OAuth Pro subscription breaks when ANTHROPIC_AUTH_TOKEN/ANTHROPIC_BASE_URL set in env — users workaround via OpenRouter

Problem

Claude Code with Pro subscription OAuth fails with 401 Invalid bearer token when environment variables \ANTHROPIC_AUTH_TOKEN\ or \ANTHROPIC_BASE_URL\ are set in the active shell session — even after a successful \/login\.

Root cause

The internal \m$()\ / \x$()\ function in \cli.js\ returns \false\ (disabling OAuth mode) if \ANTHROPIC_AUTH_TOKEN\ is present in the environment. Claude Code silently falls out of OAuth mode and tries to use a non-existent API key → 401.

Additionally, if a project's \.env\ file contains \ANTHROPIC_API_KEY\ (common when a bot/app shares the same server), Claude Code reads it automatically and creates an auth conflict with the OAuth credentials.

Impact

This is especially common on Linux VPS/servers where:

• A Python/Node bot uses \ANTHROPIC_API_KEY\ or \ANTHROPIC_AUTH_TOKEN\ in the same environment
• The developer also runs Claude Code on the same machine with Pro OAuth subscription

The workaround users are discovering: Route Claude model calls through OpenRouter instead of Anthropic directly — this is a direct revenue loss for Anthropic.

Reproduction

1. Have a valid Claude Pro OAuth session (\~/.claude/.credentials.json\ with \user:inference\ scope)
2. Set \ANTHROPIC_AUTH_TOKEN=anything\ in the shell
3. Run \claude\ → 401 on every request despite valid credentials

Fix

\\\bash
unset ANTHROPIC_BASE_URL ANTHROPIC_AUTH_TOKEN
claude
\\\

Suggested improvements

1. Better error message: When 401 occurs with OAuth credentials, check if \ANTHROPIC_AUTH_TOKEN\ / \ANTHROPIC_API_KEY\ env vars are set and explicitly warn the user
2. OAuth mode should take precedence over stale env vars when valid credentials file exists and user explicitly logged in via \/login\
3. Warn on startup if conflicting env vars are detected alongside OAuth credentials

Environment

• Claude Code v2.1.73
• Ubuntu 24.04 LTS
• Pro subscription via claude.ai OAuth