/**
 * RetryBudget — per-request retry accounting.
 *
 * Frontier models can refuse independently on the same turn (an orchestrator
 * agent and each of its sub-agents), so retries must be budgeted **per request,
 * not per session**. `RetryBudget` enforces a maximum number of retries for
 * each distinct key (a request id, task id, or sub-agent id) and never shares
 * the allowance across keys — one runaway request cannot starve the others.
 *
 * @module RetryBudget
 * @version 1.0.0
 * @license MIT
 */
/** Construction options for {@link RetryBudget}. */
export interface RetryBudgetOptions {
    /** Maximum retries allowed per key. Must be a non-negative integer. */
    maxPerKey: number;
}
/**
 * Per-key retry allowance.
 *
 * @example
 * ```typescript
 * const budget = new RetryBudget({ maxPerKey: 2 });
 * while (budget.tryConsume(requestId)) {
 *   const r = await attempt();
 *   if (r.ok) break;
 * }
 * ```
 */
export declare class RetryBudget {
    private readonly max;
    private readonly consumed;
    constructor(options: RetryBudgetOptions);
    /**
     * Consume one retry for `key`. Returns `false` (without consuming) once the
     * per-key budget is exhausted.
     *
     * @param key  Request/task/sub-agent identifier. Must be a non-empty string.
     */
    tryConsume(key: string): boolean;
    /** Retries already consumed for `key`. */
    used(key: string): number;
    /** Retries still available for `key`. */
    remaining(key: string): number;
    /** The configured per-key maximum. */
    getMax(): number;
    /** Reset one key, or all keys when `key` is omitted. */
    reset(key?: string): void;
}
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