export interface CompressionOptions {
    /** Don't compress bodies smaller than this many bytes. Default `1024`. Enforced by peeking the body
     * (see below) since runtimes rarely expose `Content-Length` on a constructed `Response`. */
    readonly threshold?: number;
    /** Decide whether a `Content-Type` is worth compressing. Default: text, JSON/+json, JS, XML/+xml,
     * NDJSON, wasm, SVG. Already-compressed media (images, video, archives) is skipped. */
    readonly compressible?: (contentType: string) => boolean;
}
/**
 * Transparently **gzip** responses when the client sends `Accept-Encoding: gzip` and the body is a
 * compressible type larger than `threshold`. Uses the Web-standard `CompressionStream`, so it runs
 * on every nifra runtime including the edge; gzip is the one encoding `CompressionStream`
 * guarantees everywhere, so brotli isn't offered.
 *
 * Built on the portable `onResponseBody` tier for framework-serialized bytes, with a stream-safe raw
 * fallback for handler-returned/proxied Responses. The common JSON path stays on Node's direct
 * writer; raw streams are compressed incrementally without being fully buffered.
 *
 * Skips: clients that don't accept gzip, already-encoded responses, bodyless responses,
 * `Range` responses (206 / `Content-Range`), `Cache-Control: no-transform`, non-compressible
 * types, and bodies below `threshold` (gzip's ~20-byte overhead would enlarge them). Adds
 * `Vary: Accept-Encoding`.
 *
 * **Security (BREACH).** Compression makes the response length depend on its content, so a response
 * that mixes a secret with attacker-reflected input leaks the secret through the compressed size
 * (the BREACH class of attacks). This applies to any HTTP compression, not this middleware
 * specifically. Nifra's own CSRF tokens are HMAC-signed per session and safe to compress, but if a
 * response body reflects request input **and** carries a per-request secret, exclude that route via
 * `compressible`/route scoping, or split the secret and the reflection into separate responses.
 *
 * ```ts
 * app.use(compression())
 * ```
 */
export declare function compression(options?: CompressionOptions): import("@nifrajs/core").IdentityPlugin<never>;
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