/**
 * Surface 11 (V0.4) — `toW3CTraceContext(event, opts?)`.
 *
 * Pure mapper from a {@link DarwinTrajectoryEvent} to the
 * [W3C Trace Context](https://www.w3.org/TR/trace-context/) `traceparent`
 * header format so consumers can propagate Darwin trajectories into
 * external systems (Langfuse, Honeycomb, Datadog APM, Tempo) without
 * pulling in `@opentelemetry/api` as a dependency.
 *
 * Format reference (spec §3.2.2):
 *
 *   traceparent = version "-" trace-id "-" parent-id "-" trace-flags
 *
 * - `version` = `"00"` (we emit only the current spec version).
 * - `trace-id` = 32 hex chars. We map LangChain's UUID `parentRunId` (if
 *   present) by stripping dashes — UUID is 32 hex chars + 4 dashes — so
 *   the strip yields exactly 32 chars. If `parentRunId` is undefined we
 *   fall back to `runId` (top-level invokes form their own trace).
 * - `parent-id` = 16 hex chars. We map LangChain's UUID `runId` by
 *   stripping dashes and TAKING THE FIRST 16 chars (parent-id is shorter
 *   than trace-id by spec design — first 16 chars of a UUID are random
 *   enough that collision probability per-trace is negligible).
 * - `trace-flags` = `"01"` (sampled). We always emit sampled — consumers
 *   that want head-based sampling should drop the entire event upstream
 *   rather than fiddle with the flag.
 *
 * The W3C spec forbids `trace-id == "00000000000000000000000000000000"`
 * and `parent-id == "0000000000000000"`. If either UUID strips to those
 * all-zero strings we return `undefined` rather than emit an invalid
 * header that downstream parsers reject.
 *
 * **Pure, no I/O, no allocation surprises.** The function builds a single
 * string. Safe to call inside `onTrajectory` hot paths.
 *
 * NEW V0.4 (S1235).
 */
import type { DarwinTrajectoryEvent } from "./with-darwin-evolution.js";
/** Options accepted by {@link toW3CTraceContext}. */
export interface ToW3CTraceContextOptions {
    /**
     * Override the trace-flags byte. Default `"01"` (sampled). Set `"00"`
     * for not-sampled — consumers can use this to mark trajectories that
     * would otherwise be sampled out before they reach the W3C-aware
     * exporter.
     */
    traceFlags?: "00" | "01";
}
/** Return shape: a single W3C-compliant `traceparent` header value. */
export interface W3CTraceContext {
    /** Full `traceparent` header value (spec §3.2). */
    traceparent: string;
    /** 32-hex trace ID — convenience accessor. */
    traceId: string;
    /** 16-hex span ID (the W3C `parent-id` slot) — convenience accessor. */
    spanId: string;
}
/**
 * Convert a {@link DarwinTrajectoryEvent} into a W3C `traceparent` header
 * value. Returns `undefined` when no usable runId is present or when the
 * stripped UUIDs collapse to the all-zero strings the spec forbids.
 *
 * @example
 * ```ts
 * import { toW3CTraceContext, DarwinCallbackHandler } from "darwin-langgraph";
 *
 * const handler = new DarwinCallbackHandler({
 *   nodeMap: { research: "researcher" },
 *   onTrajectory: async (event) => {
 *     const ctx = toW3CTraceContext(event);
 *     if (!ctx) return;
 *     await fetch("https://langfuse.example/api/traces", {
 *       method: "POST",
 *       headers: { traceparent: ctx.traceparent },
 *       body: JSON.stringify({ trace: event.trajectory }),
 *     });
 *   },
 * });
 * ```
 */
export declare function toW3CTraceContext(event: DarwinTrajectoryEvent, opts?: ToW3CTraceContextOptions): W3CTraceContext | undefined;
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