Toggle KEEP-ALIVE on the user's session sandbox — the chat twin of the ◉ keep-alive control in the SANDBOX pane. on: true holds the sandbox up across idle periods (so it doesn't wind down between uses) until turned off or the daily keep-alive clock runs out; on: false returns it to the standard free idle window (which shuts it down on inactivity). USE THIS when the user asks to keep their sandbox alive / warm / persistent / from timing out, or to stop keeping it alive. Keep-alive spends a per-ACCOUNT daily clock (the Studio only; banked Sandbox Time top-ups extend it — get_allowances has the live number), so an anonymous caller is told to log in. Never name an old plan. Needs wallet_address.