/**
 * Dispatch a one-shot W3C `context-request` event from `host` and
 * return whatever value the closest ancestor provider answered with.
 *
 * @param host - Element to dispatch from. The event bubbles and is
 * composed so any DOM ancestor (or document-level handler) can answer.
 * @param key - The context key to request.
 * @returns The resolved value, or `undefined` if no provider answered.
 *
 * @internal
 */
export declare function requestContext<T>(host: HTMLElement, key: string): T | undefined;
/**
 * Subscribe to a context key via the W3C `context-request` protocol's
 * subscribe mode. The listener fires immediately with the current
 * value (if a provider answers) and again on every subsequent change.
 *
 * @param host - Element to dispatch from.
 * @param key - The context key to subscribe to.
 * @param listener - Called with the resolved value and on every change.
 * @returns Teardown function that stops the subscription.
 *
 * @internal
 */
export declare function subscribeToContext<T>(host: HTMLElement, key: string, listener: (value: T | undefined) => void): () => void;