[BUG] When `ANTHROPIC_API_KEY` env variable is set, Claude shows a conflict warning on startup

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 I set the ANTHROPIC_API_KEY env variable, the following message shows up:

 ⚠Auth conflict: Both a token (claude.ai) and an API key (ANTHROPIC_API_KEY) are set. This may lead to unexpected behavior.
    • Trying to use claude.ai? Unset the ANTHROPIC_API_KEY environment variable, or claude /logout then say "No" to the API key
    approval before login.
    • Trying to use ANTHROPIC_API_KEY? claude /logout to sign out of claude.ai.

It doesn't make much sense though, since it's not possible to have just the ANTHROPIC_API_KEY set without being logged in.

If you log out, set the variable, and re-launch Claude, it asks you to log in (with either console login or OAuth).

If I own an API key that doesn't belong to my account, I still have to authenticate somehow, so I pick my regular account and log in with OAuth.

What Should Happen?

Claude should allow using an API key (via ANTHROPIC_API_KEY) that doesn't belong to my logged-in account without showing a conflict warning.

Error Messages/Logs

Steps to Reproduce

• Set the ANTHROPIC_API_KEY environment variable (with an API key that doesn't belong to your logged-in account)
• Launch/restart Claude
• Log in to Claude via OAuth
• The conflict warning appears on startup

Claude Model

Sonnet (default)

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.0.14

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

_No response_