import { Context } from './context';
/**
 * Context attribute key for trace context data.
 * Stores {@link TraceContextData} (W3C traceparent/tracestate strings).
 */
export declare const TRACE_SPAN_ATTRIBUTE = "dxos.trace-span";
/**
 * W3C Trace Context wire format for propagating trace identity.
 * Stored on DXOS {@link Context} attributes and carried across RPC boundaries.
 *
 * Because these are plain strings (not live runtime objects), they remain valid
 * after the originating span ends — enabling long-lived contexts (`this._ctx`)
 * to serve as parents for later child spans without a retention cache.
 *
 * @see https://www.w3.org/TR/trace-context/
 */
export type TraceContextData = {
    /**
     * W3C `traceparent` header value.
     * Format: `{version}-{traceId}-{spanId}-{traceFlags}` (e.g., `00-abc...def-012...789-01`).
     */
    traceparent: string;
    /** Optional W3C `tracestate` header value carrying vendor-specific trace data. */
    tracestate?: string;
};
/**
 * Codec for propagating trace identity across RPC boundaries.
 *
 * Hardcoded in `RpcPeer` — every outgoing request calls {@link encode} to
 * extract W3C trace context from the DXOS `Context`, and every incoming
 * request calls {@link decode} to reconstruct a DXOS `Context` carrying the
 * caller's trace context.
 *
 * This works because `TRACE_SPAN_ATTRIBUTE` stores serializable
 * {@link TraceContextData} strings, not opaque runtime objects.
 */
export declare class ContextRpcCodec {
    /**
     * Read the W3C trace context from a DXOS `Context` for an outgoing RPC.
     *
     * @returns `TraceContextData` to attach to the wire message, or `undefined`
     *          if the context has no active trace.
     */
    static encode(ctx: Context): TraceContextData | undefined;
    /**
     * Reconstruct a DXOS `Context` from W3C trace context received in an
     * incoming RPC request.
     *
     * @returns A `Context` carrying the trace context, or `Context.default()`
     *          if the data is missing/invalid.
     */
    static decode(traceContext: TraceContextData): Context;
}
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