[BUG] when ANTHROPIC_BETA is set, Claude code does not respect ANTHROPIC_MODEL config

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?

When ANTHROPIC_BETA is set, Claude Code does not respect the ANTHROPIC_MODEL configuration, even when using AWS Bedrock with a specific application inference profile.
Environment:
• CLAUDE_CODE_USE_BEDROCK=1
• ANTHROPIC_MODEL configured with a Bedrock application inference profile for Sonnet 4.5
• ANTHROPIC_BETA is set

What Should Happen?

Claude Code should respect the ANTHROPIC_MODEL configuration and use the specified Bedrock application inference profile (Sonnet 4.5) regardless of whether ANTHROPIC_BETA is set.

Error Messages/Logs

Model is automatically changed to default Anthropic model, which leads to not enough budget error because I am using bedrock model with AWS auth, not Anthropic account.

Steps to Reproduce

Steps to Reproduce:

1. Set CLAUDE_CODE_USE_BEDROCK=1
2. Configure ANTHROPIC_MODEL with a Bedrock application inference profile for Sonnet 4.5
3. Set ANTHROPIC_BETA environment variable
4. Run Claude Code
5. Observe that the configured model is not being used

Claude Model

Other

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.0.41

Platform

AWS Bedrock

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

This appears to be a configuration precedence issue where the beta flag overrides the model selection configuration.