[BUG] OAuth login broken on headless/HPC SSH environments — redirect URI not supported`

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?

Claude Code OAuth login is broken on headless HPC/SSH environments. The browser-based OAuth flow fails with:

Authorization failed
Redirect URI https://platform.claude.com/oauth/code/callback is not supported by client.

This redirect URI error appears to be a server-side regression — the callback URL is not being accepted by Anthropic's OAuth server. This worked previously.

Attempting the workaround of extracting the OAuth token from a working local machine and setting ANTHROPIC_AUTH_TOKEN fails with:

API Error: 401 {"type":"error","error":{"type":"authentication_error","message":"OAuth authentication is currently not supported."}}

This leaves Pro subscribers on HPC systems with no viable authentication path:

• The browser redirect is broken server-side
• The token env var workaround is blocked by the OAuth deprecation
• API keys require a separate paid Console account (not included with Pro)

What Should Happen?

Expected Behavior

Either:

• The OAuth redirect URI works correctly, OR
• A manual code-paste fallback is shown in the browser when the redirect fails

Impact

This affects all Pro/Max subscribers using Claude Code on HPC clusters (NERSC, XSEDE, university clusters, etc.) — a significant user group for research computing. These environments are inherently headless and cannot use browser-redirect OAuth flows.

Workaround

None currently available for Pro subscribers. API key auth requires a separate Console billing account.

Error Messages/Logs

Steps to Reproduce

Steps to Reproduce

1. Install Claude Code on a headless Linux HPC system (e.g. NERSC Perlmutter) accessed via SSH
2. Run claude and attempt /login
3. Copy the login URL and open it in a local browser
4. Authenticate successfully — browser shows redirect failure:

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

1. No code is shown to paste back into the terminal

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.97 (Claude Code)

Platform

Anthropic API

Operating System

Other Linux

Terminal/Shell

iTerm2

Additional Information

_No response_