Model Deprecation Warnings

What: Claude Code now displays proactive warnings when using models approaching retirement dates. Details:

• Warns users when using Claude 3 Opus (retiring January 5-15, 2026 depending on provider)
• Warns users when using Claude 3.7 Sonnet (retiring February-May 2026 depending on provider)
• Displays as a high-priority notification: "⚠ [Model Name] will be retired on [Date]. Consider switching to a newer model."
• Different retirement dates based on provider (Bedrock, Vertex, or first-party API)
• Evidence: $x7() at line 483888, jX1() at line 483910, KW9() at line 483919