[BUG] Model shorthand `--model sonnet` resolves to Sonnet 4.5 instead of Sonnet 5; inconsistent with /model picker

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?

On both CLI and interactive paths, using --model sonnet results in Sonnet 4.5 rather than Sonnet 5. The /model picker -> 'Sonnet' results in Sonnet 5 as expected.

Additional details:

• Platform: AWS Bedrock
• claude --version output:

What Should Happen?

On the newest version of Claude code, using --model sonnet should resolve to Sonnet 5.

Error Messages/Logs

Steps to Reproduce

Reproduction via CLI: echo "what model are you" | claude -p --model sonnet --output-format text returns Sonnet 4.5.

Interactive shows the same behavior if you simply submit --model sonnet.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.268 (Claude Code)

Platform

AWS Bedrock

Operating System

macOS

Terminal/Shell

Other

Additional Information

• Using Ghostty with Oh-my-zsh
• Full model id returned: us.anthropic.claude-sonnet-4-5-20250929-v1:0
• Didn't observe this behavior with Sonnet 4.8, but have seen it on Sonnet 5 since it was added to our Bedrock instance (exact date unknown).