Anthropic shifts Claude Cowork from local VMs to cloud-based inference and sandboxing

Anthropic’s Cowork previously executed tool calls in an Anthropic-provided VM that ran locally on users’ devices, while model inference occurred in the cloud. The local VM was introduced to support capability, safety, and security by mapping in only the data explicitly added to a session.

Users reported dissatisfaction with the local VM’s impact on disk space, battery life, and performance, as well as session interruptions when closing laptops. The redesign moves both model inference and the VM to the cloud, with each session running in its own isolated sandbox that does not share state with other sessions.

In the new architecture, the desktop app is responsible for handling file-access tool calls when the cloud-based VM requests access to local files. Anthropic states this change addresses issues such as using Cowork from a phone, maintaining continuous work, and preserving battery life without sacrificing functionality.