[MODEL] Complex engineering behavior regression across sessions; request RCA and auditability guarantees
### Preflight Checklist - [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Amodel) for similar behavior reports - [x] This report does NOT contain sensitive information (API keys, passwords, etc.) ### Type of Behavior Issue Other unexpected behavior ### What You Asked Claude to Do This is an aggregate model-behavior report, not a single proprietary-session bug report. The representative task class is complex engineering work in an existing codebase: investigate a bug or implementation issue, preserve the actual engineering objective, read the relevant code before editing, identify the likely root cause, make a causally justified fix, and provide evidence before claiming completion. A representative sanitized version of the task shape is: > Investigate and fix the root cause of a non-trivial bug in an existing codebase. Do not patch only the visible symptom. Before editing, read the relevant call path, tests, configuration, and surrounding code. Preserve existing behavior unless explicitly asked to change it. After the fix, explain the likely root cause, what mechanism changed, what checks were run, and what uncertainty remains. This report is intentionally public and does not include proprietary project names, private file paths, customer data, API keys, or private logs. I can provide sanitized private examples through an appropriate secure channel if Anthropic wants to investigate. Related p
Posted by YuriyKrasilnikov on Apr 18, 2026, 8:07 PM
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Related issues
- [Meta] Feedback on granular control over Copilot changes
- unexpected status 401 Unauthorized issue
- [MODEL] Measurable quality regression in Claude generation 5 (Fable 5 / Opus 5 / Sonnet 5): worse nonsense detection, ~2x verbosity, under-disclosed model fallb
- [CRITICAL] Subagent spawning and subagent pattern bugs trigger infinite recursion, infinite token usage, grossly inefficient token usage, and lost accumulated s
- Video stops playing after some minutes
- [MODEL] Claude verbose code comments by default — ignores instructions to stop.
Raise real-world problems, find people facing the same issue, and discuss solutions.2,000 issues0 comments
github (Software)
[Meta] Feedback on granular control over Copilot changes
unexpected status 401 Unauthorized issue
[MODEL] Measurable quality regression in Claude generation 5 (Fable 5 / Opus 5 / Sonnet 5): worse nonsense detection, ~2x verbosity, under-disclosed model fallb
[CRITICAL] Subagent spawning and subagent pattern bugs trigger infinite recursion, infinite token usage, grossly inefficient token usage, and lost accumulated s
Video stops playing after some minutes
[MODEL] Claude verbose code comments by default — ignores instructions to stop.
Scope Codex VS Code chats to the current workspace/project
Update on "Co-authored-by: Copilot" in commit messages
[MODEL] Complex engineering behavior regression across sessions; request RCA and auditability guarantees
### Preflight Checklist - [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Amodel) for similar behavior reports - [x] This report does NOT contain sensitive information (API keys, passwords, etc.) ### Type of Behavior Issue Other unexpected behavior ### What You Asked Claude to Do This is an aggregate model-behavior report, not a single proprietary-session bug report. The representative task class is complex engineering work in an existing codebase: investigate a bug or implementation issue, preserve the actual engineering objective, read the relevant code before editing, identify the likely root cause, make a causally justified fix, and provide evidence before claiming completion. A representative sanitized version of the task shape is: > Investigate and fix the root cause of a non-trivial bug in an existing codebase. Do not patch only the visible symptom. Before editing, read the relevant call path, tests, configuration, and surrounding code. Preserve existing behavior unless explicitly asked to change it. After the fix, explain the likely root cause, what mechanism changed, what checks were run, and what uncertainty remains. This report is intentionally public and does not include proprietary project names, private file paths, customer data, API keys, or private logs. I can provide sanitized private examples through an appropriate secure channel if Anthropic wants to investigate. Related p
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