`browser_take_screenshot` saves screenshots to a host-only temp path (e.g. `/var/folders/...`) when using a remote container, making them inaccessible from the workspace

[suin2]

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Summary

When running Cursor in a remote container/devcontainer, the Browser Extension MCP tool browser_take_screenshot reports a saved screenshot path under a host macOS temp directory (e.g. /var/folders/...). That path is not accessible from inside the container/workspace, so the agent (and workspace file APIs) cannot read/inspect the screenshot.

Environment

• Remote runtime: Docker / devcontainer (Linux 6.10.14-linuxkit)
• Workspace path: /home/developer/regression-test
• Browser tooling: Cursor Browser Extension MCP (mcp_cursor-browser-extension_*)
• Host OS: likely macOS (inferred from returned path prefix /var/folders/...)
• Cursor version: (fill in)

Steps to Reproduce

1. Open Cursor with a remote container/devcontainer workspace.
2. Use the Browser Extension tool to open any page (e.g. http://localhost:3000/).
3. Call browser_take_screenshot (full page or element).
4. Observe the tool result: it returns a saved file path like:
   • /var/folders/.../T/cursor-browser-extension/.../current-cat-page.png
5. Try to read the screenshot from inside the container/workspace (e.g. via file viewer / workspace APIs / agent read_file).
6. The screenshot cannot be found/read because it is outside the workspace and on the host filesystem.

Expected Behavior

One of:

• Save screenshots into the workspace (or allow specifying an output path relative to workspace), and return that path.
• Or return screenshot data directly (binary/base64).
• Or automatically copy the host temp screenshot into the workspace and return the workspace path.

Operating System

MacOS

Current Cursor Version (Menu → About Cursor → Copy)

Version: 2.2.17
VSCode Version: 1.105.1
Commit: cf858ca030e9c9a99ea444ec6efcbcfc40bfda70
Date: 2025-12-11T18:30:06.649Z
Electron: 37.7.0
Chromium: 138.0.7204.251
Node.js: 22.20.0
V8: 13.8.258.32-electron.0
OS: Darwin arm64 24.6.0

Additional Information

Actual behavior

• Screenshot is saved to a host-only temp path (example below).
• Inside the container/workspace, the file is not accessible/readable (e.g. agent read_file fails because it’s not in the workspace).

Example output (from tool result)

• Returned path:
  • /var/folders/6w/ndj_jwqx77z_lyq7ftl_4szh0000gn/T/cursor-browser-extension/1766488655632/current-cat-page.png

Impact

This blocks automated UI verification/regression testing workflows in remote containers because screenshots cannot be inspected by the agent or workspace tooling without manual host-path mounting.

Suggested fix

Add an option like downloadPath / outputPath that writes to the workspace, or always mirror screenshots into the workspace when running in a remote environment.

Does this stop you from using Cursor

Sometimes - I can sometimes use Cursor

[deanrie]

Hey, thanks for the report.

Got it. The Browser Extension MCP runs on the host and saves screenshots to the host temp folder, which isn’t accessible from inside the devcontainer workspace.

I’ll pass this to the dev team to fix.

Your idea about a downloadPath option or automatically copying files into the workspace makes sense. I’ll keep you posted when there’s a fix.