StateFieldDef

Declaration for a single state field in a middleware’s state property.

Type is inferred from the default value. If a reducer is provided, writes dispatch through it: state.field = delta → reducer(current, delta).

Example

state: {
  totalCost: { default: 0, reducer: (prev, delta) => prev + delta },
  isActive: { default: true },  // type inferred as boolean
}

T = unknown

default: T

Default value. TypeScript infers the field type from this.

optional reducer?: (prev, delta) => T

Optional reducer for merge semantics. Without it, writes use last-write-wins.

T

T

T