[BUG] API Error 404: model claude-opus-4-5-20251101 not found - persists across machines and locations

Description

Getting a persistent 404 error when trying to use Claude Code. The error occurs across different machines and physical locations, indicating this is an account-level issue.

Error Message

API Error: 404 {"type":"error","error":{"type":"not_found_error","message":"model: claude-opus-4-5-20251101"},"request_id":"req_011CXogvAmvS5osjnLnazkix"}

Steps to Reproduce

1. Launch Claude Code
2. Error appears automatically

Environment

• Occurs on multiple machines
• Occurs in different physical locations
• Persists despite correct local settings (~/.claude/settings.json shows "model": "sonnet")

Additional Context

• This appears to be an account-level backend issue
• The model claude-opus-4-5-20251101 either doesn't exist or the account is incorrectly configured to try to use it
• Local configuration is set correctly to use "sonnet"
• Request ID for debugging: req_011CXogvAmvS5osjnLnazkix

Expected Behavior

Claude Code should use the configured model (sonnet) or fall back gracefully if a model is unavailable.

Actual Behavior

Claude Code fails with 404 error trying to access non-existent model.