[BUG] Authentication fails immediately after successful /login in Claude Code v1.0.71

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Title: Authentication fails immediately after successful /login in
Claude Code v1.0.71

Description:

Bug Report

Version: Claude Code v1.0.71Platform: macOS (Darwin
24.6.0)Installation: Native (Homebrew)

Summary

After successfully logging in with /login, Claude Code immediately
shows "Invalid API key" for any user input and becomes completely
unusable. This appears to be a critical authentication regression in
v1.0.71.

Steps to Reproduce

1. Start Claude Code in any directory
2. Run /login and select "Anthropic Console account"
3. Complete OAuth authentication successfully (shows "Login

successful")

1. Try to send any message to Claude
2. Claude Code responds with "Invalid API key · Please run /login"

Expected Behavior

After successful OAuth login, Claude Code should accept and process
user messages normally.

Actual Behavior

• /login shows "Login successful"
• Status bar continues to show "Missing API key · Run /login"
• Any user input results in "Invalid API key · Please run /login"
• Claude Code becomes completely unusable

Additional Context

• Authentication works from some directories but not others

(directory-specific bug)

• OAuth credentials are stored correctly in config but not recognized

by Claude Code

• Issue persists across multiple login attempts
• Environment variable ANTHROPIC_API_KEY was previously rejected and is

in the rejected list

• /status shows Auth Token: none even after successful login

Configuration Details

• installMethod: "unknown" (may be related)
• Had MCP server configured (BigQuery) but removed it during

troubleshooting

• Config file was previously large (4.6MB) due to excessive

conversation history

• Issue persists even after cleaning config file

Workarounds Attempted

• Multiple /login attempts
• Unsetting ANTHROPIC_API_KEY environment variable
• Resetting project-specific configuration
• Removing and re-adding API keys
• Installing Google Cloud SDK and Python 3.11 (for MCP server)

Impact

This makes Claude Code completely unusable for affected users. The
authentication system appears to have a critical regression that
prevents normal operation despite successful login.