/**
 * Backup and restore core module.
 *
 * Produces full-`.cleo/` snapshots containing tasks.db, brain.db, config.json
 * and project-info.json using the safest available method for each file type:
 *
 *   - SQLite databases: `VACUUM INTO` via the live native handle (see
 *     {@link ../store/sqlite-backup.ts}). This is the ONLY safe way to
 *     snapshot a WAL-mode SQLite database while it is open — raw filesystem
 *     copies can capture torn writes or stale WAL frames.
 *
 *   - JSON files: atomic tmp-then-rename via {@link atomicWriteSync} so a
 *     partial write can never corrupt the backup target.
 *
 * Snapshots are recorded under `.cleo/backups/sqlite/` with a JSON sidecar
 * (`{backupId}.meta.json`) enumerating which files were captured and how.
 * Restores read the same sidecars and materialize each file back into the
 * live `.cleo/` directory.
 *
 * This is the backing store for the `cleo backup` and `cleo restore backup`
 * CLI verbs (see packages/cleo/src/cli/commands/backup.ts and restore.ts).
 *
 * ## Canonical backup path (T10315 · ADR-013 §10 · Saga T10281 / Epic T10284)
 *
 * Both this module and {@link ../store/sqlite-backup.ts} (the auto session-end
 * snapshotter) write to the SAME directory: `.cleo/backups/sqlite/`. The two
 * producers use distinguishable filename schemes that coexist:
 *
 *   - `vacuumIntoBackupAll` writes `tasks-YYYYMMDD-HHmmss.db` /
 *     `brain-YYYYMMDD-HHmmss.db` (no sidecar).
 *   - `createBackup` writes `<file>.<backupId>` + `<backupId>.meta.json`,
 *     where `backupId = <type>-YYYYMMDD-HHmmss` (matching the same local-time
 *     timestamp format).
 *
 * The legacy `.cleo/backups/snapshot/` directory is retained as a read-only
 * fallthrough for one deprecation window — `listSystemBackups` enumerates
 * both directories and tags legacy entries via `legacy: true`, and
 * `restoreBackup` searches the legacy directory if no candidate is found in
 * the canonical directory. A one-time `DeprecationWarning` fires when the
 * legacy directory is consulted.
 *
 * @task T4783
 * @task T5158 — extended to use VACUUM INTO for .db files and atomicWrite for JSON
 * @task T10315 — ratified `.cleo/backups/sqlite/` as the single canonical path
 *                (ADR-013 §10). The previous `.cleo/backups/snapshot/` is now
 *                a deprecated read-only fallthrough for one release.
 */
/** Internal: reset the once-flag (test seam). */
export declare function _resetLegacyWarningOnce(): void;
/** Result shape returned by {@link createBackup}. */
export interface BackupResult {
    /** Unique backup identifier (timestamped). */
    backupId: string;
    /** Absolute path to the directory containing the snapshot files. */
    path: string;
    /** ISO-8601 timestamp when the backup was created. */
    timestamp: string;
    /** Backup category (`snapshot`, `safety`, `migration`). */
    type: string;
    /** Files that were successfully captured into this backup. */
    files: string[];
}
/** Result shape returned by {@link restoreBackup}. */
export interface RestoreResult {
    /** Whether any files were actually restored (false if none matched). */
    restored: boolean;
    /** The backup identifier that was restored. */
    backupId: string;
    /** ISO-8601 timestamp of the original backup. */
    timestamp: string;
    /** File names that were successfully restored back into `.cleo/`. */
    filesRestored: string[];
}
/**
 * Create a backup of the canonical CLEO data files.
 *
 * Produces safe copies via VACUUM INTO (for SQLite) and atomicWrite
 * (for JSON) into `.cleo/backups/sqlite/`. Writes a `{backupId}.meta.json`
 * sidecar describing the snapshot.
 *
 * The backup file naming uses the unified `YYYYMMDD-HHmmss` local-time format
 * (matching `sqlite-backup.ts:formatTimestamp`) so all snapshot files in
 * `.cleo/backups/sqlite/` share one timestamp convention. The `type` field
 * (`snapshot` by default) is embedded in the `backupId` to distinguish manual
 * snapshots from auto-snapshots and from `safety`/`migration` backups.
 *
 * Opens both `tasks.db` and `brain.db` through their canonical drizzle
 * accessors before snapshotting so that the native DB handles are live
 * when `safeSqliteSnapshot` asks for them. This makes the function
 * self-contained — callers do not need to pre-open the DBs.
