1. For prototyping and testing purposes, sandbox name can be provided, and it will be used for all requests across the lifecycle of an agent
2. If no sandbox name is provided, agent engine name will be provided, and we will automatically create one sandbox per session, and the sandbox has TTL set for a year.
If the sandbox stored in the session hits the TTL, it will not be in "STATE_RUNNING" so a new sandbox will be created.
Co-authored-by: Lusha Wang <lusha@google.com>
PiperOrigin-RevId: 874415933
Lusha WangandCopybara-Service