import { Buffer } from 'node:buffer';
/**
 * Server-side caches for upstream proxy fetches.
 *
 * ## Why
 *
 * Proxy URLs arriving from the client carry per-request auth artefacts (`sig`,
 * `_pt`, `_ts`) that change across renders. CDNs key on full URL so each
 * rotation produces a unique edge cache entry and upstream origins take the hit
 * on every render. Caching the *upstream response* here — keyed on the inner
 * resource URL (or normalized param set) — dedupes those fetches across every
 * request that resolves to the same upstream, regardless of how the caller
 * authenticated.
 *
 * Safe because `withSigning` runs before any cache path: unsigned requests 403
 * before they can do a cache lookup. Cache stores hold only responses produced
 * from legitimately-authenticated requests.
 *
 * ## Binary payloads
 *
 * Image/blob responses are stored as base64 strings so they round-trip cleanly
 * through every unstorage driver (memory, filesystem, redis, cloudflare kv).
 * The 33% size overhead is tolerable; the alternative is relying on each driver
 * to preserve Buffer/ArrayBuffer which is not universal.
 */
export interface CachedBinaryResponse {
    base64: string;
    contentType: string | null;
}
export interface CachedBinaryFetchOptions {
    headers?: Record<string, string>;
    timeout?: number;
    redirect?: 'follow' | 'manual';
    ignoreResponseError?: boolean;
}
export interface CachedBinaryResult extends CachedBinaryResponse {
    body: Buffer;
    status: number;
}
/**
 * Cache upstream binary/image fetches. Returns a helper that restores the
 * response body as a Buffer so the handler can pipe it straight to the client.
 */
export declare function createCachedBinaryFetch(name: string, maxAge: number): (url: string, opts?: CachedBinaryFetchOptions) => Promise<CachedBinaryResult>;
/**
 * Cache upstream JSON/text fetches. `getKey` is caller-controlled so handlers
 * can normalize on whichever inner params identify the resource (tweet ID,
 * post URL, query hash).
 */
export declare function createCachedJsonFetch<T>(name: string, maxAge: number, getKey: (url: string, opts?: {
    headers?: Record<string, string>;
}) => string): (url: string, opts?: {
    headers?: Record<string, string>;
    timeout?: number;
}) => Promise<T>;