OAuth authentication fails in headless/Docker environments: "Redirect URI not supported by client"

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?

When attempting to authenticate Claude Code in a Docker container (no browser available),
the OAuth flow fails with:

> Autorisierung fehlgeschlagen. Redirect URI https:/platform.claude.com/oauth/code/callback is not supported by client.

What Should Happen?

After authorizing in the browser, a code should be displayed that can be pasted back
into the terminal (as the UI suggests with "Paste code here if prompted >").

## Workaround Attempts

• Copying ~/.claude.json from an authenticated host into the container → token is

session-bound and results in "Not logged in" when making actual requests

Error Messages/Logs

Steps to Reproduce

1. Run Claude Code in a Docker container without a browser (e.g., Jupyter base image)
2. Select Option 1 (Claude account with subscription) or Option 2 (Anthropic Console)
3. Copy the displayed authorization URL and open it in a browser on the host machine
4. Log in and click "Authorize"
5. → Error: "Redirect URI https:/platform.claude.com/oauth/code/callback is not supported by client"

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.76

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

_No response_