/**
 * Pure, total structural alignment + metric aggregation for comparing two
 * traces. Never throws (cycle-guarded), never does I/O. Deltas are honest: a
 * span present in only one trace has NO delta (never a fabricated 1:1 diff).
 */
import type { TraceSpan } from "./types.js";
export interface TraceMetrics {
    durationMs: number | null;
    totalTokens: number;
    costUsd: number;
    hasError: boolean;
    spanCount: number;
}
/** Aggregate whole-trace metrics: root duration, summed tokens/cost, any-error flag. Total. */
export declare function traceMetrics(root: TraceSpan): TraceMetrics;
export interface NumericDelta {
    from: number | null;
    to: number | null;
    deltaPct: number | null;
}
export interface AlignDelta {
    durationMs?: NumericDelta;
    tokens?: NumericDelta;
    costUsd?: NumericDelta;
}
export interface AlignRow {
    key: string;
    depth: number;
    a?: TraceSpan;
    b?: TraceSpan;
    status: "matched" | "only-in-a" | "only-in-b";
    /** Present ONLY when status === "matched" — an unpaired span has no honest delta. */
    delta?: AlignDelta;
}
/**
 * Align two span trees structurally, matching children by name (greedy,
 * first-unused). Produces a flat, depth-annotated row list: matched pairs
 * carry a delta; only-in-a / only-in-b rows do not. Cycle-safe via a visited
 * set on span ids (a malformed self-referential tree cannot loop).
 */
export declare function alignSpanTrees(a: TraceSpan, b: TraceSpan): AlignRow[];