import { Observable, type OperatorFunction } from "rxjs";
/**
 * Dynamic counterpart to `switchMap(() => combineLatest(...))` for records,
 * with stable branches by key.
 *
 * Each record key gets its own long-lived branch. Branches are only
 * created/removed when keys are added/removed; value updates are pushed through
 * the existing key branch.
 */
export declare function combineLatestByKey<Input extends Record<string, unknown>, R>(project: (source$: Observable<Input[Extract<keyof Input, string>]>, key: Extract<keyof Input, string>) => Observable<R>): OperatorFunction<Input, Record<Extract<keyof Input, string>, R>>;