A sandbox with no time limit can be funded up to 12 hours ahead

Set leaseSeconds (from its first lease, 1,800 seconds, to 43,200) on create or :update (--lease in the CLI, lease_seconds= in Python, .leaseSeconds() in Java, LeaseSeconds in Go), and each renewal funds it that far ahead instead of 1,800 seconds. It is renewed when half is left, so it keeps running for at least half of leaseSeconds if Runtime's control plane cannot renew it. Each renewal holds that much time's credit at the sandbox's rates; what it does not use is released. A sandbox on the free usage renews by 1,800 seconds until the account has credit. Only an owner's, an admin's or an account-wide key may set it, on a sandbox one of those made. If that key or member loses the right, a sandbox funded past its first lease is paused or stopped at once, as its lease's end would. A sandbox's details include its leaseSeconds.