SQLAlchemy sessions enter a failed state after SQL errors.
Without rollback(), all subsequent queries on the same session
fail with InFailedSqlTransaction. Added try/except with rollback
in _mark_duplicate, _mark_duplicate_to, _write_review, cross-group
pass, and the main phase1 loop.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>