationIntegration:
         # EntityId format is @dafx-writeragent@<uuid_hex>
         expected_entity_id = f"@dafx-writeragent@{uuid_hexes[0]}"
         assert entity_calls[0]["entity_id"] == expected_entity_id
-        # generate_unique_id called 3 times: thread + 2 correlation IDs
+        # generate_unique_id called 3 times: session + 2 correlation IDs
         assert executor.generate_unique_id.call_count == 3
 
     def test_multiple_agents_in_orchestration(self, executor_with_multiple_uuids: tuple[Any, Mock, list[str]]) -> None:
@@ -334,12 +334,12 @@ class TestOrchestrationIntegration:
         writer = DurableAIAgent(executor, "WriterAgent")
         editor = DurableAIAgent(executor, "EditorAgent")
 
-        writer_thread = writer.get_new_thread()
-        editor_thread = editor.get_new_thread()
+        writer_session = writer.create_session()
+        editor_session = editor.create_session()
 
         # Call both agents - returns AgentTasks
-        writer_task = writer.run("Write", thread=writer_thread)
-        editor_task = editor.run("Edit", thread=editor_thread)
+        writer_task = writer.run("Write", session=writer_session)
+        editor_task = editor.run("Edit", session=editor_session)
 
         assert isinstance(writer_task, AgentTask)
         assert isinstance(editor_task, AgentTask)