[BUG] model: opus alias resolves to Opus 4.1 instead of available Opus 4.5 on Bedrock

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 a plugin agent specifies model: opus, Claude Code resolves it to global.anthropic.claude-opus-4-1-20250805-v1:0
(Opus 4.1) even when Opus 4.5 is available and configured. The main conversation correctly uses Opus 4.5, but subagents
fail.

What Should Happen?

model: opus should resolve to the latest available Opus version or match the user's configured ANTHROPIC_MODEL
setting.

Error Messages/Logs

  API Error (global.anthropic.claude-opus-4-1-20250805-v1:0): 400 The provided model identifier is invalid.                   

Steps to Reproduce

1. Configure Claude Code with AWS Bedrock using Opus 4.5
2. Run a plugin agent that specifies model: opus (e.g., /pr-review-toolkit:review-pr which uses code-reviewer agent)
3. Agent fails with invalid model error

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.29

Platform

AWS Bedrock

Operating System

macOS

Terminal/Shell

IntelliJ IDEA terminal

Additional Information

Workaround: Change model: opus to model: inherit in affected plugin agents:
e.g.:

 sed -i '' 's/^model: opus\$/model: inherit/'                                                                                
 ~/.claude/plugins/marketplaces/claude-plugins-official/plugins/pr-review-toolkit/agents/*.md