/**
 * Fit the run into the machine's memory by choosing fewer workers.
 *
 * Every worker is a separate V8 isolate that re-reads and re-parses the config's
 * data files, so memory grows LINEARLY with the job count. Measured on a
 * 160 000-row surname CSV: 170 MB at one worker, 1057 MB at eight — while the
 * wall clock stayed at 0.6 s either way. Paying six times the memory for no
 * time at all is the worst kind of default.
 *
 * The decision is made silently. Someone generating test data may be an
 * analyst rather than an engineer, and telling them about isolates, cores and
 * heap growth helps nobody; the tool should simply not put itself in a position
 * where it dies halfway. Slower and finished beats faster and killed.
 *
 * Note that switching ENGINE does not help here. A large value list has to be
 * resident whatever the engine does with rows — measured at 172 MB for stream,
 * disk and memory alike. The only lever for list size is the worker count.
 */
import { type DataSourceOptions } from '../data-source/index.js';
/** Total on-disk size of every `src=` file the config reads. */
export declare function dataFileBytes(sources: readonly string[], options?: DataSourceOptions): number;
/** Every `src="…"` in the source, in document order. Cheap textual scan. */
export declare function declaredSources(source: string): string[];
export interface JobBudget {
    /** Workers the machine can actually afford. */
    readonly jobs: number;
    /** True when the request was reduced — the caller may mention it if asked explicitly. */
    readonly reduced: boolean;
}
/**
 * Reduce a job count until the run fits in memory.
 *
 * Never returns 0: one worker always runs, because refusing outright would be
 * less useful than being slow. If even one worker looks too large, that is a
 * problem no job count can fix and the engine choice already handles the row
 * side of it.
 */
export declare function fitJobsToMemory(params: {
    readonly jobs: number;
    readonly dataBytes: number;
    readonly totalBytes?: number;
}): JobBudget;
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