export declare function json(status: number, body: unknown): Response;
export declare function resolvePeer(req: Request): string;
/**
 * Constant-time byte comparison. Falls back to a manual XOR accumulator if
 * `node:crypto.timingSafeEqual` isn't available. Always processes every byte
 * of the longer input so length itself doesn't leak via timing.
 */
export declare function timingSafeEqual(a: Uint8Array, b: Uint8Array): boolean;
export declare function isAuthorized(req: Request, tokens: ReadonlySet<string>): boolean;
/**
 * Extract allow-listed passthrough headers from an inbound request. Keys are
 * lowercased; empty values are dropped. Called once per request in
 * `handleFormatEndpoint`; parsers then read `options.headers`.
 */
export declare function captureRequestHeaders(headers: Headers): Record<string, string>;
/**
 * Resolve a prompt-cache identity from inbound request body + headers.
 * Order of precedence (first wins):
 *   1. Body `prompt_cache_key`
 *   2. Body `metadata.{prompt_cache_key,session_id,conversation_id}`
 *   3. Header `x-prompt-cache-key`
 *   4. Header `session_id` / `conversation_id` (Codex / ChatGPT-OAuth surface)
 *   5. Header `x-session-id` / `x-conversation-id` (common informal)
 * Returns undefined when none present; the gateway then derives a stable
 * UUID from the request's stable parts.
 */
export declare function resolvePromptCacheKey(body: unknown, headers?: Headers): string | undefined;
/**
 * CORS headers for the auth-gateway. Currently echoes a wildcard origin; the
 * request is accepted so future tightening can mirror `Origin` without
 * threading the request through every caller.
 */
export declare function corsHeaders(_req: Request): Record<string, string>;
/**
 * Re-emit `response` with CORS headers merged. The original response body is
 * passed through unchanged. Used by the gateway wrapper so every outbound
 * format-endpoint response carries the same CORS surface as the preflight.
 */
export declare function withCors(response: Response, req: Request): Response;