A cloud environment is a saved configuration that every cloud session runs inside. It controls three things: network access, environment variables, and setup scripts.1
Defaults
With no environment yet, onboarding sets up a Default environment with Trusted network access, creating it or prompting you depending on plan. The same environments apply to every surface, plus Claude Tag and routines; Claude Tag channel sessions use organization-level environments only.1
The network policy is the setting most likely to surprise: a blocked domain simply cannot be reached, and the failure shows up inside the session as a proxy 403 or an egress-blocked error, not as a configuration warning.1
Anthropic-hosted versus self-hosted
Sessions can run in a self-hosted environment on your own infrastructure, which moves several guarantees to you:1
| Layer | Anthropic-hosted | Self-hosted |
|---|---|---|
| Isolation | One Anthropic-managed VM per session | Your deployment’s responsibility |
| Network | Limited by default, can be disabled; a default allowed-domain list applies | You restrict egress at your own boundary |
| Git credentials | Kept outside the sandbox; a proxy authenticates with scoped credentials | Supplied by your deployment |
| API credentials | On Pro and Max, keys stay outside the sandbox and are attached after requests leave it | Not available (nor yet on Team or Enterprise) |
Even with network access disabled, Claude Code can still reach the Anthropic API, which may allow data to leave the VM: disabled network is not an air gap.1