export interface HostAdapter {
    id: string;
    label: string;
    /** True when this host is usable in the current environment. */
    detect: () => boolean;
}
export declare class HostRegistry {
    private hosts;
    register(a: HostAdapter): this;
    get(id: string): HostAdapter | undefined;
    all(): HostAdapter[];
    /** Hosts present in this environment (detect() true, swallowing errors). */
    available(): HostAdapter[];
}
/** True if `bin --version` runs. Used by the built-in adapters' detect(). */
export declare function commandExists(bin: string): boolean;
/** The built-in hosts. Detection is injectable per-adapter for tests. */
export declare function defaultHostRegistry(): HostRegistry;
/** Run `fn` for each host (sequentially, isolated), collecting per-host results. */
export declare function fanOutHosts<T>(hosts: HostAdapter[], fn: (h: HostAdapter) => Promise<T> | T): Promise<Array<{
    host: string;
    result: T | null;
    error?: string;
}>>;
export declare const LAYER_LEVELS: readonly ["global", "language", "framework", "repo"];
/** All ancestor prefixes of a layer path, shallowest first. */
export declare function ancestorsOf(layer: string): string[];
/** True if `a` is an ancestor of (or equal to) `b` at a path boundary. */
export declare function isAncestorOrEqual(a: string, b: string): boolean;
export declare function layerDepth(layer: string): number;
/**
 * Pick the most-specific champion applicable to an install's layer: the deepest
 * manifest whose layer is an ancestor-or-equal of `installLayer`. Layers the
 * install can't clear fall back to the parent (return the next-deepest). Null if
 * none applies.
 */
export declare function selectChampionForLayer<M extends {
    layer?: string;
}>(manifests: M[], installLayer: string): M | null;
//# sourceMappingURL=harness-hosts.d.ts.map