/**
 * Shared redirect safety helpers for all adapters.
 *
 * Guarantees:
 *   - Location is free of CR/LF/NUL (header-injection boundary)
 *   - Dangerous URI schemes (javascript/data/vbscript/file) are rejected
 *   - Non-ASCII / non-header-safe bytes are percent-encoded so
 *     Node's setHeader / validateHeaderValue never throws mid-send
 *   - Already-percent-encoded sequences and ASCII URI structure are preserved
 *   - Only 301/302/303/307/308 are accepted; everything else coerces to 302
 */
export type RedirectStatus = 301 | 302 | 303 | 307 | 308;
/**
 * Normalize a redirect status code.
 *
 * Allowed: 301, 302, 303, 307, 308.
 * Missing / invalid values coerce to 302 (never hang or leak a raw 999).
 */
export declare function normalizeRedirectStatus(status?: number | null): RedirectStatus;
/**
 * Normalize a redirect Location value.
 *
 * - Rejects CR/LF/NUL with HttpError 400 (bounded failure before send)
 * - Rejects javascript/data/vbscript/file schemes with HttpError 400
 * - Percent-encodes non-ASCII so the value is a valid HTTP header token
 *   for Node's validateHeaderValue / setHeader
 * - Leaves already-encoded sequences and URI-reserved ASCII intact
 *
 * @throws {HttpError} when location is unsafe or not a string
 */
export declare function normalizeRedirectLocation(url: string): string;
/**
 * Prepare redirect status + Location for adapters.
 * Call this *before* marking the response as sent.
 */
export declare function prepareRedirect(url: string, status?: number | null): {
    location: string;
    status: RedirectStatus;
};