state-machine-diagramming

Domain-entity state machine modeling. Distinct from UI state-transition-mapping: this is the business lifecycle of entities (Order / User / Subscription / Document / Claim). Per state: invariants + allowed/disallowed ops + entry/exit effects. Per transition: trigger + guard + effect + rollback + idempotency. Flat / hierarchical (sub-states) / parallel (orthogonal regions). Transition matrix + explicit invalid transitions + side-effect catalog. Mermaid stateDiagram-v2 with optional PNG export.