Entity model overview

Fabric's "entities" are not database rows. They are typed identifiers in registries. Five registries make up the ontology surface:

A FabricModule populates these registries at app startup. Nothing else is allowed to write to them at runtime.

How they relate

Object types

A registered object type is a string the platform recognizes as a kind of entity. Validation rule: PascalCase alphanumeric (/^[A-Z][a-zA-Z0-9]*$/). Every event's subjectType must reference a registered subject type (which usually equals an object type).

The platform pre-registers a small set of cross-industry governance types and zero industry types. See built-ins.

Action IDs

Format: <namespace>.<snake_case_verb> — e.g. orders.submit. Validation regex: /^[a-z][a-z0-9-]*\.[a-z][a-z0-9_]*$/.

Two stability rules:

• An action ID is permanent. Renaming it breaks every audit log row, every policy reference, every projection that filtered on it.
• The action's version field is for implementation changes (handler logic, schema). The ID itself is immutable.

Event types

Format: PascalCase past-tense fact (PlanAccepted, LeadIngested). Registered via FabricModule.eventTypes. Schema versioning is per-event-type with an integer eventSchemaVersion on each envelope.

Policy IDs

Format: <id>.v<integer> — e.g. orders.payment_consent.v1. The version is part of the ID. A new version is a new policy. Old invocations remain bound to whichever version evaluated them.

State machines

Registered per entityType. A state machine is a graph of (from, to, causedByAction) transitions plus an optional guard predicate. The runtime calls validateTransition before atomic action handlers run.

States carry a StateClass:

type StateClass =
  | "initial"
  | "active"
  | "action_required"
  | "waiting"
  | "terminal"
  | "exception";

public enum StateClass
{
    Initial,
    Active,
    ActionRequired,
    Waiting,
    Terminal,
    Exception
}

Used by UI to render badges and by reporting to compute funnel/conversion metrics.

See also

• Built-in entities — the fixed set the platform pre-registers.
• Extending with vertical types — adding your own.
• Invariants — state-machine and registry constraints.