/**
 * Context-drift engine — SINGLE SOURCE.
 *
 * A pure, snapshot comparison: given a `project.faf` and its directory, report
 * the mtime relationship between the .faf and each AI-context file it feeds
 * (CLAUDE.md, AGENTS.md, .cursorrules, GEMINI.md). A target NEWER than the .faf
 * has drifted — the human edited the context file and the DNA hasn't caught up.
 *
 * No console, no ANSI, no process.exit. The CLI `faf drift` renders the human
 * table on top of this; `faf drift --json` emits this shape with a metadata
 * header; the VS Code extension imports `computeDrift` directly (faf-cli as a
 * library, never a shell-out). One comparison, every consumer.
 */
/** AI-context files the .faf feeds — the drift targets, in report order. */
export declare const CONTEXT_FILES: string[];
/** mtime window (ms) inside which a target counts as in sync with the .faf. */
export declare const DRIFT_TOLERANCE_MS = 1000;
/** 'newer' = target newer than the .faf → needs sync. */
export type DriftStatus = 'newer' | 'older' | 'in-sync' | 'missing';
export interface DriftTarget {
    /** Context-file name, e.g. 'CLAUDE.md'. */
    file: string;
    /** Whether the file exists alongside the .faf. */
    exists: boolean;
    /** File mtime in epoch ms, or null when missing. */
    mtime_ms: number | null;
    /** 'newer' = target newer than the .faf → needs sync. */
    status: DriftStatus;
    /** mtime_ms - source_mtime_ms, or null when missing. */
    delta_ms: number | null;
}
export interface DriftReport {
    /** The `project.faf` path compared against. */
    source: string;
    /** .faf mtime in epoch ms. */
    source_mtime_ms: number;
    targets: DriftTarget[];
    /** Count of targets with status 'newer' or 'older'. */
    drifted: number;
    /** Count of targets with status 'in-sync'. */
    in_sync: number;
    /** Count of targets with status 'missing'. */
    missing: number;
}
/**
 * Compare a `project.faf` against its AI-context files by mtime.
 *
 * @param fafPath  path to `project.faf`
 * @param dir      directory holding the context files; defaults to the .faf's
 *                 own directory. Never `process.cwd()` — the CLI passes it
 *                 explicitly, and a library caller (the VS Code extension)
 *                 passes the .faf's directory, which for a monorepo sub-package
 *                 is the package dir, not the workspace root.
 */
export declare function computeDrift(fafPath: string, dir?: string): DriftReport;