初始化demo

agent_demo/persistence/base.py

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+import re
+from abc import ABC, abstractmethod
+from dataclasses import dataclass, field
+from typing import List
+
+SAFE_ID = re.compile(r"^[a-zA-Z0-9._-]")
+
+
+def sanitize_id(value: str, fallback:str) -> str:
+    """Sanitize a string to be used as an ID by removing unsafe characters."""
+    return SAFE_ID.sub("_", value) or fallback
+
+
+@dataclass
+class Session:
+    """Conversasion history for one (user_id, session_id) pair.
+    ``message`` is in Strands / Bedrock-converse format (provider-neutral::
+        {"role": "user"|"assistant"|"system",
+         "content": [{"text": ...} | {"toolUse": ...} | {"toolResult": ...} ]})
+    """
+    session_id: str
+    user_id: str
+    messages: List[dict] = field(default_factory=list)
+    
+
+class SessionStore(ABC):
+    """Abstract base class for session storage backends."""
+
+    @abstractmethod
+    def load(self, user_id: str, session_id: str) -> Session:
+        """Return prior history for the key (empty Session if none exists yet)."""
+        pass
+
+    @abstractmethod
+    def save(self, session: Session) -> None:
+        """Save a session to the store."""
+        pass
+    
+    @abstractmethod
+    def clear(self, user_id: str, session_id: str) -> None:
+        """Clear a session from the store."""
+        pass