/**
 * RuntimeTracer, lightweight OTel-compatible span factory.
 *
 * Implements span creation, parent/child relationships, attributes, events,
 * and export without depending on the @opentelemetry/* packages.
 *
 * Design principles:
 * - All public methods are synchronous; export is async fire-and-forget
 * - End-after-end is a no-op (spans are immutable once ended)
 * - Export failures are caught and logged; they never block the runtime
 */
import type { Span, SpanAttributes, TracerConfig } from './types.js';
import { SpanKind } from './types.js';
/**
 * RuntimeTracer, creates spans and routes completed spans to exporters.
 *
 * Usage:
 * ```ts
 * const span = tracer.startSpan('turn.lifecycle', { traceId, parentSpanId });
 * span.setAttribute('turn.id', turnId);
 * span.end();
 * ```
 */
export declare class RuntimeTracer {
    private readonly config;
    constructor(config: TracerConfig);
    /**
     * Start a new span.
     *
     * @param name - Human-readable span name.
     * @param opts - Optional trace/parent context and kind.
     */
    startSpan(name: string, opts?: {
        /** Existing trace ID to join. If omitted, a new trace is started. */
        traceId?: string | undefined;
        /** Parent span ID. Makes this span a child of the parent. */
        parentSpanId?: string | undefined;
        /** Span kind (defaults to INTERNAL). */
        kind?: SpanKind | undefined;
        /** Override start time in epoch ms (defaults to Date.now()). */
        startTimeMs?: number | undefined;
        /** Initial attributes. */
        attributes?: SpanAttributes | undefined;
    }): Span;
    /**
     * Flush all exporters. Call during graceful shutdown.
     */
    flush(): Promise<void>;
    /**
     * Shut down all exporters.
     */
    shutdown(): Promise<void>;
    /** Fire-and-forget export to all registered exporters. */
    private _export;
}
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