* PR1: Add core context provider types and tests
New types in _sessions.py (no changes to existing code):
- SessionContext: per-invocation state with extend_messages/get_messages/
extend_instructions/extend_tools and read-only response property
- _ContextProviderBase: base class with before_run/after_run hooks
- _HistoryProviderBase: storage base with load/store flags, abstract
get_messages/save_messages, default before_run/after_run
- AgentSession: lightweight session with state dict, to_dict/from_dict
- InMemoryHistoryProvider: built-in provider storing in session.state
35 unit tests covering all classes and configuration flags.
* feat: keyword-only params, stateless InMemoryHistoryProvider, deep serialization
- Make before_run/after_run parameters keyword-only
- InMemoryHistoryProvider stores ChatMessage objects directly (no per-cycle serialization)
- Deep serialization via to_dict/from_dict only at session boundary
- State type registry for automatic deserialization of registered types
- Updated tests for new serialization approach
* feat: add new-pattern provider implementations for external packages
- _RedisContextProvider(BaseContextProvider) - Redis search/vector context
- _RedisHistoryProvider(BaseHistoryProvider) - Redis-backed message storage
- _Mem0ContextProvider(BaseContextProvider) - Mem0 semantic memory
- _AzureAISearchContextProvider(BaseContextProvider) - Azure AI Search (semantic + agentic)
All use temporary _ prefix names for side-by-side coexistence with existing providers.
Will be renamed in PR2 when old ContextProvider/ChatMessageStore are removed.
* test: add tests for new-pattern provider implementations
- 32 tests for _RedisContextProvider and _RedisHistoryProvider
- 29 tests for _Mem0ContextProvider
- 17 tests for _AzureAISearchContextProvider
* fix: address PR review comments and CI failures
- Move module docstring before imports in _sessions.py (review comment)
- Import TYPE_CHECKING unconditionally in Redis _context_provider.py (NameError on Python <3.12)
- Fix Mem0 test_init_auto_creates_client_when_none to patch at class level
* feat: add source attribution to extend_messages
Set attribution marker in additional_properties for each message
added via extend_messages(), matching the tool attribution pattern.
Uses setdefault to preserve any existing attribution.
* refactor: make attribution value a dict with source_id key
* add attribution and use sets for filters
* Add source_type to message attribution and copy messages in extend_messages
- SessionContext.extend_messages now accepts source as str or object with
source_id attribute; when an object is passed, its class name is recorded
as source_type in the attribution dict
- Messages are shallow-copied before attribution is added so callers'
original objects are never mutated
- Filter framework-internal keys (attribution) from A2A wire metadata
to prevent leaking internal state over the wire
* fix: correct mypy type: ignore comment from union-attr to attr-defined
* set attribution to _attribution
* adjusted naming of bools
