/**
 * `singleFlight` / `memoizeAsync` — in-flight promise coalescing.
 *
 * The fleet hand-rolls this shape at least nine times: honeybook's
 * `apiVersionPromise` (self-clearing memoized fetch), infinitecampus's
 * `loginInFlight`, onehome's `capturePromise`, vibo's `loginInFlight` +
 * `reauthInFlight`, alltrails's `ensureApiKey`/`bridgeReady`, tripadvisor's
 * `bridgeReady`, artsonia's `ensureStarted`, and redfin's promise-caching
 * `LocalityPoolCache`. Two primitives cover all of them:
 *
 *  - {@link singleFlight} — one shared in-flight promise, cleared on settle
 *    (the login/refresh/bridge-ready guard).
 *  - {@link memoizeAsync} — a keyed promise cache that coalesces concurrent
 *    loads and evicts a rejected load so the next call retries (the keyed
 *    loader cache).
 */
/**
 * Wrap an async `fn` so concurrent calls share ONE in-flight invocation. The
 * in-flight promise is cleared once it settles, so the next call starts fresh
 * and a rejection doesn't poison later callers (every waiter of the failed
 * flight still sees the rejection).
 *
 * This is the guard `createOAuth2Refresher` embeds, exposed standalone for
 * login flows, bridge-start, and API-version fetches.
 */
export declare function singleFlight<T>(fn: () => Promise<T>): () => Promise<T>;
/** The keyed async cache returned by {@link memoizeAsync}. */
export interface AsyncMemo<K, V> {
    /** Load (or return the cached/in-flight load of) the value for `key`. */
    get(key: K): Promise<V>;
    /** Drop one key so the next {@link get} reloads it. */
    delete(key: K): void;
    /** Drop everything. */
    clear(): void;
    /** Number of cached (or in-flight) keys. */
    readonly size: number;
}
/**
 * Memoize an async `loader` by key, caching the **promise** so concurrent
 * `get`s of the same key coalesce onto one load. A load that REJECTS is
 * evicted as it settles — the rejection reaches every coalesced waiter, but
 * the next `get` retries instead of replaying the cached failure.
 *
 * `delete`/`clear` cover invalidation and the `_reset*` test hooks the donor
 * repos (redfin, zola) exposed by hand.
 */
export declare function memoizeAsync<K, V>(loader: (key: K) => Promise<V>): AsyncMemo<K, V>;
//# sourceMappingURL=single-flight.d.ts.map