/**
 * Line-level diff used for the edit-approval preview.
 *
 * Pure functions only: no I/O, no framework imports — unit-testable in
 * isolation. The diff is computed with jsdiff's `structuredPatch` — the same
 * reference implementation the harness's write/edit result cards use
 * (`@deepseek-ai/dsh-tool-fs`), with the same 3-line context window — so the
 * approval preview and the post-approval result card derive from the same
 * algorithm. Each unified-diff hunk line carries its own role (` ` context,
 * `-` removed, `+` added), which this module maps onto the `+`/`-`/` `
 * prefixed lines shown in the approval panel headline, with exact 1-based
 * line numbers from the hunk start lines and a `⋯` gap row between hunks.
 *
 * @module dsh-edit-approval/diff
 */
export type DiffLineType = 'add' | 'remove' | 'context' | 'gap';
/** One aligned line of the diff. */
export interface DiffLine {
    readonly type: DiffLineType;
    readonly text: string;
    /** 1-based original line number; present on remove/context lines. */
    readonly oldLine?: number;
    /** 1-based new line number; present on add/context lines. */
    readonly newLine?: number;
}
/**
 * A `gap` line marks the unchanged run between two separate hunks (rendered
 * as `⋯`). jsdiff already merges hunks whose context windows would overlap,
 * so a gap row appears only where lines are genuinely skipped.
 */
/**
 * Context lines shown on each side of an applied hunk. Mirrors
 * `@deepseek-ai/dsh-tool-fs`'s `DIFF_CONTEXT`, so the preview's context
 * window matches the harness diff card exactly.
 */
export declare const DIFF_CONTEXT = 3;
/**
 * Compute a line-level diff between two texts. Line roles and 1-based line
 * numbers come straight from the unified-diff hunks (`oldStart`/`newStart`
 * per hunk), so they are exact rather than derived. Identical texts yield an
 * empty diff (no hunks); a trailing-newline-only change yields a real
 * `-`/`+` pair instead of a phantom empty line.
 */
export declare function computeLineDiff(oldText: string, newText: string): DiffLine[];
/** Default prefix markers: add is green (`+`), remove is red (`-`), context grey (` `), hunk gap (`⋯`). */
export declare const DEFAULT_PREFIX: Readonly<Record<DiffLineType, string>>;
export interface DiffRenderOptions {
    /** Per-type prefix; missing types fall back to {@link DEFAULT_PREFIX}. */
    readonly prefix?: Readonly<Partial<Record<DiffLineType, string>>>;
    /** Cap on emitted lines; the tail is summarized with "… N more lines". 0 = no cap. */
    readonly maxLines?: number;
    /** Prefix 1-based line numbers (old for removals, new for additions, both for context). */
    readonly lineNumbers?: boolean;
}
/**
 * Render a diff as multi-line text for the approval reason. Long diffs are
 * capped (default 500 lines) so the panel stays scannable; the approval
 * panel body scrolls, so a large edit is still reviewable in parts.
 */
export declare function renderDiff(diff: readonly DiffLine[], options?: DiffRenderOptions): string;
/** Number of changed lines (additions + removals); context and gap rows do not count. */
export declare function countChangedLines(diff: readonly DiffLine[]): number;
/** Count of added lines, for the summary header. */
export declare function countInsertions(diff: readonly DiffLine[]): number;
/** Count of removed lines, for the summary header. */
export declare function countDeletions(diff: readonly DiffLine[]): number;