/**
 * Tree flattening + the reader-mode transcript row model. Pure and total.
 * `flattenVisible` order is the contract every renderer (tree, waterfall,
 * transcript) shares, so selection/keyboard indices agree across views.
 */
import type { FlatSpan, TraceSpan, TranscriptRow } from "./types.js";
/**
 * Above this many visible rows, renderers switch from the recursive path to
 * the react-virtual flat-list (blueprint Corner 2 Q9; langfuse uses 350, the
 * lens origin uses 200 — virtualization only when it earns its complexity).
 */
export declare const VIRTUALIZE_THRESHOLD = 200;
/**
 * Depth-first flatten of ALL spans (ignores collapse) — resolve-by-id / envelope input. Cycle-safe:
 * a self-referential or repeated child is visited at most once (a malformed trace cannot stack-overflow).
 */
export declare function flattenAll(root: TraceSpan): TraceSpan[];
/**
 * Depth-first flatten of VISIBLE spans (a node in `collapsed` contributes no descendants). Cycle-safe:
 * each span id is emitted at most once.
 */
export declare function flattenVisible(root: TraceSpan, collapsed: Set<string>): FlatSpan[];
/**
 * Flatten a span tree into the ordered reader-mode transcript feed. Pre-order
 * walk so `span`-row order matches `flattenVisible`. A fan-out node emits a
 * `group-header` row BEFORE its child rows so the view can collapse the group.
 */
export declare function toTranscriptRows(root: TraceSpan): TranscriptRow[];