Dart DevTools fails to connect in vscode-serve-web (Connection Refused to 127.0.0.1)

[heunghingwan]

Environment:

• VS Code Version: 1.119.0
• Dart/Flutter Extension Version: v3.134.0
• Start Command: code serve-web
• OS: Linux

Description:

When using VS Code via serve-web (browser-based), the Dart/Flutter extension attempts to launch or connect to DevTools using 127.0.0.1. However, in a web-based IDE sandbox, 127.0.0.1 refers to the user's local machine (client) rather than the remote host where the DevTools server is actually running.

Steps to Reproduce:

1. Launch VS Code using code serve-web or a similar web-based hosting.
2. Start a Flutter/Dart project.
3. Click on "Flutter" from the Activity Bar.
4. The embedded Webview or the redirected URL fails because it points to http://127.0.0.1:9100.

[kenzieschmoll]

CC @DanTup