import { type FairShareCounters } from './fair-share.ts';
import type { WorkerInfo } from './types.ts';
/**
 * Return `true` when `worker` is eligible for the given `activityName` and
 * optional `queue` constraint, and has spare capacity.
 *
 * This is the single canonical gate every routing policy relies on — it
 * extracts the capacity+queue+activity filter out of `findWorker` so the loop
 * body reads as a simple linear scan.
 */
export declare function matchesWorkerCapabilities(worker: WorkerInfo, activityName: string, queue: string | undefined): boolean;
/**
 * Pick the worker with the lowest in-flight count. Ties broken by stable
 * worker id ordering so the choice is deterministic across runs.
 *
 * `eligible` must be non-empty — the caller is responsible for this precondition.
 */
export declare function pickLeastLoaded(eligible: WorkerInfo[]): WorkerInfo;
/**
 * Round-robin selection with a per-(queue, activity) cursor so two activities
 * sharing a queue advance independently. Mutates `cursor` in place, advancing
 * the entry for this (queue, activity) pair.
 *
 * `eligible` must be non-empty — the caller is responsible for this precondition.
 */
export declare function pickRoundRobin(eligible: WorkerInfo[], cursor: Map<string, number>, queue: string | undefined, activityName: string): WorkerInfo;
/**
 * Fair-share selection: the worker carrying the fewest in-flight tasks for
 * `fairShareKey` wins, ties broken by overall in-flight count then stable id
 * order. The score snapshot is built synchronously so the ranking is consistent
 * across the full candidate set.
 *
 * `eligible` must be non-empty — the caller is responsible for this precondition.
 */
export declare function pickFairShare(eligible: WorkerInfo[], counters: FairShareCounters, fairShareKey: string): WorkerInfo;