/**
 * `src/services/observability/results-baseline-artifact.ts`
 *
 * WHY THIS MODULE EXISTS — the tracked artifact and the comparison against it
 * are separated from the computation, so the question "what does the baseline
 * say?" and the question "what does the machine measure right now?" can be
 * answered by different modules.
 *
 * The tracked artifact lives at `.peaks/observability/results-baseline.json`.
 * It is NOT CI-enforceable: its source data is gitignored session state
 * (`.peaks/_runtime/<sessionId>/metrics/slices.jsonl`), so a CI runner has
 * nothing to compare against. This module never wires the artifact into a
 * gate; it only reads it, writes it, and reports drift against it.
 */
import { type BaselineDrift, type BaselineRowKind, type BaselineTolerance, type ResultsBaseline } from './results-baseline.js';
/** Absolute path of the tracked artifact for a project root. */
export declare function resultsBaselinePath(projectRoot: string): string;
/** The tracked artifact, or null when this project has none yet. */
export declare function readTrackedResultsBaseline(projectRoot: string): ResultsBaseline | null;
/** Regenerate the tracked artifact and return the path it was written to. */
export declare function writeResultsBaseline(projectRoot: string, baseline: ResultsBaseline): string;
/** The tolerance that applies to a row kind, read from the tracked artifact. */
export declare function toleranceFor(tolerance: BaselineTolerance, kind: BaselineRowKind): number;
/**
 * Compare a freshly computed baseline with the tracked one. A missing row or
 * a metric-version mismatch is drift; so is a value that moved further than
 * the tolerance its kind allows.
 */
export declare function compareResultsBaseline(computed: ResultsBaseline, tracked: ResultsBaseline): BaselineDrift[];