[FEATURE] Support /copy command in VS Code extension

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

I frequently switch between the Claude Code CLI and the VS Code extension. A key utility in the CLI is the /copy command, which allows for quick clipboard actions. Currently, the VS Code extension does not support this command.

This creates a friction point in my workflow because I have to manually highlight and copy text in the extension UI, whereas I'm used to the efficiency of slash commands in the terminal. Having /copy support (or a dedicated UI button for the same effect) would ensure feature parity and a more consistent developer experience across platforms.

Proposed Solution

I would like to see the /copy command implemented in the VS Code extension's chat input, functioning identically to the CLI version:

1. Slash Command: Typing /copy in the chat box should copy the last assistant response to the system clipboard.
2. UI Integration: Ideally, a small "Copy" button/icon could also be added to the top-right corner of each message block for quick access via mouse.
3. Feedback: A brief "Copied to clipboard" toast notification or status bar message would be helpful to confirm the action.

Alternative Solutions

Currently, I have to:

• Manually highlight the text with the mouse and use Cmd+C / Ctrl+C. This is much slower than the keyboard-centric workflow I'm used to in the terminal.
• Switch back to the CLI if I know I'll need to copy large chunks of code frequently.

There are no other built-in ways to achieve the same efficiency within the VS Code extension UI.

Priority

Critical - Blocking my work

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

_No response_