[Bug] Incorrect Model Naming in /model Command (Sonnet 4.5 shows as Sonnet 4)

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?

The /model command in Claude Code displays incorrect model names in the UI.

Current Behavior ❌

1. Default (recommended) Opus 4.1 for up to 20% of usage limits, then use Sonnet 4 ✔
2. Sonnet Sonnet 4 for daily use

Expected Behavior ✅

1. Default (recommended) Opus 4.1 for up to 20% of usage limits, then use Sonnet 4.5 ✔
2. Sonnet Sonnet 4.5 for daily use

What Should Happen?

The /model command UI should correctly display "Sonnet 4.5" instead of "Sonnet 4".
The underlying model is already correct (claude-sonnet-4-5-20250929), so only the UI display string needs fixing.

Error Messages/Logs

No runtime errors.  
This is purely a **UI display bug**.  
Logs confirm that the correct model (`claude-sonnet-4-5-20250929`) is being used internally.

Steps to Reproduce

1. Open Claude Code (v2.0.1).
2. Run the /model command to view available models.
3. Observe the displayed model names:

• Default shows "Sonnet 4"
• Sonnet option also shows "Sonnet 4"

1. Compare against the official announcement and logs, which show "Sonnet 4.5".

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude Code Version: 2.0.1

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_