/**
 * M-split-graph — Nexus DB topology split migration (T9150 ADR-072).
 *
 * Migrates from a single `nexus.db` to two file families:
 *   - `nexus-registry.db` (global, registry + metadata tables)
 *   - `nexus-graph/<projectId>.db` (per-project, nodes + relations)
 *
 * This migration is IDEMPOTENT: running it twice is safe.
 * If `nexus-version.json` shows `topology: "split"`, this is a no-op.
 *
 * ROLLBACK: pass `rollback: true` to re-merge back into a single `nexus.db`.
 *
 * @task T9150
 * @see ADR-072 docs/adr/ADR-072-nexus-db-split.md
 */
export interface SplitMigrationOptions {
    /** Path to `nexus.db` (default: `<cleoHome>/nexus.db`). */
    nexusDbPath?: string;
    /** Perform a dry-run scan only — no file writes. */
    dryRun?: boolean;
}
export interface SplitMigrationResult {
    status: 'already-split' | 'migrated' | 'dry-run';
    projectCount: number;
    legacyFile?: string;
    durationMs: number;
}
/**
 * Execute the nexus DB split migration (ADR-072).
 *
 * Steps:
 * 1. Check nexus-version.json — skip if already split.
 * 2. Create nexus-registry.db and copy registry tables.
 * 3. For each project in project_registry, create nexus-graph/<id>.db
 *    and copy nexus_nodes + nexus_relations + nexus_contracts.
 * 4. Rename nexus.db → nexus.db.legacy.<ts>.
 * 5. Write nexus-version.json {topology: "split", migratedAt, legacyFile}.
 */
export declare function migrateToSplit(opts?: SplitMigrationOptions): Promise<SplitMigrationResult>;
export interface RollbackOptions {
    /** Force rollback even if version file doesn't indicate split topology. */
    force?: boolean;
}
export interface RollbackResult {
    status: 'rolled-back' | 'not-split' | 'no-legacy-file';
    durationMs: number;
}
/**
 * Roll back the nexus DB split — re-merges into a single `nexus.db`.
 *
 * Reads `legacyFile` from `nexus-version.json` and copies it back.
 * Then deletes `nexus-registry.db` and `nexus-graph/`.
 */
export declare function rollbackSplit(opts?: RollbackOptions): Promise<RollbackResult>;
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