[Bug] Opus 5.5 false positive on harmless prompt causes persistent session failures via transcript contamination

Bug Description
Opus 5.5 false positive [reasoning_extraction] on a harmless prompt; the flagged phrase keeps killing sessions via the transcript

Claude Code 2.1.283 (VS Code + CLI), Windows 10, claude-opus-5-5, 2026-09-26.

Minimal repro (transcript attached to the Feedback ID below): a fresh session in an empty folder, one ordinary work prompt (asking for a draft in Russian before a Swedish message) → "Opus 5.5's safeguards flagged this message". Request req_011CfSF3qMFSbZEuGKXem4iG, Message msg_011CfSF3qpXdLsQJDWy2b9Py.

Impact: the phrase stays in the local .jsonl transcript, so any later session that reads it gets flagged too; several work sessions were lost this way. Sonnet 5 is not affected. Claude Code blocks redacting my own transcripts ("Session Transcript Tampering").

Requests: review the false positive; show what triggered the flag; allow recovering the session instead of a hard stop; provide a supported way to remove a flagged message from a transcript.

Environment Info

• Platform: win32
• Terminal: null
• Version: 2.1.283
• Feedback ID: f89f051b-0a05-4eb4-8441-4afb5e7d4eee

Errors

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