Evidence at a glance
Execution Moved, Not Inference
Anthropic’s Felix Rieseberg described an architectural change to Claude Cowork. In the old version, model inference already ran in the cloud, but tool calls and code execution took place in a local virtual machine shipped with the desktop app. The new version moves both inference and the VM to the cloud. Cowork is designed to let Claude carry out multi-step work, and this change concerns where that work runs, not where the model first began running.
That distinction explains why this looks like a move to the cloud without being a migration from local inference. The local VM used disk space, battery, and computing resources, and work stopped when a laptop was closed. Rieseberg cited those user complaints as reasons for the change, alongside the goals of accessing Cowork from a phone and letting work continue.
Why the VM Was Local in the First Place
Moving the VM off the computer is more than removing a resource-hungry component. Anthropic’s engineering explanation of local Cowork says code ran in an isolated Linux VM, separated from the host using platform virtualization. Rieseberg also said the VM was added for capability, safety, and security, and that the old version mapped in only data users explicitly added to a session. In other words, the local VM served both as an execution environment and as a boundary limiting access to host resources.
To preserve isolation, the new design has to establish an execution boundary in the cloud rather than merely run a process on a remote machine. Anthropic’s architecture overview says each cloud session gets its own temporary sandbox, shares no state with other sessions, and is destroyed when the session ends. That describes the basic shape of the isolation model. Public materials do not specify the VM image, runtime implementation, or defenses against particular attacks, so the phrase “independent sandbox” alone is not quantitative evidence of overall security.
The Desktop Stops Hosting the Sandbox and Becomes a File Gateway
Cloud execution does not mean Cowork is entirely disconnected from the user’s computer. When a task needs a local file, the cloud service routes the request through Anthropic’s connection to Claude Desktop, which performs the relevant file-access call. Access is limited to folders the user has connected and remains subject to the permissions already set. The architecture therefore does not simply move all data to the cloud. It separates the execution environment from the local-resource gateway.
That gateway also creates a new data path. Anthropic’s usage guidance says the cloud obtains copies of files needed for a task, and that those copies are deleted when the session is deleted. Selected files therefore travel beyond the local boundary and enter the cloud execution flow. An isolated sandbox addresses separation between sessions, but it does not replace decisions about which files are sent to the cloud, how long they are retained, or what permissions apply. The available materials do not specify a more detailed deletion timeline or recovery mechanism for those copies.
Continuing After You Close the Laptop Has a Condition
The promise that work continues after you close a laptop applies only to the parts of a task that no longer need local resources. A cloud VM can keep running without the user’s computer doing the execution, but Claude Desktop must be online to provide file-access calls when a task needs local files. Anthropic’s usage guidance draws the distinction plainly: a cloud session can continue, while local-file access becomes unavailable when the desktop app is closed.
This does not contradict the claim that cloud work can keep running. It identifies the portion of the task dependency chain that still resides on the user’s device. Writing, organizing, or other work based on information already available in the cloud may benefit more from the move. Work that repeatedly reads or writes local files remains constrained by desktop availability. The materials do not say whether file requests can queue or how they recover after a desktop disconnection, so “the task continues” should not be read as “every step continues.”
The Migration Boundary Is in the Rollout and the Task Type
The change does not switch every Cowork task at once. Anthropic’s Help Center says that, starting October 6, 2026, new Cowork tasks created by Pro and Max users run in the cloud, while tasks already started locally remain on the local machine. This separates the old and new execution paths and means technical teams assessing the impact must account for in-flight work as well as the default architecture for new tasks.
A practical choice starts with file dependencies, rather than treating either the cloud or the local machine as universally preferable. Cloud execution reduces the local VM’s resource burden for tasks that do not need ongoing access to computer files and may benefit from long runtimes or phone access. If a task must keep operating on local files, its design needs to account both for desktop availability and for copies of those files entering cloud processing. Public materials give no quantified gains in performance, battery life, or VM storage use. The architectural trade-off is clear, but its precise benefits cannot yet be calculated from the available evidence.