[BUG] OAuth token expires 5-10 times within a single session, requiring constant /login

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?

OAuth token expires 5-10 times within a single session, requiring constant /login. This is not the "every 8 hours" issue —
it happens every few minutes during active use. No pattern to which tool triggers it.

What Should Happen?

OAuth token should be refreshed automatically before expiration. A single /login at session start should be sufficient for
the entire session. The refresh token should be used transparently without user intervention.

Error Messages/Logs

API Error: 401 {"type":"error","error":{"type":"authentication_error","message":"Invalid authentication
  credentials"},"request_id":"req_..."}
  · Please run /login

  This error appears 5-10 times per 1-2 hour session, unpredictably.
  Environment: Windows 11 Pro, Claude Max 5x plan, Anthropic OAuth auth.

  Related: #1757 (42 upvotes), #5893 (48 upvotes), #31095, #12447

Steps to Reproduce

1. Start Claude Code session, /login
2. Use tools normally (Read, Bash, WebFetch, Agent, etc.)
3. After a few tool calls, any tool fails with 401
4. Run /login → "Login successful"
5. Continue working → fails again within minutes
6. Repeat 5-10 times per session

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.71

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_