import type { ToolUsageSummary, UsageBucket } from "../utils/types.js";
import type { IMetricsStore } from "../storage/interfaces.js";
export declare class MetricsStore implements IMetricsStore {
    private readonly metricsPath;
    private cachedEntries;
    private cachedMtime;
    constructor(twiningDir: string);
    /** Read all metrics, using mtime cache when possible */
    private readAll;
    /** Get tool usage summary, optionally filtered by time */
    getToolUsageSummary(since?: string): Promise<ToolUsageSummary[]>;
    /** Get usage over time in buckets */
    getUsageOverTime(bucketMinutes?: number): Promise<UsageBucket[]>;
    /** Get error breakdown by tool and error code */
    getErrorBreakdown(): Promise<Array<{
        tool_name: string;
        error_code: string;
        count: number;
    }>>;
}
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