import type { ConfigFactory, UnresolvedConfigHandler } from './adapters/ConfigFactory';
import { type MOSConfig } from './config';
import type { MOSProxyLogger } from './logger';
import type { MOSConfigInput } from './types';
export interface ConfigResolutionOptions {
    /** Either a static config (normalized once) or a per-request factory returning a full config. */
    input: MOSConfigInput | ConfigFactory;
    onUnresolved: UnresolvedConfigHandler | null;
    maxCachedConfigs: number;
    logger: MOSProxyLogger;
}
/** Thrown when no config could be resolved for a request and the host has no last-known-good fallback. */
export declare class ConfigUnresolvableError extends Error {
    readonly host: string;
    constructor(host: string, options?: {
        cause?: unknown;
    });
}
/**
 * Resolves the config for a request. A static config is normalized once up front. A factory runs per
 * request and its result is normalized and cached by content. If the factory throws or its config
 * won't normalize, we fall back to the handler, then the host's last-known-good config, then throw.
 */
export declare class ConfigResolution {
    private readonly source;
    private readonly onUnresolved;
    private readonly maxCachedConfigs;
    private readonly logger;
    private readonly cache;
    private readonly lastGoodByHost;
    constructor(opts: ConfigResolutionOptions);
    resolve(request: Request): Promise<MOSConfig | Response>;
    private remember;
    private rememberGood;
    private touch;
    private logFailure;
    private failOver;
}