Anthropic Moves Cowork Execution VM to the Cloud

Anthropic has overhauled the architecture of its Cowork assistant tool, shifting the execution of its virtual machine (VM) entirely to the cloud. Previously, while Cowork ran Claude model inference in the cloud, it executed tool calls inside a local VM shipped to the user's computer. This local setup was originally chosen to ensure capability, safety, and security by mapping in only the specific data explicitly added to a session.

However, users frequently complained about the heavy local footprint of this approach. Running a virtual machine locally caused significant drains on laptop battery life, consumed substantial disk space, and degraded overall system performance. Furthermore, because the VM was tied to the local hardware, any active tasks would immediately halt the moment a user closed their laptop lid.

To resolve these pain points, the new version of Cowork hosts both the model inference and the VM in the cloud. Under this new paradigm, each user session is allocated its own isolated sandbox that does not share state with other sessions. When the cloud-based VM requires access to a local resource, such as a file on the user's device, the Cowork desktop application steps in to handle that specific file-access tool call.

This architectural shift dramatically improves the user experience for developers and practitioners. By offloading the VM, users can run intensive Cowork tasks without sacrificing their device's battery life or performance. It also enables persistent workflows that continue running even when a computer is shut, and allows developers to access and monitor their Cowork sessions directly from mobile phones.