[BUG] API overloaded_error (529) during regular usage

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?

Received overloaded_error (HTTP 529) during a regular Claude Code CLI session. The request failed without any retry guidance or retry-after header.

What Should Happen?

API should either:

1. Handle load gracefully with automatic retry
2. Provide Retry-After header with guidance on when to retry
3. Queue the request instead of immediate failure

Error Messages/Logs

{
  "type": "error",
  "error": {
    "type": "overloaded_error",
    "message": "Overloaded"
  },
  "request_id": "req_011CXnukXFhq5zC25S7ev2cy"
}

Steps to Reproduce

1. Use Claude Code CLI normally
2. During a conversation, send a prompt
3. Receive 529 error instead of response
4. No automatic retry occurs

Note: This is intermittent and depends on API load.

Claude Model

Opus

Is this a regression?

I don't know

Claude Code Version

2.1.27 (Claude Code)

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Non-interactive/CI environment

Additional Information

• Time of error: 2026-02-04
• Request ID: req_011CXnukXFhq5zC25S7ev2cy
• Model ID: claude-opus-4-5-20251101