[BUG] [Opus 4.8] Generating non-existent information as user input during "invisible turns" and attempting to proceed based on that.

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?

Opus 4.8 more frequently generates non-existent "user instructions" during invisible "thinking" states, attempting to proceed with a course of action completely different from my true intentions.
(For example, attempting to adopt a course of action that has been thoroughly documented and rejected in previous sessions.)
When this occurs, if the code hasn't been changed yet, I need to immediately abandon the session; if changes have already been made, I need to rewind and undo the code edits.
Then, I simply give the same prompt again in a clean context and hope that Claude proceeds with the correct work.

Again, this wastes limited anthropic computing resources and creates inefficiencies in service operation.
You should optimize your service operations and save the costs necessary to serve your users. This directly impacts your sustainability.
And of course, we users should not be charged rate limits or API fees for token waste caused by model flaws that are not our fault.

This is a clear step backward. At least, this wasn't the case right after Opus 4.8 was released.
They followed my instructions, simply asked questions about what was missing, and confirmed my intentions before proceeding.

What on earth is going on?

Feedback ID: b2f82110-a4e4-41e7-b0ea-9cc83e06809e

What Should Happen?

Claude should act according to my instructions and take additional steps to clarify any insufficient, missing, or ambiguous instructions.

Error Messages/Logs

Steps to Reproduce

It happens randomly. There is no procedure that can be perfectly reproduced.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.177

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

_No response_