/**
 * NEXUS index diff — compare relation/node counts between two git commits.
 *
 * Runs an incremental pipeline re-analysis against the current working tree
 * state and compares relation/node counts against the pre-analysis snapshot.
 * Reports new relations, removed relations, and regression classification.
 *
 * @task T1473
 */
import { type EngineResult } from '../engine-result.js';
/** Health classification for a diff result. */
export type NexusDiffHealth = 'STABLE' | 'RELATIONS_ADDED' | 'RELATIONS_REDUCED' | 'REGRESSIONS_DETECTED';
/** Options for {@link diffNexusIndex}. */
export interface NexusDiffOptions {
    /** Git ref for the "before" snapshot (default: 'HEAD~1'). */
    beforeRef?: string;
    /** Git ref for the "after" snapshot (default: 'HEAD'). */
    afterRef?: string;
    /** Override the project ID (default: derived from repoPath). */
    projectIdOverride?: string;
}
/** Result envelope for {@link diffNexusIndex}. */
export interface NexusDiffResult {
    /** Resolved "before" ref. */
    beforeRef: string;
    /** Resolved "after" ref. */
    afterRef: string;
    /** Short SHA for beforeRef. */
    beforeSha: string;
    /** Short SHA for afterRef. */
    afterSha: string;
    /** Project ID. */
    projectId: string;
    /** Absolute repository path. */
    repoPath: string;
    /** Changed files detected between the refs. */
    changedFiles: string[];
    /** Node count before the incremental run. */
    nodesBefore: number;
    /** Node count after. */
    nodesAfter: number;
    /** New nodes added. */
    newNodes: number;
    /** Nodes removed. */
    removedNodes: number;
    /** Relation count before. */
    relationsBefore: number;
    /** Relation count after. */
    relationsAfter: number;
    /** New relations added. */
    newRelations: number;
    /** Relations removed. */
    removedRelations: number;
    /** Health classification. */
    healthStatus: NexusDiffHealth;
    /** Regression messages (empty if none). */
    regressions: string[];
}
/**
 * Diff the NEXUS index between two git commits.
 *
 * Snapshots current node/relation counts, runs an incremental pipeline for
 * the changed files, then re-counts to compute deltas. Regressions are
 * flagged when more than 5 relations are removed or any nodes are removed.
 *
 * @param repoPath - Absolute path to the repository.
 * @param opts     - Optional before/after git refs and project ID override.
 * @returns Diff result with health classification.
 *
 * @example
 * const result = await diffNexusIndex('/home/user/myproject');
 * console.log(result.healthStatus, result.regressions);
 */
export declare function diffNexusIndex(repoPath: string, opts?: NexusDiffOptions): Promise<NexusDiffResult>;
export declare function nexusDiff(repoPath: string, beforeRef?: string, afterRef?: string, projectId?: string): Promise<EngineResult<NexusDiffResult>>;
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