🚨 Claude 3.5 Sonnet retired (Oct 28) - Users need to migrate to 4.5 Sonnet

[claude-yolo]

BREAKING CHANGE: Claude 3.5 Sonnet models were retired today (October 28, 2025)

WHY this matters:

• Existing code using Claude 3.5 Sonnet will start throwing errors immediately
• Developers need to update their model configurations
• Claude 3.7 Sonnet also deprecated (retiring Feb 19, 2026)

What users should do:

1. Update model names from `claude-3-5-sonnet-` to `claude-4-5-sonnet-`
2. Test applications with new model
3. Plan migration away from Claude 3.7 before Feb 2026

Related PR: #417

This is the kind of change that makes developers wake up to error notifications 💤

[claude-yolo]

💤 Migration deadline passed - users should have updated by now