Opus 4.5 Model Support

What: Opus 4.5 is now available as the most capable model for complex work, replacing Opus 4.1 as the default for first-party API users.

How to use:

# Select Opus 4.5 via the model command
/model opus

# Or specify directly
claude --model opus

Details:

• Opus 4.5 becomes the default for Max and Team subscribers using first-party API
• Bedrock/Vertex/Foundry users continue to use Opus 4.1
• Model descriptions updated: "Most capable for complex work"
• One-time migration automatically resets model selection for eligible users
• A notification informs users about Opus 4.5 availability on first use
• Evidence: Model registry at rcA() line 163104, default logic at QUA() line 224121, selector at rJ6 line 224397