[BUG] model alias "haiku" not resolving correctly to the actual Haiku model

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?

• Launched with --model haiku
• Ran /model command which showed "Set model to haiku" but displayed Sonnet's model ID
• Expected: Should use actual Haiku model (claude-haiku-4-5-*)

Actual result: The Model id appears as: Set model to haiku (claude-sonnet-4-5-20250929)

What Should Happen?

Should use actual Haiku model (claude-haiku-4-5-*)

Error Messages/Logs

Actual: Set model to haiku (claude-sonnet-4-5-20250929)

Steps to Reproduce

Scenario 1:

• Launch with claude --model haiku
• Verify the model

Result: Even after starting with Haiku, the model used is Sonnet

Scenario 2:

• In the open claude session, run /model command and select Haiku.

Result: Even after switching to haiku, the response shows Sonnet's model ID like: "Set model to haiku (claude-sonnet-4-5-20250929)"

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.0.76

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_