Architecture

Three pieces:

• Contracts\Operations — the single write surface (start, advanceStep, complete, fail, sweepStalled). Depend on this, never the concrete class.
• OperationManager — the default implementation, bound in the service provider. It is the one write path that keeps status honest to the state machine and dispatches events. Mutations run here, never through model events.
• Models\Operation — the persisted record. status only moves through transitionTo(), which refuses illegal moves.

Input value objects (DataObjects\*) carry intent so method signatures stay stable as options grow. The manager resolves the Operation class through config('operations.models.operation'), so a host can subclass it.