/**
 * Filesystem snapshot tracking for the forge harness.
 *
 * Records a `.bak` copy of every file touched by mutating tools
 * (`write` / `edit` / `multi_patch`) in `tool.execute.before` and exposes a
 * lookup used by the `fs_undo` tool to roll back.
 *
 * Storage layout (user preference: under the plugin data dir):
 *   <dataDir>/snapshots/<sessionId>/<ts>-<fileTag>.bak
 *
 * `fileTag` is the workspace-relative path with non-alphanumerics replaced by
 * underscores, matching the legacy forgecode layout so existing snapshots
 * remain restorable after the path move.
 */
export declare const SNAPSHOTS_SUBDIR = "snapshots";
export interface SnapshotLocation {
    dataDir: string;
    sessionId: string;
    workingDir: string;
}
export interface SnapshotEntry {
    sessionDir: string;
    entry: string;
    ts: number;
}
export declare function fileTag(relPath: string): string;
export declare function snapshotsRoot(dataDir: string): string;
export declare function sessionSnapshotsDir(dataDir: string, sessionId: string): string;
/**
 * Capture the current content of `absPath` into a snapshot file. No-op when
 * the file does not exist (e.g. a new `write` creating a file for the first
 * time — nothing to roll back to).
 */
export declare function captureSnapshot(absPath: string, loc: SnapshotLocation): Promise<string | null>;
/**
 * List all snapshots for a specific workspace-relative file across every
 * session under `dataDir`, newest first.
 */
export declare function findSnapshots(dataDir: string, workingDir: string, file: string): Promise<SnapshotEntry[]>;
/**
 * Restore the content stored at the given snapshot entry back onto `absPath`.
 * Returns the timestamp recorded on the snapshot.
 */
export declare function restoreSnapshot(absPath: string, snap: SnapshotEntry): Promise<number>;
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