export declare const SUPPORT_ALLOWED_EXTENSIONS: readonly string[];
/**
 * `accept` value for <input type="file">. Derived from EXT_TO_MIME so it always
 * matches the validator. Includes both MIME types and extension hints so the
 * native picker filters correctly across browsers/OSes.
 */
export declare const SUPPORT_ATTACHMENT_ACCEPT: string;
/** Human-readable allowed-types label for error messages. */
export declare const SUPPORT_ALLOWED_TYPES_LABEL: string;
/**
 * Max attachment size, mirroring the backend cap
 * (`global-support-svc` SUPPORT_MAX_FILE_SIZE_BYTES, default 5 GiB; the service
 * throws "Attachment exceeds the maximum support upload size" past this). We
 * reject oversized files here too so the user gets immediate feedback instead
 * of waiting through a long upload only to be rejected server-side.
 */
export declare const SUPPORT_MAX_ATTACHMENT_BYTES: number;
export declare function isAllowedAttachment(file: File): boolean;
/**
 * Split a selection into allowed/rejected. Drag-drop and "All files" picker
 * overrides bypass the `accept` attribute, so callers must validate here too.
 */
export declare function partitionAttachments(files: File[]): {
    accepted: File[];
    rejected: File[];
};
export declare function rejectedAttachmentsMessage(rejected: File[]): string;