b2ec1f99b9
Add user_id parameter to all ThreadMetaStore abstract methods. Implement owner isolation in MemoryThreadMetaStore with _get_owned_record helper. Add check_access to base class and memory implementation. Add make_thread_store factory to simplify deps.py initialization. Add memory-backend isolation tests. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>