FsmConfig

Defined in: types.ts:343

Configuration object for creating an FSM.

Example

// TCtx inferred as { tickCount: number }, TStates inferred from states object:
createFsm({
  id: "traffic-light",
  initialState: "green",         // validated against state keys
  context: { tickCount: 0 },     // inference site for TCtx
  states: {
    green:  { timeout: "yellow" }, // "yellow" validated against state keys
    yellow: { timeout: "red" },
    red:    { timeout: "green" },
  },
});

Type Parameters

TCtx

TCtx

The context type (Fsm) or client type (BehavioralFsm). For Fsm, this is inferred from the context property. For BehavioralFsm, it’s the client object type provided explicitly or as a generic parameter.

TStates

TStates extends Record<string, Record<string, unknown>> = Record<string, Record<string, unknown>>

The literal states object type. Captured by the factory function’s generic parameter (ideally with const to preserve string literal types). Defaults to a loose record for unconstrained usage.

Properties

context?

optional context: TCtx

Defined in: types.ts:370

Initial context data. The type is inferred from this value and flows into every handler’s ctx parameter.

For BehavioralFsm, this property is optional and serves only as a type constraint — the client object IS the context.

---

id

id: string

Defined in: types.ts:351

Unique identifier for this FSM

---

initialState

initialState: NoInfer<keyof TStates & string>

Defined in: types.ts:361

The state to start in. Must be a key of states.

Wrapped in NoInfer to prevent TypeScript from using this value as an inference site for TStates. Without it, initialState: "green" could narrow TStates to only have a “green” key. We want inference to come exclusively from the states property.

---

states

states: ValidateStates<TCtx, TStates>

Defined in: types.ts:373

State definitions. Keys become the state name union.