Anthropic pins Cowork's local file reach to a single open desktop app

The control deciding whether an agent can touch a work machine's folders is whether an application is running. Anthropic's support documentation says a cloud session can read and write files in folders a user has connected only while the Claude Desktop app is open on that computer, and only when the session was started on desktop ^[8]. If the app is closed, the session keeps running in the cloud and cannot reach those files ^[8].

Everything that reaches the machine routes the same way. Local file access, local connectors, and browser use and computer use started from web or mobile all work through the desktop app ^[10]. Desktop is described as the full Cowork experience, the one surface where Claude can also use local files and the browser directly ^[7]. Of the four places a session can begin, one reaches the local environment on its own and three depend on that app being open on the right computer ^[18]. The exception is narrow: in the Chrome side panel Claude can read the tab the user is on without the desktop app, though driving a browser through a task still needs it ^[12].

The permission model described in the article belongs to the person who set it up, covering folders the user has connected and the permissions the user has already set ^[9]. Sessions and files are attached to the Claude account and follow it between devices ^[2]. The article points to two other documents, one for how cloud and local sessions are isolated and one for safety guidance ^[14]. It covers the user's surfaces and does not describe administrator or workspace-level controls ^[20].

There is also less of a moment where a user declares that work is agentic. In the current layout, chat and Cowork share one message box, and the user picks "Cowork" in the bottom left corner and "Chat" to go back ^[3]. In what the article calls the new Claude experience, that selector is gone: describe the task in any conversation and Claude takes it from there ^[6]. Opening the Chrome side panel starts a Cowork session with no selector at all ^[4]. On those two surfaces a question and a task begin the same way ^[19].

File reach is still limited to folders someone connected, and Cowork will not change a project's contents, so a user has to add anything worth keeping ^[11]. Background work continues after the laptop closes, and scheduled tasks run with no device online ^[5].

For this quarter the choice is narrow and practical: whether the Claude Desktop app and the Claude in Chrome extension are managed as endpoint software, since those two are where a cloud session gets to a local disk and a live browser tab ^[10][12]. The feature set is still moving. Cowork in the cloud is in beta with some features not yet available, computer use is in beta for Pro and Max plans, and the browser built into the desktop app was described as rolling out gradually during the week ^[13][15]. Artifacts are a separate case: those created on or after August 19, 2026 work on the desktop app and web, while live artifacts from before that date are desktop only ^[16].