/**
 * Heading-anchor slug utilities — a pure-TypeScript port of the Rust
 * `slugify` / `next_slug` / `SlugAllocator` in
 * `crates/zfb-content/src/plugins/heading_links.rs`.
 *
 * These functions produce the `id` attribute values that appear on
 * `<h2>`–`<h6>` elements in the rendered HTML.  They are intentionally
 * **not** compatible with npm `github-slugger`: stripped punctuation
 * collapses to a `-` separator (`"a,b"` → `"a-b"`), and leading/trailing
 * whitespace / stripped chars emit nothing rather than a stray dash.
 *
 * ⚠️  These functions produce heading-anchor slugs (e.g. `"hello-world"`
 * for `<h2 id="hello-world">`).  They are **different** from
 * `_relPathToSlug` in `content.ts`, which converts a file-system relative
 * path into a URL slug for `CollectionEntry.slug`.
 *
 * Parity is enforced by the shared fixture at
 * `crates/zfb-content/tests/fixtures/slugify-parity.json`, consumed by
 * both a Rust integration test and the `slugify.test.ts` vitest suite.
 */
/**
 * Produce a heading-anchor slug from `input`, matching the Rust
 * `slugify()` in `crates/zfb-content/src/plugins/heading_links.rs`.
 *
 * Algorithm (per Unicode code point):
 * - whitespace or stripped punctuation → emit ONE `-` unless the last
 *   emitted character was already a `-` (leading separators are skipped
 *   because `lastDash` starts `true`).
 * - anything else → push `ch.toLowerCase()` (per-code-point, not
 *   whole-string, to avoid Greek final-sigma context collapsing).
 * - finally pop ONE trailing `-` if present.
 *
 * Divergence from npm github-slugger (intentional — parity target is
 * the Rust function, not npm):
 * - `"a,b"` → `"a-b"` (stripped punctuation emits a dash, not nothing)
 * - `"  --weird-- "` → `"--weird--"` (existing dashes/underscores pass
 *   through unchanged)
 */
export declare function slugify(input: string): string;
/**
 * Strategy-aware slug allocator for a single document.
 *
 * Mirrors Rust `SlugAllocator` in heading_links.rs:70-118.
 *
 * @param strategy `"flat"` (default) — per-document dedup counter, mirrors
 *   github-slugger numbering.  `"hierarchical"` — each slug is prefixed with
 *   its ancestor chain and deduped on the full candidate path.
 *
 * Depth contract: callers pass `depth` values 2–6 (h2–h6).  h1 is never
 * allocated — it is handled by the page layout, not the markdown body.
 */
export declare class SlugAllocator {
    private readonly strategy;
    private seen;
    /** Hierarchical ancestor stack of `[depth, finalId]` pairs. Unused in flat mode. */
    private stack;
    constructor(strategy?: "flat" | "hierarchical");
    /**
     * Allocate the slug for a heading of `depth` (2–6) whose slugified text
     * is `base`.  Returns `""` for an empty `base` without mutating state.
     */
    allocate(depth: number, base: string): string;
    /**
     * Clear all per-document state (dedup counters AND the hierarchical
     * ancestor stack).  Call between documents to avoid slug counter leakage.
     */
    reset(): void;
}