 *
 * Async because opening the database engines requires async migration
 * reconciliation (ADR-012). The CLI dispatch layer awaits this result.
 *
 * @task T10315 — write target moved from `.cleo/backups/snapshot/` to
 *                `.cleo/backups/sqlite/` per ADR-013 §10.
 */
export declare function createBackup(projectRoot: string, opts?: {
    type?: string;
    note?: string;
    /**
     * Maximum number of backup files to keep per type directory.
     * Oldest files are rotated out when this cap is exceeded.
     * Defaults to {@link DEFAULT_MAX_SNAPSHOTS} (10).
     *
     * @task T9194
     */
    maxSnapshots?: number;
}): Promise<BackupResult>;
/** A single backup entry returned by listSystemBackups. */
export interface BackupEntry {
    /** Unique backup identifier (timestamped). */
    backupId: string;
    /** Backup category (`snapshot`, `safety`, `migration`). */
    type: string;
    /** ISO-8601 timestamp when the backup was created. */
    timestamp: string;
    /** Optional human-readable note attached at creation time. */
    note?: string;
    /** File names captured in this backup. */
    files: string[];
    /**
     * `true` when this entry was discovered under the deprecated legacy
     * `.cleo/backups/snapshot/` directory. Surfaces in the `cleo backup list`
     * envelope so the operator knows the entry is read-only and will become
     * unreachable in the release following T10315.
     *
     * @task T10315
     */
    legacy?: boolean;
}
/**
 * List all available system backups (`snapshot`, `safety`, `migration`).
 *
 * Reads `.meta.json` sidecar files written by {@link createBackup}. Walks
 * both the canonical `.cleo/backups/sqlite/` directory AND the deprecated
 * `.cleo/backups/snapshot/` directory (ADR-013 §10 read-side deprecation
 * window). Entries discovered under the legacy directory are tagged with
 * `legacy: true` so callers can surface a warning.
 *
 * This is a pure read operation — it does not modify any files. A one-time
 * `DeprecationWarning` is emitted via `process.emitWarning` when the legacy
 * directory yields ≥1 entry.
 *
 * @task T4783
 * @task T10315 — added canonical-dir scan + legacy-dir read fallthrough.
 */
export declare function listSystemBackups(projectRoot: string): BackupEntry[];
/**
 * Restore a backup into the live `.cleo/` directory.
 *
 * This operation overwrites the in-place copies of the files recorded in
 * the backup's sidecar. SQLite files are restored via a plain `copyFileSync`
 * because restore runs BEFORE the next CLEO process opens the database — no
 * WAL is active at that point — so a filesystem copy is safe. Callers must
 * ensure no CLEO process is concurrently writing to the target database.
 *
 * JSON files are restored via `atomicWrite` (tmp-then-rename) so a crash
 * mid-restore cannot produce a truncated config.
 *
 * Search order (T10315 / ADR-013 §10): canonical `.cleo/backups/sqlite/`
 * first, then legacy `.cleo/backups/{snapshot,safety,migration}/` as a
 * read-only fallthrough (emits a one-time DeprecationWarning if used).
 *
 * @task T10315
 */
export declare function restoreBackup(projectRoot: string, params: {
    backupId: string;
    force?: boolean;
}): RestoreResult;
/** Result of restoring an individual file from backup. */
export interface FileRestoreResult {
    /** Whether the file was actually restored. */
    restored: boolean;
    /** The filename that was restored. */
    file: string;
    /** The backup file path restored from. */
    from: string;
    /** The target path that was written. */
    targetPath: string;
    /** Whether this was a dry-run. */
    dryRun?: boolean;
}
/**
 * Restore an individual file (tasks.db or config.json) from the most recent backup.
 *
 * Moves the backing logic from `backupRestore` in system-engine.ts into core.
 * Uses `getTaskPath` / `getConfigPath` from `../paths.js` (respects CLEO_DIR).
 * Imports `listBackups` and `restoreFromBackup` from the store layer.
 *
 * @param projectRoot - Absolute path to the project root
 * @param fileName - File to restore: 'tasks.db' or 'config.json'
 * @param opts - Optional restore flags
 * @returns Result of the restore operation
 *
 * @task T5329
 * @task T1571
 */
export declare function fileRestore(projectRoot: string, fileName: string, opts?: {
    dryRun?: boolean;
}): Promise<FileRestoreResult>;
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