[BUG] Sonnet 4.5 in new Claude Code v. > 2. degraded quality, adherence to rules, premature victory, not following and forgetting rules been told 1 prompt earlier

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?

With the new version of Claude Code > 2.x and the newly introduced Sonnet 4.5, I experience:

• Degraded coding quality. Claude Code forgets the rules, the advises, the swearing, the momorized rules (the quick switch # to memorize)
• Code and functions in the very same source file are not looked at, instead the implementation is started and the source is cluttered with used/non-used functions and methods. Telling Claude to look at it, often results in "Yes, You right. Everything is working now."
• premature victory declaring. Not even touched, not tested, did nothing -> declaring victory. "Fix everything you did not fix" reveal -> nothing was implemented at all. The victory was just declared without touching the problematic code at all.
• Do not follow directory advises to put the test-suites and test/debugging files into propper directory. Cluttering my code base with 1000s of small test files
• do not follow its own plan created
• forgetting the todos, not finishing exisiting todos
• debuging in circles. When told where the propblem is, start to debug in circles again with the same problem
• .do not follow suggestions. Told "look up the legacy files first to get inspiration of how we solved the problem earlier" -> do not follow the advise and continue doing its work, in the course do not even load the files to get the inspiration

Downgraded to CC 1.0.111.

Which version still using Sonnet 3.x -> i would like to try that. Sonnet 4.5 is talking much but doing nothing. I need a worker and not a talker.

What Should Happen?

• my advises should be followed
• the rules must be followed
• the circle debug must stop
• the premature victory must stop
• the todos are important, no finishing declaration until all are resolved
• no lying that everything has been resolved without even touching the problem
• I want it just to follow the rules i define.That would solve a lot of my problems. Rules should be GOD for claude.

Error Messages/Logs

no error messages for wrong and faulty behavior avaible.

Steps to Reproduce

• use it on a complex codebase. If its more than 5 lines of code, Claude code 2.x with Sonnet 4.5 will have problems to see the overall picture, like with my codebase.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

1.0.111

Claude Code Version

1.0.111

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

_No response_