The mandatory Commit Message Format block hard-coded 'Claude Opus 4.6', which stayed stale for months after the model moved on. Replace with the generic 'Co-Authored-By: Claude <noreply@anthropic.com>' and note that the harness-appended model-identifier variant is equally valid. Pinned versions are the root cause of this drift class (CLAUDE-CLEANUP.md section 4). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>