/**
 * Same rule as PROFORMA PDF: numeric prefix from invoice display when present,
 * otherwise lifetime O&M bill sequence (1, 2, 3, …) for the scheme.
 */
export declare function selectOmBillNumber(displayInvoiceNo: string, lifetimeRank: number): string;
/**
 * 1-based position of this invoice among non-deleted scheme invoices (billing period, then created_at).
 */
export declare function resolveOmBillLifetimeRankForInvoiceId(invoiceId: string): Promise<number>;
export declare function resolveOmBillNumberForInvoice(params: {
    invoiceId: string;
    invoiceNumberDisplay: string;
}): Promise<string>;
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