import { ref as litRef } from "lit-html/directives/ref.js";
export interface MatesRef<T extends Element = Element> {
    readonly value: T | undefined;
    __subscribe: (fn: (el: T | undefined) => void) => () => void;
    readonly __isMatesRef__: true;
}
/**
 * Creates a `MatesRef<T>` — a reactive reference that holds a DOM element,
 * or `undefined` when no element is currently attached.
 *
 * The actual value is managed exclusively by the `setRef` directive; you
 * should never call `__set` directly.
 *
 * @typeParam T - The element type held by this ref (defaults to `Element`).
 *
 * ### Members
 * - **`value`** — the current element, or `undefined` before the element is
 *   attached (pre-render) or after it is detached (unmount / conditional render).
 * - **`__subscribe(fn)`** — registers a subscriber that fires synchronously
 *   whenever `value` changes (element attached *or* detached). Returns an
 *   unsubscribe function.
 * - **`__isMatesRef__`** — type discriminator; always `true`. Used by
 *   `setRef` to distinguish a `MatesRef` from a plain lit-html `Ref`.
 *
 * @example
 * ```ts
 * const inputRef = ref<HTMLInputElement>();
 *
 * inputRef.__subscribe((el) => {
 *   if (el) el.focus(); // focus on mount
 * });
 *
 * // In a template:
 * html`<input ${setRef(inputRef)} type="text" />`;
 *
 * // After render:
 * inputRef.value; // HTMLInputElement
 * ```
 */
export declare function ref<T extends Element = Element>(): MatesRef<T>;
/**
 * A lit-html directive that attaches a DOM element to a `MatesRef` created by
 * `ref()`, or forwards to a plain lit-html `Ref` / callback for backwards
 * compatibility.
 *
 * ### Lifecycle behaviour
 * - **Element added to the DOM** — `ref.value` is set to the element and all
 *   subscribers fire synchronously.
 * - **Element removed from the DOM** — `ref.value` is set to `undefined` and
 *   all subscribers fire synchronously.
 *
 * @param r - A `MatesRef<T>` (created by `ref()`), a lit-html `Ref` object,
 *   or a lit-html ref callback. When `r.__isMatesRef__` is `true` the
 *   `MatesRef` path is used; otherwise the value is passed straight through
 *   to lit-html's own `ref` directive.
 *
 * @example
 * ```ts
 * const inputRef = ref<HTMLInputElement>();
 *
 * inputRef.__subscribe((el) => {
 *   if (el) el.focus(); // focus on mount
 * });
 *
 * // In a template:
 * html`<input ${setRef(inputRef)} type="text" />`;
 *
 * // After render:
 * inputRef.value; // HTMLInputElement
 * ```
 */
export declare function setRef<T extends Element = Element>(r: MatesRef<T> | Parameters<typeof litRef>[0]): import("lit-html/directive").DirectiveResult<typeof import("lit-html/directives/ref.js").RefDirective>;
export type { MatesRef as Ref };
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