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Where does Cowork actually run, and where do your files live?

Last updated 2026-08-17 · Confidence: documented — Anthropic’s architecture overview and Cowork help pages; the VM’s internals and disk paths are reported from a January 2026 teardown, the Windows restart friction from issue threads.

Cowork never works directly in your file system: it runs in a cloud sandbox or a local virtual machine, and your output is only a normal file if you told it to work in a folder you can see.

Two places it runs

Section titled “Two places it runs”
  • Cloud (now the default). Per Get started with Claude Cowork, “Claude’s work runs on Anthropic’s servers, in an isolated environment, and your sessions and files are saved to your Claude account” — work continues with the laptop closed.
  • Local (desktop app). The architecture overview: the agent loop runs natively, but “code execution runs in an isolated virtual machine” under “the platform’s hypervisor (Apple Virtualization.framework on macOS, Hyper-V on Windows)”. A teardown found a full Ubuntu VM — a real mini-computer — whose disk images live at ~/Library/Application Support/Claude/vm_bundles/ on Mac. Windows needs the Virtual Machine Platform feature (the WSL2 hypervisor layer) enabled plus a full restart.

Where files land

Section titled “Where files land”

“Local file access is limited to folders the member has connected” — those folders are mounted into the VM, so files written there are ordinary files. Anything created without a working folder stays in the session’s sandbox or VM image: on disk only as an opaque .img, effectively invisible. So pick “Work in a folder” you can open in Finder; deleted cloud tasks purge from Anthropic’s storage within 30 days.

That’s also why the desktop app, not the browser, is what grants local file access — and why tools launched inside the sandbox see the VM’s folders, not your Mac’s.

Q&A from calls

Section titled “Q&A from calls”

How do you move Cowork’s files into Claude Code? Ask Cowork to copy everything into a connected real folder, then open that folder in Claude Code — files are the only transferable state; chats don’t move (see Cowork vs Code). Claude Code itself keeps work as plain files, with session history under ~/.claude kept 30 days by default — extendable via the cleanupPeriodDays setting, not by asking support.

Sources

Section titled “Sources”