Ruby/Rails library by Julik Tarkhanov for durable workflow execution. Core design: a workflow is an Active Record with a DSL of step/wait declarations at class level; each step's block is instance-evaluated inside the workflow. Every workflow has a polymorphic 'hero' association linking it to any domain record (user, payment, billing cycle) — state lives on the hero, the workflow drives state changes. Uses Active Job as a trigger (not a carrier) — each enqueued job targets one specific step_execution row, so deleting step_executions turns stale jobs into no-ops (idempotency via DB). Fine-grained locking before/after step execution prevents races without keeping DB transactions open during work. Ships flow control (cancel!, finish!, skip, reattempt, pause), configurable exception handling, Active Support instrumentations, a housekeeping cron job to resume workflows stranded by crashed workers, an exhaustive manual.md (also feedable to LLMs), and tagged logs. Explicit non-features: no built-in step idempotency (developer's responsibility), no structured rollback, no suspend/resume-inside-step (in progress). Runs on SQLite, MySQL, Postgres — no Kafka/Redis/RabbitMQ/gRPC required. Dual license (LGPL core + paid admin UI). Mounts as a Rails engine providing an admin with workflow class listing, per-workflow timeline, paused/failed inspection with step source + exception, manual resume, and APM deep-links. Used in production in Kora (email assistant) and Porsche TUI.