/**
 * Spawn the index warm-up worker and report what it cost.
 *
 * See indexWarmupWorker.ts for the measurements this exists for. The parent
 * side is deliberately thin: it decides whether to warm at all, and it never
 * waits — a warm-up that has not finished simply means the first query pays for
 * the part not yet read, which is the behaviour without it anyway.
 */
export interface WarmupReport {
    steps: Array<{
        name: string;
        ms: number;
        rows: number;
    }>;
    failed: Array<{
        name: string;
        error: string;
    }>;
    totalMs: number;
}
export interface WarmupOptions {
    dbPath: string;
    labelsDbPath: string;
    budgetMs?: number;
    /** Injected in tests; the real one resolves next to the compiled worker. */
    workerUrl?: URL;
}
/**
 * Is warming worth doing at all?
 *
 * `:memory:` has nothing to warm, and INDEX_WARMUP=off is the escape hatch for
 * an environment where a second reader of the same file is not free (a slow
 * network share, a container with a hard IOPS cap).
 */
export declare function shouldWarmIndexes(dbPath: string, labelsDbPath: string): boolean;
/**
 * Run the warm-up in a worker thread. Resolves with what each step cost;
 * rejects only if the worker itself could not run.
 */
export declare function warmIndexes(opts: WarmupOptions): Promise<WarmupReport>;
/** One line naming the two most expensive steps — the ones worth acting on. */
export declare function renderWarmupReport(report: WarmupReport): string;
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