/**
 * Classification strategies for the ClassifierRouter.
 *
 * - `classifyHeuristic` — zero-cost, no LLM. Generalizes the existing binary
 *   task classifier scorer (fast vs reasoning) into five difficulty tiers.
 * - `classifyLlm` — runs a cheap "classifier model" via an injected generate
 *   function, asking for a schema-constrained difficulty verdict. Falls back to
 *   the heuristic on any failure.
 * - `classifyJev` — one round trip to a decision model, which answers
 *   difficulty, capabilities, risk and model choice *simultaneously* and
 *   reports a calibrated confidence. Falls back to the heuristic on any
 *   failure or when the verdict is not confident enough to act on.
 */
import type { ClassifierCandidate, ClassifierContextScope, ClassifierDecideFn, ClassifierDecision, ClassifierDifficulty, ClassifierGenerateFn, ClassifierModelRef, ClassifierRouterInput } from "../types/index.js";
/** Difficulty tiers, ordered easiest → hardest. */
export declare const CLASSIFIER_DIFFICULTIES: ClassifierDifficulty[];
/**
 * Heuristic classifier — maps the binary fast/reasoning scores plus prompt
 * length into one of five difficulty tiers. Deterministic and dependency-free.
 */
export declare function classifyHeuristic(input: ClassifierRouterInput): ClassifierDecision;
/**
 * LLM classifier — asks a cheap model for a schema-constrained verdict.
 * Falls back to the heuristic if the model is unavailable, times out, or
 * returns output that does not match the schema.
 */
export declare function classifyLlm(input: ClassifierRouterInput, generate: ClassifierGenerateFn, classifierModel?: ClassifierModelRef, timeoutMs?: number, candidates?: ClassifierCandidate[]): Promise<ClassifierDecision>;
/**
 * How much context the request needs, narrowest → widest. Ordered, because a
 * decision model places things on a scale reliably and names numbers badly:
 * asking "how many tokens" would get digits read as text, while asking "which
 * of these four descriptions fits" gets a calibrated position.
 */
export declare const CLASSIFIER_CONTEXT_SCOPES: ClassifierContextScope[];
/**
 * Map a score answer onto a compaction threshold, clamped so it can only ever
 * lower the default.
 */
export declare function contextScopeToThreshold(index: number): number;
/**
 * Decision-model classifier — one request answers difficulty, capabilities,
 * risk and model selection at once.
 *
 * Latency is flat in question count (1 question ~393ms, 400 ~465ms), so the
 * capability questions are effectively free and are asked speculatively even
 * when nothing downstream may need them. This is the opposite of the LLM
 * strategy's economics, where every extra field costs output tokens.
 *
 * Returns the heuristic verdict — never throws — when no decision provider is
 * configured, the call fails, or the answer is not confident enough to act on.
 */
export declare function classifyJev(input: ClassifierRouterInput, decide: ClassifierDecideFn, timeoutMs?: number, candidates?: ClassifierCandidate[], thresholds?: {
    upgrade?: number;
    downgrade?: number;
}): Promise<ClassifierDecision>;