VSCode devcontainer with azureauth aad not completing

[nstraus]

We are working with agency within a linux devcontainer in vscode. When starting up agency azureauth aad is used to authenticate with copilot and other MCP services provided by agency. The VSCode devcontainer automatically opens the port that is utilized by azureauth when authentication completes through the browser but the browser on the host machine is unable to reach back to the devcontainer to pass back the authentication response.

az login works within devcontainers so we suspect there is an issue with the azureauth aad flow specifically. When using the agency installation script, the call to azureauth aad will not work unless the Azure Devops Codespaces Authentication extension is installed. This does not allow the call when starting copilot to succeed, however.

Quickest way I am able to reproduce this:

1. In VSCode open the command palette with Ctrl + P
2. New Dev Container
3. Select an option (the offical Python 3 option worked for my testing)
4. Wait for the container to open
5. Open a terminal within the VSCode devcontainer
6. Run the install command for agency (fails when the browser tries to call back to the container, though you can see the port is opened correctly through the VSCode UI)

[clarkbreyman]

FWIW - az account get-access-token --tenant ... --scope ... --output json doesn't have this issue .

[clarkbreyman]

@nstraus - see the workaround I added to #461