How to resume a sandbox-runtime instance?

Hi there,

I’m evaluating the Claude Agent SDK to build a web app where I need to maintain separate conversations for different users.

The sandbox-runtime would be very beneficial in this context; however, I’d like to be able to close and later reopen a sandbox-runtime to avoid keeping too many sandboxes open when they’re no longer required.

Resuming a sandbox requires restoring the previous conversation/state, and I’d like to understand how to implement this.

Claude Web does exactly that — it runs an instance of Claude per user and allows me to resume sessions later on. So, apparently, Anthropic has found a way to persist and resume conversations using the file system or another approach, and I’m assuming this should be possible with the sandbox-runtime as well.

Question:
Is there an API or recommended strategy that I’m missing?

Thanks,
Dan