import { type UsageTokens } from "@tokenometer/core";
import type { ModelCandidate, RouteDecision, RouteRequest } from "./types.ts";
export type BudgetState = "ok" | "warn" | "exhausted";
export type BudgetStepSource = "actual" | "estimated";
export interface BudgetAwareRouterOptions {
    maxBudgetUsd: number;
    /** Fraction of budget at which routing enters warn/degraded mode. Default 0.8. */
    warnAt?: number;
    /** Optional lower quality bar used once the chain reaches warnAt. */
    degradedQualityBar?: number;
}
export interface BudgetStepRecord {
    source: BudgetStepSource;
    model: ModelCandidate;
    totalUsd: number;
    inputUsd: number;
    cachedInputUsd: number;
    outputUsd: number;
    usage?: UsageTokens;
}
export interface BudgetSnapshot {
    maxBudgetUsd: number;
    spentUsd: number;
    remainingUsd: number;
    percentUsed: number;
    state: BudgetState;
    steps: BudgetStepRecord[];
}
export interface BudgetRouteStepRequest extends Omit<RouteRequest, "maxCostUsd"> {
    /** Optional per-step cap. The effective cap is min(remaining budget, this value). */
    maxStepCostUsd?: number;
}
export interface BudgetRouteStepResult {
    decision: RouteDecision;
    snapshotBefore: BudgetSnapshot;
    effectiveQualityBar: number;
    maxCostUsd: number;
}
export interface RecordActualUsageInput {
    model: ModelCandidate;
    usage: UsageTokens;
}
export declare class BudgetAwareRouter {
    readonly maxBudgetUsd: number;
    readonly warnAt: number;
    readonly degradedQualityBar?: number;
    private spentUsd;
    private steps;
    constructor(options: BudgetAwareRouterOptions);
    routeStep(request: BudgetRouteStepRequest): BudgetRouteStepResult;
    recordActualUsage(input: RecordActualUsageInput): BudgetStepRecord;
    recordEstimatedStep(decision: RouteDecision): BudgetStepRecord;
    getSnapshot(): BudgetSnapshot;
    reset(): void;
    private record;
}
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