/**
 * Line-by-line diff utilities for the workflow-file preview viewer.
 *
 * Uses a textbook longest-common-subsequence algorithm. O(m·n) time/space
 * which is fine for the workflow-file scale we expect (≤200 lines either
 * side); no dep needed.
 */
export type DiffKind = 'add' | 'del' | 'eq';
export interface DiffLine {
    kind: DiffKind;
    text: string;
}
/**
 * Compute a line-level diff between `before` and `after`.
 *
 * Returns an ordered list of lines where:
 *   - `kind: 'eq'`  → present in both, unchanged
 *   - `kind: 'add'` → present only in `after` (will be added by the write)
 *   - `kind: 'del'` → present only in `before` (will be removed by the write)
 *
 * When `before` is the empty string, every line in `after` is returned as
 * `add` — the natural "new file" rendering.
 */
export declare function diffLines(before: string, after: string): DiffLine[];