/**
 * Cross-replica per-key CUMULATIVE cost quota ([ref] P0-1). A thin {@link QuotaTracker} over the
 * shared {@link WriteBehindCounter}: atomic write-behind aggregation, eventually consistent (SOFT
 * limiting — boundary overspend is bounded by the flush interval and backstopped by the HARD per-task
 * `maxCostUsd` gate). `scope_key` is opaque (principal today; team/feature later — [ref] N3).
 */
import type { Pool } from "mysql2/promise";
import type { QuotaDecision, QuotaLimits, QuotaTracker } from "../observability/cost-quota.js";
import { type CounterDegradeHook } from "./write-behind-counter.js";
export declare class TiDBCostQuota implements QuotaTracker {
    private readonly counter;
    /** [ref]:限额=比较参数(行里只有花费);窗长换代经 counter.setWindowMs(桶键语义见那里)。 */
    private limitMicroUsd;
    private refreshRequested;
    private refreshIntervalMs;
    constructor(pool: Pool, limitMicroUsd: number, windowMs: number, now?: () => number, onDegraded?: CounterDegradeHook, queryTimeoutMs?: number);
    setLimits(next: QuotaLimits): void;
    private syncRefresh;
    check(scopeKey: string): QuotaDecision;
    add(scopeKey: string, micro: number): void;
    flush(): Promise<void>;
    refresh(): Promise<void>;
    reap(): Promise<number>;
    startRefresh(intervalMs?: number): this;
    stop(): void;
}
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