import type { Filter } from '@puregram/api';
import type { Middleware } from '../dispatch/hooks.js';
/**
 * gate a middleware on a filter — runs it on match, calls `next()` otherwise.
 * uses the filter's `kinds` metadata for the same fast-path as `tg.on(filter, …)`.
 * the middleware sees the narrowed update type
 *
 * @example
 * ```ts
 * tg.useHook('onUpdate', when(f.chat.private, async (u, next) => {
 *   console.log('[private]', u.kind)
 *   await next()
 * }), { priority: 'high' })
 * ```
 */
export declare function when<Base, Mod>(filter: Filter<Base, Mod>, mw: Middleware<Base & Mod>): Middleware<unknown>;
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