[BUG] ## Issue: Quality degradation in Claude Opus 4.5

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?

Description

Claude Opus 4.5 performance has significantly degraded compared to previous versions, while the price is higher.

### Observed problems

1. Basic architecture mistakes: Hardcodes sensitive values (API keys, URLs) in shared libraries when it should be external configuration

1. Does not follow clear instructions: After multiple corrections, keeps making the same mistakes

1. Unnecessarily complex code: Creates projects, files and structures that were not requested instead of simple solutions

1. Lack of planning: Writes code without thinking first, then patches instead of doing it right from the start

### Context
Requested task: A singleton Angular service to integrate Instana in microfrontends.

Result: Multiple failed attempts with hardcoded configuration, files in wrong locations, and repetitive errors.

### Impact

• Time wasted
• Money spent on a premium model with worse results than previous versions
• User frustration

### Model
claude-opus-4-5-20251101

What Should Happen?

It was better a week ago

Error Messages/Logs

It was better a week ago

Steps to Reproduce

run

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

claude-opus-4-5-20251101

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_