/**
 * The line-level diff behind the paper view's snapshot comparison: a simple
 * LCS diff of two texts (common prefix/suffix trimmed first), plus the
 * display compaction that folds long unchanged runs into gap markers so the
 * panel never mounts one row per unchanged line. Pure functions, no JSX.
 * @module dsh-client-ui-mimir/client/snapshot-diff
 */
/** One row of the line diff between a snapshot and the current source. */
export type SnapshotDiffRow = {
    readonly type: 'same';
    readonly oldLine: number;
    readonly newLine: number;
    readonly text: string;
} | {
    readonly type: 'del';
    readonly oldLine: number;
    readonly text: string;
} | {
    readonly type: 'add';
    readonly newLine: number;
    readonly text: string;
};
/**
 * Diff two texts line by line: `before` (the snapshot) against `after` (the
 * current source). Rows carry 1-based line numbers of the side they belong
 * to. Identical texts yield only `same` rows.
 */
export declare function diffLines(before: string, after: string): SnapshotDiffRow[];
/**
 * One display row of the compacted diff: either a real diff row or a gap
 * marker folding `count` unchanged lines.
 */
export type SnapshotDiffDisplayRow = SnapshotDiffRow | {
    readonly type: 'gap';
    readonly count: number;
};
/**
 * Fold long `same` runs into gap markers, keeping {@link DIFF_CONTEXT_LINES}
 * context lines on each side of every change. Runs of at most twice the
 * context stay expanded — folding them would save nothing.
 */
export declare function collapseDiffRows(rows: readonly SnapshotDiffRow[]): SnapshotDiffDisplayRow[];
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