feat(core, ui): Add /agents refresh command. (#16204)

packages/core/src/agents/a2a-client-manager.ts

@@ -104,6 +104,15 @@ export class A2AClientManager {
     return agentCard;
   }
 
+  /**
+   * Invalidates all cached clients and agent cards.
+   */
+  clearCache(): void {
+    this.clients.clear();
+    this.agentCards.clear();
+    debugLogger.debug('[A2AClientManager] Cache cleared.');
+  }
+
   /**
    * Sends a message to a loaded agent.
    * @param agentName The name of the agent to send the message to.