/**
 * 2FA setup QR rendering with a font-independent fallback.
 *
 * The compact QR uses Unicode half-block glyphs — some terminal fonts (web
 * terminals, fallback fonts without Block Elements) draw those as thin
 * dashes/underscores, making the QR unscannable (lab report 2026-08-19).
 * "big" mode instead paints SPACES with ANSI background colors: nothing to
 * scan depends on any glyph, only on color support.
 */
export type QrMode = 'small' | 'big';
/**
 * The otpauth account label. Every install used to render the same
 * "NebulaNotebook: local" entry, so a user running Nebula in two places got
 * two indistinguishable authenticator entries — and no way to tell which
 * 6-digit code belongs to which server. Host:port makes them self-labeling.
 * Colons are separators in the otpauth label grammar, so they are replaced.
 */
export declare function accountLabel(host: string, port: number | string): string;
export declare function renderQr(otpAuthUrl: string, mode: QrMode): string;
export declare function buildSetupInstructions(secret: string, otpAuthUrl: string, qrString: string): string;