/**
 * Status-column coverage cache (AC-17, NFR2): `aidlc status` must stay
 * filesystem-cheap, so coverage is cached at
 * `.aidlc/cache/traceability/<instance>.json` — outside tracked state
 * (derived data, design F5) — keyed by a stat hash of every input coverage
 * depends on, including ALL instances' requirements.md (the uniqueness rule
 * makes coverage cross-instance, design F2). Cache hit costs stats only;
 * corrupt or absent cache degrades to recompute (fail-soft).
 *
 * Requirements: traceability-ids/AC-17
 */
import type { CoverageSummary } from './types.js';
/**
 * Coverage summary for the status column, cached by input stat hash.
 *
 * @returns null when the criterion does not apply to the instance.
 */
export declare function coverageForStatus(projectRoot: string, instanceName: string): CoverageSummary | null;
/** Format a coverage summary for the status table cell. */
export declare function formatCoverage(coverage: CoverageSummary): string;
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