Change register_user() to use db.flush() instead of db.commit() and remove db.rollback() to follow the established architecture: - Services use flush() for database operations - Endpoints handle transaction commit - Exception handlers manage rollback This resolves SVC-006 architecture violation. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>