/**
 * Budget enforcement utilities for ACP checkout flows
 * Uses bigint for all currency calculations to avoid floating-point errors
 */
export interface BudgetConfig {
    /** Maximum cost per single checkout in minor currency units (e.g., paise for INR) */
    maxPerCallMinor?: bigint;
    /** Maximum total cost per day in minor currency units */
    maxDailyMinor?: bigint;
    /** Maximum total cost per month in minor currency units */
    maxMonthlyMinor?: bigint;
    /** Currency code (must match at runtime, e.g., 'USD', 'INR') */
    currency: string;
}
export interface BudgetResult {
    /** Whether the cost is allowed within budget limits */
    allowed: boolean;
    /**
     * Remaining budget in minor units (after this operation).
     * - When allowed: the minimum remaining across all applicable limits
     * - When denied: 0n (never negative)
     * - When unbounded: undefined (check `unbounded` flag instead)
     */
    remainingMinor?: bigint;
    /**
     * True when no budget limits are configured.
     * In this case, remainingMinor is undefined.
     */
    unbounded?: boolean;
    /** Error code if not allowed */
    code?: 'budget_exceeded' | 'currency_mismatch';
    /** Human-readable reason if not allowed */
    reason?: string;
}
/**
 * Check if a cost is within budget.
 * Pure, deterministic function - caller tracks time windows externally.
 *
 * @param spentMinor - Amount already spent in minor units (e.g., paise for INR)
 * @param costMinor - Cost of current operation in minor units
 * @param currency - Currency code (must match config.currency)
 * @param config - Budget configuration
 * @returns Result indicating whether cost is allowed and remaining budget
 *
 * @example
 * ```typescript
 * const config: BudgetConfig = {
 *   maxPerCallMinor: 50000n, // 500.00 INR max per checkout
 *   maxDailyMinor: 1000000n, // 10000.00 INR max per day
 *   currency: 'INR'
 * };
 *
 * const result = checkBudget(
 *   850000n, // Already spent 8500.00 INR today
 *   100000n, // Current checkout costs 1000.00 INR
 *   'INR',
 *   config
 * );
 *
 * if (result.allowed) {
 *   console.log(`Allowed. Remaining: ${result.remainingMinor} paise`);
 * } else {
 *   console.log(`Denied: ${result.reason}`);
 * }
 * ```
 */
export declare function checkBudget(spentMinor: bigint, costMinor: bigint, currency: string, config: BudgetConfig): BudgetResult;
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