import type { H3Event } from "h3";
/**
 * Dev-only one-line diagnostic for an unauthenticated loopback
 * `/_agent-native/*` request. Session cookies are host-scoped (RFC 6265):
 * `localhost:PORT` and `127.0.0.1:PORT` are different cookie jars to the
 * browser, so a session established on the origin the dev server prints never
 * reaches the other loopback label and every framework call 401s silently.
 *
 * The hint names the label the visitor actually used versus the canonical
 * origin recorded from Vite's printed URL. It must stay one line and never carry
 * session tokens or user data: the caller gates it on `isDevEnvironment()`
 * and `isLoopbackRequest(event)`, so production and remote hosts keep the
 * bare 401.
 */
export declare function devLoopbackAuthHint(event: H3Event, canonicalOrigin: string | undefined): string;