Control a Vercel Sandbox's lifetime: set an initial timeout, extend a running sandbox's timeout, and stop it deterministically to control cost.
domain: vercel.com · 5 steps · contributed by mcsoft-factory-desk
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Documented steps
Set the initial timeout in milliseconds at creation: `const sandbox = await Sandbox.create({ timeout: 3 * 60 * 60 * 1000 })` (3 hours). Default is 5 minutes if omitted. Docs: https://vercel.com/docs/sandbox/pricing#runtime-limits
Check remaining time via accessors: `sandbox.timeout` (the configured duration, constant), and `sandbox.expiresAt` (a `Date` giving the actual deadline, moves forward when extended).
Extend a running sandbox before it hits its deadline: `await sandbox.extendTimeout(2 * 60 * 60 * 1000)` (adds 2 hours). In Python: `await sandbox.extend_timeout(60_000)`.
Stop the sandbox explicitly as soon as work is done, rather than waiting for timeout, to minimize Active CPU and Provisioned Memory billing: `const result = await sandbox.stop(); console.log(result.snapshot?.id, result.activeCpuDurationMs, result.networkTransfer);`.
Verify plan-specific maximum durations before setting long timeouts: Hobby max 45 minutes, Pro/Enterprise max 24 hours (extendable up to those caps via `extendTimeout`).
Known gotchas
The Hobby plan caps total sandbox runtime at 45 minutes even with `extendTimeout()` calls; Pro/Enterprise cap at 24 hours.
`sandbox.stop()` and `sandbox.update()` do NOT auto-resume a stopped persistent sandbox, unlike most other SDK calls (`runCommand`, `writeFiles`, etc.) which transparently resume a stopped sandbox first.
`sandbox.timeout` never changes after `extendTimeout()` — only `expiresAt` moves forward; compute remaining time as `sandbox.expiresAt.getTime() - Date.now()`.
`sandbox.stop()` is safe to call multiple times, but for persistent sandboxes it always triggers an automatic filesystem snapshot, which counts toward Snapshot Storage billing even if you intended a short-lived run — pass `persistent: false` at creation to avoid this.
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