Runtime changelog, 22 September 2026

What shipped in Runtime Cloud on 22 September 2026: custom images; volumes; previews; a desktop in any sandbox; code interpreter; network rules per sandbox; interactive terminals; read-only keys and daily spending limits; buy credit by card; referrals; a 20-hour free trial; one line connects your agent; runtime run; in the official MCP registry; the withruntime package; API 0.2.0; a hundred commands at once; idle sandboxes pause themselves; retries you never see; and ask support anywhere.

Custom images

Build an image from a package list, a public image or a Dockerfile, and start every sandbox from it.

Volumes

Persistent disks that outlive sandboxes, attached read-write to one or read-only to many.

Previews

Give any port in a sandbox an HTTPS address at runtimehost.com, private with a token unless you make it public.

A desktop in any sandbox

Start a Linux desktop and drive it with clicks, keys and screenshots, or watch it live.

Code interpreter

A notebook-style Python or JavaScript session in a sandbox, with charts returned as images.

Network rules per sandbox

Allow or deny hosts, turn the internet off, and open host:port pairs such as a database on a paid account.

Interactive terminals

runtime sandbox shell opens a real terminal in a sandbox, and the API serves one over WebSocket.

Read-only keys and daily spending limits

An owner can give an agent a key that changes nothing, or cap what it may spend in any 24 hours.

Buy credit by card

Add any amount from $10 to $10,000, with no subscription.

Referrals

Refer a company and you both get credit equal to its first top-up, up to $500 each.

A 20-hour free trial

Every new account gets 20 sandbox hours (now 100) with no card.

One line connects your agent

claude mcp add --scope user runtime -- npx -y withruntime mcp (or the same for Codex and Cursor) is the whole setup; the agent asks for one browser approval.

runtime run

One command creates a sandbox, runs your command, prints its output and stops it, connecting the machine on first use.

In the official MCP registry

Runtime Cloud is listed for any MCP client to find.

The withruntime package

Both SDKs publish as withruntime on npm and PyPI, and the old names still install it.

API 0.2.0

One API for every product, over HTTP/2, with a public OpenAPI document.

A hundred commands at once

One key can have 128 requests in flight, so an agent can fan out without refusals.

Idle sandboxes pause themselves

A sandbox left on the default lease and never used pauses after five minutes (now any sandbox after a minute with nothing happening in it), so it stops paying the running rate.

Retries you never see

A brief outage answers 503 with Retry-After, and both SDKs retry it with the same idempotency key.

Ask support anywhere

Ask from the dashboard, with runtime support, or at support@withruntime.com.