VS Code extension triggers Windows Firewall "allow public/private networks" prompt on every extension-host load (managed machine)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Environment: Windows 11 Enterprise (org-managed, managed Windows Firewall + Defender), VS Code 1.126.0, Claude Code extension 2.1.193.

Symptom: Every time the extension host loads/restarts (new window, reload extensions), Windows Firewall shows "Do you want to allow public and private networks to access this app?" for Code.exe, noting "This setting is managed by your organization."

Isolation done:

• Extension Bisect identified anthropic.claude-code as the cause.
• With ALL extensions disabled: no prompt. With every extension EXCEPT Claude Code enabled: no prompt. Only with Claude Code enabled does it fire.
• Rolling back to older extension versions does not stop it.
• Verified via Get-NetTCPConnection that the extension's listeners are all on 127.0.0.1.

The puzzle: Docs state the IDE MCP server binds to 127.0.0.1 only, and loopback binds shouldn't trigger a firewall prompt. The prompt firing suggests the extension (or a helper it spawns) attempts a non-loopback bind (e.g. 0.0.0.0/all-interfaces) at least transiently during activation. On a managed machine where the firewall can't be modified, this produces a recurring, un-dismissable prompt.

Ask: Ensure the activation-time socket binds strictly to loopback so managed Windows Firewall doesn't challenge it.

What Should Happen?

The Claude Code extension should bind its IDE integration server strictly to loopback (127.0.0.1) during activation, so that managed Windows Firewall does not fire the "allow public and private networks" prompt. No firewall prompt should appear when opening a new window or reloading the extension host.

Error Messages/Logs

Steps to Reproduce

1. On a Windows 11 machine with an org-managed Windows Firewall, install the Claude Code VS Code extension (anthropic.claude-code).
2. Open VS Code, then open a new window (Ctrl+Shift+N) — or reload the window / restart the extension host.
3. Observe: Windows Firewall shows "Do you want to allow public and private networks to access this app?" for Code.exe, noting "This setting is managed by your organization."
4. Confirm it's this extension: run "Help: Start Extension Bisect" — it identifies anthropic.claude-code. Disable Claude Code only (all other extensions enabled) and open a new window → no prompt. Re-enable Claude Code → prompt returns.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.165

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_