/**
 * Handoff frontmatter — writer.
 *
 *       Phase 1, Task 4.
 *
 * Serializes a `HandoffFrontmatter` plus a body string into a single
 * markdown file with the canonical layout:
 *
 *   ---
 *   rid: "..."
 *   slice_id: "..."
 *   ...
 *   ---
 *
 *   <body verbatim>
 *
 * The output of `writeHandoff` is round-trip compatible with
 * `parseHandoff` — writing then parsing recovers the same frontmatter
 * fields and body.
 */
import type { HandoffFrontmatter } from './handoff-types.js';
export declare function writeHandoff(filePath: string, frontmatter: HandoffFrontmatter, body: string): void;