Opus 4.6: Agent didn't verify production code before declaring methods "removed" and deleting tests

Preflight Checklist

• [x] I have searched existing issues for similar behavior reports
• [x] This report does NOT contain sensitive information (API keys, passwords, etc.)

Type of Behavior Issue

Claude modified files I didn't ask it to modify

What You Asked Claude to Do

There's a serious degradation of quality in code generation and bug fix capability recently. Claude Code is not taking time to think through the problem. I use 4.6. Just a note.

What Claude Actually Did

Rushed for the implementation

Expected Behavior

Think through the problem and investigate the issue.

Files Affected

None, only lower quality output

Permission Mode

Accept Edits was ON (auto-accepting changes)

Can You Reproduce This?

Sometimes (intermittent)

Steps to Reproduce

Just ask to address warning outputs

Claude Model

Opus

Relevant Conversation

Impact

Medium - Extra work to undo changes

Claude Code Version

4.6

Platform

Anthropic API

Additional Context

_No response_