Configure cloud environments changedcloud-environments
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### Time limits
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242242## What's available in cloud sessions
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244In Anthropic-hosted environments, each session gets a fresh virtual machine (VM) running Ubuntu 24.04 on x86\_64, regardless of your own operating system and CPU architecture, with your repository cloned and common toolchains pre-installed. When a dependency provides precompiled binaries, such as Ruby gems with native extensions or prebuilt Python wheels, use its x86\_64 Linux build to match the VM. This section covers the Anthropic-hosted defaults, the built-in GitHub tools, how to [run tests and services](#run-tests-start-services-and-add-packages), and the [resource limits](#resource-limits) each VM gets.
244In Anthropic-hosted environments, each session gets a fresh virtual machine (VM) running Ubuntu 24.04 on x86\_64, regardless of your own operating system and CPU architecture, with your repository cloned and common toolchains pre-installed. When a dependency provides precompiled binaries, such as Ruby gems with native extensions or prebuilt Python wheels, use its x86\_64 Linux build to match the VM. This section covers the Anthropic-hosted defaults, the built-in GitHub tools, how to [run tests and services](#run-tests-start-services-and-add-packages), the [resource limits](#resource-limits) each VM gets, and the [time limits](#time-limits) on long-running work.
245245
246246<Note>
247247 Sessions your organization routes to a [self-hosted environment](/docs/en/self-hosted-environments) run on your own runners instead, with the tools your runner image provides.
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364364The VM may stop tasks that need significantly more memory, such as large build jobs or memory-intensive tests. For workloads beyond these limits, use [Remote Control](/docs/en/remote-control) to run Claude Code on your own hardware, or run cloud sessions in a [self-hosted environment](/docs/en/self-hosted-environments) on compute your organization operates.
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366### Time limits
367
368In Anthropic-hosted environments, these time limits apply to long-running work in a cloud session, such as a build, an install, or a test run. Each entry links to the section that defines the limit.
369
370* **Commands Claude runs**: a cloud environment doesn't set its own command timeout, so the Bash tool's defaults apply. Claude waits 2 minutes for a command by default and can ask for up to 10 minutes. When a command reaches its [timeout](/docs/en/tools-reference#timeout-and-output-limits), Claude Code [moves it to the background](/docs/en/tools-reference#background-commands) instead of stopping it, unless the command starts with `sleep`.
371* **SessionStart hooks**: Claude Code cancels a `command` hook after 600 seconds unless you set [`timeout`](/docs/en/hooks#common-fields), in seconds, on the hook entry. Claude Code doesn't enforce the timeout on a hook you run with [`async: true`](/docs/en/hooks#run-hooks-in-the-background).
372* **Setup script**: a script that takes longer than roughly five minutes isn't cached. [Script requirements](#script-requirements) covers how to stay under that.
373* **Idle sessions**: a session stops after a period of inactivity and its VM is reclaimed. [Environment expired](/docs/en/claude-code-on-the-web#environment-expired) covers what counts as inactive and how to reopen the session.
374
375To raise the command timeouts for an environment's sessions, add [`BASH_DEFAULT_TIMEOUT_MS` and `BASH_MAX_TIMEOUT_MS`](/docs/en/env-vars#variables) to its [environment variables](#set-environment-variables). Both take milliseconds. For example, `BASH_DEFAULT_TIMEOUT_MS=600000` makes 10 minutes the default.
376
366377## Setup scripts
367378
368379A setup script is a Bash script that runs when a new cloud session starts, before Claude Code launches. Use setup scripts to install dependencies, configure tools, or fetch anything the session needs that isn't pre-installed.
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383394A setup script has three constraints to write around:
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385396* **Exit zero**: if the script exits non-zero, the session fails to start. Append `|| true` to non-critical commands so an intermittent install failure doesn't block the session.
386* **Finish within five minutes**: keep the script's total runtime under roughly five minutes so the [environment cache](#environment-caching) can build. Run independent installs in parallel with `&` and `wait`, and move any single download that won't fit into a [SessionStart hook](#setup-scripts-vs-sessionstart-hooks) that launches it in the background.
397* **Finish within five minutes**: keep the script's total runtime under roughly five minutes so the [environment cache](#environment-caching) can build. When setup takes longer than that, the environment isn't cached. Run independent installs in parallel with `&` and `wait`, and move any single download that won't fit into a [SessionStart hook](#setup-scripts-vs-sessionstart-hooks) that launches it in the background. If new sessions stall or fail during setup, see [New sessions hang or time out during setup](/docs/en/web-quickstart#new-sessions-hang-or-time-out-during-setup).
387398* **Network access for installs**: package installs need to reach registries. The default **Trusted** level covers [common package registries](#default-allowed-domains) including npm, PyPI, RubyGems, and crates.io; with **None** network access, installs fail.
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389400### Environment caching
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391The setup script runs the first time you start a session in an environment. After it completes, Anthropic snapshots the filesystem and reuses that snapshot as the starting point for later sessions. New sessions start with your dependencies, tools, and Docker images already on disk, and skip the setup script step. This keeps startup fast even when the script installs large toolchains or pulls container images.
402The setup script runs the first time you start a session in an environment. When setup completes within [roughly five minutes](#script-requirements), Anthropic snapshots the filesystem and reuses that snapshot as the starting point for later sessions. New sessions start with your dependencies, tools, and Docker images already on disk, and skip the setup script step. This keeps startup fast even when the script installs large toolchains or pulls container images. If setup takes longer than roughly five minutes, the environment isn't cached.
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393404The cache is a filesystem snapshot, so it keeps what the setup script writes to disk and loses anything that was only running. Packages you install, Docker images you pull, and files you write all carry over. A database the script started, a `docker compose up` stack, or any other background process doesn't; start those per session by asking Claude or with a [SessionStart hook](#setup-scripts-vs-sessionstart-hooks).
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