[FEATURE] Cowork: Allow folder selection/mounting mid-session

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

Until approximately Feb 8-9, 2026, Cowork had the ability for Claude to request folder access mid-session. This presented the user with a file browser to select and mount a folder without restarting. This capability has since disappeared — the agent no longer has a tool to request folder access, and there's no UI mechanism for the user to add a folder once a session is running.
The only option now is to end the session and start a new one, losing all conversational context.

Proposed Solution

Either restore the agent-side tool that allowed Claude to request folder access mid-session, or add a persistent UI control (perhaps next to the prompt input) that lets the user mount a folder at any point during a conversation.

Alternative Solutions

Starting a new session with the folder pre-selected works, but loses all conversation context — which can be substantial in exploratory sessions.

Priority

Medium - Would be very helpful

Feature Category

File operations

Use Case Example

Conversations are inherently exploratory. Users often don't know at the start which files they'll need. Today I was exploring Cowork's architecture with Claude and we wanted to examine files on my local filesystem — but had no way to grant access without abandoning the conversation. This capability existed recently and its removal is a meaningful regression in the Cowork workflow.

Additional Context

MacOS, claude desktop app (v 1.1.2685 (f39a62))