export declare const RASTER_ICON_MIME_ALLOWLIST: readonly ["image/png", "image/jpeg", "image/webp", "image/gif"];
export type RasterIconMime = (typeof RASTER_ICON_MIME_ALLOWLIST)[number];
/** True iff `mime` is a raster image type allowed as an icon. */
export declare function isRasterImageMime(mime: string | null | undefined): boolean;
export declare const MAX_ICON_EMOJI_BYTES = 64;
/**
 * Validate an icon emoji. Returns `{ ok: true }` for a single emoji grapheme,
 * or `{ ok: false, error }` with a human-readable reason otherwise.
 *
 * Rules:
 *  - non-empty, ≤ MAX_ICON_EMOJI_BYTES bytes
 *  - no control characters
 *  - exactly ONE grapheme cluster (via Intl.Segmenter)
 *  - that grapheme contains at least one Extended_Pictographic code point
 *    (so plain ASCII letters/digits and bare symbols are rejected)
 */
export declare function validateIconEmoji(raw: string): {
    ok: true;
} | {
    ok: false;
    error: string;
};
/** Convenience boolean form of {@link validateIconEmoji}. */
export declare function isValidIconEmoji(raw: string): boolean;