/**
 * LLM Usage Tracker Interface.
 *
 * Tracks token usage and estimated cost per LLM operation.
 * Supports monthly budget enforcement and per-feature tracking.
 *
 * Part of Phase 6B: Cost/Privacy Controls.
 */
import type { LlmProvider } from './ILlmService';
/**
 * LLM feature identifiers for per-feature tracking and toggles.
 */
export type LlmFeature = 'summarization' | 'extraction' | 'deduplication' | 'curation' | 'test';
/**
 * All valid LLM feature values.
 */
export declare const LLM_FEATURE_VALUES: readonly LlmFeature[];
/**
 * Type guard for LlmFeature.
 */
export declare function isValidLlmFeature(value: string): value is LlmFeature;
/**
 * A single LLM usage record.
 */
export interface ILlmUsageRecord {
    readonly timestamp: string;
    readonly provider: LlmProvider;
    readonly model: string;
    readonly feature: LlmFeature;
    readonly inputTokens: number;
    readonly outputTokens: number;
    readonly estimatedCostUsd: number;
}
/**
 * LLM usage tracker.
 * Append-only log of usage records with cost aggregation and budget checks.
 */
export interface ILlmUsageTracker {
    /**
     * Record a usage event.
     */
    record(usage: Omit<ILlmUsageRecord, 'timestamp'>): Promise<void>;
    /**
     * Get usage records, optionally filtered by date.
     * @param since - Only return records after this date
     */
    getUsage(since?: Date): Promise<readonly ILlmUsageRecord[]>;
    /**
     * Get total estimated cost, optionally filtered by date.
     * Defaults to current calendar month if no date provided.
     * @param since - Only sum costs after this date
     */
    getTotalCost(since?: Date): Promise<number>;
    /**
     * Check if usage is within the configured monthly budget.
     * Returns true if no budget limit is configured.
     */
    isWithinBudget(): Promise<boolean>;
}
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