/**
 * SigV4 signing for the Lambda-flavor retriever's query Function URL.
 *
 * The Lambda retriever flavor (backend/terraform/demo/retriever-lambda.tf)
 * exposes its `query` role behind a Lambda Function URL with AWS_IAM auth, not
 * an open HTTP endpoint like the K8s/Quarkus flavor's NLB. So when the
 * configured retriever URL is a Function URL, the MCP must sign the POST with
 * SigV4 (service "lambda") using the standard AWS credential chain.
 *
 * Detection is by hostname shape (`*.lambda-url.<region>.on.aws`), so flipping
 * the demo between flavors is pure config: point __SAVE_LOG10X_RETRIEVER_URL__
 * at the Function URL (+ the lambda flavor's bucket) and the MCP signs
 * automatically — no flag.
 */
/** True when the URL is a Lambda Function URL (so SigV4 is required). */
export declare function isLambdaFunctionUrl(url: string): boolean;
/** Region embedded in a Lambda Function URL hostname, or null. */
export declare function lambdaUrlRegion(url: string): string | null;
/**
 * SigV4-sign and POST a JSON body to a Lambda Function URL, returning the
 * fetch Response. The Function URL IS the query endpoint (no extra path);
 * the handler reads the request body as the query payload.
 */
export declare function signedLambdaUrlPost(url: string, jsonBody: string): Promise<Response>;