export declare const STREAMING_PAGE_HEADER = "x-absolute-stream";
/** Headers for a STREAMING html page response — `text/html` plus the streaming
 *  marker so {@link withPageCacheHeaders} marks it `no-cache` (no ETag). */
export declare const streamingPageHeaders: (extra?: HeadersInit) => Headers;
/** Options for {@link withPageCacheHeaders}. */
export type PageCacheOptions = {
    /** Opt a *streaming* page into the buffered-ETag path: buffer its whole
     *  body before sending so it can carry a content-hash `ETag` and serve a
     *  `304` on repeat visits. This trades streaming's fast first byte for the
     *  revalidation saving, so only set it on pages whose output is static
     *  enough that the 304 is worth losing the stream (e.g. a marketing page).
     *  No effect on already-buffered pages — those are ETagged regardless. */
    bufferStreamForEtag?: boolean;
};
/** Apply the SPA cache policy to a page Response. HTML gets `no-cache` (+ a
 *  content-hash `ETag` / `304` for buffered responses); non-HTML responses
 *  (redirects, JSON, etc.) pass through untouched. Safe to call on every page
 *  handler's final response.
 *
 *  Streaming pages skip the ETag (their headers flush before the body renders)
 *  unless the caller passes `bufferStreamForEtag`, which buffers the stream so
 *  it can be hashed — see {@link PageCacheOptions}. */
export declare const withPageCacheHeaders: (response: Response, request?: Request, options?: PageCacheOptions) => Promise<Response>;