/**
 * Canary / A-B routing for federation remotes.
 *
 * Map a remote name to several `FederationRemote` variants with weights;
 * `pickWeightedRemote()` resolves a single variant per request. Sticky-by-key
 * mode (default) makes a given user/session land on the same variant across
 * navigations — required for cache-busting and progressive rollouts.
 */
import type { FederationRemote } from './remote-loader.js';
export interface WeightedVariant {
    /** A `FederationRemote` plus its share of traffic. */
    remote: FederationRemote;
    /** Relative weight. Must be > 0. Variants are normalized to sum to 1. */
    weight: number;
    /** Optional label exposed via telemetry (e.g. 'v1', 'canary', 'rollout'). */
    label?: string;
}
export interface WeightedRemoteEntry {
    /** Logical remote name (matches the host route table). */
    name: string;
    variants: WeightedVariant[];
}
export interface PickOptions {
    /**
     * Stable key per user/session. When provided, the same key always lands on
     * the same variant for the same `WeightedRemoteEntry`. Default: random.
     */
    key?: string;
    /** Override the RNG (tests). Returns a number in [0, 1). */
    random?: () => number;
}
export interface PickResult {
    remote: FederationRemote;
    variant: WeightedVariant;
    /** Hash bucket in [0, 1). Useful for logging. */
    bucket: number;
}
/** Resolve a single variant for the entry. Throws on empty / invalid entries. */
export declare function pickWeightedRemote(entry: WeightedRemoteEntry, opts?: PickOptions): PickResult;
/**
 * Resolve a whole `Record<string, WeightedRemoteEntry>` into a flat
 * `Record<string, FederationRemote>` suitable for `RemoteOutlet` / `prefetchRoute`.
 *
 * Pass the same `key` you'd use in CDN cache-busting to keep a user pinned
 * across navigations.
 */
export declare function resolveWeightedRemotes(entries: Record<string, WeightedRemoteEntry>, opts?: PickOptions): {
    remotes: Record<string, FederationRemote>;
    picks: Record<string, PickResult>;
};
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