import { StringScalarType } from './common';
/**
 * Emits a distributed trace span to the configured telemetry sink
 * (e.g., OpenTelemetry). The span is linked to the workflow's trace
 * context (`traceId`, `spanId`) for end-to-end observability across
 * workflow executions, activities, and child workflows.
 *
 * By default (`config.once = true`), the trace is emitted exactly once
 * per workflow execution — it will not re-fire on replay.
 *
 * ## Examples
 *
 * ```typescript
 * import { Durable } from '@hotmeshio/hotmesh';
 *
 * // Emit trace spans at key workflow milestones
 * export async function orderWorkflow(orderId: string): Promise<void> {
 *   await Durable.workflow.trace({
 *     'order.id': orderId,
 *     'order.stage': 'started',
 *   });
 *
 *   const { processPayment } = Durable.workflow.proxyActivities<typeof activities>();
 *   await processPayment(orderId);
 *
 *   await Durable.workflow.trace({
 *     'order.id': orderId,
 *     'order.stage': 'payment_completed',
 *   });
 * }
 * ```
 *
 * ```typescript
 * // Trace on every re-execution (for debugging replay behavior)
 * await Durable.workflow.trace(
 *   { 'debug.counter': counter, 'debug.phase': 'retry' },
 *   { once: false },
 * );
 * ```
 *
 * @param {StringScalarType} attributes - Key-value attributes to attach to the trace span.
 * @param {{ once: boolean }} [config={ once: true }] - If `true`, trace fires only once (idempotent).
 * @returns {Promise<boolean>} `true` if tracing succeeded.
 */
export declare function trace(attributes: StringScalarType, config?: {
    once: boolean;
}): Promise<boolean>;