Type Alias Narrow<T, P>

Narrow: P extends (input: T) => boolean
    ? [GuardTarget<P>] extends [never] ? T : NarrowObject<T, GuardTarget<P>>
    : P extends Record<string, unknown>
        ? NarrowObject<T, P>
        : T extends P ? Extract<T, P> : T

Narrows input when pattern is a shallow object, literal discriminant, or type predicate.