fix: restore public store and invalidateSession on LettaBot (#515)

src/core/bot.ts

@@ -187,7 +187,7 @@ export function resolveHeartbeatConversationKey(
 }
 
 export class LettaBot implements AgentSession {
-  private store: Store;
+  readonly store: Store;
   private config: BotConfig;
   private channels: Map<string, ChannelAdapter> = new Map();
   private messageQueue: Array<{ msg: InboundMessage; adapter: ChannelAdapter }> = [];
@@ -485,6 +485,14 @@ export class LettaBot implements AgentSession {
     return this.sessionManager.warmSession();
   }
 
+  /**
+   * Invalidate cached session(s), forcing a fresh session on next message.
+   * The next message will create a fresh session using the current store state.
+   */
+  invalidateSession(key?: string): void {
+    this.sessionManager.invalidateSession(key);
+  }
+
   // =========================================================================
   // Channel management
   // =========================================================================