[BUG] Multiple devcontainers cannot run Claude Code simultaneously after macOS 26.1 upgrade

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:

• Platform: Anthropic API
• Claude CLI version: 2.1.227
• Operating System: macOS 26.1
• Terminal: VS Code devcontainer terminal

Bug Description:
Running Claude Code CLI inside two simultaneous VSCode devcontainers stopped working after upgrading from macOS 26.0 to 26.1. The second container always
gets "Connection refused" when trying to connect via the socat tunnel on port 6655.

What Should Happen?

Expected Behavior:
Both containers can run Claude Code CLI simultaneously, as they did on macOS 26.0.

Error Messages/Logs

Actual Behavior:
  The second container cannot connect. Investigation shows socat TCP-LISTEN:6655,fork,reuseaddr TCP:host.docker.internal:6655 fails with Connection reset
  by peer — nothing is listening on host.docker.internal:6655 for the second container.

Steps to Reproduce

Steps to Reproduce:

1. Open two VSCode windows, each attached to a separate devcontainer
2. Both devcontainers have forwardPorts: [6655] in devcontainer.json
3. Run claude in the first container — works fine
4. Run claude in the second container — "Connection refused" immediately

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

unknown - auto update on

Claude Code Version

2.1.228

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

Additional Context:
This worked correctly on macOS 26.0. The VSCode Claude Code extension appears to only bind to port 6655 once, so only one container can use it. A
workaround of chaining socat relays (Mac port 6656 → 6655) works but is not sustainable. A configurable port setting in the extension or devcontainer
feature would resolve this.